United States
Environmental Protection
Agency
EPA/600/R-14/413b
Revised September 2015
www2.epa.gov/water-research
Storm Water Management Model
User's Manual Version 5.1
ITV
Office of Research and Development
Water Supply and Water Resources Division
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EPA-600/R-14/413b
Revisied September 2015
Storm Water Management Model
User's Manual Version 5.1
by
Lewis A. Rossman
Environmental Scientist, Emeritus
U.S. Environmental Protection Agnecy
National Risk Management
Laboratory Office of Research and
Development U.S. Environmental
Protection Agency 26 Martin Luther
King Drive Cincinnati, OH 45268
September 2015
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ACKNOWLEDGEMENTS
This manual was prepared by Lewis A. Rossman, Environmental Scientist Emeritus, U.S.
Environmental Protection Agency, Office of Research and Development, National Risk
Management Research Laboratory.
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DISCLAIMER
The information in this document has been funded wholly or in part by the U.S. Environmental
Protection Agency (EPA). It has been subjected to the Agency's peer and administrative review,
and has been approved for publication as an EPA document. Note that approval does not signify
that the contents necessarily reflect the views of the Agency. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
NOTICE: This report was prepared as an account of work sponsored by an agency of the United
States Government. Neither the United States Government, nor any agency thereof, nor any of
their employees, nor any of their contractors, subcontractors, or their employees, make any
warranty, express or implied, or assume any legal liability or responsibility for the accuracy,
completeness, or usefulness of any information, apparatus, product, or process disclosed, or
represent that its use would not infringe privately owned rights. Reference herein to any specific
commercial product, process, or service by trade name, trademark, manufacturer, or otherwise,
does not necessarily constitute or imply its endorsement, recommendation, or favoring by the
United States Government, any agency thereof, or any of their contractors or subcontractors. The
views and opinions expressed herein do not necessarily state or reflect those of the United States
Government, any agency thereof, or any of their contractors.
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CONTENTS
ACKNOWLEDGEMENTS II
DISCLAIMER Ill
CHAPTER 1 - INTRODUCTION 12
1.1 What is SWMM 12
1.2 Modeling Capabilities 13
1.3 Typical Applications of SWMM 14
1.4 Installing EPA SWMM 14
1.5 Steps in Using SWMM 15
1.6 About This Manual 16
CHAPTER 2 - QUICK START TUTORIAL 18
2.1 Example Study Area 18
2.2 Project Setup 18
2.3 Drawing Objects 21
2.4 Setting Object Properties 24
2.5 Running a Simulation 28
2.6 Simulating Water Quality 38
2.7 Running a Continuous Simulation 42
CHAPTER 3 - SWMM'S CONCEPTUAL MODEL 46
3.1 Introduction 46
3.2 Visual Objects 46
3.3 Non-Visual Objects 57
3.4 Computational Methods 72
CHAPTER 4 - SWMM'S MAIN WINDOW 80
4.1 Overview 80
4.2 Main Menu 81
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4.3 Toolbars 84
4.4 Status Bar 86
4.5 Study Area Map 87
4.6 Project Browser 88
4.7 Map Browser 89
4.8 Property Editor 91
4.9 Setting Program Preferences 92
CHAPTER 5 -WORKING WITH PROJECTS 94
5.1 Creating a New Project 94
5.2 Opening an Existing Project 94
5.3 Saving a Project 94
5.4 Setting Project Defaults 95
5.5 Measurement Units 97
5.6 Link Offset Conventions 97
5.7 Calibration Data 98
5.8 Viewing All Project Data 100
CHAPTER 6 -WORKING WITH OBJECTS 101
6.1 Types of Objects 101
6.2 Adding Objects 101
6.3 Selecting and Moving Objects 102
6.4 Editing Objects 103
6.5 Converting an Object 104
6.6 Copying and Pasting Objects 104
6.7 Shaping and Reversing Links 104
6.8 Shaping a Subcatchment 105
6.9 Deleting an Object 105
6.10 Editing or Deleting a Group of Objects 105
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CHAPTER 7 -WORKING WITH THE MAP 108
7.1 Selecting a MapTheme 108
7.2 Setting the Map's Dimensions 108
7.3 Utilizing a Backdrop Image 109
7.4 Measuring Distances 113
7.5 Zooming the Map 113
7.6 Panning the Map 114
7.7 Viewing at Full Extent 114
7.8 Finding an Object 114
7.9 Submitting a Map Query 115
7.10 Using the Map Legends 116
7.11 Using the Overview Map 118
7.12 Setting Map Display Options 118
7.13 Exporting the Map 122
CHAPTER 8 - RUNNING A SIMULATION 124
8.1 Setting Simulation Options 124
8.2 Setting Reporting Options 131
8.3 Starting a Simulation 132
8.4 Troubleshooting Results 133
CHAPTER 9 - VIEWING RESULTS 136
9.1 Viewing a Status Report 136
9.2 Viewing Summary Results 136
9.3 Time Series Results 140
9.4 Viewing Results on the Map 141
9.5 Viewing Results with a Graph 142
9.6 Customizing a Graph's Appearance 148
9.7 Viewing Results with a Table 153
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9.8 Viewing a Statistics Report 156
CHAPTER 10 - PRINTING AND COPYING 160
10.1 Selecting a Printer 160
10.2 Setting the Page Format 161
10.3 Print Preview 162
10.4 Printing the Current View 162
10.5 Copying to the Clipboard orto a File 162
CHAPTER 11 - FILES USED BY SWMM 164
11.1 Project Files 164
11.2 Report and Output Files 164
11.3 Rainfall Files 165
11.4 Climate Files 165
11.5 Calibration Files 166
11.6 Time Series Files 167
11.7 Interface Files 168
CHAPTER 12 - USING ADD-IN TOOLS 173
12.1 What Are Add-In Tools 173
12.2 Configuring Add-In Tools 174
APPENDIX A - USEFUL TABLES 177
A.1 Units of Measurement 177
A.2 Soil Characteristics 178
A.3 NRCS Hydrologic Soil Group Definitions 179
A.4 SCS Curve Numbers 180
A.5 Depression Storage 181
A.6 Manning's n - Overland Flow 182
A.7 Manning's n - Closed Conduits 183
A.8 Manning's n -Open Channels 184
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A.9 Water Quality Characteristics of Urban Runoff 185
A.10 Culvert Code Numbers 186
A.11 Culvert Entrance Loss Coefficients 189
A.12 Standard Elliptical Pipe Sizes 190
A.13 Standard Arch Pipe Sizes 191
APPENDIX B - VISUAL OBJECT PROPERTIES 195
B.1 Rain Gage Properties 195
B.2 Subcatchment Properties 196
B.3 Junction Properties 198
B.4 Outfall Properties 199
B.5 Flow Divider Properties 200
B.6 Storage Unit Properties 202
B.7 Conduit Properties 204
B.8 Pump Properties 205
B.9 Orifice Properties 206
B.10 Weir Properties 207
B.11 Outlet Properties 208
B.12 Map Label Properties 209
APPENDIX C - SPECIALIZED PROPERTY EDITORS 210
C.1 Aquifer Editor 210
C.2 Climatology Editor 212
C.3 Control Rules Editor 220
C.4 Cross-Section Editor 225
C.5 Curve Editor 226
C.6 Groundwater Flow Editor 227
C.7 Groundwater Equation Editor 230
C.8 Infiltration Editor 231
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C.9 Inflows Editor 234
C.10 Initial Buildup Editor 239
C.11 Land Use Editor 240
C.12 Land Use Assignment Editor 244
C.13 LID Control Editor 245
C.14 LID Group Editor 251
C.15 LID Usage Editor 252
C.16 Pollutant Editor 254
C.17 Snow Pack Editor 256
C.18 Time Pattern Editor 260
C.19 Time Series Editor 261
C.20 Title/Notes Editor 263
C.21 Transect Editor 264
C.22 Treatment Editor 266
C.23 Unit Hydrograph Editor 268
APPENDIX D - COMMAND LINE SWMM 270
APPENDIX E - ERROR AND WARNING MESSAGES 343
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LIST OF FIGURES
FIGURE 2-1 EXAMPLE STUDY AREA 18
FIGURE 2-2 DEFAULT ID LABELING FOR TUTORIAL EXAMPLE 19
FIGURE 2-3 MAP OPTIONS DIALOG 21
FIGURE 2-4 SUBCATCHMENTS AND NODES FOR EXAMPLE STUDY AREA 22
FIGURE 2-5 PROPERTY EDITOR WINDOW 24
FIGURE 2-6 GROUP EDITOR DIALOG 25
FIGURE 2-7 TIME SERIES EDITOR 27
FIGURE 2-8 TITLE/NOTES EDITOR 28
FIGURE 2-9 SIMULATION OPTIONS DIALOG 29
FIGURE 2-10 PORTION OF A STATUS REPORT 30
FIGURE 2-11 NODE FLOODING SUMMARY TABLE 31
FIGURE 2-12 CONDUIT SURCHARGE SUMMARY TABLE 31
FIGURE 2-13 VIEWING COLOR-CODED RESULTS ON THE STUDY AREA MAP 32
FIGURE 2-14 TIME SERIES PLOT DIALOGS 34
FIGURE 2-15 TIME SERIES PLOT OF LINK FLOWS 34
FIGURE 2-16 PROFILE PLOT DIALOG 35
FIGURE 2-17 EXAMPLE PROFILE PLOT 36
FIGURE 2-18 DYNAMIC WAVE SIMULATION OPTIONS 37
FIGURE 2-19 POLLUTANT EDITOR DIALOG 39
FIGURE 2-20 LAND USE EDITOR DIALOG 39
FIGURE 2-21 DEFINING A TSS BUILDUP FUNCTION 40
FIGURE 2-22 LAND USE ASSIGNMENT DIALOG 41
FIGURE 2-23 RUNOFF TSS FROM SELECTED SUBCATCHMENTS 42
FIGURE 2-24 STATISTICS SELECTION DIALOG 44
FIGURE 2-25 EXAMPLE STATISTICS REPORT 45
FIGURE 3-1 PHYSICAL OBJECTS USED TO MODEL A DRAINAGE SYSTEM 47
FIGURE 3-2 CONCRETE Box CULVERT 53
FIGURE 3-3 AREAL DEPLETION CURVE FOR A NATURAL AREA 59
FIGURE 3-4 AN RDM UNIT HYDROGRAPH 61
FIGURE 3-5 EXAMPLE OF A NATURAL CHANNEL TRANSECT 62
FIGURE 3-6 ADJUSTMENT OF SUBCATCHMENT PARAMETERS AFTER LID PLACEMENT 71
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FIGURE 3-7 CONCEPTUAL VIEW OF SURFACE RUNOFF 73
FIGURE 3-8 TWO-ZONE GROUNDWATER MODEL 74
FIGURE 3-9 CONCEPTUAL DIAGRAM OF A BIO-RETENTION CELL LID 78
FIGURE 8-1 FLOW INSTABILITY INDEX FOR A FLOW HYDROGRAPH 135
FIGURE 11-1 COMBINING ROUTING INTERFACE FILES 171
LIST OF TABLES
TABLE 3-1 AVAILABLE CROSS SECTION SHAPES FOR CONDUITS 52
TABLE 3-2 AVAILABLE TYPES OF WEIRS 56
TABLE 9-1 TIME SERIES VARIABLES AVAILABLE FOR VIEWING 141
TABLE D-1 GEOMETRIC PARAMETERS OF CONDUIT CROSS SECTIONS 313
TABLE D-2 POLLUTANT BUILDUP FUNCTIONS (T is ANTECEDENT DRY DAYS) 326
TABLE D-3 POLLUTANT WASH OFF FUNCTIONS 327
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CHAPTER 1 -INTRODUCTION
1.1
What is SWMM
The EPA Storm Water Management Model (SWMM) is a dynamic rainfall-runoff simulation model
used for single event or long-term (continuous) simulation of runoff quantity and quality from
primarily urban areas. The runoff component of SWMM operates on a collection of subcatchment
areas that receive precipitation and generate runoff and pollutant loads. The routing portion of
SWMM transports this runoff through a system of pipes, channels, storage/treatment devices,
pumps, and regulators. SWMM tracks the quantity and quality of runoff generated within each
subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during
a simulation period comprised of multiple time steps.
Wet Weather FUws
SWMM was first developed in 19711 and has undergone several major upgrades since then2. It
continues to be widely used throughout the world for planning, analysis and design related to
storm water runoff, combined sewers, sanitary sewers, and other drainage systems in urban
1 Metcalf & Eddy, Inc., University of Florida, Water Resources Engineers, Inc. "Storm Water
Management Model, Volume I - Final Report", 11024DOC07/71, Water Quality Office,
Environmental Protection Agency, Washington, DC, July 1971.
2 Huber, W.C. and Dickinson, R.E., "Storm Water Management Model, Version 4: User's Manual,
EPA/600/3-88/001 a, Environmental Research Laboratory, U.S. Environmental Protection Agency,
Athens, GA, October 1992.
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areas, with many applications in non-urban areas as well. The current edition, Version 5, is a
complete re-write of the previous release.
Running under Windows, SWMM 5 provides an integrated environment for editing study area
input data, running hydrologic, hydraulic and water quality simulations, and viewing the results in
a variety of formats. These include color-coded drainage area and conveyance system maps,
time series graphs and tables, profile plots, and statistical frequency analyses.
This latest re-write of SWMM was produced by the Water Supply and Water Resources Division
of the U.S. Environmental Protection Agency's National Risk Management Research Laboratory
with assistance from the consulting firm of CDM-Smith.
1.2 Modeling Capabilities
SWMM accounts for various hydrologic processes that produce runoff from urban areas. These
include:
• time-varying rainfall
• evaporation of standing surface water
• snow accumulation and melting
• rainfall interception from depression storage
• infiltration of rainfall into unsaturated soil layers
• percolation of infiltrated water into groundwater layers
• interflow between groundwater and the drainage system
• nonlinear reservoir routing of overland flow
• capture and retention of rainfall/runoff with various types of low impact development (LID)
practices.
Spatial variability in all of these processes is achieved by dividing a study area into a collection of
smaller, homogeneous subcatchment areas, each containing its own fraction of pervious and
impervious sub-areas. Overland flow can be routed between sub-areas, between subcatchments,
or between entry points of a drainage system.
SWMM also contains a flexible set of hydraulic modeling capabilities used to route runoff and
external inflows through a drainage system network of pipes, channels, storage/treatment units
and diversion structures. These include the ability to:
• handle networks of unlimited size
• use a wide variety of standard closed and open conduit shapes as well as natural
channels
• model special elements such as storage/treatment units, flow dividers, pumps, weirs, and
orifices
• apply external flows and water quality inputs from surface runoff, groundwater interflow,
rainfall-dependent infiltration/inflow, dry weather sanitary flow, and user-defined inflows
• utilize either kinematic wave or full dynamic wave flow routing methods
• model various flow regimes, such as backwater, surcharging, reverse flow, and surface
ponding
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• apply user-defined dynamic control rules to simulate the operation of pumps, orifice
openings, and weir crest levels.
In addition to modeling the generation and transport of runoff flows, SWMM can also estimate the
production of pollutant loads associated with this runoff. The following processes can be modeled
for any number of user-defined water quality constituents:
• dry-weather pollutant buildup over different land uses
• pollutant washoff from specific land uses during storm events
• direct contribution of rainfall deposition
• reduction in dry-weather buildup due to street cleaning
• reduction in washoff load due to BMPs
• entry of dry weather sanitary flows and user-specified external inflows at any point in the
drainage system
• routing of water quality constituents through the drainage system
• reduction in constituent concentration through treatment in storage units or by natural
processes in pipes and channels.
1.3 Typical Applications of SWMM
Since its inception, SWMM has been used in thousands of sewer and stormwater studies
throughout the world. Typical applications include:
• design and sizing of drainage system components for flood control
• sizing of detention facilities and their appurtenances for flood control and water quality
protection
• flood plain mapping of natural channel systems
• designing control strategies for minimizing combined sewer overflows
• evaluating the impact of inflow and infiltration on sanitary sewer overflows
• generating non-point source pollutant loadings for waste load allocation studies
• evaluating the effectiveness of BMPs for reducing wet weather pollutant loadings.
1.4 Installing EPA SWMM
EPA SWMM Version 5 is designed to run under all versions of the Microsoft Windows personal
computer operating system. It is distributed as a single file, swmm51xxx_setup.exe (where xxx is
the current release number which as of this writing is 010) that contains a self-extracting setup
program. To install EPA SWMM:
l. Select Run from the Windows Start menu.
2. Enter the full path and name of the setup file or click the Browse button to locate it on
your computer.
3. Click the OK button type to begin the setup process.
The setup program will ask you to choose a folder (directory) where the SWMM program files will
be placed. The default folder is c:\Program Files\EPA SWMM 5.1. After the files are installed
your Start Menu will have a new item named EPA SWMM 5.1. To launch SWMM, simply select
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this item off of the Start Menu, and then select EPA SWMM 5.1 from the submenu that appears.
(The name of the executable file that runs SWMM under Windows is epaswmm5.exe.)
A user's personal settings for running SWMM are stored in a folder named EPASWMM under the
user's Application Data directory (e.g., Users\\AppData\Roaming\EPASWMM for
Windows 7). If you need to save these settings to a different location, you can install a shortcut to
SWMM 5 on the desktop whose target entry includes the name of the SWMM 5 executable
followed by /s , where is the name of the folder where the personal
settings will be stored. An example might be:
"c:\Program Files\EPA SWMM 5.1\epaswmm5.exe"/s "My Folders\SWMM5\".
Several example data sets have been included with the installation package to help users
become familiar with the program. They are placed in a sub-folder named EPA SWMM
Projects\Examples in the user's My Documents folder. Each example consists of a .INP file that
holds the project's data along with a .7X7file that describes the system being modeled.
To remove EPA SWMM from your computer, do the following:
l. Select Settings from the Windows Start menu.
2. Select Control Panel from the Settings menu.
3. Double-click on the Add/Remove Programs item.
4. Select EPA SWMM 5.1 from the list of programs that appears.
5. Click the Add/Remove button.
1.5 Steps in Using SWMM
One typically carries out the following steps when using EPA SWMM to model a study area:
l. Specify a default set of options and object properties to use (see Section 5.4).
2. Draw a network representation of the physical components of the study area (see Section
6.2).
3. Edit the properties of the objects that make up the system (see Section 6.4).
4. Select a set of analysis options (see Section 8.1).
5. Run a simulation (see Section 8.2).
6. View the results of the simulation (see Chapter 9).
For building larger systems from scratch it will be more convenient to replace Step 2 by collecting
study area data from various sources, such as CAD drawings or CIS files, and transferring these
data into a SWMM input file whose format is described in Appendix D of this manual.
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1.6 About This Manual
Chapter 2 presents a short tutorial to help get started using EPA SWMM. It shows how to add
objects to a SWMM project, how to edit the properties of these objects, how to run a single event
simulation for both hydrology and water quality, and how to run a long-term continuous
simulation.
Chapter 3 provides background material on how SWMM models stormwater runoff within a
drainage area. It discusses the behavior of the physical components that comprise a stormwater
drainage area and collection system as well as how additional modeling information, such as
rainfall quantity, dry weather sanitary inflows, and operational control, are handled. It also
provides an overview of how the numerical simulation of system hydrology, hydraulics and water
quality behavior is carried out.
Chapter 4 shows how the EPA SWMM graphical user interface is organized. It describes the
functions of the various menu options and toolbar buttons, and how the three main windows - the
Study Area Map, the Browser panel, and the Property Editor—are used.
Chapter 5 discusses the project files that store all of the information contained in a SWMM model
of a drainage system. It shows how to create, open, and save these files as well as how to set
default project options. It also discusses how to register calibration data that are used to compare
simulation results against actual measurements.
Chapter 6 describes how one goes about building a network model of a drainage system with
SWMM. It shows how to create the various physical objects (subcatchment areas, drainage pipes
and channels, pumps, weirs, storage units, etc.) that make up a system, how to edit the
properties of these objects, and how to describe the way that externally imposed inflows,
boundary conditions and operational controls change overtime.
Chapter 7 explains how to use the study area map that provides a graphical view of the system
being modeled. It shows how to view different design and computed parameters in color-coded
fashion on the map, how to re-scale, zoom, and pan the map, how to locate objects on the map,
how to utilize a backdrop image, and what options are available to customize the appearance of
the map.
Chapter 8 shows how to run a simulation of a SWMM model. It describes the various options that
control how the analysis is made and offers some troubleshooting tips to use when examining
simulation results.
Chapter 9 discusses the various ways in which the results of an analysis can be viewed. These
include different views of the study area map, various kinds of graphs and tables, and several
different types of special reports.
Chapter 10 explains how to print and copy the results discussed in Chapter 9.
Chapter 11 describes how EPA SWMM can use different types of interface files to make
simulations runs more efficient.
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Chapter 12 describes how add-in tools can be registered and share data with SWMM. These
tools are external applications launched from SWMM's graphical user interface that can extend its
capabilities.
The manual also contains several appendixes:
Appendix A- provides several useful tables of parameter values, including a table of units of
expression for all design and computed parameters.
Appendix B - lists the editable properties of all visual objects that can be displayed on the
study area map and be selected for editing using point and click.
Appendix C - describes the specialized editors available for setting the properties of non-visual
objects.
Appendix D - provides instructions for running the command line version of SWMM and
includes a detailed description of the format of a project file.
Appendix E - lists all of the error messages and their meaning that SWMM can produce.
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CHAPTER 2 - QUICK START TUTORIAL
This chapter provides a tutorial on how to use EPA SWMM. If you are not familiar with the
elements that comprise a drainage system, and how these are represented in a SWMM model,
you might want to review the material in Chapter 3 first.
2.1 Example Study Area
In this tutorial we will model the drainage system serving a 12-acre residential area. The system
layout is shown in Figure 2-1 and consists of subcatchment areas3 S1 through S3, storm sewer
conduits C1 through C4, and conduit junctions J1 through J4. The system discharges to a creek
at the point labeled Out1. We will first go through the steps of creating the objects shown in this
diagram on SWMM's study area map and setting the various properties of these objects. Then we
will simulate the water quantity and quality response to a 3-inch, 6-hour rainfall event, as well as a
continuous, multi-year rainfall record.
Figure 2-1 Example study area
2.2 Project Setup
Our first task is to create a new SWMM project and make sure that certain default options are
selected. Using these defaults will simplify the data entry tasks later on.
l. Launch EPA SWMM if it is not already running and select File » New from the Main
Menu bar to create a new project.
2. Select Project » Defaults to open the Project Defaults dialog.
3 A subcatchment is an area of land containing a mix of pervious and impervious surfaces whose
runoff drains to a common outlet point, which could be either a node of the drainage network or
another subcatchment.
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3. On the ID Labels page of the dialog, set the ID Prefixes as shown in Figure 2-2. This will
make SWMM automatically label new objects with consecutive numbers following the
designated prefix.
Project Defaults
ID Labels Subcatchments | Nodes/Links
Object
Rain Gages
Subcatchments
Junctions
Outfalls
Dividers
Storage Units
Conduits
Pumps
Regulators
ID Increment
ID Prefix
Gage I
S
J
Out
C
1
Save as defaults for all new projects
Figure 2-2 Default ID labeling for tutorial example
4. On the Subcatchments page of the dialog set the following default values:
Area
Width
% Slope
% Imperv.
N-lmperv.
N-Perv.
Dsto re-Imperv.
Dstore-Perv
%Zero-lmperv.
Infil. Model
- Method
- Suction Head
- Conductivity
- Initial Deficit
4
400
0.5
50
0.01
0.10
0.05
0.05
25
Modified Green-Ampt
3.5
0.5
0.26
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5. On the Nodes/Links page set the following default values:
Node Invert 0
Node Max. Depth 4
Node Ponded Area 0
Conduit Length 400
Conduit Geometry
- Barrels 1
- Shape Circular
- Max. Depth 1.0
Conduit Roughness 0.01
Flow Units CFS
Link Offsets DEPTH
Routing Model Kinematic Wave
6. Click OK to accept these choices and close the dialog. If you wanted to save these
choices for all future new projects you could check the Save box at the bottom of the form
before accepting it.
Next we will set some map display options so that ID labels and symbols will be displayed as we
add objects to the study area map, and links will have direction arrows.
l. Select Tools » Map Display Options to bring up the Map Options dialog (see Figure 2-
3).
2. Select the Subcatchments page, set the Fill Style to Diagonal and the Symbol Size to 5.
3. Then select the Nodes page and set the Node Size to 5.
4. Select the Annotation page and check off the boxes that will display ID labels for
Subcatchments, Nodes, and Links. Leave the others un-checked.
5. Finally, select the Flow Arrows page, select the Filled arrow style, and set the arrow size
to 7.
6. Click the OK button to accept these choices and close the dialog.
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Map Options
Subcatchments
Nodes
Links
Labels
Annotation
Symbols
Flow Arrows
Background
Fill Style
G Clear
;• solid
(*) Diagonal
O Cross Hatch
Symbol Size 5
Border Size 1
[7] Display link to outlet
OK
Figure 2-3 Map options dialog
Before placing objects on the map we should set its dimensions.
l. Select View » Dimensions to bring up the Map Dimensions dialog.
2. You can leave the dimensions at their default values for this example.
Finally, look in the status bar at the bottom of the main window and check that the Auto-Length
feature is off.
2.3 Drawing Objects
We are now ready to begin adding components to the Study Area Map4. We will start with the
subcatchments.
l. Begin by selecting the Subcatchments category (under Hydrology) in the Project
Browser panel (on the left side of the main window).
4 Drawing objects on the map is just one way of creating a project. For large projects it might be
more convenient to first construct a SWMM project file external to the program. The project file is
a text file that describes each object in a specified format as described in Appendix D of this
manual. Data extracted from various sources, such as CAD drawings or CIS files, can be used to
create the project file.
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2. Then click the * button on the toolbar underneath the object category listing in the
Project panel (or select Project | Add a New Subcatchment from the main menu).
Notice how the mouse cursor changes shape to a pencil when you move it over the map.
3. Move the mouse to the map location where one of the corners of subcatchment S1 lies
and left-click the mouse.
4. Do the same for the next three corners and then right-click the mouse (or hit the Enter
key) to close up the rectangle that represents subcatchment S1. You can press the Esc
key if instead you wanted to cancel your partially drawn subcatchment and start over
again. Don't worry if the shape or position of the object isn't quite right. We will go back
later and show how to fix this.
5. Repeat this process for subcatchments S2 and S35.
Observe how sequential ID labels are generated automatically as we add objects to the map.
Next we will add in the junction nodes and the outfall node that comprise part of the drainage
network.
l. To begin adding junctions, select the Junctions category from the Project Browser
(under Hydraulics -> Nodes) and click the * button or select Project | Add a New
Junction from the main menu..
2. Move the mouse to the position of junction J1 and left-click it. Do the same for junctions
J2 through J4.
3. To add the outfall node, select Outfalls from the Project Browser, click the * button or
select Project | Add a New Outfall from the main menu, move the mouse to the outfall's
location on the map, and left-click. Note how the outfall was automatically given the name
Out1.
At this point your map should look something like that shown in Figure 2-4.
,n
J2
Figure 2-4 Subcatchments and nodes for example study area
5 If you right-click (or press Enter) after adding the first point of a subcatchment's outline, the
subcatchment will be shown as just a single point.
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Now we will add the storm sewer conduits that connect our drainage system nodes to one
another. (You must have created a link's end nodes as described previously before you can
create the link.) We will begin with conduit C1, which connects junction J1 to J2.
l. Select the Conduits from the Project Browser (under Hydraulics -> Links) and press the
* button or select Project | Add a New Conduit from the main menu. The mouse
cursor will change shape to a cross hair when moved onto the map.
2. Left-click the mouse on junction J1. Note how the mouse cursor changes shape to a
pencil.
3. Move the mouse over to junction J2 (note how an outline of the conduit is drawn as you
move the mouse) and left-click to create the conduit. You could have cancelled the
operation by either right clicking or by hitting the key.
4. Repeat this procedure for conduits C2 through C4.
Although all of our conduits were drawn as straight lines, it is possible to draw a curved link by
left-clicking at intermediate points where the direction of the link changes before clicking on the
end node.
To complete the construction of our study area schematic we need to add a rain gage.
l. Select the Rain Gages category from the Project Browser panel (under Hydrology) and
either click the * button or select Project | Add a New Rain Gage from the main menu.
2. Move the mouse over the Study Area Map to where the gage should be located and left-
click the mouse.
At this point we have completed drawing the example study area. Your system should look like
the one in Figure 2-1. If a rain gage, subcatchment or node is out of position you can move it by
doing the following:
l. If the ^ button on the Map Toolbar is not already depressed, click it to place the map in
Object Selection mode.
2. Click on the object to be moved.
3. Drag the object with the left mouse button held down to its new position.
To re-shape a subcatchment's outline:
l. With the map in Object Selection mode, click on the subcatchment's centroid (indicated
by a solid square within the subcatchment) to select it.
2. Then click the [^ button on the Map Toolbar to put the map into Vertex Selection mode.
3. Select a vertex point on the subcatchment outline by clicking on it (note how the selected
vertex is indicated by a filled solid square).
4. Drag the vertex to its new position with the left mouse button held down.
23
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5. If need be, vertices can be added or deleted from the outline by right-clicking the mouse
and selecting the appropriate option from the popup menu that appears.
6. When finished, click the ^ button to return to Object Selection mode.
This same procedure can also be used to re-shape a link.
2.4 Setting Object Properties
As visual objects are added to our project, SWMM assigns them a default set of properties. To
change the value of a specific property for an object we must select the object into the Property
Editor (see Figure 2-5). There are several different ways to do this. If the Editor is already visible,
then you can simply click on the object or select it from the Project Browser. If the Editor is not
visible then you can make it appear by one of the following actions:
• double-click the object on the map,
• or right-click on the object and select Properties from the pop-up menu that appears,
• or select the object from the Project Browser and then click the Browser's "^ button.
Subcatchment SI
Property
Name
(o)
Value
SI
X-Coordinate 4756,309
Y-Coordinate 6653,696
Description
Tag
Rain Gage
Outlet
Area
Width
Gagel
Jl
4
400
>.
D
T
Name of node or another
subcatchmentthat receives runoff
Figure 2-5 Property editor window
Whenever the Property Editor has the focus you can press the F1 key to obtain a more detailed
description of the properties listed.
Two key properties of our subcatchments that need to be set are the rain gage that supplies
rainfall data to the subcatchment and the node of the drainage system that receives runoff from
24
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the subcatchment. Since all of our subcatchments utilize the same rain gage, Gagel, we can use
a shortcut method to set this property for all subcatchments at once:
l. From the main menu select Edit »Select All.
2. Then select Edit » Group Edit to make a Group Editor dialog appear (see Figure 2-6).
3. Select Subcatchment as the type of object to edit, Rain Gage as the property to edit, and
type in Gagel as the new value.
4. Click OK to change the rain gage of all subcatchments to Gagel. A confirmation dialog
will appear noting that 3 subcatchments have changed. Select "No" when asked to
continue editing.
Group Editor
For objects of type
with Tag equal to
edit the property
by replacing it with
Subcatchment
Rain Gage
Gagel
Figure 2-6 Group editor dialog
To set the outlet node of our subcatchments we have to proceed one by one, since these vary by
subcatchment:
l. Double click on subcatchment S1 or select it from the Project Browser and click the
Browser's & button to bring up the Property Editor.
2. Type J1 in the Outlet field and press Enter. Note how a dotted line is drawn between the
subcatchment and the node.
3. Click on subcatchment S2 and enter J2 as its Outlet.
4. Click on subcatchment S3 and enter J3 as its Outlet.
We also wish to represent area S3 as being less developed than the others. Select S3 into the
Property Editor and set its % Imperviousness to 25.
25
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The junctions and outfall of our drainage system need to have invert elevations assigned to them.
As we did with the subcatchments, select each junction individually into the Property Editor and
set its Invert Elevation to the value shown below6
Node
J1
J2
J3
J4
Out1
Invert
96
90
93
88
85
Only one of the conduits in our example system has a non-default property value. This is conduit
C4, the outlet pipe, whose diameter should be 1.5 instead of 1 ft. To change its diameter, select
conduit C4 into the Property Editor and set the Max. Depth value to 1.5.
In order to provide a source of rainfall input to our project we need to set the rain gage's
properties. Select Gagel into the Property Editor and set the following properties:
Rain Format INTENSITY
Rain Interval 1:00
Data Source TIMESERIES
Series Name TS1
As mentioned earlier, we want to simulate the response of our study area to a 3-inch, 6-hour
design storm. A time series named TS1 will contain the hourly rainfall intensities that make up this
storm. Thus we need to create a time series object and populate it with data. To do this:
l. From the Project Browser select the Time Series category of objects.
2. Click the * button on the Browser to bring up the Time Series Editor dialog (see Figure
2-7)7.
3. Enter TS1 in the Time Series Name field.
4. Enter the values shown in Figure 2-7 into the Time and Value columns of the data entry
grid (leave the Date column blank8).
5. You can click the View button on the dialog to see a graph of the time series values.
Click the OK button to accept the new time series.
6 An alternative way to move from one object of a given type to the next in order (or to the
previous one) in the Property Editor is to hit the Page Down (or Page Up) key.
7 The Time Series Editor can also be launched directly from the Rain Gage Property Editor by
selecting the editor's Series Name field and double clicking on it.
8 Leaving off the dates for a time series means that SWMM will interpret the time values as hours
from the start of the simulation. Otherwise, the time series follows the date/time values specified
by the user.
26
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Time Series Name
TS1
Description
Use external data file named below
m
0 Enter time series data in the table below
No dates means times are relative to start of simulation,
Date
(M/D/YJ
Time
(H:M)
0
1
2
3
4
5
6
Value
0
05
1
0.75
05
0.25
0
6
T
Figure 2-7 Time series editor
Having completed the initial design of our example project it is a good idea to give it a title and
save our work to a file at this point. To do this:
l. Select the Title/Notes category from the Project Browser and click the & button.
2. In the Project Title/Notes dialog that appears (see Figure 2-8), enter "Tutorial Example"
as the title of our project and click the OK button to close the dialog.
3. From the File menu select the Save As option.
4. In the Save As dialog that appears, select a folder and file name under which to save this
project. We suggest naming the file tutorial.inp. (An extension of .inp will be added to
the file name if one is not supplied.)
5. Click Save to save the project to file.
27
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Title/Notes Editor
Tutorial Example
Use title line as header for printing
OK
Cancel
Figure 2-8 Title/Notes editor
The project data are saved to the file in a readable text format. You can view what the file looks
like by selecting Project » Details from the main menu. To open our project at some later time,
you would select the Open command from the File menu.
2.5 Running a Simulation
Setting Simulation Options
Before analyzing the performance of our example drainage system we need to set some options
that determine how the analysis will be carried out. To do this:
l. From the Project Browser, select the Options category and click the & button.
2. On the General page of the Simulation Options dialog that appears (see Figure 2-9),
select Kinematic Wave as the flow routing method. The infiltration method should
already be set to Modified Green-Ampt. The Allow Ponding option should be
unchecked.
3. On the Dates page of the dialog, set the End Analysis time to 12:00:00.
4. On the Time Steps page, set the Routing Time Step to 60 seconds.
5. Click OK to close the Simulation Options dialog.
28
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Simulation
General
Options
Dates
Process Mode
Time Steps
\r
Dynamic Wave | Files
[7] Rainfall/Runoff
D Rainfall Dependent L'l
D Snow Melt
^ Groundwater
[Vj Flow Routing
D Water Quality
Routing Mods
,1
O Steady Flow
•j*1 Kinematic Wave
Dynamic Wave
OK
Infiltration Model
Morton
Modifiec
Morton
Green-Ampt
o Modified
Green-Ampt
Curve Number
Miscellaneous
F] Allow Ponding
Q Report Control
Actions
! ; Report Input Summary
Minimum Conduit Slope
0
Cancel
(%}
Help
Figure 2-9 Simulation options dialog
Starting a Simulation
We are now ready to run the simulation. To do so, select Project » Run Simulation (or click the
@ button). If there was a problem with the simulation, a Status Report will appear describing
what errors occurred. Upon successfully completing a run, there are numerous ways in which to
view the results of the simulation. We will illustrate just a few here.
Viewing the Status Report
The Status Report contains useful information about the quality of a simulation run, including a
mass balance on rainfall, infiltration, evaporation, runoff, and inflow/outflow for the conveyance
system. To view the report select Report » Status (or click the H button on the Standard
Toolbar and then select Status Report from the drop down menu). A portion of the report for the
system just analyzed is shown in Figure 2-10.
29
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EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.010)
Tutorial Example
NOTE: The summary statistics displayed in this report are
based on results found at every computational time step,
not just on results from each reporting time step.
Flow Units CFS
Process Models:
Rainfall/Runoff YES
RDII NO
Snowmelt NO
Groundwater NO
Flow Routing YES
Ponding Allowed NO
Water Quality NO
Infiltration Method MODIFIED_GREEN_AMPT
Flow Routing Method KINWAVE
Starting Date JUN-27-2002 00:00:00
Ending Date JUN-27-2002 12:00:00
Antecedent Dry Days 0.0
Report Time Step 00:15:00
Wet Time Step 00:15:00
Dry Time Step 01:00:00
Routing Time Step 60.00 sec
Runoff Quantity Continuity
Depth
inches
Total Precipitation
Evaporation Loss ...
Infiltration Loss ..
Surface Runoff
Final Storage
Continuity Error (%)
Flow Routing Continuity
Volume
acre-feet
Wet Weather Inflow
Groundwater Inflow
Figure 2-10 Portion of a Status Report
For the system we just analyzed the report indicates the quality of the simulation is quite good,
with negligible mass balance continuity errors for both runoff and routing (-0.39% and 0.03%,
30
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respectively, if all data were entered correctly). Also, of the 3 inches of rain that fell on the study
area, 1.75 infiltrated into the ground and essentially the remainder became runoff.
Viewing the Summary Report
The Summary Report contains tables listing summary results for each subcatchment, node and
link in the drainage system. Total rainfall, total runoff, and peak runoff for each subcatchment,
peak depth and hours flooded for each node, and peak flow, velocity, and depth for each conduit
are just some of the outcomes included in the summary report.
To view the Summary Report select Report | Summary from the main menu (or click the U
button on the Standard Toolbar and then select Summary Report from the drop down menu).
The report's window has a drop down list from which you select a particular report to view. For
our example, the Node Flooding Summary table (Figure 2-11) indicates there was internal
flooding in the system at node J2. Note. The Conduit Surcharge Summary table (Figure 2-12)
shows that Conduit C2, just downstream of node J2, was at full capacity and therefore appears to
be slightly undersized.
In SWMM flooding will occur whenever the water surface at a node exceeds the maximum
assigned depth. Normally such water will be lost from the system. The option also exists to have
this water pond atop the node and be re-introduced into the drainage system when capacity
exists to do so.
iH Summary Results
Topic: Node Flooding T Click a column headerto sort the column.
Node
J2
Hours
Flooded
Maximum
Rate
CFS
1.05 ! 0.77
Day of
Maximum
Flooding
0
Hour of
Maximum
Flooding
03:01
| CD || H ||-£3-|
Total
Flood
Volume
10A6gal
0.018
Maximum
Ponded
Volume
1000 ft3
0.000
Figure 2-11 Node flooding summary table
Topic: Conduit Surcharge
T Click a column headerto sort the column.
Conduit
C2
Hours
Both Ends
Full
1.03 i
Hours
Upstream
Full
1.03
Hours
Dn stream
Full
1.03
Hours
Above
Normal
Flow
1.05
Hours
Capacity
Limited
1.03
Figure 2-12 Conduit surcharge summary table
31
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Viewing Results on the Map
Simulation results (as well as some design parameters, such as subcatchment area, node invert
elevation, and link maximum depth) can be viewed in color-coded fashion on the study area map.
To view a particular variable in this fashion:
l. Select the Map page of the Browser panel.
2. Select the variables to view for Subcatchments, Nodes, and Links from the dropdown
combo boxes appearing in the Themes panel. In Figure 2-13, subcatchment runoff and
link flow have been selected for viewing.
SJSWMM 5.1-tutorial.inp
File Edit View Project Report Tools Window Help
D G£ y a
Project Map
Themes
Subcatchments
Runoff T
Nodes
None T
Links
Flow
Time Period
Date
06/27/2002
Time of Day
05:45:00
D
Elapsed Time
0.05:45:00
Animator
H < W >
1 0
3
E O
H
Study Area Map
J3
C3, ,
J1
Out1
T
C4
<
J4
*-
C2
Auto-Length: Off ^ Offsets: Depth "• Flow Units: CFS " *f Zoom Level: 100% X,Y: 5665.533,-2547.721
Figure 2-13 Viewing color-coded results on the Study Area Map
32
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3. The color-coding used for a particular variable is displayed with a legend on the study
area map. To toggle the display of a legend, select View » Legends.
4. To move a legend to another location, drag it with the left mouse button held down.
5. To change the color-coding and the breakpoint values for different colors, select View »
Legends » Modify and then the pertinent class of object (or if the legend is already
visible, simply right-click on it). To view numerical values for the variables being displayed
on the map, select Tools » Map Display Options and then select the Annotation page
of the Map Options dialog. Use the check boxes for Subcatchment Values, Node Values,
and Link Values to specify what kind of annotation to add.
6. The Date / Time of Day / Elapsed Time controls on the Map Browser can be used to
move through the simulation results in time. Figure 2-13 depicts results at 5 hours and 45
minutes into the simulation.
7. You can use the controls in the Animator panel of the Map Browser (see Figure 2-13) to
animate the map display through time. For example, pressing the ^ button will run the
animation forward in time.
Viewing a Time Series Plot
To generate a time series plot of a simulation result:
l . Select Report » Graph » Time Series or simply click W; on the Standard Toolbar.
2. A Time Series Plot Selection dialog will appear. It is used to select the objects and
variables to be plotted.
For our example, the Time Series Plot Selection dialog can be used to graph the flow in conduits
C1 and C2 as follows (refer to Figure 2-14a):
l . Click the Add button on the dialog to view the Data Series Selection dialog (Figure 2-
2 . Select conduit C1 (either on the map or in the Project Browser) and select Flow as the
variable to be plotted. Click the Accept button to return to the Time Series Plot Selection
dialog.
3 . Repeat steps 1 and 2 for conduit C2.
4 . Press OK to create the plot which should look like the graph in Figure 2-1 5.
33
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(a)
(b)
Time Series Plot Selection
'Q'1 Elapsed Time
Data Series
Date/Time
Add
OK
Data Series Selection
Specify the object and variable to plot
(Click an object on the map to select it)
Object Type Link
Object Name Cl
Variable
Flow
Legend Label
Axis * Left •'} Right
Help
Figure 2-14 Time series plot dialogs
: Graph - LinkCl Flow,.,
Link Cl flow (CFS) •
Link C2 flow (CFS}
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
6810
Elapsed Time (hours)
12
14
Figure 2-15 Time series plot of link flows
34
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After a plot is created you can:
• customize its appearance by selecting Report » Customize or by clicking the Hf1
button on the Standard Toolbar or by simply right clicking on the plot,
• copy it to the clipboard and paste it into another application by selecting Edit » Copy To
or clicking ^ on the Standard Toolbar
• print it by selecting File » Print or File » Print Preview (use File » Page Setup first
to set margins, orientation, etc.).
Viewing a Profile Plot
SWMM can generate profile plots showing how water surface depth varies across a path of
connected nodes and links. Let's create such a plot for the conduits connecting junction J1 to the
outfall Out1 of our example drainage system. To do this:
l . Select Report » Graph » Profile on the main menu or simply click
Toolbar.
j on the Standard
2 . Either enter J1 in the Start Node field of the Profile Plot Selection dialog that appears
(see Figure 2-16) or select it on the map or from the Project Browser and click the *
button next to the field.
Profile Plot Selection
Create Profile
Start Node
Jl
End Node
OutL
Links in Profile
C2
C4
Find Path
Save Current Profile
> X
OK
Cancel
Figure 2-16 Profile plot dialog
3. Do the same for node Out 1 in the End Node field of the dialog.
35
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4. Click the Find Path button. An ordered list of the links forming a connected path between
the specified Start and End nodes will be displayed in the Links in Profile box. You can
edit the entries in this box if need be.
5. Click the OK button to create the plot, showing the water surface profile as it exists at the
simulation time currently selected in the Map Browser (see Figure 2-17 for hour 02:45).
Profile-NodeJl-Out!
Water Elevation Profile: NodeJI - Out1
900 800 700 600 500 400 300 200 100 0
Distance (ft)
06/27/2002 02:45:00
Figure 2-17 Example profile plot
As you move through time using the Map Browser or with the Animator control, the water depth
profile on the plot will be updated. Observe how node J2 becomes flooded between hours 2 and
3 of the storm event. A Profile Plot's appearance can be customized and it can be copied or
printed using the same procedures as for a Time Series Plot.
Running a Full Dynamic Wave Analysis
In the analysis just run we chose to use the Kinematic Wave method of routing flows through our
drainage system. This is an efficient but simplified approach that cannot deal with such
phenomena as backwater effects, pressurized flow, flow reversal, and non-dendritic layouts.
SWMM also includes a Dynamic Wave routing procedure that can represent these conditions.
This procedure, however, requires more computation time, due to the need for smaller time steps
to maintain numerical stability.
36
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Most of the effects mentioned above would not apply to our example. However we had one
conduit, C2, which flowed full and caused its upstream junction to flood. It could be that this pipe
is actually being pressurized and could therefore convey more flow than was computed using
Kinematic Wave routing. We would now like to see what would happen if we apply Dynamic
Wave routing instead.
To run the analysis with Dynamic Wave routing:
l . From the Project Browser, select the Options category and click the
button.
2 . On the General page of the Simulation Options dialog that appears, select Dynamic
Wave as the flow routing method.
3. On the Dynamic Wave page of the dialog, use the settings shown in Figure 2-1 89.
Simulation Options
1 General j Dates 1 Time Steps
Inertial Terms
Normal Flow Criterion
Force Main Equation
Dynamic Wave
TilesH
Dampen •*•
Slope
& Froude
-
Hazen-Williams T
[7] Use Variable Time Steps Adjusted By
Minimum Variable Time Step (sec)
Time Step
For Conduit Lengthening (sec)
Minimum Nodal Surface Area (sq. feet)
Maximum Trials per Time Step
Head Convergence Tolerance (feet)
Number of Threads
1 ™~> „. ' J '/ I....-" t* L
! OK 1
Cancel
75
0.5
0
". %
12.557
8
0.005
1
Help
T
Figure 2-18 Dynamic wave simulation options
9 Normally when running a Dynamic Wave analysis, one would also want to reduce the routing
time step (on the Time Steps page of the dialog). We will keep it at 60 seconds.
37
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4. Click OK to close the form and select Project » Run Simulation (or click the v
button) to re-run the analysis.
If you look at the Summary Report for this run, you will see that there is no longer any junction
flooding and that the peak flow carried by conduit C2 has been increased from 3.52 cfs to 4.04
cfs.
2.6 Simulating Water Quality
In the next phase of this tutorial we will add water quality analysis to our example project. SWMM
has the ability to analyze the buildup, washoff, transport and treatment of any number of water
quality constituents. The steps needed to accomplish this are:
l. Identify the pollutants to be analyzed.
2. Define the categories of land uses that generate these pollutants.
3. Set the parameters of buildup and washoff functions that determine the quality of runoff
from each land use.
4. Assign a mixture of land uses to each subcatchment area
5. Define pollutant removal functions for nodes within the drainage system that contain
treatment facilities.
We will now apply each of these steps, with the exception of number 5, to our example project10.
We will define two runoff pollutants; total suspended solids (TSS), measured as mg/L, and total
Lead, measured in ug/L. In addition, we will specify that the concentration of Lead in runoff is a
fixed fraction (0.25) of the TSS concentration. To add these pollutants to our project:
l. Under the Quality category in the project Browser, select the Pollutants sub-category
beneath it.
2. Click the * button to add a new pollutant to the project.
3. In the Pollutant Editor dialog that appears (see Figure 2-19), enter TSS for the pollutant
name and leave the other data fields at their default settings.
4. Click the OK button to close the Editor.
5. Click the * button on the Project Browser again to add our next pollutant.
6. In the Pollutant Editor, enter Lead for the pollutant name, select UG/L for the
concentration units, enter TSS as the name of the Co-Pollutant, and enter 0.25 as the
Co-Fraction value.
10 Aside from surface runoff, SWMM also allows pollutants to be introduced into the nodes of a
drainage system through user-defined time series of direct inflows, dry weather inflows,
groundwater interflow, and rainfall dependent inflow/infiltration
38
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7. Click the OK button to close the Editor.
In SWMM, pollutants associated with runoff are generated by specific land uses assigned to
subcatchments. In our example, we will define two categories of land uses: Residential and
Undeveloped. To add these land uses to the project:
l. Under the Quality category in the Project Browser, select the Land Uses sub-category
and click the * button.
2. In the Land Use Editor dialog that appears (see Figure 2-20), enter Residential in the
Name field and then click the OK button.
3. Repeat steps 1 and 2 to create the Undeveloped land use category.
Pollutant Editor
Property
Name
Units
Rain Concen,
GW Concen,
I&I Concen,
DWF Concen,
Init, Concen,
Decay Coeff,
Snow Only
Co-Pollutant
Co-Fraction
Value
ITSS
MG/L
0,0
0,0
0,0
0,0
0,0
0,0
NO
User-assigned name of the pollutant.
Land Use Editor
General
Buildup I Washoffj
Property
Land Use Name
Description
STREET SWEEPING
Interval
Availability
Last Swept
Value
i Resident! a I
0
0
0
User assigned name of land use,
Figure 2-19 Pollutant editor dialog
Figure 2-20 Land use editor dialog
Next we need to define buildup and washoff functions for TSS in each of our land use categories.
Functions for Lead are not needed since its runoff concentration was defined to be a fixed fraction
of the TSS concentration. Normally, defining these functions requires site-specific calibration.
In this example we will assume that suspended solids in Residential areas builds up at a constant
rate of 1 pound per acre per day until a limit of 50 Ibs per acre is reached. For the Undeveloped
39
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area we will assume that buildup is only half as much. For the washoff function, we will assume a
constant event mean concentration of 100 mg/L for Residential land and 50 mg/L for
Undeveloped land. When runoff occurs, these concentrations will be maintained until the
available buildup is exhausted. To define these functions for the Residential land use:
l. Select the Residential land use category from the Project Browser and click the &
button.
2. In the Land Use Editor dialog, move to the Buildup page (see Figure 2-21).
3. Select TSS as the pollutant and ROW (for Power function) as the function type.
4. Assign the function a maximum buildup of 50, a rate constant of 1.0, a power of 1 and
select AREA as the normalizer.
5. Move to the Washoff page of the dialog and select TSS as the pollutant, EMC as the
function type, and enter 100 for the coefficient. Fill the other fields with 0.
6. Click the OK button to accept your entries.
Now do the same for the Undeveloped land use category, except use a maximum buildup of 25, a
buildup rate constant of 0.5, a buildup power of 1, and a washoff EMC of 50.
L
and Use Editor
General
Buildup
Pollutant
Property
Function
Max. Buildup
Rate Constant
Power/Sat. Consta
Normalizer
Buildup function:
exponential, SAT =
series.
OK ]
'wash off
g|
TSS
Value
JPOW
50
1.0
nt 1
ARE
3OW = pox
saturation
:A
TS^S^^^
ver, EXP =
, EXT = external time
Cancel
Help
i
Figure 2-21 Defining a TSS buildup function
The final step in our water quality example is to assign a mixture of land uses to each
subcatchment area:
40
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l. Select subcatchment S1 into the Property Editor.
2. Select the Land Uses property and click the ellipsis button (or press Enter).
3. In the Land Use Assignment dialog that appears, enter 75 for the % Residential and 25
for the % Undeveloped (see Figure 2-22). Then click the OK button to close the dialog.
Land Use Assignment
Land Use
% of Area
Residential
Undeveloped
25
Cancel
Figure 2-22 Land use assignment dialog
4. Repeat the same three steps for subcatchment S2.
5. Repeat the same for subcatchment S3, except assign the land uses as 25% Residential
and 75% Undeveloped.
Before we simulate the runoff quantities of TSS and Lead from our study area, an initial buildup of
TSS should be defined so it can be washed off during our single rainfall event. We can either
specify the number of antecedent dry days prior to the simulation or directly specify the initial
buildup mass on each subcatchment. We will use the former method:
l. From the Options category of the Project Browser, select the Dates sub-category and
click the ^ button.
2. In the Simulation Options dialog that appears, enter 5 into the Antecedent Dry Days
field.
3. Leave the other simulation options the same as they were for the dynamic wave flow
routing we just completed.
4. Click the OK button to close the dialog.
Now run the simulation by selecting Project » Run Simulation or by clicking ^? on the
Standard Toolbar.
When the run is completed, view its Status Report. Note that two new sections have been added
for Runoff Quality Continuity and Quality Routing Continuity. From the Runoff Quality
41
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Continuity table we see that there was an initial buildup of 47.5 Ibs of TSS on the study area and
an additional 2.2 Ibs of buildup added during the dry periods of the simulation. About 47.9 Ibs
were washed off during the rainfall event. The quantity of Lead washed off is a fixed percentage
(25% times 0.001 to convert from mg to ug) of the TSS as was specified.
If you plot the runoff concentration of TSS for subcatchment S1 and S3 together on the same
time series graph, as in Figure 2-23, you will see the difference in concentrations resulting from
the different mix of land uses in these two areas. You can also see that the duration over which
pollutants are washed off is much shorter than the duration of the entire runoff hydrograph (i.e., 1
hour versus about 6 hours). This results from having exhausted the available buildup of TSS over
this period of time.
! Graph - Subcatchment SI TSS...
E)
Subcatchment S1 TSS (MG.'L) -
Subcatchment S3 TSS (MG,1!)
90.0
80.0
700
600
O 50.0
s
CO 40.0
en
300
200
100
0,0
6810
Elapsed Time (hours)
12
14
Figure 2-23 Runoff TSS from selected subcatchments
2.7 Running a Continuous Simulation
As a final exercise in this tutorial we will demonstrate how to run a long-term continuous
simulation using a historical rainfall record and how to perform a statistical frequency analysis on
the results. The rainfall record will come from a file named sta310301.dat that was included with
the example data sets provided with EPA SWMM. It contains several years of hourly rainfall
beginning in January 1998. The data are stored in the National Climatic Data Center's DSI 3240
format, which SWMM can automatically recognize.
42
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To run a continuous simulation with this rainfall record:
i. Select the rain gage Gagel into the Property Editor.
2. Change the selection of Data Source to FILE.
3. Select the File Name data field and click the ellipsis button (or press the Enter key) to
bring up a standard Windows File Selection dialog.
4. Navigate to the folder where the SWMM example files were stored, select the file named
sta310301 .dat, and click Open to select the file and close the dialog.
5. In the Station No. field of the Property Editor enter 310301.
6. Select the Options category in the Project Browser and click the ^ button to bring up
the Simulation Options form.
7. On the General page of the form, select Kinematic Wave as the Routing Method (this
will help speed up the computations).
8. On the Dates page of the form, set both the Start Analysis and Start Reporting dates to
01/01/1998, and set the End Analysis date to 01/01/2000.
9. On the Time Steps page of the form, set the Routing Time Step to 300 seconds.
10. Close the Simulation Options form by clicking the OK button and start the simulation by
selecting Project » Run Simulation (or by clicking ^on the Standard Toolbar).
After our continuous simulation is completed we can perform a statistical frequency analysis on
any of the variables produced as output. For example, to determine the distribution of rainfall
volumes within each storm event over the two-year period simulated:
l. Select Report » Statistics or click the 2 button on the Standard Toolbar.
2. In the Statistics Selection dialog that appears, enter the values shown in Figure 2-24.
3. Click the OK button to close the form.
43
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Statistics Report Selection
Object Category System
Variable Analyzed
Event Time Period
Statistic
Event Thresh olds
Precipitation
Event Volume
Separation Time
Precipitation
Event-Dependent
Total
0
0
6
OK
Figure 2-24 Statistics selection dialog
The results of this request will be a Statistics Report form (see Figure 2-25) containing four
tabbed pages: a Summary page, an Events page containing a rank-ordered listing of each event,
a Histogram page containing a plot of the occurrence frequency versus event magnitude, and a
Frequency Plot page that plots event magnitude versus cumulative frequency.
The summary page shows that there were a total of 213 rainfall events. The Events page shows
that the largest rainfall event had a volume of 3.35 inches and occurred over a 24- hour period.
There were no events that matched the 3-inch, 6-hour design storm event used in our previous
single-event analysis that had produced some internal flooding. In fact, the Summary Report for
this continuous simulation indicates that there were no flooding or surcharge occurrences over
the simulation period.
44
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Statistics - System Precipitation
Summary Events f Histogram , Frequency Plot1
SUMMARY
STATISTICS
Object ,,, System
Variable ............. Precipitation (in/hr)
Event Period ......... Variable
Event Statistic ...... Total (in)
Event Threshold Precipitation > 0.0000 (in/hr)
Event Threshold Event Volume > 0.0000 (in)
Event Threshold Separation Tinse >= 6.0 (hr)
Period of Record 01/01/1998 to 01/01/2000
Number of Events 213
Event Frequency*...... 0. 076
Minimum Value ........ 0.010
Maximum Value 3, 350
Mean Value 0.309
Std. Deviation 0.449
Skewness Coeff. ...... 3,161
*Fraction of all reporting periods belonging to an event.
Figure 2-25 Example statistics report
We have only touched the surface of SWMM's capabilities. Some additional features of the
program that you will find useful include:
• utilizing additional types of drainage elements, such as storage units, flow dividers,
pumps, and regulators, to model more complex types of systems
• using control rules to simulate real-time operation of pumps and regulators
• employing different types of externally-imposed inflows at drainage system nodes, such
as direct time series inflows, dry weather inflows, and rainfall-derived infiltration/inflow
• modeling groundwater interflow between aquifers beneath subcatchment areas and
drainage system nodes
• modeling snow fall accumulation and melting within subcatchments
• adding calibration data to a project so that simulated results can be compared with
measured values
• utilizing a background street, site plan, or topo map to assist in laying out a system's
drainage elements and to help relate simulated results to real-world locations.
You can find more information on these and other features in the remaining chapters of this
manual.
45
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CHAPTER 3 - SWMM'S CONCEPTUAL MODEL
This chapter discusses how SWMM models the objects and operational parameters that
constitute a stormwater drainage system. Details about how this information is entered into the
program are presented in later chapters. An overview is also given on the computational methods
that SWMM uses to simulate the hydrology, hydraulics and water quality behavior of a drainage
system.
3.1 Introduction
SWMM conceptualizes a drainage system as a series of water and material flows between
several major environmental compartments. These compartments and the SWMM objects they
contain include:
• The Atmosphere compartment, which generates precipitation and deposits pollutants
onto the land surface compartment. SWMM uses Rain Gage objects to represent rainfall
inputs to the system.
• The Land Surface compartment, which is represented through one or more
Subcatchment objects. It receives precipitation from the Atmospheric compartment in the
form of rain or snow; it sends outflow in the form of infiltration to the Groundwater
compartment and also as surface runoff and pollutant loadings to the Transport
compartment.
• The Groundwater compartment receives infiltration from the Land Surface compartment
and transfers a portion of this inflow to the Transport compartment. This compartment is
modeled using Aquifer objects.
• The Transport compartment contains a network of conveyance elements (channels,
pipes, pumps, and regulators) and storage/treatment units that transport water to outfalls
or to treatment facilities. Inflows to this compartment can come from surface runoff,
groundwater interflow, sanitary dry weather flow, or from user-defined hydrographs. The
components of the Transport compartment are modeled with Node and Link objects
Not all compartments need appear in a particular SWMM model. For example, one could model
just the transport compartment, using pre-defined hydrographs as inputs.
3.2 Visual Objects
Figure 3-1 depicts how a collection of SWMM's visual objects might be arranged together to
represent a stormwater drainage system. These objects can be displayed on a map in the SWMM
workspace. The following sections describe each of these objects.
46
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Raingage *9
Divider
Storage Unit
Subcatchment
Outfall
! Regulator
Pump
Figure 3-1 Physical objects used to model a drainage system
3.2.1 Rain Gages
Rain Gages supply precipitation data for one or more subcatchment areas in a study region. The
rainfall data can be either a user-defined time series or come from an external file. Several
different popular rainfall file formats currently in use are supported, as well as a standard user-
defined format. More details on these formats are presented in Section 11.3.
The principal input properties of rain gages include:
• rainfall data type (e.g., intensity, volume, or cumulative volume)
• recording time interval (e.g., hourly, 15-minute, etc.)
• source of rainfall data (input time series or external file)
• name of rainfall data source
3.2.2 Subcatchments
Subcatchments are hydrologic units of land whose topography and drainage system elements
direct surface runoff to a single discharge point. The user is responsible for dividing a study area
into an appropriate number of Subcatchments, and for identifying the outlet point of each
subcatchment. Discharge outlet points can be either nodes of the drainage system or other
Subcatchments.
Subcatchments are divided into pervious and impervious subareas. Surface runoff can infiltrate
into the upper soil zone of the pervious subarea, but not through the impervious subarea.
Impervious areas are themselves divided into two subareas - one that contains depression
storage and another that does not. Runoff flow from one subarea in a subcatchment can be
routed to the other subarea, or both subareas can drain to the subcatchment outlet.
47
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Infiltration of rainfall from the pervious area of a subcatchment into the unsaturated upper soil
zone can be described using four different models:
• Morton infiltration
• Modified Morton infiltration
• Green-Ampt infiltration
• Modified Green-Ampt infiltration
• Curve Number infiltration
To model the accumulation, re-distribution, and melting of precipitation that falls as snow on a
subcatchment, it must be assigned a Snow Pack object. To model groundwater flow between an
aquifer underneath the subcatchment and a node of the drainage system, the subcatchment must
be assigned a set of Groundwater parameters. Pollutant buildup and washoff from
subcatchments are associated with the Land Uses assigned to the subcatchment. Capture and
retention of rainfall/runoff using different types of low impact development practices (such as bio-
retention cells, infiltration trenches, porous pavement, vegetative swales, and rain barrels) can be
modeled by assigning a set of pre-designed LID controls to the subcatchment.
The other principal input parameters for subcatchments include:
• assigned rain gage
• outlet node or subcatchment
• assigned land uses
• tributary surface area
• imperviousness
• slope
• characteristic width of overland flow
• Manning's n for overland flow on both pervious and impervious areas
• depression storage in both pervious and impervious areas
• percent of impervious area with no depression storage.
3.2.3 Junction Nodes
Junctions are drainage system nodes where links join together. Physically they can represent the
confluence of natural surface channels, manholes in a sewer system, or pipe connection fittings.
External inflows can enter the system at junctions. Excess water at a junction can become
partially pressurized while connecting conduits are surcharged and can either be lost from the
system or be allowed to pond atop the junction and subsequently drain back into the junction.
The principal input parameters for a junction are:
• invert (channel or manhole bottom) elevation
48
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• height to ground surface
• ponded surface area when flooded (optional)
• external inflow data (optional).
3.2.4 Outfall Nodes
Outfalls are terminal nodes of the drainage system used to define final downstream boundaries
under Dynamic Wave flow routing. For other types of flow routing they behave as a junction. Only
a single link can be connected to an outfall node, and the option exists to have the outfall
discharge onto a subcatchment's surface.
The boundary conditions at an outfall can be described by any one of the following stage
relationships:
• the critical or normal flow depth in the connecting conduit
• a fixed stage elevation
• a tidal stage described in a table of tide height versus hour of the day
• a user-defined time series of stage versus time.
The principal input parameters for outfalls include:
• invert elevation
• boundary condition type and stage description
• presence of a flap gate to prevent backflow through the outfall.
3.2.5 Flow Divider Nodes
Flow Dividers are drainage system nodes that divert inflows to a specific conduit in a prescribed
manner. A flow divider can have no more than two conduit links on its discharge side. Flow
dividers are only active under Steady Flow and Kinematic Wave routing and are treated as simple
junctions under Dynamic Wave routing.
There are four types of flow dividers, defined by the manner in which inflows are diverted:
Cutoff Divider. diverts all inflow above a defined cutoff value.
Overflow Divider. diverts all inflow above the flow capacity of the non-diverted
conduit.
Tabular Divider: uses a table that expresses diverted flow as a function of total
inflow.
Weir Divider. uses a weir equation to compute diverted flow.
The flow diverted through a weir divider is computed by the following equation
49
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where Qd,v = diverted flow, Cw = weir coefficient, Hw = weir height and /Ms computed as
r z~>in i^min
max Xi-mm
where Q/n is the inflow to the divider, Qm,n is the flow at which diversion begins, and
O — f ff^'^
timax - w w _ jhe user-specified parameters for the weir divider are Qm/n, Hw, and Cw.
The principal input parameters for a flow divider are:
• junction parameters (see above)
• name of the link receiving the diverted flow
• method used for computing the amount of diverted flow.
3.2.6 Storage Units
Storage Units are drainage system nodes that provide storage volume. Physically they could
represent storage facilities as small as a catch basin or as large as a lake. The volumetric
properties of a storage unit are described by a function or table of surface area versus height. In
addition to receiving inflows and discharging outflows to other nodes in the drainage network,
storage nodes can also lose water from surface evaporation and from seepage into native soil.
The principal input parameters for storage units include:
• invert (bottom) elevation
• maximum depth
• depth-surface area data
• evaporation potential
• seepage parameters (optional)
• external inflow data (optional).
3.2.7 Conduits
Conduits are pipes or channels that move water from one node to another in the conveyance
system. Their cross-sectional shapes can be selected from a variety of standard open and closed
geometries as listed in Table 3-1.
Most open channels can be represented with a rectangular, trapezoidal, or user-defined irregular
cross-section shape. For the latter, a Transect object is used to define how depth varies with
distance across the cross-section (see Section 3.3.5 below). Most new drainage and sewer pipes
are circular while culverts typically have elliptical or arch shapes. Elliptical and Arch pipes come in
standard sizes that are listed in Appendix A.12 and A.13. The Filled Circular shape allows the
bottom of a circular pipe to be filled with sediment and thus limit its flow capacity. The Custom
50
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Closed Shape allows any closed geometrical shape that is symmetrical about the center line to
be defined by supplying a Shape Curve for the cross section (see Sections.3.11 below).
SWMM uses the Manning equation to express the relationship between flow rate (Q), cross-
sectional area (A), hydraulic radius (R), and slope (S) in all conduits. For standard U.S. units,
n
where n is the Manning roughness coefficient. The slope S is interpreted as either the conduit
slope or the friction slope (i.e., head loss per unit length), depending on the flow routing method
used.
For pipes with Circular Force Main cross-sections either the Hazen-Williams or Darcy-Weisbach
formula is used in place of the Manning equation for fully pressurized flow. For U.S. units the
Hazen-Williams formula is:
where C is the Hazen-Williams C-factor which varies inversely with surface roughness and is
supplied as one of the cross-section's parameters. The Darcy-Weisbach formula is:
where g is the acceleration of gravity and f is the Darcy-Weisbach friction factor. For turbulent
flow, the latter is determined from the height of the roughness elements on the walls of the pipe
(supplied as an input parameter) and the flow's Reynolds Number using the Colebrook-White
equation. The choice of which equation to use is a user-supplied option.
A conduit does not have to be assigned a Force Main shape for it to pressurize. Any of
the closed cross-section shapes can potentially pressurize and thus function as force
mains that use the Manning equation to compute friction losses.
A constant rate of exfiltration of water along the length of the conduit can be modeled by
supplying a Seepage Rate value (in/hr or mm/hr). This only accounts for seepage losses, not
infiltration of rainfall dependent groundwater. The latter can be modeled using SWMM's RDM
feature (see Section 3.3.6).
51
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Table 3-1 Available cross section shapes for conduits
Name
Circular
Filled Circular
Rectangular
-Open
Triangular
Vertical
Ellipse
Parabolic
Rectangular-
Triangular
Modified
Baskethandle
Horseshoe
Catenary
Baskethandle
Irregular
Natural
Channel
Parameters
Full Height
Full Height,
Filled Depth
Full Height
Width
Full Height,
Top Width
Full Height,
Max. Width
Full Height,
Top Width
Full Height,
Top Width
Triangle
Height
Full Height,
Bottom
Width,
Top Radius
Full Height
Full Height
Full Height
Transect
Coordinates
Shape
$32
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&.>'j
^^^^^
m
/' ''
' V ,
/ f ' *
•\
r^
V
i ,
', * /
\J
• 7 ,.^4
«^£>
^"~r^\
$.?.•'!•
1 /' ,, i
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&&
~X
r ^
t^J
\ /
V F /
^
Name
Circular Force
Main
Rectangular -
Closed
Trapezoidal
Horizontal
Ellipse
Arch
Power
Rectangular-
Round
Egg
Gothic
Semi-Elliptical
Semi-Circular
Custom
Closed Shape
Parameters
Full Height,
Roughness
Full Height,
Width
Full Height,
Base Width,
Sirlp Slonp^
Full Height,
Max. Width
Full Height,
Max. Width
Full Height,
Top Width,
Exponent
Full Height,
Top Width
Bottom
Radius
Full Height
Full Height
Full Height
Full Height
Full Height,
Shape
Curve
Coordinates
Shape
®
'f *'',/<'
\ !'
'• T '
.-"' """-,.
> • ^
<:'»-;
^«,^,«*^
f'~~~---*
( '•'' ' Jr. '5
'"' * /
\''1
\/
?yr~3
•"•••^T ' jjju&^
O
^P
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i '' ' 'j
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h>\
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**^iLLc,6t
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(^'•^
52
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A conduit can also be designated to act as a culvert (see Figure 3-2) if a Culvert Inlet Geometry
code number is assigned to it. These code numbers are listed in Appendix A.10. Culvert conduits
are checked continuously during dynamic wave flow routing to see if they operate under Inlet
Control as defined in the Federal Highway Administration's publication Hydraulic Design of
Highway Culverts Third Edition (Publication No. FHWA-HIF-12-026, April 2012). Under inlet
control a culvert obeys a particular flow versus inlet depth rating curve whose shape depends on
the culvert's shape, size, slope, and inlet geometry.
SB,.'.'
Figure 3-2 Concrete Box Culvert
The principal input parameters for conduits are:
• names of the inlet and outlet nodes
• offset height or elevation above the inlet and outlet node inverts
• conduit length
• Manning's roughness
• cross-sectional geometry
• entrance/exit losses (optional)
• seepage rate (optional)
• presence of a flap gate to prevent reverse flow (optional)
• inlet geometry code number if the conduit acts as a culvert (optional).
53
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3.2.8 Pumps
Pumps are links used to lift water to higher elevations. A pump curve describes the relation
between a pump's flow rate and conditions at its inlet and outlet nodes. Five different types of
pump curves are supported:
Typel
An off-line pump with a wet well
where flow increases incrementally
with available wet well volume •—n
Volume
Type2
An in-line pump where flow
increases incrementally with inlet
node depth.
Depth
Type3
An in-line pump where flow varies
continuously with head difference
between the inlet and outlet nodes.
Flow
Type4
A variable speed in-line pump
where flow varies continuously with
inlet node depth.
Depth
Ideal
An "ideal" transfer pump whose flow rate equals the inflow rate at its inlet node. No curve is
required. The pump must be the only outflow link from its inlet node. Used mainly for preliminary
design.
The on/off status of pumps can be controlled dynamically by specifying startup and shutoff water
depths at the inlet node or through user-defined Control Rules. Rules can also be used to
simulate variable speed drives that modulate pump flow.
54
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The principal input parameters for a pump include:
• names of its inlet and outlet nodes
• name of its pump curve (or * for an Ideal pump)
• initial on/off status
• startup and shutoff depths.
3.2.9 Flow Regulators
Flow Regulators are structures or devices used to control and divert flows within a conveyance
system. They are typically used to:
• control releases from storage facilities
• prevent unacceptable surcharging
• divert flow to treatment facilities and interceptors
SWMM can model the following types of flow regulators: Orifices, Weirs, and Outlets.
Orifices
Orifices are used to model outlet and diversion structures in drainage systems, which are typically
openings in the wall of a manhole, storage facility, or control gate. They are internally represented
in SWMM as a link connecting two nodes. An orifice can have either a circular or rectangular
shape, be located either at the bottom or along the side of the upstream node, and have a flap
gate to prevent backflow.
Orifices can be used as storage unit outlets under all types of flow routing. If not attached to a
storage unit node, they can only be used in drainage networks that are analyzed with Dynamic
Wave flow routing.
The flow through a fully submerged orifice is computed as
where Q = flow rate, C = discharge coefficient, A = area of orifice opening, g = acceleration of
gravity, and h = head difference across the orifice. The height of an orifice's opening can be
controlled dynamically through user-defined Control Rules. This feature can be used to model
gate openings and closings. Flow through a partially full orifice is computed using an equivalent
weir equation.
The principal input parameters for an orifice include:
• names of its inlet and outlet nodes
• configuration (bottom or side)
• shape (circular or rectangular)
• height or elevation above the inlet node invert
55
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discharge coefficient
time to open or close.
Weirs
Weirs, like orifices, are used to model outlet and diversion structures in a drainage system. Weirs
are typically located in a manhole, along the side of a channel, or within a storage unit. They are
internally represented in SWMM as a link connecting two nodes, where the weir itself is placed at
the upstream node. A flap gate can be included to prevent backflow.
Five varieties of weirs are available, each incorporating a different formula for computing flow
across the weir as listed in Table 3-2.
Table 3-2 Available types of weirs
Weir Type
Transverse
Side flow
V- notch
Trapezoidal
Roadway
Cross Section
Shape
Rectangular
Rectangular
Triangular
Trapezoidal
Rectangular
Flow Formula
CwLh^
CwLh^
CwSh^
CwLh^+CwsSh^
CwLh^
Cw = weir discharge coefficient, L = weir length, S = side slope of
V-notch or trapezoidal weir, h = head difference across the weir,
Cws = discharge coefficient through sides of trapezoidal weir.
The Roadway weir is a broad crested rectangular weir used model roadway crossings usually in
conjunction with culvert-type conduits (see Figure 3-2). It uses curves from the Federal Highway
Administration publication Hydraulic Design of Highway Culverts Third Edition (Publication No.
FHWA-HIF-12-026, April 2012) to determine CM/as a function of h and roadway width.
Weirs can be used as storage unit outlets under all types of flow routing. If not attached to a
storage unit, they can only be used in drainage networks that are analyzed with Dynamic Wave
flow routing.
The height of the weir crest above the inlet node invert can be controlled dynamically through
user-defined Control Rules. This feature can be used to model inflatable dams.
Weirs can either be allowed to surcharge or not. A surcharged weir will use an equivalent orifice
equation to compute the flow through it. Weirs placed in open channels would normally not be
allowed to surcharge while those placed in closed diversion structures or those used to represent
storm drain inlet openings would be allowed to.
56
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The principal input parameters for a weir include:
• names of its inlet and outlet nodes
• shape and geometry
• crest height or elevation above the inlet node invert
• discharge coefficient.
Outlets
Outlets are flow control devices that are typically used to control outflows from storage units.
They are used to model special head-discharge relationships that cannot be characterized by
pumps, orifices, or weirs. Outlets are internally represented in SWMM as a link connecting two
nodes. An outlet can also have a flap gate that restricts flow to only one direction.
Outlets attached to storage units are active under all types of flow routing. If not attached to a
storage unit, they can only be used in drainage networks analyzed with Dynamic Wave flow
routing.
A user-defined rating curve determines an outlet's discharge flow as a function of either the
freeboard depth above the outlet's opening or the head difference across it. Control Rules can be
used to dynamically adjust this flow when certain conditions exist.
The principal input parameters for an outlet include:
• names of its inlet and outlet nodes
• height or elevation above the inlet node invert
• function or table containing its head (or depth) - discharge relationship.
3.2.10 Map Labels
Map Labels are optional text labels added to SWMM's Study Area Map to help identify particular
objects or regions of the map. The labels can be drawn in any Windows font, freely edited and be
dragged to any position on the map.
3.3 Non-Visual Objects
In addition to physical objects that can be displayed visually on a map, SWMM utilizes several
classes of non-visual data objects to describe additional characteristics and processes within a
study area.
57
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3.3.1 Climatology
Temperature
Air temperature data are used when simulating snowfall and snowmelt processes during runoff
calculations. They can also be used to compute daily evaporation rates. If these processes are
not being simulated then temperature data are not required. Air temperature data can be supplied
to SWMM from one of the following sources:
• a user-defined time series of point values (values at intermediate times are interpolated)
• an external climate file containing daily minimum and maximum values (SWMM fits a
sinusoidal curve through these values depending on the day of the year).
For user-defined time series, temperatures are in degrees F for US units and degrees C for
metric units. The external climate file can also be used to directly supply evaporation and wind
speed as well.
Evaporation
Evaporation can occur for standing water on subcatchment surfaces, for subsurface water in
groundwater aquifers, for water traveling through open channels, and for water held in storage
units. Evaporation rates can be stated as:
• a single constant value
• a set of monthly average values
• a user-defined time series of values
• values computed from the daily temperatures contained in an external climate file
• daily values read directly from an external climate file.
If rates are read directly from a climate file, then a set of monthly pan coefficients should also be
supplied to convert the pan evaporation data to free water-surface values. An option is also
available to allow evaporation only during periods with no precipitation.
Note that the evaporation rates supplied to SWMM are potential rates. The actual amount of
water evaporated will depend on the amount of water available.
Wind Speed
Wind speed is an optional climatic variable that is only used for snowmelt calculations. SWMM
can use either a set of monthly average speeds or wind speed data contained in the same
climate file used for daily minimum/maximum temperatures.
Snowmelt
Snowmelt parameters are climatic variables that apply across the entire study area when
simulating snowfall and snowmelt. They include:
58
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• the air temperature at which precipitation falls as snow
• heat exchange properties of the snow surface
• study area elevation, latitude, and longitude correction
Areal Depletion
Areal depletion refers to the tendency of accumulated snow to melt non-uniformly over the
surface of a subcatchment. As the melting process proceeds, the area covered by snow gets
reduced. This behavior is described by an Areal Depletion Curve that plots the fraction of total
area that remains snow covered against the ratio of the actual snow depth to the depth at which
there is 100% snow cover. A typical ADC for a natural area is shown in Figure 3-3. Two such
curves can be supplied to SWMM, one for impervious areas and another for pervious areas.
o
"•S
is
0.8
0.6
04
0.2
0 0.2 0.4 0.6 0,8 1
Fraction Snow Covered Area
Figure 3-3 Areal depletion curve fora natural area
Climate Adjustments
Climate Adjustments are optional modifications applied to the temperature, evaporation rate, and
rainfall intensity that SWMM would otherwise use at each time step of a simulation. Separate sets
of adjustments that vary periodically by month of the year can be assigned to these variables.
They provide a simple way to examine the effects of future climate change without having to
modify the original climatic time series.
In a similar manner, a set of monthly adjustments can be applied to the hydraulic conductivity
used in computing rainfall infiltration on pervious land surfaces and exfiltration from storage
nodes and conduits. These can reflect the increase of hydraulic conductivity with increasing
temperature or the effect that seasonal changes in land surface conditions, such as frozen
ground, can have on infiltration capacity.
59
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3.3.2 Snow Packs
Snow Pack objects contain parameters that characterize the buildup, removal, and melting of
snow over three types of sub-areas within a subcatchment:
• The Plowable snow pack area consists of a user-defined fraction of the total impervious
area. It is meant to represent such areas as streets and parking lots where plowing and
snow removal can be done.
• The Impervious snow pack area covers the remaining impervious area of a
subcatchment.
• The Pervious snow pack area encompasses the entire pervious area of a subcatchment.
Each of these three areas is characterized by the following parameters:
• Minimum and maximum snow melt coefficients
• minimum air temperature for snow melt to occur
• snow depth above which 100% areal coverage occurs
• initial snow depth
• initial and maximum free water content in the pack.
In addition, a set of snow removal parameters can be assigned to the Plowable area. These
parameters consist of the depth at which snow removal begins and the fractions of snow moved
onto various other areas.
Subcatchments are assigned a snow pack object through their Snow Pack property. A single
snow pack object can be applied to any number of subcatchments. Assigning a snow pack to a
subcatchment simply establishes the melt parameters and initial snow conditions for that
subcatchment. Internally, SWMM creates a "physical" snow pack for each subcatchment, which
tracks snow accumulation and melting for that particular subcatchment based on its snow pack
parameters, its amount of pervious and impervious area, and the precipitation history it sees.
3.3.3 Aquifers
Aquifers are sub-surface groundwater zones used to model the vertical movement of water
infiltrating from the subcatchments that lie above them. They also permit the infiltration of
groundwater into the drainage system, or exfiltration of surface water from the drainage system,
depending on the hydraulic gradient that exists. Aquifers are only required in models that need to
explicitly account for the exchange of groundwater with the drainage system or to establish base
flow and recession curves in natural channels and non-urban systems. The parameters of an
aquifer object can be shared by several subcatchments but there is no exchange of groundwater
between subcatchments. A drainage system node can exchange groundwater with more than
one subcatchment.
Aquifers are represented using two zones - an un-saturated zone and a saturated zone. Their
behavior is characterized using such parameters as soil porosity, hydraulic conductivity,
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evapotranspiration depth, bottom elevation, and loss rate to deep groundwater. In addition, the
initial water table elevation and initial moisture content of the unsaturated zone must be supplied.
Aquifers are connected to subcatchments and to drainage system nodes through a
subcatchment's Groundwater Flow property. This property also contains parameters that govern
the rate of groundwater flow between the aquifer's saturated zone and the drainage system node.
3.3.4 Unit Hydrographs
Unit Hydrographs (UHs) estimate rainfall-dependent infiltration/inflow (RDM) into a sewer system.
A UH set contains up to three such hydrographs, one for a short-term response, one for an
intermediate-term response, and one for a long-term response. A UH group can have up to 12
UH sets, one for each month of the year. Each UH group is considered as a separate object by
SWMM, and is assigned its own unique name along with the name of the rain gage that supplies
rainfall data to it.
Each unit hydrograph, as shown in Figure 3-4, is defined by three parameters:
• R: the fraction of rainfall volume that enters the sewer system
• T: the time from the onset of rainfall to the peak of the UH in hours
• K: the ratio of time to recession of the UH to the time to peak
Qpeak
3
o
Time
Figure 3-4 An RDM unit hydrograph
Each unit hydrograph can also have a set of Initial Abstraction (IA) parameters associated with it.
These determine how much rainfall is lost to interception and depression storage before any
excess rainfall is generated and transformed into RDM flow by the hydrograph. The IA parameters
consist of:
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• a maximum possible depth of IA (inches or mm),
• a recovery rate (inches/day or mm/day) at which stored IA is depleted during dry periods,
• an initial depth of stored IA (inches or mm).
To generate RDM into a drainage system node, the node must identify (through its Inflows
property) the UH group and the area of the surrounding sewershed that contributes RDM flow.
An alternative to using unit hydrographs to define RDM flow is to create an external RDM
interface file, which contains RDM time series data. See Section 11.7 Interface Files.
W Unit hydrographs could also be used to replace SWMM's main rainfall-runoff process that
uses Subcatchment objects, provided that properly calibrated UHs are utilized. In this
case what SWMM calls RDM inflow to a node would actually represent overland runoff.
3.3.5 Transects
Transects refer to the geometric data that describe how bottom elevation varies with horizontal
distance over the cross section of a natural channel or irregular-shaped conduit. Figure 3-5
displays an example transect for a natural channel.
Transect 92
Qverbark •» Channe-
304
303
802
801
800
799
798
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
Station (ft)
Figure 3-5 Example of a natural channel transect
Each transect must be given a unique name. Conduits refer to that name to represent their
shape. A special Transect Editor is available for editing the station-elevation data of a transect.
SWMM internally converts these data into tables of area, top width, and hydraulic radius versus
channel depth. In addition, as shown in Figure 3-5, each transect can have a left and right
overbank section whose Manning's roughness can be different from that of the main channel.
This feature can provide more realistic estimates of channel conveyance under high flow
conditions.
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3.3.6 External Inflows
In addition to inflows originating from subcatchment runoff and groundwater, drainage system
nodes can receive three other types of external inflows:
• Direct Inflows - These are user-defined time series of inflows added directly into a node.
They can be used to perform flow and water quality routing in the absence of any runoff
computations (as in a study area where no subcatchments are defined).
• Dry Weather Inflows - These are continuous inflows that typically reflect the contribution
from sanitary sewage in sewer systems or base flows in pipes and stream channels.
They are represented by an average inflow rate that can be periodically adjusted on a
monthly, daily, and hourly basis by applying Time Pattern multipliers to this average
value.
• Rainfall-Dependent Infiltration/Inflow (RDM) - These are stormwater flows that enter
sanitary or combined sewers due to "inflow" from direct connections of downspouts,
sump pumps, foundation drains, etc. as well as "infiltration" of subsurface water through
cracked pipes, leaky joints, poor manhole connections, etc. RDM can be computed for a
given rainfall record based on set of triangular unit hydrographs (UH) that determine a
short-term, intermediate-term, and long-term inflow response for each time period of
rainfall. Any number of UH sets can be supplied for different sewershed areas and
different months of the year. RDM flows can also be specified in an external RDM interface
file.
Direct, Dry Weather, and RDM inflows are properties associated with each type of drainage
system node (junctions, outfalls, flow dividers, and storage units) and can be specified when
nodes are edited. They can be used to perform flow and water quality routing in the absence of
any runoff computations (as in a study area where no subcatchments are defined). It is also
possible to make the outflows generated from an upstream drainage system be the inflows to a
downstream system by using interface files. See Section 11.7 for further details.
3.3.7 Control Rules
Control Rules determine how pumps and regulators in the drainage system will be adjusted over
the course of a simulation. Some examples of these rules are:
Simple time-based pump control:
RULE R1
IF SIMULATION TIME > 8
THEN PUMP 12 STATUS = ON
ELSE PUMP 12 STATUS = OFF
Multiple-condition orifice gate control:
RULE R2A
IF NODE 23 DEPTH > 12
AND LINK 165 FLOW > 100
THEN ORIFICE R55 SETTING = 0.5
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RULE R2B
IF NODE 23 DEPTH > 12
AND LINK 165 FLOW > 200
THEN ORIFICE R55 SETTING = 1.0
RULE R2C
IF NODE 23 DEPTH <= 12
OR LINK 165 FLOW <= 100
THEN ORIFICE R55 SETTING = 0
Pump station operation:
RULE R3A
IF NODE N1 DEPTH > 5
THEN PUMP N1A STATUS = ON
RULE R3B
IF NODE N1 DEPTH > 7
THEN PUMP N1B STATUS = ON
RULE R3C
IF NODE N1 DEPTH <= 3
THEN PUMP N1A STATUS = OFF
AND PUMP N1B STATUS = OFF
Modulated weir height control:
RULE R4
IF NODE N2 DEPTH >= 0
THEN WEIR W25 SETTING = CURVE C25
Appendix C.3 describes the control rule format in more detail and the special Editor used to edit
them.
3.3.8 Pollutants
SWMM can simulate the generation, inflow and transport of any number of user-defined
pollutants. Required information for each pollutant includes:
• pollutant name
• concentration units (i.e., milligrams/liter, micrograms/liter, or counts/liter)
• concentration in rainfall
• concentration in groundwater
• concentration in inflow/infiltration
• concentration in dry weather flow
• initial concentration throughout the conveyance system
• first-order decay coefficient.
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Co-pollutants can also be defined in SWMM. For example, pollutant X can have a co-pollutant Y,
meaning that the runoff concentration of X will have some fixed fraction of the runoff
concentration of Y added to it.
Pollutant buildup and washoff from subcatchment areas are determined by the land uses
assigned to those areas. Input loadings of pollutants to the drainage system can also originate
from external time series inflows as well as from dry weather inflows.
3.3.9 Land Uses
Land Uses are categories of development activities or land surface characteristics assigned to
subcatchments. Examples of land use activities are residential, commercial, industrial, and
undeveloped. Land surface characteristics might include rooftops, lawns, paved roads,
undisturbed soils, etc. Land uses are used solely to account for spatial variation in pollutant
buildup and washoff rates within subcatchments.
The SWMM user has many options for defining land uses and assigning them to subcatchment
areas. One approach is to assign a mix of land uses for each subcatchment, which results in all
land uses within the subcatchment having the same pervious and impervious characteristics.
Another approach is to create subcatchments that have a single land use classification along with
a distinct set of pervious and impervious characteristics that reflects the classification.
The following processes can be defined for each land use category:
• pollutant buildup
• pollutant washoff
• street cleaning.
Pollutant Buildup
Pollutant buildup that accumulates within a land use category is described (or "normalized") by
either a mass per unit of subcatchment area or per unit of curb length. Mass is expressed in
pounds for US units and kilograms for metric units. The amount of buildup is a function of the
number of preceding dry weather days and can be computed using one of the following functions:
Power Function: Pollutant buildup (B) accumulates proportionally to time (t) raised to some
power, until a maximum limit is achieved,
B=Min(ci,C2tC3)
where C? = maximum buildup possible (mass per unit of area or curb length), €2 = buildup rate
constant, and Cs = time exponent.
Exponential Function: Buildup follows an exponential growth curve that approaches a maximum
limit asymptotically,
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where C? = maximum buildup possible (mass per unit of area or curb length) and €2 = buildup
rate constant (1/days).
Saturation Function: Buildup begins at a linear rate that continuously declines with time until a
saturation value is reached,
C2+t
where C? = maximum buildup possible (mass per unit area or curb length) and 62 = half-
saturation constant (days to reach half of the maximum buildup).
External Time Series: This option allows one to use a Time Series to describe the rate of
buildup per day as a function of time. The values placed in the time series would have units of
mass per unit area (or curb length) per day. One can also provide a maximum possible buildup
(mass per unit area or curb length) with this option and a scaling factor that multiplies the time
series values.
Pollutant Washoff
Pollutant washoff from a given land use category occurs during wet weather periods and can be
described in one of the following ways:
Exponential Washoff: The washoff load (I/I/) in units of mass per hour is proportional to the
product of runoff raised to some power and to the amount of buildup remaining,
W = C,qClB
where C? = washoff coefficient, €2 = washoff exponent, q = runoff rate per unit area (inches/hour
or mm/hour), and 8 = pollutant buildup in mass units. The buildup here is the total mass (not per
area or curb length) and both buildup and washoff mass units are the same as used to express
the pollutant's concentration (milligrams, micrograms, or counts).
Rating Curve Washoff: The rate of washoff I/I/ in mass per second is proportional to the runoff
rate raised to some power,
W = C,QC2
where C? = washoff coefficient, €2 = washoff exponent, and Q = runoff rate in user-defined flow
units.
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Event Mean Concentration: This is a special case of Rating Curve Washoff where the exponent
is 1.0 and the coefficient Ci represents the washoff pollutant concentration in mass per liter
(Note: the conversion between user-defined flow units used for runoff and liters is handled
internally by SWMM).
Note that in each case buildup is continuously depleted as washoff proceeds, and washoff
ceases when there is no more buildup available.
Washoff loads for a given pollutant and land use category can be reduced by a fixed percentage
by specifying a BMP Removal Efficiency that reflects the effectiveness of any BMP controls
associated with the land use. It is also possible to use the Event Mean Concentration option by
itself, without having to model any pollutant buildup at all.
Street Sweeping
Street sweeping can be used on each land use category to periodically reduce the accumulated
buildup of specific pollutants. The parameters that describe street sweeping include:
• days between sweeping
• days since the last sweeping at the start of the simulation
• the fraction of buildup of all pollutants that is available for removal by sweeping
• the fraction of available buildup for each pollutant removed by sweeping
Note that these parameters can be different for each land use, and the last parameter can vary
also with pollutant.
3.3.10 Treatment
Removal of pollutants from the flow streams entering any drainage system node is modeled by
assigning a set of treatment functions to the node. A treatment function can be any well-formed
mathematical expression involving:
• the pollutant concentration
• the removals of other pollutants
• any of several process variables, such as flow rate, depth, hydraulic residence time, etc.
The result of the treatment function can be either a concentration (denoted by the letter C) or a
fractional removal (denoted by R). For example, a first-order decay expression for BOD exiting
from a storage node might be expressed as:
C = BOD *exp(-0.05 *HRT)
where HRT is the reserved variable name for hydraulic residence time. The removal of some
trace pollutant that is proportional to the removal of total suspended solids (TSS) could be
expressed as:
R = 0.75*R TSS
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Section C.22 provides more details on how user-defined treatment equations are supplied to the
program.
3.3.11 Curves
Curve objects are used to describe a functional relationship between two quantities. The following
types of curves are used in SWMM:
• Storage - describes how the surface area of a Storage Unit node varies with water depth.
• Shape - describes how the width of a customized cross-sectional shape varies with
height for a Conduit link.
• Diversion - relates diverted outflow to total inflow for a Flow Divider node.
• Tidal - describes how the stage at an Outfall node changes by hour of the day.
• Pump - relates flow through a Pump link to the depth or volume at the upstream node or
to the head delivered by the pump.
• Rating - relates flow through an Outlet link to the freeboard depth or head difference
across the outlet.
• Control - determines how the control setting of a pump or flow regulator varies as a
function of some control variable (such as water level at a particular node) as specified in
a Modulated Control rule.
Each curve must be given a unique name and can be assigned any number of data pairs.
3.3.12 Time Series
Time Series objects are used to describe how certain object properties vary with time. Time
series can be used to describe:
• temperature data
• evaporation data
• rainfall data
• water stage at outfall nodes
• external inflow hydrographs at drainage system nodes
• external inflow pollutographs at drainage system nodes
• control settings for pumps and flow regulators..
Each time series must be given a unique name and can be assigned any number of time-value
data pairs. Time can be specified either as hours from the start of a simulation or as an absolute
date and time-of-day. Time series data can either be entered directly into the program or be
accessed from a user-supplied Time Series file.
For rainfall time series, it is only necessary to enter periods with non-zero rainfall
amounts. SWMM interprets the rainfall value as a constant value lasting over the
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recording interval specified for the rain gage that utilizes the time series. For all other
types of time series, SWMM uses interpolation to estimate values at times that fall in
between the recorded values.
For times that fall outside the range of the time series, SWMM will use a value of 0 for
rainfall and external inflow time series, and either the first or last series value for
temperature, evaporation, and water stage time series.
3.3.13 Time Patterns
Time Patterns allow external Dry Weather Flow (DWF) to vary in a periodic fashion. They consist
of a set of adjustment factors applied as multipliers to a baseline DWF flow rate or pollutant
concentration. The different types of time patterns include:
Monthly - one multiplier for each month of the year
Daily - one multiplier for each day of the week
Hourly - one multiplier for each hour from 12 AM to 11 PM
Weekend - hourly multipliers for weekend days
Each Time Pattern must have a unique name and there is no limit on the number of patterns that
can be created. Each dry weather inflow (either flow or quality) can have up to four patterns
associated with it, one for each type listed above.
3.3.14 LID Controls
LID Controls are low impact development practices designed to capture surface runoff and
provide some combination of detention, infiltration, and evapotranspiration to it. They are
considered as properties of a given subcatchment, similar to how Aquifers and Snow Packs are
treated. SWMM can explicitly model eight different generic types of LID controls:
Bio-retention Cells are depressions that contain vegetation grown in an
engineered soil mixture placed above a gravel drainage bed. They
provide storage, infiltration and evaporation of both direct rainfall and
runoff captured from surrounding areas.
Rain Gardens are a type of bio-retention cell consisting of just the
engineered soil layer with no gravel bed below it.
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Green Roofs are another variation of a bio-retention cell that have a soil
layer laying atop a special drainage mat material that conveys excess
percolated rainfall off of the roof.
Infiltration Trenches are narrow ditches filled with gravel that intercept
runoff from upslope impervious areas. They provide storage volume and
additional time for captured runoff to infiltrate the native soil below.
Continuous Permeable Pavement systems are excavated areas filled
with gravel and paved over with a porous concrete or asphalt mix.
Normally all rainfall will immediately pass through the pavement into the
gravel storage layer below it where it can infiltrate at natural rates into
the site's native soil. Block Paver systems consist of impervious paver
blocks placed on a sand or pea gravel bed with a gravel storage layer
below. Rainfall is captured in the open spaces between the blocks and
conveyed to the storage zone and native soil below.
Rain Barrels (or Cisterns) are containers that collect roof runoff during
storm events and can either release or re-use the rainwater during dry
periods.
Rooftop Disconnection has downspouts discharge to pervious
landscaped areas and lawns instead of directly into storm drains. It can
also model roofs with directly connected drains that overflow onto
pervious areas.
Vegetative Swales are channels or depressed areas with sloping sides
covered with grass and other vegetation. They slow down the
conveyance of collected runoff and allow it more time to infiltrate the
native soil beneath it.
Bio-retention cells, infiltration trenches, and permeable pavement systems can contain optional
drain systems in their gravel storage beds to convey excess captured runoff off of the site and
prevent the unit from flooding. They can also have an impermeable floor or liner that prevents any
infiltration into the native soil from occurring. Infiltration trenches and permeable pavement
systems can also be subjected to a decrease in hydraulic conductivity overtime due to clogging.
Although some LID practices can also provide significant pollutant reduction benefits, at this time
SWMM only models the reduction in runoff mass load resulting from the reduction in runoff flow
volume.
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There are two different approaches for placing LID controls within a subcatchment:
• place one or more controls in an existing subcatchment that will displace an equal amount of
non-LID area from the subcatchment
• create a new subcatchment devoted entirely to just a single LID practice.
The first approach allows a mix of LIDs to be placed into a subcatchment, each treating a
different portion of the runoff generated from the non-LID fraction of the subcatchment. Note that
under this option the subcatchment's LIDs act in parallel - it is not possible to make them act in
series (i.e., have the outflow from one LID control become the inflow to another LID). Also, after
LID placement the subcatchment's Percent Impervious and Width properties may require
adjustment to compensate for the amount of original subcatchment area that has now been
replaced by LIDs (see Figure 3-6 below). For example, suppose that a subcatchment which is
40% impervious has 75% of that area converted to a permeable pavement LID. After the LID is
added the subcatchment's percent imperviousness should be changed to the percent of
impervious area remaining divided by the percent of non-LID area remaining. This works out to (1
- 0.75)*40 / (100 - 0.75*40) or 14.3 %.
Width
Width
Before LIDs
After LIDs
Figure 3-6 Adjustment of subcatchment parameters after LID placement
Under this first approach the runoff available for capture by the subcatchment's LIDs is the runoff
generated from its impervious area. If the option to re-route some fraction of this runoff to the
pervious area is exercised, then only the remaining impervious runoff (if any) will be available for
LID treatment. Also note that green roofs and roof disconnection only treat the precipitation that
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falls directly on them and do not capture runoff from other impervious areas in their
subcatchment.
The second approach allows LID controls to be strung along in series and also allows runoff from
several different upstream subcatchments to be routed onto the LID subcatchment. If these
single-LID subcatchments are carved out of existing subcatchments, then once again some
adjustment of the Percent Impervious, Width and also the Area properties of the latter may be
necessary. In addition, whenever an LID occupies the entire subcatchment the values assigned
to the subcatchment's standard surface properties (such as imperviousness, slope, roughness,
etc.) are overridden by those that pertain to the LID unit.
Normally both surface and drain outflows from LID units are routed to the same outlet location
assigned to the parent subcatchment. However one can choose to return all LID outflow to the
pervious area of the parent subcatchment and/or route the drain outflow to a separate designated
outlet. (When both of these options are chosen, only the surface outflow is returned to the
pervious sub-area.)
3.4 Computational Methods
SWMM is a physically based, discrete-time simulation model. It employs principles of
conservation of mass, energy, and momentum wherever appropriate. This section briefly
describes the methods SWMM uses to model stormwater runoff quantity and quality through the
following physical processes:
• Surface Runoff • Infiltration
• Groundwater • Snowmelt
• Flow Routing • Surface Ponding
• Water Quality Routing
3.4.1 Surface Runoff
The conceptual view of surface runoff used by SWMM is illustrated in Figure 3-7 below. Each
subcatchment surface is treated as a nonlinear reservoir. Inflow comes from precipitation and any
designated upstream subcatchments. There are several outflows, including infiltration,
evaporation, and surface runoff. The capacity of this "reservoir" is the maximum depression
storage, which is the maximum surface storage provided by ponding, surface wetting, and
interception. Surface runoff per unit area, Q, occurs only when the depth of water in the
"reservoir" exceeds the maximum depression storage, ds, in which case the outflow is given by
Manning's equation. Depth of water over the subcatchment (d) is continuously updated with time
by solving numerically a water balance equation over the subcatchment.
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Precipitation
V
Evaporation
A
Runoff
Infiltration
Figure 3-7 Conceptual view of surface runoff
3.4.2 Infiltration
Infiltration is the process of rainfall penetrating the ground surface into the unsaturated soil zone
of pervious subcatchments areas. SWMM offers four choices for modeling infiltration:
Morton's Method
This method is based on empirical observations showing that infiltration decreases exponentially
from an initial maximum rate to some minimum rate over the course of a long rainfall event. Input
parameters required by this method include the maximum and minimum infiltration rates, a decay
coefficient that describes how fast the rate decreases over time, and a time it takes a fully
saturated soil to completely dry.
Modified Morton Method
This is a modified version of the classical Morton Method that uses the cumulative infiltration in
excess of the minimum rate as its state variable (instead of time along the Morton curve),
providing a more accurate infiltration estimate when low rainfall intensities occur. It uses the same
input parameters as does the traditional Morton Method.
Green-Ampt Method
This method for modeling infiltration assumes that a sharp wetting front exists in the soil column,
separating soil with some initial moisture content below from saturated soil above. The input
parameters required are the initial moisture deficit of the soil, the soil's hydraulic conductivity, and
the suction head at the wetting front. The recovery rate of moisture deficit during dry periods is
empirically related to the hydraulic conductivity.
Modified Green-Ampt Method
This method modifies the original Green-Ampt procedure by not depleting moisture deficit in the
top surface layer of soil during initial periods of low rainfall as was done in the original method.
This change can produce more realistic infiltration behavior for storms with long initial periods
where the rainfall intensity is below the soil's saturated hydraulic conductivity.
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Curve Number Method
This approach is adopted from the NRCS (SCS) Curve Number method for estimating runoff. It
assumes that the total infiltration capacity of a soil can be found from the soil's tabulated Curve
Number. During a rain event this capacity is depleted as a function of cumulative rainfall and
remaining capacity. The input parameters for this method are the curve number and the time it
takes a fully saturated soil to completely dry.
SWMM also allows the infiltration recovery rate to be adjusted by a fixed amount on a monthly
basis to account for seasonal variation in such factors as evaporation rates and groundwater
levels. This optional monthly soil recovery pattern is specified as part of a project's Evaporation
data.
3.4.3 Groundwater
Figure 3-8 is a definitional sketch of the two-zone groundwater model that is used in SWMM. The
upper zone is unsaturated with a variable moisture content of 6. The lower zone is fully saturated
and therefore its moisture content is fixed at the soil porosity 4>. The fluxes shown in the figure,
expressed as volume per unit area per unit time, consist of the following:
Upper
Zone
Zone
A- /r
KXXXXXXXXXXXXI p
-------
After computing the water fluxes that exist during a given time step, a mass balance is written for
the change in water volume stored in each zone so that a new water table depth and unsaturated
zone moisture content can be computed for the next time step.
3.4.4 Snowmelt
The snowmelt routine in SWMM is a part of the runoff modeling process. It updates the state of
the snow packs associated with each subcatchment by accounting for snow accumulation, snow
redistribution by areal depletion and removal operations, and snow melt via heat budget
accounting. Any snowmelt coming off the pack is treated as an additional rainfall input onto the
subcatchment.
At each runoff time step the following computations are made:
l. Air temperature and melt coefficients are updated according to the calendar date.
2. Any precipitation that falls as snow is added to the snow pack.
3. Any excess snow depth on the plowable area of the pack is redistributed according to the
removal parameters established for the pack.
4. Areal coverage of snow on the impervious and pervious areas of the pack is reduced
according to the Areal Depletion Curves defined for the study area.
5. The amount of snow in the pack that melts to liquid water is found using:
a. a heat budget equation for periods with rainfall, where melt rate increases with
increasing air temperature, wind speed, and rainfall intensity
b. a degree-day equation for periods with no rainfall, where melt rate equals the
product of a melt coefficient and the difference between the air temperature and
the pack's base melt temperature.
6. If no melting occurs, the pack temperature is adjusted up or down based on the product
of the difference between current and past air temperatures and an adjusted melt
coefficient. If melting occurs, the temperature of the pack is increased by the equivalent
heat content of the melted snow, up to the base melt temperature. Any remaining melt
liquid beyond this is available to runoff from the pack.
7. The available snowmelt is then reduced by the amount of free water holding capacity
remaining in the pack. The remaining melt is treated the same as an additional rainfall
input onto the subcatchment.
3.4.5 Flow Routing
Flow routing within a conduit link in SWMM is governed by the conservation of mass and
momentum equations for gradually varied, unsteady flow (i.e., the Saint Venant flow equations).
The SWMM user has a choice on the level of sophistication used to solve these equations:
• Steady Flow Routing
• Kinematic Wave Routing
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• Dynamic Wave Routing
Each of these routing methods employs the Manning equation to relate flow rate to flow depth
and bed (or friction) slope. For user-designated Force Main conduits, either the Hazen-Williams
or Darcy-Weisbach equation can be used when pressurized flow occurs.
Steady Flow Routing
Steady Flow routing represents the simplest type of routing possible (actually no routing) by
assuming that within each computational time step flow is uniform and steady. Thus it simply
translates inflow hydrographs at the upstream end of the conduit to the downstream end, with no
delay or change in shape. The normal flow equation is used to relate flow rate to flow area (or
depth).
This type of routing cannot account for channel storage, backwater effects, entrance/exit losses,
flow reversal or pressurized flow. It can only be used with dendritic conveyance networks, where
each node has only a single outflow link (unless the node is a divider in which case two outflow
links are required). This form of routing is insensitive to the time step employed and is really only
appropriate for preliminary analysis using long-term continuous simulations.
Kinematic Wave Routing
This routing method solves the continuity equation along with a simplified form of the momentum
equation in each conduit. The latter assumes that the slope of the water surface equal the slope
of the conduit.
The maximum flow that can be conveyed through a conduit is the full normal flow value. Any flow
in excess of this entering the inlet node is either lost from the system or can pond atop the inlet
node and be re-introduced into the conduit as capacity becomes available.
Kinematic wave routing allows flow and area to vary both spatially and temporally within a
conduit. This can result in attenuated and delayed outflow hydrographs as inflow is routed
through the channel. However this form of routing cannot account for backwater effects,
entrance/exit losses, flow reversal, or pressurized flow, and is also restricted to dendritic network
layouts. It can usually maintain numerical stability with moderately large time steps, on the order
of 1 to 5 minutes. If the aforementioned effects are not expected to be significant then this
alternative can be an accurate and efficient routing method, especially for long-term simulations.
Dynamic Wave Routing
Dynamic Wave routing solves the complete one-dimensional Saint Venant flow equations and
therefore produces the most theoretically accurate results. These equations consist of the
continuity and momentum equations for conduits and a volume continuity equation at nodes.
With this form of routing it is possible to represent pressurized flow when a closed conduit
becomes full, such that flows can exceed the full normal flow value. Flooding occurs when the
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water depth at a node exceeds the maximum available depth, and the excess flow is either lost
from the system or can pond atop the node and re-enter the drainage system.
Dynamic wave routing can account for channel storage, backwater, entrance/exit losses, flow
reversal, and pressurized flow. Because it couples together the solution for both water levels at
nodes and flow in conduits it can be applied to any general network layout, even those containing
multiple downstream diversions and loops. It is the method of choice for systems subjected to
significant backwater effects due to downstream flow restrictions and with flow regulation via
weirs and orifices. This generality comes at a price of having to use much smaller time steps, on
the order of a thirty seconds or less (SWMM can automatically reduce the user-defined maximum
time step as needed to maintain numerical stability).
3.4.6 Ponding and Pressurization
Normally in flow routing, when the flow into a junction exceeds the capacity of the system to
transport it further downstream, the excess volume overflows the system and is lost. An option
exists to have instead the excess volume be stored atop the junction, in a ponded fashion, and be
reintroduced into the system as capacity permits. Under Steady and Kinematic Wave flow routing,
the ponded water is stored simply as an excess volume. For Dynamic Wave routing, which is
influenced by the water depths maintained at nodes, the excess volume is assumed to pond over
the node with a constant surface area. This amount of surface area is an input parameter
supplied for the junction.
Alternatively, the user may wish to represent the surface overflow system explicitly. In open
channel systems this can include road overflows at bridges or culvert crossings as well as
additional floodplain storage areas. In closed conduit systems, surface overflows may be
conveyed down streets, alleys, or other surface routes to the next available stormwater inlet or
open channel. Overflows may also be impounded in surface depressions such as parking lots,
back yards or other areas.
In sewer systems with pressurized pipes and force mains the hydraulic head at junction nodes
can at times exceed the ground elevation under Dynamic Wave routing. This would normally
result in an overflow which, as described above, can either be lost or ponded. SWMM allows the
user to specify an additional "surcharge" depth for junction nodes that lets them pressurize and
prevents any outflow until this additional depth is exceeded. If both ponding and pressurization
are specified for a node ponding takes precedence and the surcharge depth is ignored. Neither
ponding nor pressurization applies to storage nodes.
3.4.7 Water Quality Routing
Water quality routing within conduit links assumes that the conduit behaves as a continuously
stirred tank reactor (CSTR). Although a plug flow reactor assumption might be more realistic, the
differences will be small if the travel time through the conduit is on the same order as the routing
time step. The concentration of a constituent exiting the conduit at the end of a time step is found
by integrating the conservation of mass equation, using average values for quantities that might
change over the time step such as flow rate and conduit volume.
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Water quality modeling within storage unit nodes follows the same approach used for conduits.
For other types of nodes that have no volume, the quality of water exiting the node is simply the
mixture concentration of all water entering the node.
The pollutant concentration in both a conduit and a storage node will be reduced by a first-order
decay reaction if the pollutant's first-order decay coefficient is not zero.
3.4.8 LID Representation
LID controls are represented by a combination of vertical layers whose properties are defined on
a per-unit-area basis. This allows LIDs of the same design but differing area coverage to easily
be placed within different subcatchments of a study area. During a simulation SWMM performs a
moisture balance that keeps track of how much water moves between and is stored within each
LID layer. As an example, the layers used to model a bio-retention cell and the flow pathways
between them are shown in Figure 3-9. The various possible layers consist of the following:
Rainfall ET
Overflow * f
Runon
,— <
^
Surface Layers
/
i
Soil Layer '
Storage Layer
Inflltratk
B
-0-
Percolat
4
on
Underdrain
Infiltration
Figure 3-9 Conceptual diagram of a bio-retention cell LID
The Surface Layer corresponds to the ground (or pavement) surface that receives direct
rainfall and runon from upstream land areas, stores excess inflow in depression storage, and
generates surface outflow that either enters the drainage system or flows onto downstream
land areas.
The Pavement Layer is the layer of porous concrete or asphalt used in continuous permeable
pavement systems, or is the paver blocks and filler material used in modular systems.
The So;7 Layer is the engineered soil mixture used in bio-retention cells to support vegetative
growth. It can also be a sand layer placed beneath a pavement layer to provide bedding and
filtration.
The Storage Layer is a bed of crushed rock or gravel that provides storage in bio-retention
cells, porous pavement, and infiltration trench systems. For a rain barrel it is simply the barrel
itself.
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• The Drain System conveys water out of the gravel storage layer of bio-retention cells,
permeable pavement systems, and infiltration trenches (typically with slotted pipes) into a
common outlet pipe or chamber. For rain barrels it is simply the drain valve at the bottom of
the barrel while for rooftop disconnection it is the roof gutter and downspout system.
• The Drainage Mat Layer is a mat or plate placed between the soil media and the roof in a
green roof whose purpose is to convey any water that drains through the soil layer off of the
roof.
Table 3-3 indicates which combination of layers applies to each type of LID (x means required, o
means optional).
Table 3-3 Layers used to model different types of LID units
LID Type
Bio-Retention Cell
Rain Garden
Green Roof
Permeable Pavement
Infiltration Trench
Rain Barrel
Roof Disconnection
Vegetative Swale
Surface
X
X
X
X
X
X
X
Pavement
X
Soil
X
X
X
0
Storage
0
X
X
X
Drain
0
0
0
X
X
Drainage Mat
X
All of the LID controls provide some amount of rainfall/runoff storage and evaporation of stored
water (except for rain barrels). Infiltration into native soil occurs in vegetative swales and can also
occur in bio-retention cells, rain gardens, permeable pavement systems, and infiltration trenches
if those systems do not employ an optional impermeable bottom liner. Infiltration trenches and
permeable pavement systems can also be subjected to clogging. This reduces their hydraulic
conductivity overtime proportional to the cumulative hydraulic loading they receive.
The performance of the LID controls placed in a subcatchment is reflected in the overall runoff,
infiltration, and evaporation rates computed for the subcatchment as normally reported by
SWMM. SWMM's Status Report also contains a section entitled LID Performance Summary that
provides an overall water balance for each LID control placed in each subcatchment. The
components of this water balance include total inflow, infiltration, evaporation, surface runoff,
drain flow and initial and final stored volumes, all expressed as inches (or mm) over the LID's
area. Optionally, the entire time series of flux rates and moisture levels for a selected LID control
in a given subcatchment can be written to a tab delimited text file for easy viewing and graphing
in a spreadsheet program (such as Microsoft Excel).
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CHAPTER 4 - SWMM'S MAIN WINDOW
This chapter discusses the essential features of SWMM's workspace. It describes the main menu
bar, the tool and status bars, and the three windows used most often - the Study Area Map, the
Browser, and the Property Editor. It also shows how to set program preferences.
4.1
Overview
The EPA SWMM main window is pictured below. It consists of the following user interface
elements: a Main Menu, several Toolbars, a Status Bar, the Study Area Map window, a Browser
panel, and a Property Editor window. A description of each of these elements is provided in the
sections that follow.
I! SWMM 5,1 - Examplel.inp
File Edit V -. !-n= i ;
. D & y d; % M •
£2
Project Map
Project/Map Browser
Hydrology
j • Hydraulics
\ • • Nodes
; 4 Links
i i !••• Conduits
; \ :•••• Pumps
\ \ !••- Orifices
\ \ L Weirs
Outlets
i Conduits
I4
J5
I6
J7
|s
110
Main Menu
S
H
Toolbars
Conduitl
Property Editor
IS!
Property
Value
Name 1
Inlet Node 9
Outlet Node 10
Description
Tag
Shape CIRCULAR
Max. Depth 1,5
Length 400
User-assigned name of Conduit
Auto-Length: Off - Offsets: Depth -r Flow Units; CFS * E'J Zoom Level: 100% XV: 3656,915,10026.596
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4.2
Main Menu
The Main Menu located across the top of the EPA SWMM main window contains a collection of
menus used to control the program. These include:
• File Menu
• Edit Menu
• View Menu
• Project Menu
• Report Menu
• Tools Menu
• Window Menu
• Help Menu
File Menu
The File Menu contains commands for opening and saving data files and for printing:
Command
Description
New Creates a new SWMM project
Open Opens an existing project
Reopen Reopens a recently used project
Save Saves the current project
Save As Saves the current project under a different name
Export Exports study area map to a file in a variety of formats;
Exports current results to a Hot Start file;
Exports the current result's Status/Summary reports
Combine Combines two Routing Interface files together
Page Setup Sets page margins and orientation for printing
Print Preview Previews a printout of the currently active view (map, report,
graph, or table)
Print Prints the current view
Exit Exits EPA SWMM
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Edit Menu
The Edit Menu contains commands for editing and copying:
Command
Description
Copy To Copies the currently active view (map, report, graph or table)
to the clipboard or to a file
Select Object Enables the user to select an object on the map
Select Vertex Enables the user to select the vertex of a subcatchment or
link
Select Region Enables the user to delineate a region on the map for
selecting multiple objects
Select All Selects all objects when the map is the active window or all
cells of a table when a tabular report is the active window
Find Object Locates a specific object by name on the map
Edit Object Edits the properties of the currently selected object
Delete Object Deletes the currently selected object
Group Edit Edits a property for the group of objects that fall within the
outlined region of the map
Group Delete Deletes a group of objects that fall within the outlined region
of the map
View Menu
The View Menu contains commands for viewing the Study Area Map:
Command
Description
Dimensions Sets reference coordinates and distance units for the study
area map
Backdrop Allows a backdrop image to be added, positioned, and
viewed behind the map
Pan Pans across the map
Zoom In Zooms in on the map
Zoom Out Zooms out on the map
Full Extent Redraws the map at full extent
Query Highlights objects on the map that meet specific criteria
Overview Toggles the display of the Overview Map
Objects Toggles display of classes of objects on the map
Legends Controls display of the map legends
Toolbars Toggles display of toolbars
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Project Menu
The Project menu contains commands related to the current project being analyzed:
Command
Description
Summary
Details
Defaults
Calibration Data
Add a New Object
Run Simulation
Lists the number of each type of object in the project
Shows a detailed listing of all project data
Edits a project's default properties
Registers files containing calibration data with the project
Adds a new object to the project
Runs a simulation
Report Menu
The Report menu contains commands used to report analysis results in different formats:
Command
Description
Status
Summary
Graph
Table
Statistics
Customize
Displays a status report for the most recent simulation run
Displays summary results in tabular form
Displays simulation results in graphical form
Displays simulation results in tabular form
Displays a statistical analysis of simulation results
Customizes the display style of the currently active graph
Tools Menu
The Tools menu contains commands used to configure program preferences, study area map
display options, and external add-in tools:
Command
Program
Preferences
Map Display
Options
Configure Tools
Description
Sets program preferences, such as font size, confirm
deletions, number of decimal places displayed, etc.
Sets appearance options for the Map, such as object size,
annotation, flow direction arrows, and back-ground color
Adds, deletes, or modifies external add-in tools
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Window Menu
The Window Menu contains commands for arranging and selecting windows within the SWMM
workspace:
Command Description
Cascade Arranges windows in cascaded style, with the study area
map filling the entire display area
Tile Minimizes the study area map and tiles the remaining
windows vertically in the display area
Close All Closes all open windows except for the study area map
Window List Lists all open windows; the currently selected window has
the focus and is denoted with a check mark
Help Menu
The Help Menu contains commands forgetting help in using EPA SWMM:
Command Description
Help Topics Displays the Help system's Table of Contents
How Do I Displays a list of topics covering the most common
operations
Measurement Units Shows measurement units for all of SWMM's parameters
Error Messages Lists the meaning of all error messages
Tutorial Presents a short tutorial introducing the user to EPA
SWMM
About Lists information about the version of EPA SWMM being
used
4.3 Toolbars
Toolbars provide shortcuts to commonly used operations. There are three such toolbars:
• Standard Toolbar
• Map Toolbar
• Object Toolbar
Individual toolbars can be made visible or invisible by selecting View » Toolbars from the Main
Menu.
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The Standard Toolbar contains buttons for the following commonly used commands:
0 Creates a new project (File » New)
\jSr Opens an existing project (File » Open)
y Saves the current project (File » Save)
^ Prints the currently active window (File » Print)
Hd Copies selection to the clipboard or to a file (Edit » Copy To)
J4 Finds a specific object on the Study Area Map (Edit » Find Object)
?{] Makes a visual query of the study area map (View » Query)
i® Toggles the display of the Overview Map (View » Overview)
^ Runs a simulation (Project » Run Simulation)
HI Displays a run's Status or Summary reports (Report » Status and Report
» Summary appear in a dropdown menu)
Ny Creates a profile plot of simulation results (Report » Graph » Profile)
H£ Creates a time series plot of simulation results (Report » Graph » Time
Series)
HI] Creates a time series table of simulation results (Report » Table)
|£ Creates a scatter plot of simulation results (Report » Graph » Scatter)
2 Performs a statistical analysis of simulation results (Report » Statistics)
Hf1 Modifies display options for the currently active view (Tools » Map Display
Options or Report » Customize)
3^, Arranges windows in cascaded style, with the study area map filling the
entire display area (Window » Cascade)
The Map Toolbar contains the following buttons for viewing the study area map:
^ Selects an object on the map (Edit » Select Object)
[^ Selects link or subcatchment vertex points (Edit » Select Vertex)
jj£ Selects a region on the map (Edit » Select Region)
O Pans across the map (View » Pan)
<±^ Zooms in on the map (View » Zoom In)
G^ Zooms out on the map (View » Zoom Out)
H Draws map at full extent (View » Full Extent)
^ Measures a length or area on the map
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The Object Toolbar contains buttons for adding visual objects to a project via the study area
map.
9? Adds a rain gage to the map.
^ Adds a subcatchment to the map
O Adds a junction node to the map
V Adds an outfall node to the map
O Adds a flow divider node to the map
bid Adds a storage unit node to the map
*-< Adds a conduit link to the map
(71 Adds a pump link to the map
•H Adds an orifice link to the map
Q Adds a weir link to the map
3 Adds an outlet link to the map
T Adds a text label to the map
4.4 Status Bar
The Status Bar appears at the bottom of SWMM's Main Window and is divided into six sections:
Auto-Length: Off ' Offsets: Depth " Flow Units: CFS " | Zoom Level: 100% X,Y: -1103,723,53,191
Auto-Length
Indicates whether the automatic computation of conduit lengths and subcatchment areas is
turned on or off. The setting can be changed by clicking the drop down arrow.
Offsets
Indicates whether the positions of links above the invert of their connecting nodes are expressed
as a Depth above the node invert or as the Elevation of the offset. Click the drop down arrow to
change this option. If changed, a dialog box will appear asking if all existing offsets in the current
project should be changed or not (i.e., convert Depth offsets to Elevation offsets or Elevation
offsets to Depth offsets, depending on the option selected)
Flow Units
Displays the current flow units that are in effect. Click the drop down arrow to change the choice
of flow units. Selecting a US flow unit means that all other quantities will be expressed in US
units, while choosing a metric flow unit will force all quantities to be expressed in metric units. The
units of previously entered data are not automatically adjusted if the unit system is changed.
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Run Status
I results are not available because no simulation has been run yet.
-| results are up to date.
•-'I results are out of date because project data have changed.
^| results are not available because the last simulation had errors.
Zoom Level
Displays the current zoom level for the map (100% is full-scale).
XY Location
Displays the map coordinates of the current position of the mouse pointer.
4.5 Study Area Map
The Study Area Map (shown below) provides a planar schematic diagram of the objects
comprising a drainage system. Its pertinent features are as follows:
Study Area Map
The location of objects and the distances between them do not necessarily have to
conform to their actual physical scale.
Selected properties of these objects, such as water quality at nodes or flow velocity in
links, can be displayed by using different colors. The color-coding is described in a
Legend, which can be edited.
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New objects can be directly added to the map and existing objects can be selected for
editing, deleting, and repositioning.
A backdrop drawing (such as a street or topographic map) can be placed behind the
network map for reference.
The map can be zoomed to any scale and panned from one position to another.
Nodes and links can be drawn at different sizes, flow direction arrows added, and object
symbols, ID labels and numerical property values displayed.
The map can be printed, copied onto the Windows clipboard, or exported as a DXF file or
Windows metafile.
4.6 Project Browser
The Project Browser panel (shown below) appears when the Project tab on the left panel of
SWMM's main window is selected. It provides access to all of the data objects in a project. The
vertical sizes of the list boxes in the browser can be adjusted by using the splitter bar located just
below the upper list box. The width of the Browser panel can be adjusted by using the splitter bar
located along its right edge.
The upper list box displays the various categories of data objects
available to a SWMM project. The lower list box lists the name of
each individual object of the currently selected data category.
Project Map
;•••• Climatology
Hydrology
j Hydraulics
I • Nodes
! * - Links
| | !•••• Conduits
I ! !•••• Pumps
| i ;•••• Orifices
| j [..-Weirs
\ I i.- Outlets
II
Conduits
[ 10001
10003
10004
10005
10006
10007
The buttons between the two list boxes are used as follows:
* adds a new object
~ deletes the selected object
& edits the selected object
"fr moves the selected object up one position
® moves the selected object down one position
z+ sorts the objects in ascending order
Selections made in the Project Browser are coordinated with
objects highlighted on the Study Area Map, and vice versa. For
example, selecting a conduit in the Browser will cause that
conduit to be highlighted on the map, while selecting it on the
map will cause it to become the selected object in the Browser.
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4.7 Map Browser
The Map Browser panel (shown below) appears when the Map tab on the left panel of the
SWMM's main window is selected. It controls the mapping themes and time periods viewed on
the Study Area Map. The width of the Map Browser panel can be adjusted by using the splitter
bar located along its right edge. The Map Browser consists of the following three panels that
control what results are displayed on the map:
Project! Map
Themes The Themes panel selects a set of variables to view in color-
Subcatchments coded fashion on the Map.
Area w
Nodes
Invert T
Links
Flow -r
Time Period j^g jjme perjoc| panel selects which time period of the
Date simulation results are viewed on the Map.
06/27/2002
Time of Day
00:15:00
Elapsed Time
0,00:15:00
Animator
_ The Animator panel controls the animated display of the Study
Area Map and all Profile Plots overtime.
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The Themes panel of the Map Browser is used to select a thematic variable to view in color-
coded fashion on the Study Area Map.
Themes
Sub catchments Subcatchments - selects the theme to display for the subcatchment
w areas shown on the Map.
Nodes Nodes - selects the theme to display for the drainage system nodes
Invert -r shown on the Map.
Links
Links - selects the theme to display for the drainage system links
shown on the Map.
The Time Period panel of the Map Browser allows is used to select a time period in which to view
computed results in thematic fashion on the Study Area Map.
Time Period
Date
06 ,-'27 ,-'2002 -r Date - selects the day for which simulation results will be viewed.
Imeo ay Time of Day - selects the time of the current day (in
' ' T hours:minutes:seconds) for which simulation results will be viewed.
< \ r
Elapsed Time Elapsed Time - selects the elapsed time from the start of the
0,01:00:00 I simulation (in days.hours:minutes:seconds) for which results will be
viewed.
The Animator panel of the Map Browser contains controls for animating the Study Area Map and
all Profile Plots through time i.e., updating map color-coding and hydraulic grade line profile
depths as the simulation time clock is automatically moved forward or back. The meaning of the
control buttons are as follows:
Animator M Returns to the starting period.
M 4 H *• ^ Starts animating backwards in time
pi H Stops the animation
^ Starts animating forwards in time
The slider bar is used to adjust the animation speed.
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4.8 Property Editor
The Property Editor (shown to the right) is used to edit
the properties of data objects that can appear on the
Study Area Map. It is invoked when one of these objects
is selected (either on the Map or in the Project Browser)
and double-clicked or when the Project Browser's Edit
button & is clicked.
Key features of the Property Editor include:
• The Editor is a grid with two columns - one for
the property's name and the other for its value.
• The columns can be re-sized by re-sizing the
header at the top of the Editor with the mouse.
• A hint area is displayed at the bottom of the
Editor with an expanded description of the
property being edited. The size of this area can
be adjusted by dragging the splitter bar located
just above it.
Conduit 10 H
Property
Name
Inlet Node
Outlet Node
Description
Tag
Shape
Max. Depth
Length
Roughness
Inlet Offset
Value
10
17 ; [
18
IGRCULAR ...J
2
400
0.01
0
Click to edit the conduit's cross
section geometry
The Editor window can be moved and re-sized via the normal Windows operations.
Depending on the property, the value field can be one of the following:
o a text box in which you enter a value
o a dropdown combo box from which you select a value from a list of choices
o a dropdown combo box in which you can enter a value or select from a list of choices
o an ellipsis button which you click to bring up a specialized editor.
The field in the Editor that currently has the focus will have a focus rectangle drawn
around it.
Both the mouse and the Up and Down arrow keys on the keyboard can be used to move
between property fields.
The Page Up key can be used to select the previous object of the same type (as listed in
the Project Browser) into the Editor, while the Page Down key will select the next object
of the same type into the Editor.
To begin editing the property with the focus, either begin typing a value or hit the Enter
key.
To have the program accept edits made in a property field, either press the Enter key or
move to another property. To cancel the edits, press the Esc key.
The Property Editor can be hidden by clicking the button in the upper right corner of its
title bar.
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4.9 Setting Program Preferences
Program preferences allow one to customize certain program features. To set program
preferences, select Program Preferences from the Tools menu. A Preferences dialog form will
appear containing two tabbed pages - one for General Preferences and one for Numerical
Precision.
Preferences
General Options
m
Numerical Precision
[3 Blinking Map Highlighter
G/] Flyover Map Labeling
(3 Confirm Deletions
O Automatic Backup File
[3 Tab Delimited Project File
0 Report Elapsed Time by Default
0 Prompt to Save Results
D Clear File List
Style Theme
Windows w
| OK
Cancel Help
Preferences
| General Options
Numerical Precision
gii
Select number of decimal places for
computed results^
Subcatch Parameter
Precipitation -r
Node Parameter
Depth w
Link Parameter
Flow T
OK
Cancel
Decimals
2 ;
Decimals
e ;
Decimals
2 *
Help
The following preferences can be set on the General Preferences page of the Preferences dialog:
Preference
Description
Blinking Map Highlighter
Flyover Map Labeling
Confirm Deletions
Automatic Backup File
Check to make the selected object on the study area map
blink on and off
Check to display the ID label and current theme value in a
hint-style box whenever the mouse is placed over an object
on the study area map
Check to display a confirmation dialog box before deleting
any object
Check to save a backup copy of a newly opened project to
disk named with a .bak extension
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Report Elapsed Time by
Default
Prompt to Save Results
Clear File List
Style Theme
Check to use elapsed time (rather than date/time) as the
default for time series graphs and tables.
If left unchecked then simulation results are automatically
saved to disk when the current project is closed. Otherwise
the user will be asked if results should be saved.
Check to clear the list of most recently used files that appears
when File » Reopen is selected from the Main Menu
Selects a color theme to use for SWMM's user interface (see
below for some examples)
Preferences
Genera! Options : Numerical Precision 1
i J Blinking Map Highlighter i
| •/ Flyover Map Labeling j
i V Confirm Deletions i
i Automatic Backup File i
| J Tab Delimited Project File |
i J Report Elapsed Time by Default i
j / Prompt to Save Results j
I Clear File List j
Style Theme; i
Windows T i
OK • ' Cancel | [ Help |
n^^^^^^^^^^^^jfpreference, ' ' ' ' X
1 1 General Options Numerical Precision
i i V Blinking Map Highlighter
i i */ Flyover Map Labeling
i i •>/ Confirm Deletions
1 1 Automatic Backup File
1 1
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CHAPTER 5 -WORKING WITH PROJECTS
Project files contain all of the information used to model a study area. They are usually named
with a .INP extension. This section describes how to create, open, and save EPA SWMM projects
as well as setting their default properties.
5.1 Creating a New Project
To create a new project:
l . Select File » New from the Main Menu or click 0 on the Standard Toolbar.
2 . You will be prompted to save the existing project (if changes were made to it) before the
new project is created.
3 . A new, unnamed project is created with all options set to their default values.
A new project is automatically created whenever EPA SWMM first begins.
If you are going to use a backdrop image with automatic area and length calculation, then
it is recommended that you set the map dimensions immediately after creating the new
project (see Section 7.2 Setting the Map's Dimensions).
5.2 Opening an Existing Project
To open an existing project stored on disk:
l . Either select File » Open from the Main Menu or click & on the Standard Toolbar.
2 . You will be prompted to save the current project (if changes were made to it).
3 . Select the file to open from the Open File dialog form that will appear.
4 . Click Open to open the selected file.
To open a project that was worked on recently:
l . Select File » Reopen from the Main Menu.
2 . Select a file from the list of recently used files to open.
5.3 Saving a Project
To save a project under its current name either select File » Save from the Main Menu or click
H on the Standard Toolbar.
To save a project using a different name:
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l. Select File » Save As from the Main Menu.
2. A standard File Save dialog form will appear from which you can select the folder and
name that the project should be saved under.
5.4 Setting Project Defaults
Each project has a set of default values that are used unless overridden by the SWMM user.
These values fall into three categories:
1. Default ID labels (labels used to identify nodes and links when they are first created)
2. Default subcatchment properties (e.g., area, width, slope, etc.)
3. Default node/link properties (e.g., node invert, conduit length, routing method).
To set default values for a project:
l. Select Project » Defaults from the Main Menu.
2. A Project Defaults dialog will appear with three pages, one for each category listed
above.
Project Defaults
ID Labels I Sub catchments Nodes/Links
Object
ID Prefix
Rain Gages
Sub catchments
Junctions
Outfalls
Dividers
Storage Units
Conduits
Pumps
Regulators
ID Increment
[I] Save as defaults for all new projects
OK
Cancel
Help
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3. Check the box in the lower left of the dialog form if you want to save your choices for use
in all new future projects as well.
4. Click OK to accept your choice of defaults.
The specific items for each category of defaults will be discussed next.
Default ID Labels
The ID Labels page of the Project Defaults dialog form is used to determine how SWMM will
assign default ID labels for the visual project components when they are first created. For each
type of object you can enter a label prefix in the corresponding entry field or leave the field blank
if an object's default name will simply be a number. In the last field you can enter an increment to
be used when adding a numerical suffix to the default label. As an example, if C were used as a
prefix for Conduits along with an increment of 5, then as conduits are created they receive default
names of C5, C10, C15, and so on. An object's default name can be changed by using the
Property Editor for visual objects or the object-specific editor for non-visual objects.
Default Subcatchment Properties
The Subcatchment page of the Project Defaults dialog sets default property values for newly
created subcatchments. These properties include:
• Subcatchment Area
• Characteristic Width
• Slope
• % Impervious
• Impervious Area Roughness
• Pervious Area Roughness
• Impervious Area Depression Storage
• Pervious Area Depression Storage
• % of Impervious Area with No Depression Storage
• Infiltration Method
The default properties of a Subcatchment can be modified later by using the Property Editor.
Default Node/Link Properties
The Nodes/Links page of the Project Defaults dialog sets default property values for newly
created nodes and links. These properties include:
• Node Invert Elevation
• Node Maximum Depth
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• Node Ponded Area
• Conduit Length
• Conduit Shape and Size
• Conduit Roughness
• Flow Units
• Link Offsets Convention
• Routing Method
• Force Main Equation
The defaults automatically assigned to individual objects can be changed by using the object's
Property Editor. The choice of Flow Units and Link Offsets Convention can be changed directly
on the main window's Status Bar.
5.5 Measurement Units
SWMM can use either US units or SI metric units. The choice of flow units determines what unit
system is used for all other quantities:
• selecting CFS (cubic feet per second), GPM (gallons per minutes), or MGD (million
gallons per day) for flow units implies that US units will be used throughout
• selecting CMS (cubic meters per second), LPS (liters per second), or MLD (million liters
per day) as flow units implies that SI units will be used throughout.
Flow units can be selected directly on the main window's Status Bar or by setting a project's
default values. In the latter case the selection can be saved so that all new future projects will
automatically use those units.
F":
The units of previously entered data are not automatically adjusted if the unit system is
changed.
5.6 Link Offset Conventions
Conduits and flow regulators (orifices, weirs, and outlets) can be offset some distance above the
invert of their connecting end nodes as depicted below:
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There are two different conventions available for specifying the location of these offsets. The
Depth convention uses the offset distance from the node's invert (distance between © and ©, in
the figure above). The Elevation convention uses the absolute elevation of the offset location (the
elevation of point © in the figure). The choice of convention can be made on the Status Bar of
SWMM's main window or on the Node/Link Properties page of the Project Defaults dialog. When
this convention is changed, a dialog will appear giving one the option to automatically re-calculate
all existing link offsets in the current project using the newly selected convention
5.7 Calibration Data
SWMM can compare the results of a simulation with measured field data in its Time Series Plots,
which are discussed in section 9.4. Before SWMM can use such calibration data they must be
entered into a specially formatted text file and registered with the project.
Calibration Files
Calibration Files contain measurements of a single parameter at one or more locations that can
be compared with simulated values in Time Series Plots. Separate files can be used for each of
the following parameters:
• Subcatchment Runoff
• Subcatchment Pollutant Washoff
• Groundwater Flow
• Groundwater Elevation
• Snow Pack Depth
• Node Depth
• Node Lateral Inflow
• Node Flooding
• Node Water Quality
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• Link Flow Rate
• Link Flow Depth
• Link Flow Velocity
The format of the file is described in Section 11.5.
Registering Calibration Data
To register calibration data residing in a Calibration File:
l. Select Project » Calibration Data from the Main Menu.
2. In the Calibration Data dialog form shown below, click in the box next to the parameter
(e.g., node depth, link flow, etc.) whose calibration data will be registered.
3. Either type in the name of a Calibration File for this parameter or click the Browse button
to search for it.
4. Click the Edit button if you want to open the Calibration File in Windows NotePad for
editing.
5. Repeat steps 2 - 4 for any other parameters that have calibration data.
6. Click OK to accept your selections.
Calibration Data
Calibration Variable
Subcatchment Runoff
Subcatchment Wash off
Node Water Depth
Link Flow Rate
Node Water Quality
Node Lateral Inflow
Node Flooding
Groundwater Flow
Groundwater Elevation
Snow Pack Depth
Link Flow Depth
Link Flow Velocity
Name of Calibration File
Cancel
Help
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5.8 Viewing All Project Data
A listing of all project data (with the exception of map coordinates) can be viewed in a non-
editable window, formatted for input to SWMM's computational engine (see below). This can be
useful for checking data consistency and to make sure that no key components are missing. To
view such a listing select Project » Details from the Main Menu. The format of the data in this
listing is the same as that used when the file is saved to disk. It is described in detail in Appendix
D.2.
& Project Data
Data Category
[TITLE]
[OPTIONS]
[EVAPORATION]
[RAINGAGES]
[SUBAREAS]
[INFILTRATION]
[JUNCTIONS]
[OUTFALLS]
[CONDUITS]
[XSECTIONS]
C3 1
Name Rain Gage Outlet
* 1 RG1 9
2 RG1 10
3 RG1 13
E 4 RG1 22
i 5 RG1 15
6 RG1 23
7 RG1 19
8 RG1 18
__J
B Juan!
Area
10
10
5
5
15
12
4
10
t
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CHAPTER 6 - WORKING WITH OBJECTS
SWMM uses various types of objects to model a drainage area and its conveyance system. This
section describes how these objects can be created, selected, edited, deleted, and repositioned.
6.1 Types of Objects
SWMM contains both physical objects that can appear on its Study Area Map, and non-physical
objects that encompass design, loading, and operational information. These objects, which are
listed in the Project Browser and were described in Chapter 3, consist of the following:
Project Title/Notes Nodes
Simulation Options Links
Climatology Transects
Rain Gages Control Rules
Subcatchments Pollutants
Aquifers Land Uses
Snow Packs Curves
Unit Hydrographs Time Series
LID Controls Time Patterns
Map Labels
6.2 Adding Objects
To add a new object to a project, select the type of object from the upper pane of the Project
Browser and either select Project » Add a New ... from the Main Menu or click the Browser's
* button. If the object has a button on the Object Toolbar you can simply click the toolbar button
instead.
If the object is a visual object that appears on the Study Area Map (a Rain Gage, Subcatchment,
Node, Link, or Map Label) it will automatically receive a default ID name and a prompt will appear
in the Status Bar telling you how to proceed. The steps used to draw each of these objects on the
map are detailed below:
Rain Gages
Move the mouse to the desired location on the Map and left-click.
Subcatchments
Use the mouse to draw a polygon outline of the subcatchment on the Map:
• left-click at each vertex
• right-click or press to close the polygon
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• press the key if you wish to cancel the action.
Nodes (Junctions, Outfalls, Flow Dividers, and Storage Units')
Move the mouse to the desired location on the Study Area Map and left-click.
Links (Conduits, Pumps, Orifices, Weirs, and Outlets')
• Left-click the mouse on the link's inlet (upstream) node.
• Move the mouse (without pressing any button) in the direction of the link's outlet
(downstream) node, clicking at all intermediate points necessary to define the link's
alignment.
• Left-click the mouse a final time over the link's outlet (downstream) node. (Pressing the right
mouse button or the key while drawing a link will cancel the operation.)
Map Labels
• Left-click the mouse on the map location where the top left corner of the label should appear.
• Enter the text for the label.
• Press to accept the label or to cancel.
For all other non-visual types of objects, an object-specific dialog form will appear that allows you
to name the object and edit its properties.
6.3 Selecting and Moving Objects
To select an object on the map:
l. Make sure that the map is in Selection mode (the mouse cursor has the shape of an
arrow pointing up to the left). To switch to this mode, either click the Select Object button
* on the Map Toolbar or choose Edit » Select Object from the Main Menu.
2. Click the mouse over the desired object on the map.
To select an object using the Project Browser:
l. Select the object's category from the upper list in the Browser.
2. Select the object from the lower list in the Browser.
Rain gages, subcatchments, nodes, and map labels can be moved to another location on the
Study Area Map. To move an object to another location:
l. Select the object on the map.
2. With the left mouse button held down over the object, drag it to its new location.
3. Release the mouse button.
The following alternative method can also be used:
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l. Select the object to be moved from the Project Browser (it must either be a rain gage,
subcatchment, node, or map label).
2. With the left mouse button held down, drag the item from the Items list box of the Data
Browser to its new location on the map.
3. Release the mouse button.
Note that the second method can be used to place objects on the map that were imported from a
project file that had no coordinate information included in it.
6.4 Editing Objects
To edit an object appearing on the Study Area Map:
l. Select the object on the map.
2. If the Property Editor is not visible either:
• double click on the object
• or right-click on the object and select Properties from the pop-up menu that appears
• or click on & in the Project Browser
• or select Edit » Edit Object from the Main Menu.
3. Edit the object's properties in the Property Editor.
Appendix B lists the properties associated with each of SWMM's visual objects.
To edit an object listed in the Project Browser:
l. Select the object in the Project Browser.
2. Either:
• click on & in the Project Browser,
• or select Edit » Edit Object from the Main Menu,
• or double-click the item in the Objects list,
• or press the key.
Depending on the class of object selected, a special property editor will appear in which the
object's properties can be modified. Appendix C describes all of the special property editors used
with SWMM's non-visual objects.
r,
The unit system in which object properties are expressed depends on the choice of units
for flow rate. Using a flow rate expressed in cubic feet, gallons or acre-feet implies that
US units will be used for all quantities. Using a flow rate expressed in liters or cubic
meters means that SI metric units will be used. Flow units are selected either from the
project's default Node/Link properties (see Sections.4) or directly from the main window's
Status Bar (see Section 4.4). The units used for all properties are listed in Appendix A.1.
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6.5 Converting an Object
It is possible to convert a node or link from one type to another without having to first delete the
object and add a new one in its place. An example would be converting a Junction node into an
Outfall node, or converting an Orifice link into a Weir link. To convert a node or link to another
type:
l. Right-click the object on the map.
2. Select Convert To from the popup menu that appears.
3. Select the new type of node or link to convert to from the sub-menu that appears.
4. Edit the object to provide any data that was not included with the previous type of object.
Only data that is common to both types of objects will be preserved after an object is converted to
a different type. For nodes this includes its name, position, description, tag, external inflows,
treatment functions, and invert elevation. For links it includes just its name, end nodes,
description, and tag.
6.6 Copying and Pasting Objects
The properties of an object displayed on the Study Area Map can be copied and pasted into
another object from the same category.
To copy the properties of an object to SWMM's internal clipboard:
l. Right-click the object on the map.
2. Select Copy from the pop-up menu that appears.
To paste copied properties into an object:
l. Right-click the object on the map.
2. Select Paste from the pop-up menu that appears.
Only data that can be shared between objects of the same type can be copied and pasted.
Properties not copied include the object's name, coordinates, end nodes (for links), tag property
and any descriptive comment associated with the object. For Map Labels, only font properties are
copied and pasted.
6.7 Shaping and Reversing Links
Links can be drawn as polylines containing any number of straight-line segments that define the
alignment or curvature of the link. Once a link has been drawn on the map, interior points that
define these line segments can be added, deleted, and moved. To edit the interior points of a link:
l. Select the link to edit on the map and put the map in Vertex Selection mode either by
clicking P- on the Map Toolbar, selecting Edit » Select Vertex from the Main Menu, or
right clicking on the link and selecting Vertices from the popup menu.
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2. The mouse pointer will change shape to an arrow tip, and any existing vertex points on
the link will be displayed as small open squares. The currently selected vertex will be
displayed as a filled square. To select a particular vertex, click the mouse over it.
3. To add a new vertex to the link, right-click the mouse and select Add Vertex from the
popup menu (or simply press the key on the keyboard).
4. To delete the currently selected vertex, right-click the mouse and select Delete Vertex
from the popup menu (or simply press the key on the keyboard).
5. To move a vertex to another location, drag it to its new position with the left mouse button
held down.
While in Vertex Selection mode you can begin editing the vertices for another link by simply
clicking on the link. To leave Vertex Selection mode, right-click on the map and select Quit
Editing from the popup menu, or simply select one of the other buttons on the Map Toolbar.
A link can also have its direction reversed (i.e., its end nodes switched) by right clicking on it and
selecting Reverse from the pop-up menu that appears. Normally, links should be oriented so that
the upstream end is at a higher elevation than the downstream end.
6.8 Shaping a Subcatchment
Subcatchments are drawn on the Study Area Map as closed polygons. To edit or add vertices to
the polygon, follow the same procedures used for links. If the subcatchment is originally drawn or
is edited to have two or less vertices, then only its centroid symbol will be displayed on the Study
Area Map.
6.9 Deleting an Object
To delete an object:
l. Select the object on the map or from the Project Browser.
2. Either click the ~ button on the Project Browser or press the key on the
keyboard, or select Edit » Delete Object from the Main Menu, or right-click the object
on the map and select Delete from the pop-up menu that appears.
You can require that all deletions be confirmed before they take effect. See the General
Preferences page of the Program Preferences dialog box described in Section 4.9.
6.10 Editing or Deleting a Group of Objects
A group of objects located within an irregular region of the Study Area Map can have a common
property edited or be deleted all together. To select such a group of objects:
l. Choose Edit » Select Region from the Main Menu or click ££• on the Map Toolbar.
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2. Draw a polygon around the region of interest on the map by clicking the left mouse button
at each successive vertex of the polygon.
3. Close the polygon by clicking the right button or by pressing the key; cancel the
selection by pressing the key.
To select all objects in the project, whether in view or not, select Edit » Select All from the Main
Menu.
Once a group of objects has been selected, you can edit a common property shared among
them:
l. Select Edit » Group Edit from the Main Menu.
2. Use the Group Editor dialog that appears to select a property and specify its new value.
The Group Editor dialog, shown below, is used to modify a property for a selected group of
objects. To use the dialog:
Group Editor
For objects of type
F] with Tag equal to
edit the property
Subcatchment
by replacing it with T 75
OK
l. Select a type of object (Subcatchments, Infiltration, Junctions, Storage Units, or
Conduits) to edit.
2. Check the "with Tag equal to" box if you want to add a filter that will limit the objects
selected for editing to those with a specific Tag value. (For Infiltration, the Tag will be that
of the subcatchment to which the infiltration parameters belong.)
3. Enter a Tag value to filter on if you have selected that option.
4. Select the property to edit.
5. Select whether to replace, multiply, or add to the existing value of the property. Note that
for some non-numerical properties the only available choice is to replace the value.
6. In the lower-right edit box, enter the value that should replace, multiply, or be added to
the existing value for all selected objects. Some properties will have an ellipsis button
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displayed in the edit box which should be clicked to bring up a specialized editor for the
property.
7. Click OK to execute the group edit.
After the group edit is executed a confirmation dialog box will appear informing you of how many
items were modified. It will ask if you wish to continue editing or not. Select Yes to return to the
Group Edit dialog box to edit another parameter or No to dismiss the Group Edit dialog.
To delete the objects located within a selected area of the map, select Edit » Group Delete
from the Main Menu. Then select the categories of objects you wish to delete from the dialog box
that appears. As an option, you can specify that only objects within the selected area that have a
specific Tag property should be deleted. Keep in mind that deleting a node will also delete any
links connected to the node.
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CHAPTER 7 -WORKING WITH THE MAP
EPA SWMM can display a map of the study area being modeled. This section describes how you
can manipulate this map to enhance your visualization of the system.
7.1 Selecting a Map Theme
A map theme displays object properties in color-coded fashion on the Study Area Map. The
dropdown list boxes on the Map Browser are used for selecting a theme to display for
Subcatchments, Nodes and Links.
& SWMM 5.1 - Examplel.inp
File Edit View Project Report Tools Window
Hdp
D
Project] Map
Themes
Subcatchments
Runoff
Nodes
Depth
Links
Flow
Time Period
Date
Study Area Map
Subcatch
Runoff
0.01
0.05
0.10
0.50
CFS
Node
Depth
0.40
Methods for changing the color-coding associated with a theme are discussed in Section 7.10
below.
7.2 Setting the Map's Dimensions
The physical dimensions of the map can be defined so that map coordinates can be properly
scaled to the computer's video display. To set the map's dimensions:
l. Select View » Dimensions from the Main Menu.
2. Enter coordinates for the lower-left and upper-right corners of the map into the Map
Dimensions dialog (see below) that appears or click the Auto-Size button to automatically
set the dimensions based on the coordinates of the objects currently included in the map.
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Map Dimensions
Lower Left
X-coordinate: 0,000
Y-coordinate: 0,000
Upper Right
X-coordinate: 10000,000
Y-coordinate: 10000,000
Map Units
• < Feet
Meters
Degrees
*:Q, None
J Auto-Length is ON. Re-compute all lengths and areas?
OK
3. Select the distance units to use for these coordinates.
4. If the Auto-Length option is in effect, check the "Re-compute all lengths and areas" box
if you would like SWMM to re-calculate all conduit lengths and subcatchment areas under
the new set of map dimensions.
5. Click the OK button to resize the map.
If you are going to use a backdrop image with the automatic distance and area
calculation feature, then it is recommended that you set the map dimensions immediately
after creating a new project. Map distance units can be different from conduit length units.
The latter (feet or meters) depend on whether flow rates are expressed in US or metric
units. SWMM will automatically convert units if necessary.
If you just want to re-compute conduit lengths and subcatchment areas without changing
the map's dimensions, then just check the Re-compute Lengths and Areas box and leave
the coordinate boxes as they are.
7.3 Utilizing a Backdrop Image
SWMM can display a backdrop image behind the Study Area Map. The backdrop image might be
a street map, utility map, topographic map, site development plan, or any other relevant picture or
drawing. For example, using a street map would simplify the process of adding sewer lines to the
project since one could essentially digitize the drainage system's nodes and links directly on top
of it.
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Study Area Map
The backdrop image must be a Windows metafile, bitmap, or JPEG image created outside of
SWMM. Once imported, its features cannot be edited, although its scale and viewing area will
change as the map window is zoomed and panned. For this reason metafiles work better than
bitmaps or JPEGs since they will not lose resolution when re-scaled. Most CAD and CIS
programs have the ability to save their drawings and maps as metafiles.
Selecting View » Backdrop from the Main Menu will display a sub-menu with the following
commands:
• Load (loads a backdrop image file into the project)
• Unload (unloads the backdrop image from the project)
• Align (aligns the drainage system schematic with the backdrop)
• Resize (resizes the map dimensions of the backdrop)
• Watermark (toggles the backdrop image appearance between normal and lightened)
To load a backdrop image select View » Backdrop » Load from the Main Menu. A Backdrop
Image Selector dialog form will be displayed. The entries on this form are as follows:
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Backdrop Image Selector
Backdrop Image File
sample.wmf
World Coordinates File (optional)
sample.bpw
[ | Scale Map to Backdrop Image
OK
Backdrop Image File
Enter the name of the file that contains the image. You can click the UU button to bring up a
standard Windows file selection dialog from which you can search for the image file.
World Coordinates File
ion
If a "world" file exists for the image, enter its name here, or click the button to search for it. A
world file contains geo-referencing information for the image and can be created from the
software that produced the image file or by using a text editor. It contains six lines with the
following information:
Line 1: real world width of a pixel in the horizontal direction.
Line 2: X rotation parameter (not used).
Line 3: Y rotation parameter (not used).
Line 4: negative of the real world height of a pixel in the vertical direction.
Line 5: real world X coordinate of the upper left corner of the image.
Line 6: real world Y coordinate of the upper left corner of the image.
If no world file is specified, then the backdrop will be scaled to fit into the center of the map
display window.
Scale Map to Backdrop Image
This option is only available when a world file has been specified. Selecting it forces the
dimensions of the Study Area Map to coincide with those of the backdrop image. In addition, all
existing objects on the map will have their coordinates adjusted so that they appear within the
new map dimensions yet maintain their relative positions to one another. Selecting this option
may then require that the backdrop be re-aligned so that its position relative to the drainage area
objects is correct. How to do this is described below.
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The backdrop image can be re-positioned relative to the drainage system by selecting View »
Backdrop » Align. This allows the backdrop image to be moved across the drainage system
(by moving the mouse with the left button held down) until one decides that it lines up properly.
The backdrop image can also be resized by selecting View » Backdrop » Resize. In this case
the following Backdrop Dimensions dialog will appear.
Backdrop Dimensions
Lower Left
Backdrop
X-coordinate: -23,360
Y-coordinate: -29.165
Upper Right
Backdrop
X-coordinate: 1463.996
Y-coordinate: 1512.277
•p1 Resize Backdrop Image Only
• • Scale Backdrop Image to Map
• • Scale Map to Backdrop Image
Map
-39,947
Map
•I -ion cor-
X^uU ,.,Ju,j
Cancel
The dialog lets you manually enter the X,Y coordinates of the backdrop's lower left and upper
right corners. The Study Area Map's dimensions are also displayed for reference. While the
dialog is visible you can view map coordinates by moving the mouse over the map window and
noting the X,Y values displayed in SWMM's Status Panel (at the bottom of the main window).
Selecting the Resize Backdrop Image Only button will resize only the backdrop, and not the
Study Area Map, according to the coordinates specified. Selecting the Scale Backdrop Image to
Map button will position the backdrop image in the center of the Study Area Map and have it
resized to fill the display window without changing its aspect ratio. The map's lower left and upper
right coordinates will be placed in the data entry fields for the backdrop coordinates, and these
fields will become disabled. Selecting Scale Map to Backdrop Image makes the dimensions of
the map coincide with the dimensions being set for the backdrop image. Note that this option will
change the coordinates of all objects currently on the map so that their positions relative to one
another remain unchanged. Selecting this option may then require that the backdrop be re-
aligned so that its position relative to the drainage area objects is correct.
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*";
Exercise caution when selecting the Scale Map to Backdrop Image option in either the
Backdrop Image Selector dialog or the Backdrop Dimensions dialog as it will modify the
coordinates of all existing objects currently on the Study Area Map. You might want to
save your project before carrying out this step in case the results are not what you
expected.
The name of the backdrop image file and its map dimensions are saved along with the rest of a
project's data whenever the project is saved to file.
For best results in using a backdrop image:
• Use a metafile, not a bitmap.
• If the image is loaded before any objects are added to the project then scale the map to
it.
7.4 Measuring Distances
To measure a distance or area on the Study Area Map:
n
l. Click i==i on the Map Toolbar.
2. Left-click on the map where you wish to begin measuring from.
3. Move the mouse over the distance being measured, left-clicking at each intermediate
location where the measured path changes direction.
4. Right-click the mouse or press to complete the measurement.
5. The distance measured in project units (feet or meters) will be displayed in a dialog box.
If the last point on the measured path coincides with the first point then the area of the
enclosed polygon will also be displayed.
7.5 Zooming the Map
To Zoom In on the Study Area Map:
l. Select View » Zoom In from the Main Menu or click ^ on the Map Toolbar.
2. To zoom in 100% (i.e., 2X), move the mouse to the center of the zoom area and click the
left button.
3. To perform a custom zoom, move the mouse to the upper left corner of the zoom area
and with the left button pressed down, draw a rectangular outline around the zoom area.
Then release the left button.
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To Zoom Out on the Study Area Map:
l. Select View » Zoom Out from the Main Menu or click ^ on the Map Toolbar.
2. The map will be returned to the view in effect at the previous zoom level.
7.6 Panning the Map
To pan across the Study Area Map window:
l. Select View » Pan from the Main Menu or click *f* on the Map Toolbar.
2. With the left button held down over any point on the map, drag the mouse in the direction
you wish to pan in.
3. Release the mouse button to complete the pan.
To pan using the Overview Map (which is described in Section 7.11 below):
l. If not already visible, bring up the Overview Map by selecting View » Overview Map
from the Main Menu or click the ® button on the Standard Toolbar.
2. If the Study Area Map has been zoomed in, an outline of the current viewing area will
appear on the Overview Map. Position the mouse within this outline on the Overview
Map.
3. With the left button held down, drag the outline to a new position.
4. Release the mouse button and the Study Area Map will be panned to an area
corresponding to the outline on the Overview Map.
7.7 Viewing at Full Extent
To view the Study Area Map at full extent, either:
• select View » Full Extent from the Main Menu, or
• press H on the Map Toolbar.
7.8 Finding an Object
To find an object on the Study Area Map whose name is known:
l. Select View » Find Object from the Main Menu or click 04 on the Standard Toolbar.
2. In the Map Finder dialog that appears, select the type of object to find and enter its name.
3. Click the Go button.
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Map Finder
Find
Named
i Go
Node
14
Adjacent Links
11
If the object exists, it will be highlighted on the map and in the Data Browser. If the map is
currently zoomed in and the object falls outside the current map boundaries, the map will be
panned so that the object comes into view.
User-assigned object names in SWMM are not case sensitive. E.g., NODE123 is
equivalent to Node123.
After an object is found, the Map Finder dialog will also list:
• the outlet connections for a subcatchment
• the connecting links for a node
• the connecting nodes for a link.
7.9 Submitting a Map Query
A Map Query identifies objects on the study area map that meet a specific criterion (e.g., nodes
which flood, links with velocity below 2 ft/sec, etc.). It can also identify which subcatchments have
LID controls and which nodes have external inflows. To submit a map query:
l. Select a time period in which to query the map from the Map Browser.
2. Select View » Query or click ?li on the Standard Toolbar.
3. Fill in the following information in the Query dialog that appears:
• Select whether to search for Subcatchments, Nodes, Links, LID Subcatchments or
Inflow Nodes.
• Select a parameter to query or the type of LID or inflow to locate.
• Select the appropriate operator: Above, Below, or Equals.
• Enter a value to compare against.
4. Click the Go button. The number of objects that meet the criterion will be displayed in the
Query dialog and each such object will be highlighted on the Study Area Map.
5. As a new time period is selected in the Browser, the query results are automatically
updated.
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6. You can submit another query using the dialog box or close it by clicking the button in the
upper right corner.
Study Area Map
After the Query box is closed the map will revert back to its original display.
7.10 Using the Map Legends
Flow
4.00
8.00
12.00
16.00
CFS
Map Legends associate a color with a range of values for the current
theme being viewed. Separate legends exist for Subcatchments, Nodes,
and Links. A Date/Time Legend is also available for displaying the date
and clock time of the simulation period being viewed on the map.
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To display or hide a map legend:
l. Select View » Legends from the Main Menu or right-click on the map and select
Legends from the pop-up menu that appears
2. Click on the type of legend whose display should be toggled on or off.
A visible legend can also be hidden by double clicking on it.
To move a legend to another location press the left mouse button over the legend, drag the
legend to its new location with the button held down, and then release the button.
To edit a legend, either select View » Legends » Modify from the Main Menu or right-click on
the legend if it is visible. Then use the Legend Editor dialog that appears to modify the legend's
colors and intervals.
The Legend Editor is used to set numerical ranges to which different colors are assigned for
viewing a particular parameter on the network map. It works as follows:
• Numerical values, in increasing order, are entered in the edit boxes to define the ranges.
Not all four boxes need to have values.
• To change a color, click on its color band in the Editor and then select a new color from
the Color Dialog that will appear.
• Click the Auto-Scale button to automatically assign ranges based on the minimum and
maximum values attained by the parameter in question at the current time period.
• The Color Ramp button is used to select from a list of built-in color schemes.
• The Reverse Colors button reverses the ordering of the current set of colors (the color in
the lowest range becomes that of the highest range and so on).
• Check Framed if you want a frame drawn around the legend.
Changes made to a legend are saved with the project's settings and remain in effect when the
project is re-opened in a subsequent session.
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7.11 Using the Overview Map
The Overview Map, as pictured below, allows one to see where in terms of the overall system the
main Study Area Map is currently focused. This zoom area is depicted by the rectangular outline
displayed on the Overview Map. As you drag this rectangle to another position the view within the
main map will be redrawn accordingly. The Overview Map can be toggled on and off by selecting
View » Overview Map from the Main Menu or by clicking ® on the Standard Toolbar. The
Overview Map window can also be dragged to any position as well as be re-sized.
. Study Area Map
Overview Map
E)
EL
7.12 Setting Map Display Options
The Map Options dialog (shown below) is used to change the appearance of the Study Area Map.
There are several ways to invoke it:
• select Tools » Map Display Options from the Main Menu or,
click the Options button HIT on the Standard Toolbar when the Study Area Map window
has the focus or,
right-click on any empty portion of the map and select Options from the popup menu that
appears.
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Map Options
Nodes
Links
Labels
Annotation
Symbols
Flow Arrows
Background
Fill Style
; Clear
Solid
o- Diagonal
Cross Hatch
Symbol Size 5
Border Size 1
Mj Display link to outlet
OK
The dialog contains a separate page, selected from the panel on the left side of the form, for each
of the following display option categories:
• Subcatchments (controls fill style, symbol size, and outline thickness of subcatchment
areas)
• Nodes (controls size of nodes and making size be proportional to value)
• Links (controls thickness of links and making thickness be proportional to value)
• Labels (turns display of map labels on/off)
• Annotation (displays or hides node/link ID labels and parameter values)
• Symbols (turns display of storage unit, pump, and regulator symbols on/off)
• Flow Arrows (selects visibility and style of flow direction arrows)
• Background (changes color of map's background).
Subcatchment Options
The Subcatchments page of the Map Options dialog controls how subcatchment areas are
displayed on the study area map.
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Option Description
Fill Style Selects style used to fill interior of subcatchment area
Symbol Size Sets the size of the symbol (in pixels) placed at the centroid of a
subcatchment area
Border Size Sets the thickness of the line used to draw a subcatchment's
border; if set to zero then only the subcatchment centroid will be
displayed
Display Link to If checked then a dashed line is drawn between the subcatchment
Outlet centroid and the subcatchment's outlet node (or outlet
subcatchment)
Node Options
The Nodes page of the Map Options dialog controls how nodes are displayed on the study area
map.
Option Description
Node Size Selects node diameter in pixels
Proportional to Select if node size should increase as the viewed parameter
Value increases in value
Display Border Select if a border should be drawn around each node
(recommended for light-colored backgrounds)
Link Options
The Links page of the Map Options dialog controls how links are displayed on the map.
Option Description
Link Size Sets thickness of links displayed on map (in pixels)
Proportional to Select if link thickness should increase as the viewed parameter
Value increases in value
Display Border Check if a black border should be drawn around each link
Label Options
The Labels page of the Map Options dialog controls how user-created map labels are displayed
on the study area map.
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Option
Description
Use Transparent
Text
At Zoom Of
Check to display label with a transparent background (otherwise
an opaque background is used)
Selects minimum zoom at which labels should be displayed;
labels will be hidden at zooms smaller than this
Annotation Options
The Annotation page of the Map Options dialog form determines what kind of annotation is
provided alongside of the objects on the study area map.
Option
Description
Rain Gage IDs
Subcatch IDs
Node IDs
Link IDs
Subcatch Values
Node Values
Link Values
Use Transparent Text
Font Size
At Zoom Of
Check to display rain gage ID names
Check to display subcatchment ID names
Check to display node ID names
Check to display link ID names
Check to display value of current subcatchment variable
Check to display value of current node variable
Check to display value of current link variable
Check to display text with a transparent background
(otherwise an opaque background is used)
Adjusts the size of the font used to display annotation
Selects minimum zoom at which annotation should be
displayed; all annotation will be hidden at zooms smaller
than this
Symbol Options
The Symbols page of the Map Options dialog determines which types of objects are represented
with special symbols on the map.
Option
Description
Display Node Symbols
Display Link Symbols
At Zoom Of
If checked then special node symbols will be used
If checked then special link symbols will be used
Selects minimum zoom at which symbols should be
displayed; symbols will be hidden at zooms smaller than this
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Flow Arrow Options
The Flow Arrows page of the Map Options dialog controls how flow-direction arrows are
displayed on the map.
Option Description
Arrow Style Selects style (shape) of arrow to display (select None to hide
arrows)
Arrow Size Sets arrow size
At Zoom Of Selects minimum zoom at which arrows should be displayed;
arrows will be hidden at zooms smaller than this
Flow direction arrows will only be displayed after a successful simulation has been made
and a computed parameter has been selected for viewing. Otherwise the direction arrow
will point from the user-designated start node to end node.
Background Options
The Background page of the Map Options dialog offers a selection of colors used to paint the
map's background with.
7.1 3 Exporting the Map
The full extent view of the study area map can be saved to file using either:
• Autodesk's DXF (Drawing Exchange Format) format,
• the Windows enhanced metafile (EMF) format,
• EPA SWMM's own ASCII text (.map) format.
The DXF format is readable by many Computer Aided Design (CAD) programs. Metafiles can be
inserted into word processing documents and loaded into drawing programs for re-scaling and
editing. Both formats are vector-based and will not lose resolution when they are displayed at
different scales.
To export the map to a DXF, metafile, or text file:
l . Select File » Export » Map.
2 . In the Map Export dialog that appears select the format that you want the map saved in.
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Map Export
Export Map To;
-6' Ted: File (.map)
Enhanced Metafile (.emf)
Drawing Exchange File (,dxf)
OK
Cancel
Help
If you select DXF format, you have a choice of how nodes will be represented in the DXF file.
They can be drawn as filled circles, as open circles, or as filled squares. Not all DXF readers can
recognize the format used in the DXF file to draw a filled circle. Also note that map annotation,
such as node and link ID labels will not be exported, but map label objects will be.
After choosing a format, click OK and enter a name for the file in the Save As dialog that appears.
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CHAPTER 8 - RUNNING A SIMULATION
After a study area has been suitably described, its runoff response, flow routing and water quality
behavior can be simulated. This section describes how to specify options to be used in the
analysis, how to run the simulation and how to troubleshoot common problems that might occur.
8.1 Setting Simulation Options
SWMM has a number of options that control how the simulation of a stormwater drainage system
is carried out. To set these options:
l. Select the Options category from the Project Browser.
2. Select one of the following categories of options to edit:
a. General Options
b. Date Options
c. Time Step Options
d. Dynamic Wave Routing Options
e. Interface File Options
f. Reporting Options
3. Click the & button on the Browser panel or select Edit » Edit Object to invoke the
appropriate editor for the chosen option category (the Simulation Options dialog is used
for the first five categories while the Reporting Options dialog is used for the last one).
The Simulations Options dialog contains a separate tabbed page for each of the first five option
categories listed above. Each page is described in more detail below.
8.1.1 General Options
The General page of the Simulation Options dialog sets values for the following options:
Process Models
This section allows you to select which of SWMM's process models will be applied to the current
project. For example, a model that contained Aquifer and Groundwater elements could be run
first with the groundwater computations turned on and then again with them turned off to see
what effect this process had on the site's hydrology. Note that if there are no elements in the
project needed to model a given process then that process option is disabled (e.g., if there were
no Aquifers defined for the project then the Groundwater check box will appear disabled in an
unchecked state).
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Simulation Options
General j Dates Time Steps
Process Models
U/j Rainfall/Runoff
Rainfall Dependent I/I
Sncv'v Melt
Ground'A-ater
M] Flow Routing
Water Quality
Routing Model
• _ • Steady Flow
'O.1 Kinematic Wave
• • Dynamic Wave
p^irn
; Dynamic Wave Files !
mj_immj||[im^^
Infiltration Model
\ • Morton
•:'_ ' Modified Morton
•,'.'• Green-Arnpt
<€»- Modified Green-Ampt
Curve Number
Miscellaneous
CH Allow Ponding
i_] Report Control Actions
[ | Report Input Summary
Minimum Conduit Slope
0 (%)
Cancel Help
Infiltration Model
This option controls how infiltration of rainfall into the upper soil zone of subcatchments is
modeled. The choices are:
• Morton
• Modified Morton
• Green-Ampt
• Modified Green-Ampt
• Curve Number
Each of these models is briefly described in section 3.4.2. Changing this option will require re-
entering values for the infiltration parameters in each subcatchment, unless the change is
between the two Morton options or the two Green-Ampt options.
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Routing Model
This option determines which method is used to route flows through the conveyance system. The
choices are:
• Steady Flow
• Kinematic Wave
• Dynamic Wave
Review section 3.4.5 for a brief description of each of these alternatives.
Allow Ponding
Checking this option will allow excess water to collect atop nodes and be re-introduced into the
system as conditions permit. In order for ponding to actually occur at a particular node, a non-
zero value for its Ponded Area attribute must be used.
Report Control Actions
Check this option if you want the simulation's Status Report to list all discrete control actions
taken by the Control Rules associated with a project (continuous modulated control actions are
not listed). This option should only be used for short-term simulation.
Report Input Summary
Check this option if you want the simulation's Status Report to list a summary of the project's
input data.
Minimum Conduit Slope
The minimum value allowed for a conduit's slope (%). If blank or zero (the default) then no
minimum is imposed (although SWMM uses a lower limit on elevation drop of 0.001 ft (0.00035
m) when computing a conduit slope).
8.1.2 Date Options
The Dates page of the Simulation Options dialog determines the starting and ending dates/times
of a simulation.
Start Analysis On
Enter the date (month/day/year) and time of day when the simulation begins.
Start Reporting On
Enter the date and time of day when reporting of simulation results is to begin. Using a date prior
to the start date is the same as using the start date.
End Analysis On
Enter the date and time when the simulation is to end.
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Start Sweeping On
Enter the day of the year (month/day) when street sweeping operations begin. The default is
January 1.
End Sweeping On
Enter the day of the year (month/day) when street sweeping operations end. The default is
December 31.
Antecedent Dry Days
Enter the number of days with no rainfall prior to the start of the simulation. This value is used to
compute an initial buildup of pollutant load on the surface of subcatchments.
If rainfall or climate data are read from external files, then the simulation dates should be
set to coincide with the dates recorded in these files.
8.1 .3 Time Step Options
The Time Steps page of the Simulation Options dialog establishes the length of the time steps
used for runoff computation, routing computation and results reporting. Time steps are specified
in days and hours:minutes:seconds except for flow routing which is entered as decimal seconds.
Reporting Time Step
Enter the time interval for reporting of computed results.
Runoff - Wet Weather Time Step
Enter the time step length used to compute runoff from subcatchments during periods of rainfall,
or when ponded water still remains on the surface, or when LID controls are still infiltrating or
evaporating runoff.
Runoff - Dry Weather Time Step
Enter the time step length used for runoff computations (consisting essentially of pollutant
buildup) during periods when there is no rainfall, no ponded water, and LID controls are dry. This
must be greater or equal to the Wet Weather time step.
Routing Time Step
Enter the time step length in decimal seconds used for routing flows and water quality
constituents through the conveyance system. Note that Dynamic Wave routing requires a much
smaller time step than the other methods of flow routing.
Steady Flow Periods
This set of options tells SWMM how to identify and treat periods of time when system hydraulics
is not changing. The system is considered to be in a steady flow period if:
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• The percent difference between total system inflow and total system outflow is below the
System Flow Tolerance,
• The percent differences between the current lateral inflow and that from the previous time
step for all points in the conveyance system are below the Lateral Flow Tolerance.
Checking the Skip Steady Flow Periods box will make SWMM keep using the most recently
computed conveyance system flows (instead of computing a new flow solution) whenever the
above criteria are met. Using this feature can help speed up simulation run times at the expense
of reduced accuracy.
8.1.4 Dynamic Wave Options
The Dynamic Wave page of the Simulation Options dialog sets several parameters that control
how the dynamic wave flow routing computations are made. These parameters have no effect for
the other flow routing methods.
Inertial Terms
Indicates how the inertial terms in the St. Venant momentum equation will be handled.
• KEEP maintains these terms at their full value under all conditions.
• DAMPEN reduces the terms as flow comes closer to being critical and ignores them
when flow is supercritical.
• IGNORE drops the terms altogether from the momentum equation, producing what is
essentially a Diffusion Wave solution.
Define Supercritical Flow By
Selects the basis used to determine when supercritical flow occurs in a conduit. The choices are:
• water surface slope only (i.e., water surface slope > conduit slope)
• Froude number only (i.e., Froude number > 1.0)
• both water surface slope and Froude number.
The first two choices were used in earlier versions of SWMM while the third choice, which checks
for either condition, is now the recommended one.
Force Main Equation
Selects which equation will be used to compute friction losses during pressurized flow for
conduits that have been assigned a Circular Force Main cross-section. The choices are either the
Hazen-Williams equation or the Darcy-Weisbach equation.
Use Variable Time Steps
Check the box if an internally computed variable time step should be used at each routing time
period and select an adjustment (or safety) factor to apply to this time step. The variable time step
is computed so as to satisfy the Courant condition within each conduit. A typical adjustment factor
would be 75% to provide some margin of conservatism. The computed variable time step will not
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be less than the minimum variable step discussed below nor be greater than the fixed time step
specified on the Time Steps page of the dialog.
Minimum Variable Time Step
This is the smallest time step allowed when variable time steps are used. The default value is 0.5
seconds. Smaller steps may be warranted, but they can lead to longer simulations runs without
much improvement in solution quality.
Time Step for Conduit Lengthening
This is a time step, in seconds, used to artificially lengthen conduits so that they meet the Courant
stability criterion under full-flow conditions (i.e., the travel time of a wave will not be smaller than
the specified conduit lengthening time step). As this value is decreased, fewer conduits will
require lengthening. A value of zero means that no conduits will be lengthened. The ratio of the
artificial length to the original length for each conduit is listed in the Flow Classification table that
appears in the simulation's Summary Report (see Section 9.2).
Minimum Nodal Surface Area
This is a minimum surface area used at nodes when computing changes in water depth. If 0 is
entered, then the default value of 12.566 ft2 (1.167 m2) is used. This is the area of a 4-ft diameter
manhole. The value entered should be in square feet for US units or square meters for SI units.
Maximum Trials per Time Step
This is the maximum number of trials that SWMM uses at each time step to reach convergence
when updating hydraulic heads at the conveyance system's nodes. The default value is 8.
Head Convergence Tolerance
When the difference in computed head at each node between successive trials is below this
value the flow solution for the current time step is assumed to have converged. The default
tolerance is 0.005 ft (0.0015 m).
Number of Threads
This selects the number of parallel computing threads to use on machines equipped with multi-
core processors. The default is 1.
Clicking the Apply Defaults label will set all the Dynamic Wave options to their default values.
8.1.5 File Options
The Files page of the Simulation Options dialog is used to specify which interface files will be
used or saved during the simulation. (Interface files are described in Chapter 11.) The page
contains a list box with three buttons underneath it. The list box lists the currently selected files,
while the buttons are used as follows:
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Add adds a new interface file specification to the list.
Edit edits the properties of the currently selected interface file.
Delete deletes the currently selected interface from the project (but not from your hard drive).
General Dates Time Steps Dynamic Wave Files
Specify interface files to use or save:
Add
Edit
Delete
When the Add or Edit buttons are clicked, an Interface File Selector dialog appears where you
can specify the type of interface file, whether it should be used or saved, and its name. The
entries on this dialog are as follows:
Interface File Selector
File Type;
HOTSTART
File Name;
tesEL.hsf
o Save File
Use File
OK
Help
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File Type
Select the type of interface file to be specified.
Use / Save Buttons
Select whether the named interface file will be used to supply input to a simulation run or whether
simulation results will be saved to it.
File Name
leal
Enter the name of the interface file or click the Browse button U2J to select from a standard
Windows file selection dialog box.
8.2 Setting Reporting Options
The Reporting Options dialog is used to select individual subcatchments, nodes, and links that
will have detailed time series results saved for viewing after a simulation has been run. The
default for new projects is that all objects will have detailed results saved for them. The dialog is
invoked by selecting the Reporting category of Options from the Project Browser and clicking the
& button (or by selecting Edit » Edit Object from the main menu).
The dialog contains three tabbed pages - one each for subcatchments, nodes, and links. It is a
stay-on-top form which means that you can select items directly from the Study Area Map or
Project Browser while the dialog remains visible.
Reporting Options
Select objects for detailed reporting;
Nodes
Links
Add
Subcatchments
Remove
Clear
Close
All Subcatchments
Help
To include an object in the set that is reported on:
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i. Select the tab to which the object belongs (Subcatchments, Nodes or Links).
2. Unselect the "AM" check box if it is currently checked.
3. Select the specific object either from the Study Area Map or from the listing in the
Project Browser.
4. Click the Add button on the dialog.
5. Repeat the above steps for any additional objects.
To remove an item from the set selected for reporting:
i. Select the desired item in the dialog's list box.
2. Click the Remove button to remove the item.
To remove all items from the reporting set of a given object category, select the object category's
page and click the Clear button.
To include all objects of a given category in the reporting set, check the "AM" box on the page for
that category (i.e., subcatchments, nodes, or links). This will override any individual items that
may be currently listed on the page.
To dismiss the dialog click the Close button.
8.3 Starting a Simulation
To start a simulation either select Project » Run Simulation from the Main Menu or click ^ on
the Standard Toolbar. A Run Status window will appear which displays the progress of the
simulation.
Run Status
*SI?V-, Computing ...
Percent Complete: 34%
Simulated Time;
Days 0 HrsiMin 01:23
Stop Minimize
To stop a run before its normal termination, click the Stop button on the Run Status window or
press the key. Simulation results up until the time when the run was stopped will be
available for viewing. To minimize the SWMM program while a simulation is running, click the
Minimize button on the Run Status window.
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If the analysis runs successfully the ~ icon will appear in the Run Status section of the Status
Bar at the bottom of SWMM's main window. Any error or warning messages will appear in a
Status Report window. If you modify the project after a successful run has been made, the status
flag changes to L-f indicating that the current computed results no longer apply to the modified
project.
8.4 Troubleshooting Results
When a run ends prematurely, the Run Status dialog will indicate the run was unsuccessful and
direct the user to the Status Report for details. The Status Report will include an error statement,
code, and description of the problem (e.g., ERROR 138: Node TG040 has initial depth greater
than maximum depth). Consult Appendix E for a description of SWMM's error messages. Even if
a run completes successfully, one should check to insure that the results are reasonable. The
following are the most common reasons for a run to end prematurely or to contain questionable
results.
Unknown ID Error Message
This message typically appears when an object references another object that was never defined.
An example would be a subcatchment whose outlet was designated as A/29, but no such
subcatchment or node with that name exists. Similar situations can exist for incorrect references
made to Curves, Time Series, Time Patterns, Aquifers, Snow Packs, Transects, Pollutants, and
Land Uses.
File Errors
File errors can occur when:
• a file cannot be located on the user's computer
• a file being used has the wrong format
• a file being written cannot be opened because the user does not have write privileges for
the directory (folder) where the file is to be stored.
Drainage System Layout Errors
A valid drainage system layout must obey the following conditions:
• An outfall node can have only one conduit link connected to it.
• A flow divider node must have exactly two outflow links.
• A node cannot have more than one dummy link connected to it.
• Under Kinematic Wave routing, a junction node can only have one outflow link and a
regulator link cannot be the outflow link of a non-storage node.
• Under Dynamic Wave routing there must be at least one outfall node in the network.
An error message will be generated if any of these conditions are violated.
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Excessive Continuity Errors
When a run completes successfully, the mass continuity errors for runoff, flow routing, and
pollutant routing will be displayed in the Run Status window. These errors represent the percent
difference between initial storage + total inflow and final storage + total outflow for the entire
drainage system. If they exceed some reasonable level, such as 10 percent, then the validity of
the analysis results must be questioned. The most common reasons for an excessive continuity
error are computational time steps that are too long or conduits that are too short.
Run Status
Run was successful.
Continuity Error
Surface Runofft
Flow Routing:
Quality Routing;
-0.27 %
0.10 %
-0.16 %
In addition to the system continuity error, the Status Report produced by a run (see Section 9.1)
will list those nodes of the drainage network that have the largest flow continuity errors. If the
error for a node is excessive, then one should first consider if the node in question is of
importance to the purpose of the simulation. If it is, then further study is warranted to determine
how the error might be reduced.
Unstable Flow Routing Results
Due to the explicit nature of the numerical methods used for Dynamic Wave routing (and to a
lesser extent, Kinematic Wave routing), the flows in some links or water depths at some nodes
may fluctuate or oscillate significantly at certain periods of time as a result of numerical
instabilities in the solution method. SWMM does not automatically identify when such conditions
exist, so it is up to the user to verify the numerical stability of the model and to determine if the
simulation results are valid for the modeling objectives. Time series plots at key locations in the
network can help identify such situations as can a scatter plot between a link's flow and the
corresponding water depth at its upstream node (see Section 9.5, Viewing Results with a Graph).
Numerical instabilities can occur over short durations and may not be apparent when time series
are plotted with a long time interval. When detecting such instabilities, it is recommended that a
reporting time step of 1 minute or less be used, at least for an initial screening of results.
The run's Status Report lists the links having the five highest values of a Flow Instability Index
(Fll). This index counts the number of times that the flow value in a link is higher (or lower) than
the flow in both the previous and subsequent time periods. The index is normalized with respect
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to the expected number of such 'turns' that would occur for a purely random series of values and
can range from 0 to 150.
As an example of how the Flow Instability Index can be used, consider Figure 8-1 shown below.
The solid line plots the flow hydrograph for the link identified as having the highest Fll value (100)
in a dynamic wave flow routing run that used a fixed time step of 30 seconds. The dashed line
shows the hydrograph that results when a variable time step was used instead, which is now
completely stable.
800
600
o
I
400
200
Fixed Time Step
(Fll = 100)
Variable Time Step
(Fll = 0)
10
12
Time (hours)
Figure 8-1 Flow Instability Index for a flow hydrograph
Flow time series plots for the links having the highest Fll's should be inspected to insure that flow
routing results are acceptably stable.
Numerical instabilities under Dynamic Wave flow routing can be reduced by:
• reducing the routing time step
• utilizing the variable time step option with a smaller time step factor
• selecting to ignore the inertial terms of the momentum equation
• selecting the option to lengthen short conduits.
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CHAPTER 9 -VIEWING RESULTS
This chapter describes the different ways in which the results of a simulation can be viewed.
These include a status report, a summary report, various map views, graphs, tables, and a
statistical frequency report.
9.1 Viewing a Status Report
A Status Report is available for viewing after each simulation. It contains:
• a summary of the main Simulation Options that are in effect
• a list of any error conditions encountered during the run
• a summary listing of the project's input data (if requested in the Simulation Options)
• a summary of the data read from each rainfall file used in the simulation
• a description of each control rule action taken during the simulation (if requested in the
Simulation Options)
• the system-wide mass continuity errors for:
o runoff quantity and quality
o groundwater flow
o conveyance system flow and water quality
• the names of the nodes with the highest individual flow continuity errors
• the names of the conduits that most often determined the size of the time step used for
flow routing (only when the Variable Time Step option is used)
• the names of the links with the highest Flow Instability Index values
• information on the range of routing time steps taken and the percentage of these that
were considered steady state.
To view the Status Report select Report » Status from the Main Menu or click the U button
and select Status Report from the drop-down menu that appears.
To copy selected text from the Status Report to a file or to the Windows Clipboard, first select the
text to copy with the mouse and then choose Edit » Copy To from the Main Menu (or press the
"^ button on the Standard Toolbar).
To save both the entire Status Report and Summary Report (discussed next) to file, select File
» Export » Status/Summary Report from the Main Menu.
9.2 Viewing Summary Results
SWMM's Summary Results report lists summary results for each subcatchment, node, and link in
the project through a selectable list of tables. To view the various summary results tables, select
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Report » Summary from the Main Menu or click the H button and select Summary Results
from the drop-down menu that appears. The Summary Results window looks as follows:
HH Summary Results
a > El
Topic: Sub catchment Runoff T Click a column header to sort the column.
Subcatchment
1
2
3
4
5
6
7
8
4
Total Total Total
Precip Runon Evap
in in in
0,00 0,00
2,65 0,00 0,00
2,65 0.00 0,00
2,65 0,00 0,00
2,65 0,00 0,00
2,65 0,00 0,00
2,65 0,00 0,00
2,65 0,00 0,00
Total Total
Infil Runoff
in in
1,16 1,48
1,21 1,43
1,16 1,49
1.16 1,49
1,24 1,40
2,27 0,38
2,14 0,51
2,25 0,40
^
The drop-down box at the upper left allows you to choose the type of results to view. The
selection of tables and the results they display are as follows:
Table
Columns
Subcatchment Runoff
Total precipitation (in or mm);
Total run-on from other subcatchments (in or mm);
Total evaporation (in or mm);
Total infiltration (in or mm);
Total runoff depth (in or mm);
Total runoff volume (million gallons or million liters);
Peak runoff (flow units);
Runoff coefficient (ratio of total runoff to total precipitation).
LID Performance
Total inflow volume
Total evaporation loss
Total infiltration loss
Total surface outflow
Total underdrain outflow
Initial storage volume
Final storage volume
Flow continuity error (%)
Note: all quantities are expressed as depths (in or mm) over the LID
unit's surface area.
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Groundwater Summary
Total surface infiltration (in or mm)
Total evaporation (in or mm)
Total lower seepage (in or mm)
Total lateral outflow (in or mm)
Maximum lateral outflow (flow units)
Average upper zone moisture content (volume fraction)
Average water table elevation (ft or m)
Final upper zone moisture content (volume fraction)
Final water table elevation (ft or m)
Subcatchment Washoff
Total mass of each pollutant washed off the subcatchment (Ibs or
kg).
Node Depth
Average water depth (ft or m);
Maximum water depth (ft or m);
Maximum hydraulic head (HGL) elevation (ft or m);
Time of maximum depth;
Maximum water depth at reporting times (ft or m).
Node Inflow
Maximum lateral inflow (flow units);
Maximum total inflow (flow units);
Time of maximum total inflow;
Total lateral inflow volume (million gallons or million liters);
Total inflow volume (million gallons or million liters);
Flow balance error (0/-
Note: Total inflow consists of lateral inflow plus inflow from
connecting links.
Node Surcharge
Hours surcharged;
Maximum height of surcharge above node's crown (ft or m);
Minimum depth of surcharge below node's top rim (ft or m).
Note: surcharging occurs when water rises above the crown of the
highest conduit and only those conduits that surcharge are listed.
Node Flooding
Hours flooded;
Maximum flooding rate (flow units);
Time of maximum flooding;
Total flood volume (million gallons or million liters);
Peak depth (for dynamic wave routing in ft or m) or peak volume
(1000 ft3 or 1000 m3) of ponded surface water.
Note: flooding refers to all water that overflows a node, whether it
ponds or not, and only those nodes that flood are listed.
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Storage Volume
Average volume of water in the facility (1000 ft3 or 1000 m3);
Average percent of full storage capacity utilized;
Percent of total stored volume lost to evaporation;
Percent of total stored volume lost to seepage;
Maximum volume of water in the facility (1000 ft3 or 1000 m3);
Maximum percent of full storage capacity utilized;
Time of maximum water stored;
Maximum outflow rate from the facility (flow units).
Outfall Loading
Percent of time that outfall discharges;
Average discharge flow (flow units);
Maximum discharge flow (flow units);
Total volume of flow discharged (million gallons or million liters);
Total mass discharged of each pollutant (Ibs or kg).
Link Flow
Maximum flow (flow units);
Time of maximum flow;
Maximum velocity (ft/sec or m/sec)
Ratio of maximum flow to full normal flow;
Ratio of maximum flow depth to full depth.
Flow Classification
Ratio of adjusted conduit length to actual length;
Fraction of all time steps spent in the following flow categories:
• dry on both ends
• dry on the upstream end
• dry on the downstream end
• subcritical flow
• supercritical flow
• critical flow at the upstream end
• critical flow at the downstream end
Fraction of all time steps flow is limited to normal flow;
Fraction of all time steps flow is inlet controlled (for culverts only).
Conduit Surcharge
Hours that conduit is full at:
• both ends
• upstream end
• downstream end
Hours that conduit flows above full normal flow;
Hours that conduit is capacity limited
Note: only conduits with one or more non-zero entries are listed and
a conduit is considered capacity limited if its upstream end is full and
the HGL slope is greater than the conduit slope.
Link Pollutant Loads
Total mass load (in Ibs or kg) of each pollutant carried by the link
over the entire simulation period.
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Pumping
Percent of time that the pump is on line;
Number of pump start-ups;
Minimum flow pumped (flow units)
Average flow pumped (flow units)
Maximum flow pumped (flow units);
Total volume pumped (million gallons or million liters);
Total energy consumed assuming 100% efficiency (Kw-hrs);
Percent of time that the pump operates below its pump curve;
Percent of time that the pump operates above its pump curve.
The summary results displayed in these tables are based on results found at every
computational time step and not just on the results from each reporting time step.
Clicking on the name of an object in the first column of the table will locate that object both in the
Project Browser and on the Study Area Map. Clicking on a column heading will sort the entries in
the table by the values in that column (alternating between ascending and descending order with
each click.
Selecting Edit » Copy To from the Main Menu or clicking ^ on the Standard Toolbar will allow
you to copy the contents of the table to either the Windows Clipboard or to a file. To save both the
entire Status Report and all tables of the Summary Report to a file select File » Export »
Status/Summary Report from the Main Menu.
9.3
Time Series Results
Computed results at each reporting time step for the variables listed in Table 9-1 are available for
viewing on the map and can be plotted, tabulated, and statistically analyzed. These variables can
be viewed only for those subcatchments, nodes, and links that were selected to have detailed
time series results saved for them. This normally includes all such objects in the project unless
the Reporting option (under the Options category in the Project Browser) was used to select
specific objects to report on.
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Table 9-1 Time series variables available for viewing
Link Variables
• flow rate (flow units)
average water depth (ft or m)
• flow velocity (ft/sec or m/sec)
• volume of water (ft3 or m3)
capacity (fraction of full area filled by flow
Subcatchment Variables
rainfall rate (in/hr or mm/hr)
snow depth (in or mm)
evaporation loss (in/day or mm/day)
infiltration loss (in/hr or mm/hr)
runoff flow (flow units)
• groundwater flow into the drainage network
(flow units)
• groundwater elevation (ft or m)
• soil moisture in the unsaturated groundwater
zone (volume fraction)
• washoff concentration of each pollutant
(mass/liter)
Node Variables
• water depth (ft or m above the node invert
elevation)
hydraulic head (ft or m, absolute elevation per
vertical datum)
stored water volume (including ponded water,
ft3 or m3)
lateral inflow (runoff + all other external
inflows, in flow units)
• total inflow (lateral inflow + upstream inflows,
in flow units)
• surface flooding (excess overflow when the
node is at full depth, in flow units)
concentration of each pollutant after any
treatment applied at the node (mass/liter)
for conduits; control setting for pumps and
regulators)
concentration of each pollutant
(mass/liter)
System-Wide Variables
air temperature (degrees F or C)
potential evaporation (in/day or mm/day)
actual evaporation (in/day or mm/day)
total rainfall (in/hr or mm/hr)
• total snow depth (in or mm)
average losses (in/hr or mm/hr)
total runoff flow (flow units)
• total dry weather inflow (flow units)
• total groundwater inflow (flow units)
• total RDM inflow (flow units)
• total direct inflow (flow units)
• total external inflow (flow units)
• total external flooding (flow units)
• total outflow from outfalls (flow units)
• total nodal storage volume (ft3 or m3)
9.4 Viewing Results on the Map
There are several ways to view the values of certain input parameters and simulation results
directly on the Study Area Map:
• For the current settings on the Map Browser, the subcatchments, nodes and links of the
map will be colored according to their respective Map Legends. The map's color coding
will be updated as a new time period is selected in the Map Browser.
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• When the Flyover Map Labeling program preference is selected (see Section 4.9),
moving the mouse over any map object will display its ID name and the value of its
current theme parameter in a hint-style box.
• ID names and parameter values can be displayed next to all subcatchments, nodes
and/or links by selecting the appropriate options on the Annotation page of the Map
Options dialog (see Section 7.12).
• Subcatchments, nodes or links meeting a specific criterion can be identified by submitting
a Map Query (see Section 7.9).
• You can animate the display of results on the network map either forward or backward in
time by using the controls on the Animator panel of the Map Browser (see Section 4.7).
• The map can be printed, copied to the Windows clipboard, or saved as a DXF file or
Windows metafile (see Section 7.13).
9.5 Viewing Results with a Graph
Analysis results can be viewed using several different types of graphs. Graphs can be printed,
copied to the Windows clipboard, or saved to a text file or to a Windows metafile. The following
types of graphs can be created from available simulation results:
Time Series Plot:
90.0
70.0
60.0
« 50.0
140.0
£30.0
20.0
10.0
0.0
Link 1602 Flow (CFS)
2 3 4 S 6
Elapsed Time (hours)
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Profile Plot:
Water Elevation Profile; Node 81009 -16009
at os
105 -
12,000 10,000
8,000 6,(M»
Distance {ft)
4,000 2,000
01/01 ,'2002 01:30:00
Link 1600 Flow v. Node 16109 Depth
Scatter Plot:
70.0
£60.0
0,
o
u- 40.0
O
S 30.0
.E 20.0
10.0
0.0
f
m
m
m
m
— . m *
0,5 1 1.5 2
Node 16109 Depth p|
2,5
You can zoom in or out of any graph by holding down the key while drawing a zoom
rectangle with the mouse's left button held down. Drawing the rectangle from left to right zooms
in, drawing it from right to left zooms out. The plot can also be panned in any direction by moving
the mouse across the plot with the left button held down
An opened graph will normally be redrawn when a new simulation is run. To prevent the
automatic updating of a graph once a new set of results is computed you can lock the current
graph by clicking the m icon in the upper left corner of the graph. To unlock the graph, click the
icon again.
Time Series Plots
A Time Series Plot graphs the values overtime of specific combinations of objects and variables.
Up to six time series can be plotted on the same graph. When only a single time series is plotted,
and that item has calibration data registered for the plotted variable, then the calibration data will
143
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be plotted along with the simulated results (see Section 5.5 for instructions on how to register
calibration data with a project).
To create a Time Series Plot:
l. Select Report » Graph » Time Series from the Main Menu or click lK on the
Standard Toolbar.
2. A Time Series Plot Selection dialog will appear. Use it to describe what objects and
quantities should be plotted.
Time Series Plot Selection
Time Periods
Start Date
06/27/2002
o Elapsed Time
Data Series
End Date
06/27/2002
Date/Time
Add
Edit
Delete
Link Cl Flow
OK
The Time Series Plot Selection dialog specifies a set of objects and their variables whose
computed time series will be graphed in a Time Series Plot. The dialog is used as follows:
l. Select a Start Date and End Date for the plot (the default is the entire simulation period).
2. Choose whether to show time as Elapsed Time or as Date/Time values.
3. Add up to six different data series to the plot by clicking the Add button above the data
series list box.
4. Use the Edit button to make changes to a selected data series or the Delete button to
delete a data series.
5. Use the Up and Down buttons to change the order in which the data series will be
plotted.
6. Click the OK button to create the plot.
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When you click the Add or Edit buttons a Data Series Selection dialog will be displayed for
selecting a particular object and variable to plot. It contains the following data fields:
Data Series Selection
Specify the object and variable to plot
(Click an object on the map to select it)
Object Type Link
Object Name C2
Variable
Legend Label
Axis
|! Accept j|
Flow
•6. Left
Right
Cancel
Object Type: The type of object to plot (Subcatchment, Node, Link or System).
Object Name: The ID name of the object to be plotted. (This field is disabled for System
variables).
Variable: The variable whose time series will be plotted (choices vary by object type).
Legend Label: The text to use in the legend for the data series. If left blank, a default label
made up of the object type, name, variable and units will be used (e.g. Link
C16Flow(CFS)).
Axis: Whether to use the left or right vertical axis to plot the data series.
As you select objects on the Study Area Map or in the Project Browser their types and ID
names will automatically appear in this dialog.
Click the Accept button to add/update the data series into the plot or click the Cancel button to
disregard your edits. You will then be returned to the Time Series Plot Selection dialog where you
can add or edit another data series.
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To make a precipitation time series display in inverted fashion on a plot, assign it to the
right axis and after the plot is displayed, use the Graph Options Dialog (see Section 9.6)
to invert the right axis and expand the scales of both the left and right axes (so it doesn't
overlap another data series).
Profile Plots
A Profile Plot displays the variation in simulated water depth with distance over a connected path
of drainage system links and nodes at a particular point in time. Once the plot has been created it
will be automatically updated as a new time period is selected using the Map Browser.
To create a Profile Plot:
l. Select Report » Graph » Profile from the main menu or press -tj on the Standard
Toolbar
2. A Profile Plot Selection dialog will appear (see below). Use it to identify the path along
which the profile plot is to be drawn.
Profile Plot Selection
Create Profile
Start Node
Jl
End Node
Outl
Find Path
Links in Profile
\C2
C4
Save Current Profile
X
OK
The Profile Plot Selection dialog is used to specify a path of connected conveyance system links
along which a water depth profile versus distance should be drawn. To define a path using the
dialog:
l. Enter the ID of the upstream node of the first link in the path in the Start Node edit field
(or click on the node on the Study Area Map and then on the I—J button next to the edit
field).
146
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2. Enter the ID of the downstream node of the last link, in the path in the End Node edit field
(or click the node on the map and then click the button next to the edit field).
Click the Find Path button to have the program automatically identify the path with the
smallest number of links between the start and end nodes. These will be listed in the
Links in Profile box.
You can insert a new link into the Links in Profile list by selecting the new link either on
the Study Area Map or in the Project Browser and then clicking the
underneath the Links in Profile list box.
5. Entries in the Links in Profile list can be deleted or rearranged by using the
button
and L—J buttons underneath the list box.
6. Click the OK button to view the profile plot.
To save the current set of links listed in the dialog for future use:
l. Click the Save Current Profile button.
2. Supply a name for the profile when prompted.
To use a previously saved profile:
l. Click the Use Saved Profile button.
2. Select the profile to use from the Profile Selection dialog that appears.
Profile plots can also be created before any simulation results are available, to help visualize and
verify the vertical layout of a drainage system. Plots created in this manner will contain a refresh
tnt\
button _*^J in the upper left corner that can be used to redraw the plot after edits are made to any
elevation data appearing in the plot.
Scatter Plots
A Scatter Plot displays the relationship between a pair of variables, such as flow rate in a pipe
versus water depth at a node. To create a Scatter Plot:
l. Select Report » Graph » Scatter from the main menu or press liE on the Standard
Toolbar
2. Specify what time interval and what pair of objects and their variables to plot using the
Scatter Plot Selection dialog that appears.
The Scatter Plot Selection dialog is used to select the objects and variables to be graphed
against one another in a scatter plot. Use the dialog as follows:
147
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Scatter Plot Select!on
Start Date
06/27/2002
X-Variable
Object Category
Nodes
Object
J2
Variable
Depth
End Date
06/27/2002
Y-Variable
Object Category
Links
Object
C2
Variable
Flow
OK
Select a Start Date and End Date for the plot (the default is the entire simulation period).
Select the following choices for the X-variable (the quantity plotted along the horizontal
axis):
a. Object Category (Subcatchment, Node or Link)
b. Object ID (enter a value or click on the object either on the Study Area Map or in
the Project Browser and then click the
button on the dialog)
c. Variable to plot (choices depend on the category of object selected).
3. Do the same for the Y-variable (the quantity plotted along the vertical axis).
4. Click the OK button to create the plot.
9.6 Customizing a Graph's Appearance
To customize the appearance of a graph:
l. Make the graph the active window (click on its title bar).
2. Select Report » Customize from the Main Menu, or click Hr on the Standard Toolbar,
or right-click on the graph.
3. Use the Graph Options dialog that appears to customize the appearance of a Time
Series or Scatter Plot, or use the Profile Plot Options dialog for a Profile Plot.
148
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Graph Options Dialog
The Graph Options dialog is used to customize the appearance of a time series plot, a scatter
plot, or a freguency plot (described in Section9.8). To use the dialog:
l. Select from among the four tabbed pages that cover the following categories of options:
General, Axes, Legend, and Styles.
2. Check the Default box if you wish to use the current settings as defaults for all new
graphs as well.
3. Select OK to accept your selections.
Graph Options
General
Panel Color
Start Background Color
White
White
End Background Color I I White
View in 3-D I }
3D Effect Percent
Main Title
25
I Make these the default options
OK
Cancel
Graph Options - General
The following options can be set on the General page of the Graph Options dialog box:
Panel Color
Start Background
Color
End Background
Color of the panel that contains the graph
Starting gradient color of graph's plotting area
Ending gradient color of graph's plotting area
149
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Color
View in 3D
3D Effect Percent
Main Title
Font
Check if graph should be drawn in 3D
Degree to which 3D effect is drawn
Text of graph's main title
Click to set the font used for the main title
The figure below shows a 3D graph with White as the Start Background Color and Sky Blue as
the End Background Color.
•gj Graph-Link C2 Flow
E)
LinkC2 Flow(CFS)
4 5 6 7 i
Elapsed Time (hours)
10 11 12
Graph Options - Axes
The Axes page of the Graph Options dialog box adjust the way that the axes are drawn on a
graph. One first selects an axis (Bottom, Left or Right (if present)) to work with and then selects
from the following options:
Gridlines
Inverted
Auto Scale
Minimum
Displays grid lines on the graph.
Inverts the scale of the right vertical axis.
Fills in the Minimum, Maximum and Increment boxes with an
automatic axis scaling.
Sets the minimum axis value (the minimum data value is shown
in parentheses). Can be left blank.
150
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Maximum Sets the maximum axis value (the maximum data value is
shown in parentheses). Can be left blank.
Increment Sets increment between axis labels. Can be left blank or set to
zero for the program to automatically select an increment.
Axis Title Text of axis title.
Font Click to select a font for the axis title.
Graph Options - Legend
The Legend page of the Graph Options dialog box controls how the legend is displayed on the
graph.
Position Selects where to place the legend.
Color Selects color to use for legend background.
Check Boxes If selected, check boxes will appear next to each legend entry,
allowing one to make the data series visible or invisible on the
graph.
Framed Places a frame around the legend.
Shadowed Places a shadow behind the legend's text.
Transparent Makes the legend background transparent.
Visible Makes the legend visible.
Symbol Width Selects the width used to draw the symbol portion of a legend
item, as a percentage of the length of the longest legend label.
Graph Options - Styles
The Styles page of the Graph Options dialog box controls how individual data series (or curves)
are displayed on a graph. To use this page:
l. Select a data series to work with from the Series combo box.
2. Edit the title used to identify this series in the legend.
3. Click the Font button to change the font used for the legend. (Other legend properties are
selected on the Legend page of the dialog.)
151
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4. Select a property of the data series you would like to modify (not all properties are
available for some types of graphs). The choices are:
• Lines
• Markers
• Patterns
• Labels
Profile Plot Options Dialog
The Profile Plot Options dialog is used to customize the appearance of a Profile Plot. The dialog
contains four pages:
Profile Plot Options
[ ] Make these the default options
OK
Cancel
Help
Colors AM
Plot Panel
s Node Labels [ Vertical Scale
Q| White
Plot Background D White
Conduit Interior D White
Water Depth Q Aqua
Display Conduits Only LJ
Colors:
Axes:
Selects the color to use for the plot window panel, the plot background, a conduit's
interior, and the depth of filled water.
Includes a "Display Conduits Only" check box that provides a closer look at the water
levels within conduits by removing all other details from the plot.
Edits the main and axis titles, including their fonts.
Selects to display horizontal and vertical axis grid lines.
152
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Node Labels:
Selects to display node ID labels either along the plot's top axis, directly on the plot
above the node's crown height, or both.
Selects the length of arrow to draw between the node label and the node's crown on
the plot (use 0 for no arrows).
Selects the font size of the node ID labels.
Vertical Sca/e:
• Lets one choose the minimum, maximum, and increment values for the vertical axis
scale, or have SWMM set the scale automatically. If the increment field contains 0 or
is left blank the program will automatically select an increment to use.
Check the Default box if you want these options (except the Vertical Scale) to apply to all new
profile plots when they are first created.
9.7 Viewing Results with a Table
Time series results for selected variables and objects can also be viewed in a tabular format.
There are two types of formats available:
• Table by Object - tabulates the time series of several variables for a single object (e.g.,
flow and water depth for a conduit).
"
H] Table -L
Days
0
0
0
0
0
0
ink?
Hours
01:00:00
02:00:00
03:00:00
04:00:00
05:00:00
06:00:00
1 (— ' 1
Flow Dep
(CFS) (ft
0.00 ! 0
2.56 0
4.87 0
5.40 0
5.23 0
1.75 0
B
th *
i i
000000
399179
550729
580890
571036
330089 „
Table by Variable - tabulates the time series of a single variable for several objects of the
same type (e.g., runoff fora group of subcatchments).
153
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IBB Table - Subcatch Runoff
Days
0
0
0
0
0
0
Hours
01:00:00
02:00:00
03:00:00
04:00:00
05:00:00
06:00:00
Subcatch
2
0.00000 |
1.24382
2.56397
4.52406
2.51151
0,69808
H^H B
Subcatch •*
5
0.00000
1,81482
3.82166
6.56211
3.58567
1,03362 ^
To create a tabular report:
l. Select Report » Table from the Main Menu or click El on the Standard Toolbar.
2. Choose the table format (either By Object or By Variable) from the sub-menu that
appears.
3. Fill in the Table by Object or Table by Variable dialogs to specify what information the
table should contain.
The Table by Object dialog is used when creating a time series table of several variables for a
single object. Use the dialog as follows:
Table by Object Selection
Start Date End Date
01/01/1998 T 01/02/1998
Time Format
Elapsed Time
Variables
Object Category
Links
Links
Flow
Velocity
Volume
: Capacity
OK
Cancel
Select a Start Date and End Date for the table (the default is the entire simulation period).
l. Choose whether to show time as Elapsed Time or as Date/Time values.
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2. Choose an Object Category (Subcatchment, Node, Link, or System).
3. Identify a specific object in the category by clicking the object either on the Study Area
button on the dialog. Only a
Map or in the Project Browser and then clicking the
single object can be selected for this type of table.
4. Check off the variables to be tabulated for the selected object. The available choices
depend on the category of object selected.
5. Click the OK button to create the table.
The Table by Variable dialog is used when creating a time series table of a single variable for one
or more objects. Use the dialog as follows:
Table by Variable Select!on
Start Date End Date
01/01/1998 * 01/02/1998
Time Format
Elapsed Time
Variables
Object Category
Sub catch merits
Sub catch merits
Precipitation
Snow Depth
Evaporation
Infiltration
OK
Help
l. Select a Start Date and End Date for the table (the default is the entire simulation period).
2. Choose whether to show time as Elapsed Time or as Date/Time values.
3. Choose an Object Category (Subcatchment, Node or Link).
4. Select a simulated variable to be tabulated. The available choices depend on the
category of object selected.
5. Identify one or more objects in the category by successively clicking the object either on
the Study Area Map or in the Project Browser and then clicking the I
dialog.
6. Click the OK button to create the table.
button on the
155
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Objects already selected can be deleted, moved up in the order or moved down in the order by
clicking the L^ , JL. , and I—* buttons, respectively.
9.8 Viewing a Statistics Report
A Statistics Report can be generated from the time series of simulation results. For a given object
and variable this report will do the following:
• segregate the simulation period into a sequence of non-overlapping events, either by
day, month, or by flow (or volume) above some minimum threshold value,
• compute a statistical value that characterizes each event, such as the mean, maximum,
or total sum of the variable over the event's time period,
• compute summary statistics for the entire set of event values (mean, standard deviation
and skewness),
• perform a frequency analysis on the set of event values.
The frequency analysis of event values will determine the frequency at which a particular event
value has occurred and will also estimate a return period for each event value. Statistical
analyses of this nature are most suitable for long-term continuous simulation runs.
To generate a Statistics Report:
l. Select Report » Statistics from the Main Menu or click 2 on the Standard Toolbar.
2. Fill in the Statistics Report Selection dialog that appears, specifying the object, variable,
and event definition to be analyzed.
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Statistics Report Selection
Object Category Subcatchment
Object Name 1
Variable Analyzed Precipitation
Event Time Period Event-Dependent
Statistic Mean
Event Thresholds
Precipitation
Event Volume
Separation Time
0
OK
Cancel
Object Category
Select the category of object to analyze (Subcatchment, Node, Link or System).
Object Name
Enter the ID name of the object to analyze. Instead of typing in an ID name, you can select the
button to select it
object on the Study Area Map or in the Project Browser and then click the
into the Object Name field.
Variable Analyzed
Select the variable to be analyzed. The available choices depend on the object category selected
(e.g., rainfall, losses, or runoff for subcatchments; depth, inflow, or flooding for nodes; depth, flow,
velocity, or capacity for links; water quality for all categories).
Event Time Period
Select the length of the time period that defines an event. The choices are daily, monthly, or
event-dependent. In the latter case, the event period depends on the number of consecutive
reporting periods where simulation results are above the threshold values defined below.
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Statistic
Choose an event statistic to be analyzed. The available choices depend on the choice of variable
to be analyzed and include such quantities as mean value, peak value, event total, event
duration, and inter-event time (i.e., the time interval between the midpoints of successive events).
For water quality variables the choices include mean concentration, peak concentration, mean
loading, peak loading, and event total load.
Event Thresholds
These define minimum values that must be exceeded for an event to occur:
• The Analysis Variable threshold specifies the minimum value of the variable being
analyzed that must be exceeded for a time period to be included in an event.
• The Event Volume threshold specifies a minimum flow volume (or rainfall volume) that
must be exceeded for a result to be counted as part of an event.
• Separation Time sets the minimum number of hours that must occur between the end of
one event and the start of the next event. Events with fewer hours are combined
together. This value applies only to event-dependent time periods (not to daily or monthly
event periods).
If a particular type of threshold does not apply, then leave the field blank.
After the choices made on the Statistics Selection dialog form are processed, a Statistics Report
is produced as shown below. It consists of four tabbed pages that contain:
• a table of event summary statistics
• a table of rank-ordered event periods, including their date, duration, and magnitude
• a histogram plot of the chosen event statistic
• an exceedance frequency plot of the event values.
The exceedance frequencies included in the Statistics Report are computed with respect to the
number of events that occur, not the total number of reporting periods.
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2 Statistics - Subcatch 1 Precipitation
! Summary ijjventsj Histogram j Frequency Plot
SUMMARY STATISTICS
Object Subcatch 1
Variable Precipitation (in/hr)
Event Period ......... Variable
Event Statistic Mean (in/hr)
Event Threshold Precipitation > 0.0000 (in/hr)
Event Threshold ...... Event Volume > 0.0000 (in)
Event Threshold Separation Time >= 6.0 (hr)
Period of Record 01/01/1998 to 05/12/2000
Number of Events 226
Event Frequency* 0.067
Minimum Value 0.010
Maximum Value ........ 0,500
Mean Value 0.058
Std. Deviation ....... 0.058
Skewness Coeff 3.001
*Fraction of all reporting periods belonging to an event.
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CHAPTER 10 - PRINTING AND COPYING
This chapter describes how to print, copy to the Windows clipboard, or copy to file the contents of
the currently active window in the SWMM workspace. This can include the study area map, a
graph, a table, or a report.
10.1 Selecting a Printer
To select a printer from among your installed Windows printers and set its properties:
l. Select File » Page Setup from the Main Menu.
2. Click the Printer button on the Page Setup dialog that appears (see below).
3. Select a printer from the choices available in the combo box in the Print Setup dialog that
appears.
4. Click the Properties button to select the appropriate printer properties (which vary with
choice of printer).
5. Click OK on each dialog to accept your selections.
Page Setup
Margins Headers/Footers
Printer.,.
Paper Size
Width: 8.5 "
Height: 11.0 "
Orientation
•O- Portrait
• ' Landscape
Margins (inches)
Left 1.00 Right 1.00
Top 1.50 Bottom 1.00
OK
Cancel
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10.2 Setting the Page Format
To format the printed page:
1. Select File » Page Setup from the main menu.
2. Use the Margins page of the Page Setup dialog form that appears (see above) to:
• Select a printer.
• Select the paper orientation (Portrait or Landscape).
• Set left, right, top, and bottom margins.
3. Use the Headers/Footers page of the dialog box (see below) to:
• Supply the text for a header that will appear on each page.
• Indicate whether the header should be printed or not and how its text should be
aligned.
• Supply the text for a footer that will appear on each page.
• Indicate whether the footer should be printed or not and how its text should be
aligned.
• Indicate whether pages should be numbered.
4. Click OK to accept your choices.
Page Setup
Margins Headers/Footers
Header
Align: Left o Lenter Right Enabled
Footer
SWMM 5.1
Align: o Left "Center "Right Enabled [7
Page Numbers Lower Right
OK
Cancel
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10.3 Print Preview
To preview a printout select File » Print Preview from the Main Menu. A Preview form will
appear which shows how each page being printed will appear. While in preview mode, the left
mouse button will re-center and zoom in on the image and the right mouse button will re-center
and zoom out.
10.4 Printing the Current View
To print the contents of the current window being viewed in the SWMM workspace, either select
File » Print from the Main Menu or click ^ on the Standard Toolbar. The following views can
be printed:
• Study Area Map (at the current zoom level)
• Status Report.
• Summary report (for the current table being viewed)
• Graphs (Time Series, Profile, and Scatter plots)
• Tabular Reports
• Statistical Reports.
10.5 Copying to the Clipboard or to a File
SWMM can copy the text and graphics of the current window being viewed to the Windows
clipboard or to a file. Views that can be copied in this fashion include the Study Area Map,
summary report tables, graphs, time series tables, and statistical reports. To copy the current
view to the clipboard or to file:
l. If the current view is a time series table, select the cells of the table to copy by dragging
the mouse over them or copy the entire table by selecting Edit » Select All from the
Main Menu.
2. Select Edit » Copy To from the Main Menu or click the ^ button on the Standard
Toolbar.
3. Select choices from the Copy dialog that appears (see below) and click the OK button.
4. If copying to file, enter the name of the file in the Save As dialog that appears and click
OK.
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Copy Chart
Copy To
•<>• Clipboard
•[•File
| OK C
Copy As
<3 Bitmap
; Metafile
• '. Data (Text)
lancel Help
Use the Copy dialog as follows to define how you want your data copied and to where:
l. Select a destination for the material being copied (Clipboard or File)
2. Select a format to copy in:
• Bitmap (graphics only)
• Metafile (graphics only)
• Data (text, selected cells in a table, or data used to construct a graph)
3. Click OK to accept your selections or Cancel to cancel the copy request.
The bitmap format copies the individual pixels of a graphic. The metafile format copies the
instructions used to create the graphic and is more suitable for pasting into word processing
documents where the graphic can be re-scaled without losing resolution. When data is copied, it
can be pasted directly into a spreadsheet program to create customized tables or charts.
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CHAPTER 11 - FILES USED BY SWMM
This section describes the various files that SWMM can utilize. They include: the project file, the
report and output files, rainfall files, the climate file, calibration data files, time series files, and
interface files. The only file required to run SWMM is the project file; the others are optional.
11.1 Project Files
A SWMM project file is a plain text file that contains all of the data used to describe a study area
and the options used to analyze it. The file is organized into sections, where each section
generally corresponds to a particular category of object used by SWMM. The contents of the file
can be viewed from within SWMM while it is open by selecting Project » Details from the Main
Menu. An existing project file can be opened by selecting File » Open from the Main Menu and
be saved by selecting File » Save (or File » Save As).
Normally a SWMM user would not edit the project file directly, since SWMM's graphical user
interface can add, delete, or modify a project's data and control settings. However, for large
projects where data currently reside in other electronic formats, such as CAD or CIS files, it may
be more expeditious to extract data from these sources and save it to a formatted project file
before running SWMM. The format of the project file is described in detail in Appendix D of this
manual.
After a project file is saved to disk, a settings file will automatically be saved with it. This file has
the same name as the project file except that its extension is .ini (e.g., if the project file were
named projectl.inp then its settings file would have the name project1.ini). It contains various
settings used by SWMM's graphical user interface, such as map display options, legend colors
and intervals, object default values, and calibration file information. Users should not edit this file.
A SWMM project will still load and run even if the settings file is missing.
11.2 Report and Output Files
The report file is a plain text file created after every SWMM run that contains the contents of both
the Status Report and all of the tables included in the Summary Results report. Refer to
Sections 9.1 and 9.2 to review their contents.
The output file is a binary file that contains the numerical results from a successful SWMM run.
This file is used by SWMM's user interface to interactively create time series plots and tables,
profile plots, and statistical analyses of a simulation's results.
Whenever a successfully run project is either saved or closed, the report and output files are
saved with the same name as the project file, but with extensions of .rpt and .out This will
happen automatically if the program preference Prompt to Save Results is turned off (see Section
4.9). Otherwise the user is asked if the current results should be saved or not. If results are saved
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then the next time the project is opened, the results from these files will automatically be available
for viewing.
11.3 Rainfall Files
SWMM's rain gage objects can utilize rainfall data stored in external rainfall files. The program
currently recognizes the following formats for storing such data:
• Hourly and fifteen minute precipitation data from over 5,500 reporting stations retrieved
using NOAA's National Climatic Data Center (NCDC) Climate Data Online service
(www.ncdc.noaa.gov/cdo-web') (space-delimited text format only).
• The older DS-3240 and related formats used for hourly precipitation by NCDC.
• The older DS-3260 and related formats used for fifteen minute precipitation by NCDC.
• HLY03 and HLY21 formats for hourly rainfall at Canadian stations, available from
Environment Canada at www.climate.weather.gc.ca.
• FIF21 format for fifteen minute rainfall at Canadian stations, also available online from
Environment Canada.
• a standard user-prepared format where each line of the file contains the station ID, year,
month, day, hour, minute, and non-zero precipitation reading, all separated by one or
more spaces.
When requesting data from NCDC's online service, be sure to specify the TEXT format option,
make sure that the data flags are included, and, for 15-minute data, select the QPCP option and
nottheQGAG one.
An excerpt from a sample user-prepared Rainfall file is as follows:
STAOl 2004 6 12 00 00 0.12
STA01 2004 6 12 01 00 0.04
STAOl 2004 6 22 16 00 0.07
This format can also accept multiple stations within the same file.
When a rain gage is designated as receiving its rainfall data from a file, the user must supply the
name of the file and the name of the recording station referenced in the file. For the standard
user-prepared format, the rainfall type (e.g., intensity or volume), recording time interval, and
depth units must also be supplied as rain gage properties. For the other file types these
properties are defined by their respective file format and are automatically recognized by SWMM.
11.4 Climate Files
SWMM can use an external climate file that contains daily air temperature, evaporation, and wind
speed data. The program currently recognizes the following formats:
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• Global Historical Climatology Network - Daily (GHCN-D) files (TEXT output format)
available from NOAA's National Climatic Data Center (NCDC) Climate Data Online
service at www.ncdc.noaa.gov/cdo-web.
• Older NCDC DS-3200 or DS-3210 files.
• Canadian climate files available from Environment Canada at
www.climate.weather.gc.ca.
• A user-prepared climate file where each line contains a recording station name, the year,
month, day, maximum temperature, minimum temperature, and optionally, evaporation
rate, and wind speed. If no data are available for any of these items on a given date, then
an asterisk should be entered as its value.
When a climate file has days with missing values, SWMM will use the value from the most recent
previous day with a recorded value.
F":
For a user-prepared climate file, the data must be in the same units as the project being
analyzed. For US units, temperature is in degrees F, evaporation is in inches/day, and
wind speed is in miles/hour. For metric units, temperature is in degrees C, evaporation is
in mm/day, and wind speed is in km/hour.
11.5 Calibration Files
Calibration files contain measurements of variables at one or more locations that can be
compared with simulated values in Time Series Plots. Separate files can be used for each of the
following:
• Subcatchment Runoff
• Subcatchment Groundwater Flow
• Subcatchment Groundwater Elevation
• Subcatchment Snow Pack Depth
• Subcatchment Pollutant Washoff
• Node Depth
• Node Lateral Inflow
• Node Flooding
• Node Water Quality
• Link Flow
• Link Velocity
• Link Depth
Calibration files are registered to a project by selecting Project » Calibration Data from the
main menu (see Section 5.7).
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The format of the file is as follows:
l. The name of the first object with calibration data is entered on a single line.
2. Subsequent lines contain the following recorded measurements for the object:
• measurement date (month/day/year, e.g., 6/21/2004) or number of whole days
since the start of the simulation
• measurement time (hours:minutes) on the measurement date or relative to the
number of elapsed days
• measurement value (for pollutants, a value is required for each pollutant).
3. Follow the same sequence for any additional objects.
An excerpt from an example calibration file is shown below. It contains flow values for two
conduits: 1030 and 1602. Note that a semicolon can be used to begin a comment. In this
example, elapsed time rather than the actual measurement date was used.
; Flows for Selected
; Conduit Days Time
r
1030
0
0
0
0
0
1602
0
0
0
0
0
0
0
1
1
0
0
1
1
Conduits
Flow
15
30
45
00
15
15
30
00
15
0
0
23
94
.88
.58
115.37
5.
38
67
68
76
.51
.93
.01
11.6 Time Series Files
Time series files are external text files that contain data for SWMM's time series objects.
Examples of time series data include rainfall, evaporation, inflows to nodes of the drainage
system, and water stage at outfall boundary nodes. The file must be created and edited outside of
SWMM, using a text editor or spreadsheet program. A time series file can be linked to a specific
time series object using SWMM's Time Series Editor (see Section C.19).
The format of a time series file consists of one time series value per line. Comment lines can be
inserted anywhere in the file as long as they begin with a semicolon. Time series values can
either be in date / time / value format or in time / value format, where each entry is separated by
one or more spaces or tab characters. For the date / time / value format, dates are entered as
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month/day/year (e.g., 7/21/2004) and times as 24-hour military time (e.g., 8:30 pm is 20:30). After
the first date, additional dates need only be entered whenever a new day occurs. For the time /
value format, time can either be decimal hours or military time since the start of a simulation (e.g.,
2 days, 4 hours and 20 minutes can be entered as either 52.333 or 52:20). An example of a time
series file is shown below:
; Rainfall Data
07/01/2003
07/06/2003
00
00
00
00
01
14
14
15
18
18
for Gage Gl
00
15
30
45
00
30
45
00
15
30
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
00000
03200
04800
02400
0100
05100
04800
03000
01000
00800
In earlier releases of SWMM 5, a time series file was required to have two header lines of
descriptive text at the start of the file that did not have to begin with the semicolon
comment character. These files can still be used as long as they are modified by inserting
a semicolon at the front of the first two lines.
When preparing rainfall time series files, it is only necessary to enter periods with non-
zero rainfall amounts. SWMM interprets the rainfall value as a constant value lasting over
the recording interval specified for the rain gage which utilizes the time series. For all
other types of time series, SWMM uses interpolation to estimate values at times that fall
in between the recorded values.
11.7 Interface Files
SWMM can use several different kinds of interface files that contain either externally imposed
inputs (e.g., rainfall or infiltration/inflow hydrographs) or the results of previously run analyses
(e.g., runoff or routing results). These files can help speed up simulations, simplify comparisons
of different loading scenarios, and allow large study areas to be broken up into smaller areas that
can be analyzed individually. The different types of interface files that are currently available
include:
• rainfall interface file
• runoff interface file
• hot start file
• RDM interface file
• routing interface files
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Consult Section 8.1, Setting Simulation Options, for instructions on how to specify interface files
for use as input and/or output in a simulation.
Rainfall and Runoff Files
The rainfall and runoff interface files are binary files created internally by SWMM that can be
saved and reused from one analysis to the next.
The rainfall interface file collates a series of separate rain gage files into a single rainfall data file.
Normally a temporary file of this type is created for every SWMM analysis that uses external
rainfall data files and is then deleted after the analysis is completed. However, if the same rainfall
data are being used with many different analyses, requesting SWMM to save the rainfall interface
file after the first run and then reusing this file in subsequent runs can save computation time.
(j)
W The rainfall interface file should not be confused with a rainfall data file. The latter is an
external text file that provides rainfall time series data for a single rain gage. The former
is a binary file created internally by SWMM that processes all of the rainfall data files
used by a project.
The runoff interface file can be used to save the runoff results generated from a simulation run. If
runoff is not affected in future runs, the user can request that SWMM use this interface file to
supply runoff results without having to repeat the runoff calculations again.
Hot Start Files
Hot start files are binary files created by SWMM that contain the full hydrologic, hydraulic and
water quality state of the study area at the end of a run. The following information is saved to the
file:
• the ponded depth and its water quality for each subcatchment
• the pollutant mass buildup on each subcatchment
• the infiltration state of each subcatchment
• the conditions of any snowpack on each subcatchment
• the unsaturated zone moisture content, water table elevation, and groundwater outflow
for each subcatchment that has a groundwater zone defined for it
• the water depth, lateral inflow, and water quality at each node of the system
• the flow rate, water depth, control setting and water quality in each link of the system.
The hydrologic state of any LID units is not saved. The hot start file saved after a run can be used
to define the initial conditions for a subsequent run.
Hot start files can be used to avoid the initial numerical instabilities that sometimes occur under
Dynamic Wave routing. For this purpose they are typically generated by imposing a constant set
of base flows (for a natural channel network) or set of dry weather sanitary flows (for a sewer
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network) over some startup period of time. The resulting hot start file from this run is then used to
initialize a subsequent run where the inflows of real interest are imposed.
It is also possible to both use and save a hot start file in a single run, starting off the run with one
file and saving the ending results to another. The resulting file can then serve as the initial
conditions for a subsequent run if need be. This technique can be used to divide up extremely
long continuous simulations into more manageable pieces.
Instructions to save and/or use a hot start file can be issued when editing the Interface Files
options available in the Project Browser (see Sections.1, Setting Simulation Options). One can
also use the File » Export » Hot Start File Main Menu command to save the results of a
current run at any particular time period to a hot start file. However, in this case only the results
for nodes, links and groundwater elevation will be saved.
RDM Files
The RDM interface file contains a time series of rainfall-dependent infiltration/inflow flows for a
specified set of drainage system nodes. This file can be generated from a previous SWMM run
when Unit Hydrographs and nodal RDM inflow data have been defined for the project, or it can be
created outside of SWMM using some other source of RDM data (e.g., through measurements or
output from a different computer program). RDM files generated by SWMM are saved in a binary
format. RDM files created outside of SWMM are text files with the same format used for routing
interface files discussed below, where Flow is the only variable contained in the file.
Routing Files
A routing interface file stores a time series of flows and pollutant concentrations that are
discharged from the outfall nodes of drainage system model. This file can serve as the source of
inflow to another drainage system model that is connected at the outfalls of the first system. A
Combine utility is available on the File menu that will combine pairs of routing interface files into a
single interface file. This allows very large systems to be broken into smaller sub-systems that
can be analyzed separately and linked together through the routing interface file. Figure 11.1
below illustrates this concept.
A single SWMM run can utilize an outflows routing file to save results generated at a system's
outfalls, an inflows routing file to supply hydrograph and pollutograph inflows at selected nodes,
or both.
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J>roi1.inp
re outl .dat
proj2.inp
save out2.dat
Combine
out1.dat + out2.dat » inp3.dat
projS.inp
use inp3.dat
Figure 11-1 Combining routing interface files
RDM / Routing File Format
RDM interface files and routing interface files have the same text format:
l. the first line contains the keyword "SWMM5" (without the quotes)
2. a line of text that describes the file (can be blank)
3. the time step used for all inflow records (integer seconds)
4. the number of variables stored in the file, where the first variable must always be flow
rate
5. the name and units of each variable (one per line), where flow rate is the first variable
listed and is always named FLOW
6. the number of nodes with recorded inflow data
7. the name of each node (one per line)
8. a line of text that provides column headings for the data to follow (can be blank)
9. for each node at each time step, a line with:
• the name of the node
• the date (year, month, and day separated by spaces)
• the time of day (hours, minutes, and seconds separated by spaces)
• the flow rate followed by the concentration of each quality constituent
Time periods with no values at any node can be skipped. An excerpt from an RDM / routing
interface file is shown below.
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SWMM5
Example File
300
1
FLOW CFS
2
Nl
N2
Node Year Mon Day Hr Min Sec Flow
Nl 2002 04 01 00 20 00 0.000000
N2 2002 04 01 00 20 00 0.002549
Nl 2002 04 01 00 25 00 0.000000
N2 2002 04 01 00 25 00 0.002549
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CHAPTER 12 - USING ADD-IN TOOLS
SWMM 5 has the ability to launch external applications from its graphical user interface that can
extend its capabilities. This section describes how such tools can be registered and share data
with SWMM 5.
12.1 What Are Add-In Tools
Add-in tools are third party applications that users can add to the Tools menu of the main SWMM
menu bar and be launched while SWMM is still running. SWMM can interact with these
applications to a limited degree by exchanging data through its pre-defined files (see Chapter 11)
or through the Windows clipboard. Add-in tools can provide additional modeling capabilities to
what SWMM already offers. Some examples of useful add-ins might include:
• a tool that performs a statistical analysis of long-term rainfall data prior to adding it to a
SWMM rain gage,
• an external spreadsheet program that would facilitate the editing of a SWMM data set,
• a unit hydrograph estimator program that would derive the R-T-K parameters for a set of
RDM unit hydrographs which could then be copied and pasted directly into SWMM's Unit
Hydrograph Editor,
• a post-processor program that uses SWMM's hydraulic results to compute suspended
solids removal through a storage unit,
• a third-party dynamic flow routing program used as a substitute for SWMM's own internal
procedure.
The screenshot below shows what the Tools menu might look like after several add-in tools have
been registered with it. The Configure Tools option is used to add, delete, or modify add-in tools.
The options below this are the individual tools that have been made available (by this particular
user) and can be launched by selecting them from the menu.
SWMM 5.1
File Edit View Project Report Tools Window Help
to *4 ?{]
Project
Map
-Title/Notes
Options
•••• Climatology
t> • Hydrology
>• Hydraulics
Program Preferences...
Map Display Options,..
ConfigureTools...
Design Storm Wizard
Excel Editor
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12.2 Configuring Add-In Tools
To configure one's personal collection of add-in tools, select Configure Tools from the Tools
menu. This will bring up the Tool Options dialog as shown below. The dialog lists the currently
available tools and has command buttons for adding a new tool and for deleting or editing an
existing tool. The up and down arrow buttons are used to change the order in which the
registered tools are listed on the Tools menu.
Tool Options
Tools
Excel Editor
Climate Adjustment Tool
Whenever the Add or Edit button is clicked on this dialog a Tool Properties dialog will appear.
This dialog is used to describe the properties of the new tool being added or the existing tool
being edited. The data entry fields of the Tool Properties dialog consist of the following:
Tool Name
This is the name to be used for the tool when it is displayed in the Tools Menu.
Program
Enter the full path name to the program that will be launched when the tool is selected. You can
click the IJ™J button to bring up a standard Windows file selection dialog from which you can
search for the tool's executable file name.
Working Directory
This field contains the name of the directory that will be used as the working directory when the
tool is launched. You can click the '-1 button to bring up a standard directory selection dialog
from which you can search for the desired directory. You can also enter the macro symbol
$PROJDIR to utilize the current SWMM project's directory or $SWMMDIR to use the directory
where the SWMM 5 executable resides. Either of these macros can also be inserted into the
Working Directory field by selecting its name in the list of macros provided on the dialog and then
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clicking the L_U button. This field can be left blank, in which case the system's current directory
will be used.
Tool Properties
Program
Working
Directory
Parameters
Macros:
Tool Name Excel Editor
Files (x86)\Microsoft Orfice\Officel2\EXCEL.EXE
SIN P FILE
$PROJDIR
$SWMMDIR
$INFFILE
53PIFILZ:
$OUIFILZ
$RIFFILI
Project directory
SWMM directory
SWMM input file
SWMM report file
SWMM output file
SWMM runoff interface
file
Disable SWMM while executing
Update SWMM after closing
OK
Cancel
Help
Parameters
This field contains the list of command line arguments that the tool's executable program expects
to see when it is launched. Multiple parameters can be entered as long as they are separated by
spaces. A number of special macro symbols have been pre-defined, as listed in the Macros list
box of the dialog, to simplify the process of listing the command line parameters. When one of
these macro symbols is inserted into the list of parameters, it will be expanded to its true value
when the tool is launched. A specific macro symbol can either be typed into the Parameters field
or be selected from the Macros list (by clicking on it) and then added to the parameter list by
clicking the I—J button. The available macro symbols and their meanings are:
$PROJDIR
$SWMMDIR
$INPFILE
The directory where the current SWMM project file resides.
The directory where the SWMM 5 executable is installed.
The name of a temporary file containing the current project's data that is
created just before the tool is launched.
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$RPTFILE The name of a temporary file that is created just before the tool is
launched and can be displayed after the tool closes by using the Report
» Status command from the main SWMM menu.
$OUTFILE The name of a temporary file to which the tool can write simulation results
in the same format used by SWMM 5, which can then be displayed after
the tool closes in the same fashion as if a SWMM run were made.
$RIFFILE The name of the Runoff Interface File, as specified in the Interface Files
page of the Simulation Options dialog, to which runoff simulation results
were saved from a previous SWMM run (see Sections 8.1 Setting
Simulation Options and 11.7lnterface Files).
As an example of how the macro expansion works, consider the entries in the Tool Properties
dialog shown previously. This Spreadsheet Editor tool wants to launch Microsoft Excel and pass it
the name of the SWMM input data file to be opened by Excel. SWMM will issue the following
command line to do this
C:\Program Files (x86)\Microsoft Office\Officel2\EXCEL.EXE $INPFILE
where the string $INPFILE will be replaced by the name of the temporary file that SWMM
creates internally that contains the current project's data.
Disable SWMM while executing
Check this option if SWMM should be hidden and disabled while the tool is executing. Normally
you will need to employ this option if the tool produces a modified input file or output file, such as
when the $INPFILE or $OUTFILE macros are used as command line parameters. When this
option is enabled, SWMM's main window will be hidden from view until the tool is terminated.
Update SWMM after closing
Check this option if SWMM should be updated after the tool finishes executing. This option can
only be selected if the option to disable SWMM while the tool is executing was first selected.
Updating can occur in two ways. If the $INPFILE macro was used as a command line parameter
for the tool and the corresponding temporary input file produced by SWMM was updated by the
tool, then the current project's data will be replaced with the data contained in the updated
temporary input file. If the $OUTFILE macro was used as a command line parameter, and its
corresponding file is found to contain a valid set of output results after the tool closes, then the
contents of this file will be used to display simulation results within the SWMM workspace.
Generally speaking, the suppliers of third-party tools will provide instructions on what settings
should be used in the Tool Properties dialog to properly register their tool with SWMM.
176
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APPENDIX A - USEFUL TABLES
A.1
Units of Measurement
PARAMETER
Area (Subcatchment)
Area (Storage Unit)
Area (Ponding)
Capillary Suction
Concentration
Decay Constant (Infiltration)
Decay Constant (Pollutants)
Depression Storage
Depth
Diameter
Discharge Coefficient:
Orifice
Weir
Elevation
Evaporation
Flow
Head
Hydraulic Conductivity
Infiltration Rate
Length
Manning's n
Pollutant Buildup
Rainfall Intensity
Rainfall Volume
Slope (Subcatchments)
Slope (Cross Section)
Street Cleaning Interval
Volume
Width
US CUSTOMARY
acres
square feet
square feet
inches
mg/L (milligrams/liter)
ug/L (micrograms/liter)
Count/L (counts/liter)
1 /hours
1/days
inches
feet
feet
dimensionless
CFS/footn
feet
inches/day
CFS (cubic feet / second)
GPM (gallons / minute)
MGD (million gallons/day)
feet
inches/hour
inches/hour
feet
seconds/meter173
mass/length
mass/acre
inches/hour
inches
percent
rise/run
days
cubic feet
feet
SI METRIC
hectares
square meters
square meters
millimeters
mg/L
ug/L
Count/L
1 /hours
1/days
millimeters
meters
meters
dimensionless
CMS/metern
meters
millimeters/day
CMS (cubic meters/second)
LPS (liters/second)
MLD (million liters/day)
meters
millimeters/hour
millimeters/hour
meters
seconds/meter173
mass/length
mass/hectare
millimeters/hour
millimeters
percent
rise/run
days
cubic meters
meters
177
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A.2
Soil Characteristics
Soil Texture Class
Sand
Loamy Sand
Sandy Loam
Loam
Silt Loam
Sandy Clay Loam
Clay Loam
Silty Clay Loam
Sandy Clay
Silty Clay
Clay
K
4.74
1.18
0.43
0.13
0.26
0.06
0.04
0.04
0.02
0.02
0.01
Y
1.93
2.40
4.33
3.50
6.69
8.66
8.27
10.63
9.45
11.42
12.60
4>
0.437
0.437
0.453
0.463
0.501
0.398
0.464
0.471
0.430
0.479
0.475
FC
0.062
0.105
0.190
0.232
0.284
0.244
0.310
0.342
0.321
0.371
0.378
WP
0.024
0.047
0.085
0.116
0.135
0.136
0.187
0.210
0.221
0.251
0.265
K = saturated hydraulic conductivity, in/hr
*F = suction head, in.
<|> = porosity, fraction
FC = field capacity, fraction
WP = wilting point, fraction
Source: Rawls, W.J. et al., (1983). J. Hyd. Engr., 109:1316.
Note: The following relation between T and K can be derived
from this table:
T = 3.23 K-°328 (R2 = 0.9)
178
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A.3 NRCS Hydrologic Soil Group Definitions
Group
Meaning
Saturated
Hydraulic
Conductivity
(in/hr)
Low runoff potential.
Water is transmitted freely through the soil. Group A soils
typically have less than 10 percent clay and more than 90
percent sand or gravel and have gravel or sand textures.
>1.42
B
Moderately low runoff potential.
Water transmission through the soil is unimpeded. Group B
soils typically have between 10 percent and 20 percent
clay and 50 percent to 90 percent sand and have loamy
sand or sandy loam textures.
0.57-1.42
Moderately high runoff potential.
Water transmission through the soil is somewhat restricted.
Group C soils typically have between 20 percent and 40
percent clay and less than 50 percent sand and have loam,
silt loam, sandy clay loam, clay loam, and silty clay loam
textures.
0.06 - 0.57
High runoff potential.
Water movement through the soil is restricted or very
restricted. Group D soils typically have greater than 40
percent clay, less than 50 percent sand, and have clayey
textures.
<0.06
Source: Hydrology National Engineering Handbook, Chapter 7, Natural Resources
Conservation Service, U.S. Department of Agriculture, January 2009.
179
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A.4 SCS Curve Numbers1
Land Use Description
Cultivated land
Without conservation treatment
With conservation treatment
Pasture or range land
Poor condition
Good condition
Meadow
Good condition
Wood or forest land
Thin stand, poor cover, no mulch
Good cover2
Open spaces, lawns, parks, golf courses, cemeteries,
etc.
Good condition: grass cover on
75% or more of the area
Fair condition: grass cover on
50-75% of the area
Commercial and business areas (85% impervious)
Industrial districts (72% impervious)
Residential3
Average lot size (% Impervious4)
1/8 ac or less (65)
1 Mac (38)
1/3ac(30)
1/2ac(25)
1 ac (20)
Paved parking lots, roofs, driveways, etc.5
Streets and roads
Paved with curbs and storm sewers5
Gravel
Dirt
Hydrologic Soil Group
A
72
62
68
39
30
45
25
39
49
89
81
77
61
57
54
51
98
98
76
72
B
81
71
79
61
58
66
55
61
69
92
88
85
75
72
70
68
98
98
85
82
C
88
78
86
74
71
77
70
74
79
94
91
90
83
81
80
79
98
98
89
87
D
91
81
89
80
78
83
77
80
84
95
93
92
87
86
85
84
98
98
91
89
Source: SCS Urban Hydrology for Small Watersheds, 2nd Ed., (TR-55), June 1986.
Footnotes:
i. Antecedent moisture condition II.
2. Good cover is protected from grazing and litter and brush cover soil.
180
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Curve numbers are computed assuming that the runoff from the house and driveway is
directed toward the street with a minimum of roof water directed to lawns where additional
infiltration could occur.
The remaining pervious areas (lawn) are considered to be in good pasture condition for these
curve numbers.
In some warmer climates of the country a curve number of 95 may be used.
A.5 Depression Storage
Impervious surfaces
Lawns
Pasture
Forest litter
0.05- 0.10 inches
0.10- 0.20 inches
0.20 inches
0.30 inches
Source: ASCE, (1992). Design & Construction of Urban Stormwater
Management Systems, New York, NY.
181
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A.6 Manning's n - Overland Flow
Surface
Smooth asphalt
Smooth concrete
Ordinary concrete lining
Good wood
Brick with cement mortar
Vitrified clay
Cast iron
Corrugated metal pipes
Cement rubble surface
Fallow soils (no residue)
Cultivated soils
Residue cover < 20%
Residue cover > 20%
Range (natural)
Grass
Short, prairie
Dense
Bermuda grass
Woods
Light underbrush
Dense underbrush
n
0.011
0.012
0.013
0.014
0.014
0.015
0.015
0.024
0.024
0.05
0.06
0.17
0.13
0.15
0.24
0.41
0.40
0.80
Source: McCuen, R. et al. (1996), Hydrology, FHWA-SA-
96-067, Federal Highway Administration, Washington,
DC
182
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A.7 Manning's n - Closed Conduits
Conduit Material
Asbestos-cement pipe
Brick
Cast iron pipe
- Cement-lined & seal coated
Concrete (monolithic)
- Smooth forms
- Rough forms
Concrete pipe
Corrugated-metal pipe
(1/2-in. x2-2/3-in. corrugations)
- Plain
- Paved invert
- Spun asphalt lined
Plastic pipe (smooth)
Vitrified clay
- Pipes
- Liner plates
Manning n
0.011 -0.015
0.013-0.017
0.011 -0.015
0.012-0.014
0.015-0.017
0.011 -0.015
0.022 - 0.026
0.018-0.022
0.011 -0.015
0.011 -0.015
0.011 -0.015
0.013-0.017
Source: ASCE (1982). Gravity Sanitary Sewer Design and Construction, ASCE Manual of
Practice No. 60, New York, NY.
183
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A.8 Manning's n - Open Channels
Channel Type
Lined Channels
- Asphalt
- Brick
- Concrete
- Rubble or riprap
- Vegetal
Excavated or dredged
- Earth, straight and uniform
- Earth, winding, fairly uniform
- Rock
- Unmaintained
Natural channels (minor streams, top width at flood
stage < 100ft)
- Fairly regular section
- Irregular section with pools
Manning n
0.013-0.017
0.012-0.018
0.011 -0.020
0.020 - 0.035
0.030 - 0.40
0.020 - 0.030
0.025 - 0.040
0.030 - 0.045
0.050-0.140
0.030-0.070
0.040-0.100
Source: ASCE (1982). Gravity Sanitary Sewer Design and Construction, ASCE Manual of
Practice No. 60, New York, NY.
184
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A.9 Water Quality Characteristics of Urban Runoff
Constituent
TSS (mg/L)
BOD (mg/L)
COD (mg/L)
Total P (mg/L)
Soluble P (mg/L)
TKN (mg/L)
N02/N03-N (mg/L)
Total Cu (ug/L)
Total Pb (ug/L)
Total Zn (ug/L)
Event Mean Concentrations
180-548
12-19
82-178
0.42 - 0.88
0.15-0.28
1.90-4.18
0.86 - 2.2
43-118
182-443
202 - 633
Source: U.S. Environmental Protection Agency. (1983). Results of the
Nationwide Urban Runoff Program (NURP), Vol. 1, NTIS PB 84-185552),
Water Planning Division, Washington, DC.
185
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A.10 Culvert Code Numbers
Circular Concrete
1 Square edge with headwall
2 Groove end with headwall
3 Groove end projecting
Circular Corrugated Metal Pipe
4 Headwall
5 Mitered to slope
6 Projecting
Circular Pipe, Beveled Ring Entrance
7 45 deg. bevels
8 33.7 deg. bevels
Rectangular Box; Flared Wingwalls
9 30-75 deg. wingwall flares
10 90 or 15 deg. wingwall flares
11 0 deg. wingwall flares (straight sides)
Rectangular Box;Flared Wingwalls and Top Edge Bevel:
12 45 deg flare; 0.43D top edge bevel
13 18-33.7 deg. flare; 0.083D top edge bevel
Rectangular Box, 90-deg Headwall, Chamfered / Beveled Inlet Edges
14 chamfered 3/4-in.
15 beveled 1 /2-in/ft at 45 deg (1:1)
16 beveled 1-in/ft at 33.7 deg (1:1.5)
Rectangular Box, Skewed Headwall, Chamfered / Beveled Inlet Edges
17 3/4" chamfered edge, 45 deg skewed headwall
18 3/4" chamfered edge, 30 deg skewed headwall
19 3/4" chamfered edge, 15 deg skewed headwall
20 45 deg beveled edge, 10-45 deg skewed headwall
Rectangular Box, Non-offset Flared Wingwalls, 3/4" Chamfer at Top of Inlet
21 45 deg (1:1) wingwall flare
22 8.4 deg (3:1) wingwall flare
23 18.4 deg (3:1) wingwall flare, 30 deg inlet skew
Rectangular Box, Offset Flared Wingwalls, Beveled Edge at Inlet Top
24 45 deg (1:1) flare, 0.042D top edge bevel
25 33.7 deg (1.5:1) flare, 0.083D top edge bevel
26 18.4 deg (3:1) flare, 0.083D top edge bevel
186
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Corrugated Metal Box
27 90 deg headwall
28 Thick wall projecting
29 Thin wall projecting
Horizontal Ellipse Concrete
30 Square edge with headwall
31 Grooved end with headwall
32 Grooved end projecting
Vertical Ellipse Concrete
33 Square edge with headwall
34 Grooved end with headwall
35 Grooved end projecting
Pipe Arch, 18" Corner Radius, Corrugated Metal
36 90 deg headwall
37 Mitered to slope
38 Projecting
Pipe Arch, 18" Corner Radius, Corrugated Metal
39 Projecting
40 No bevels
41 33.7 deg bevels
Pipe Arch, 31" Corner Radius,Corrugated Metal
42 Projecting
43 No bevels
44 33.7 deg. bevels
Arch, Corrugated Metal
45 90 deg headwall
46 Mitered to slope
47 Thin wall projecting
Circular Culvert
48 Smooth tapered inlet throat
49 Rough tapered inlet throat
Elliptical Inlet Face
50 Tapered inlet, beveled edges
51 Tapered inlet, square edges
52 Tapered inlet, thin edge projecting
187
-------
Rectangular
53 Tapered inlet throat
Rectangular Concrete
54 Side tapered, less favorable edges
55 Side tapered, more favorable edges
56 Slope tapered, less favorable edges
57 Slope tapered, more favorable edges
188
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A.11 Culvert Entrance Loss Coefficients
Type of Structure and Design of Entrance Coefficient
• Pipe. Concrete
Projecting from fill, socket end (groove-end) 0.2
Projecting from fill, sq. cut end 0.5
Headwall or headwall and wingwalls:
Socket end of pipe (groove-end) 0.2
Square-edge 0.5
Rounded (radius = D/12) 0.2
Mitered to conform to fill slope 0.7
*End-Section conforming to fill slope 0.5
Beveled edges, 33.7 ° or 45 ° bevels 0.2
Side- or slope-tapered inlet 0.2
• Pipe or Pipe-Arch. Corrugated Metal
Projecting from fill (no headwall) 0.9
Headwall or headwall and wingwalls square-edge 0.5
Mitered to conform to fill slope, paved or unpaved slope 0.7
*End-Section conforming to fill slope 0.5
Beveled edges, 33.7 ° or 45 ° bevels 0.2
Side- or slope-tapered inlet 0.2
• Box. Reinforced Concrete
Headwall parallel to embankment (no wingwalls):
Square-edged on 3 edges 0.5
Rounded on 3 edges to radius of D/12 or B/12
or beveled edges on 3 sides 0.2
Wingwalls at 30 ° to 75 ° to barrel:
Square-edged at crown 0.4
Crown edge rounded to radius of D/12:
or beveled top edge 0.2
Wingwall at 10 ° to 25 ° to barrel:
Square-edged at crown 0.5
Wingwalls parallel (extension of sides):
Square-edged at crown 0.7
Side- or slope-tapered inlet 0.2
*Note: "End Sections conforming to fill slope," made of either metal or concrete, are the
sections commonly available from manufacturers. From limited hydraulic tests they are
equivalent in operation to a headwall in both inlet and outlet control. Some end sections,
incorporating a closed taper in their design have a superior hydraulic performance. These
latter sections can be designed using the information given for the beveled inlet.
Source: Federal Highway Administration (2005). Hydraulic Design of Highway Culverts,
Publication No. FHWA-NHI-01-020.
189
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A.12 Standard Elliptical Pipe Sizes
Code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Minor Axis (in)
14
^^_ 19
22
24
27
^^_ 29
32
34
38
^^_ 43
48
53
58
^^_ 63
68
72
77
^^_ 82
87
92
97
^^^ 106
116
Major Axis (in)
23
^^— 30
34
38
42
^^— 45
49
53
60
^^— 68
76
83
91
^^— 98
106
113
121
^^^128
136
143
151
^^^166
180
Minor Axis (mm)
356
^^^483
559
610
686
^^_737
813
864
965
1092
1219
1346
1473
1600
1727
1829
1956
2083
2210
2337
2464
2692
2946
Major Axis (mm)
584
^^^762
864
965
1067
1143
1245
1346
1524
1727
1930
2108
2311
2489
2692
2870
3073
3251
3454
3632
3835
4216
4572
Note: The Minor Axis is the maximum width for a vertical ellipse and the full depth for a horizontal
ellipse while the Major Axis is the maximum width for a horizontal ellipse and the full depth for a
vertical ellipse.
Source: Concrete Pipe Design Manual, American Concrete Pipe Association, 2011
(www.concrete-pipe.org').
190
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A.13 Standard Arch Pipe Sizes
Concrete Arch Pipes
Code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Corrugated
Code
18
19
20
21
22
23
24
25
26
27
28
29
Rise (in)
11
13.5
15.5
18
22.5
26.625
31.3125
36
40
45
54
62
72
77.5
87.125
96.875
106.5
Steel, 2-2/3 x 1/2"
Rise (in)
13
15
18
20
24
29
33
38
43
47
52
57
Span (in)
18
22
26
28.5
36.25
43.75
51.125
58.5
65
73
88
102
115
122
138
154
168.75
Corrugation
Span (in)
17
21
24
28
35
42
49
57
64
71
77
83
Rise (mm)
279
343
394
457
572
676
795
914
1016
1143
1372
1575
1829
1969
2213
2461
2705
Rise (mm)
330
381
457
508
610
737
838
965
1092
1194
1321
1448
Span (mm)
457
559
660
724
921
1111
1299
1486
1651
1854
2235
2591
2921
3099
3505
3912
4286
Span (mm)
432
533
610
711
889
1067
1245
1448
1626
1803
1956
2108
191
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Corrugated Steel, 3x1" Corrugation
Code
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
Rise (in)
31
36
41
46
51
55
59
63
67
71
75
79
83
87
91
Span (in)
40
46
53
60
66
73
81
87
95
103
112
117
128
137
142
Rise (mm)
787
914
1041
1168
1295
1397
1499
1600
1702
1803
1905
2007
2108
2210
2311
Span (mm)
1016
1168
1346
1524
1676
1854
2057
2210
2413
2616
2845
2972
3251
3480
3607
192
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Structural Plate, 18" Corner Radius
Code
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
Rise (in)
55
57
59
61
63
65
67
69
71
73
75
77
79
81
83
85
87
89
91
93
95
97
100
101
103
105
107
109
111
113
115
118
119
121
Span (in)
73
76
81
84
87
92
95
98
103
106
112
114
117
123
128
131
137
139
142
148
150
152
154
161
167
169
171
178
184
186
188
190
197
199
Rise (mm)
1397
1448
1499
1549
1600
1651
1702
1753
1803
1854
1905
1956
2007
2057
2108
2159
2210
2261
2311
2362
2413
2464
2540
2565
2616
2667
2718
2769
2819
2870
2921
2997
3023
3073
Span (mm)
1854
1930
2057
2134
2210
2337
2413
2489
2616
2692
2845
2896
2972
3124
3251
3327
3480
3531
3607
3759
3810
3861
3912
4089
4242
4293
4343
4521
4674
4724
4775
4826
5004
5055
193
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Structural Plate, 31" Corner Radius
Code
Rise (in)
Span (in)
Rise (mm)
Span (mm)
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
112
114
116
118
120
122
124
126
128
130
132
134
136
138
140
142
144
146
148
150
152
154
156
158
159
162
168
170
173
179
184
187
190
195
198
204
206
209
215
217
223
225
231
234
236
239
245
247
2845
2896
2946
2997
3048
3099
3150
3200
3251
3302
3353
3404
3454
3505
3556
3607
3658
3708
3759
3810
3861
3912
3962
4013
4039
4115
4267
4318
4394
4547
4674
4750
4826
4953
5029
5182
5232
5309
5461
5512
5664
5715
5867
5944
5994
6071
6223
6274
Source: Modern Sewer Design (Fourth Edition), American Iron and Steel Institute, Washington,
DC, 1999.
194
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APPENDIX B-VISUAL OBJECT PROPERTIES
B.1 Rain Gage Properties
Name
X-Coordinate
Y-Coordinate
Description
Tag
Rain Format
Rain Interval
Snow Catch Factor
Data Source
TIME SERIES
- Series Name
DATA FILE
- File Name
- Station No.
- Rain Units
User-assigned rain gage name.
Horizontal location of the rain gage on the Study Area Map. If left blank
then the rain gage will not appear on the map.
Vertical location of the rain gage on the Study Area Map. If left blank then
the rain gage will not appear on the map.
Click the ellipsis button (or press Enter) to edit an optional description of
the rain gage.
Optional label used to categorize or classify the rain gage.
Format in which the rain data are supplied:
INTENSITY: each rainfall value is an average rate in inches/hour (or
mm/hour) over the recording interval,
VOLUME: each rainfall value is the volume of rain that fell in the recording
interval (in inches or millimeters),
CUMULATIVE: each rainfall value represents the cumulative rainfall that
has occurred since the start of the last series of non-zero values (in inches
or millimeters).
Recording time interval between gage readings in either decimal hours or
hours:minutes format.
Factor that corrects gage readings for snowfall.
Source of rainfall data; either TIMESERIES for user-supplied time series
data or F/LEfor an external data file.
Name of time series with rainfall data if Data Source selection was
TIMESERIES; leave blank otherwise (double-click to edit the series).
Name of external file containing rainfall data (see Section 1 1 .3).
Recording gage station number.
Depth units (IN or MM) for rainfall values in user-prepared files (other
standard file formats have fixed units depending on the format).
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B.2 Subcatchment Properties
Name
X-Coordinate
^-Coordinate
Description
Tag
Rain Gage
Outlet
Area
Width1
% Slope
% Imperv
N-lmperv
N-Perv
Dstore-lmperv
Dstore-Perv
% Zero-lmperv
Subarea Routing
Percent Routed
Infiltration
LID Controls
User-assigned subcatchment name.
Horizontal location of the subcatchment's centroid on the Study Area Map.
If left blank then the subcatchment will not appear on the map.
Vertical location of the subcatchment's centroid on the Study Area Map. If
left blank then the subcatchment will not appear on the map.
Click the ellipsis button (or press Enter) to edit an optional description of
the subcatchment.
Optional label used to categorize or classify the subcatchment.
Name of the rain gage associated with the subcatchment.
Name of the node or subcatchment which receives the subcatchment's
runoff.
Area of the subcatchment , including any LID controls (acres or hectares).
Characteristic width of the overland flow path for sheet flow runoff (feet or
meters).
Average percent slope of the subcatchment.
Percent of land area (excluding the area used for LID controls) which is
impervious.
Manning's n for overland flow over the impervious portion of the
subcatchment (see Section A.6 for typical values).
Manning's n for overland flow over the pervious portion of the
subcatchment (see Section A.6 for typical values).
Depth of depression storage on the impervious portion of the
subcatchment (inches or millimeters) (see Section A. 5 for typical values).
Depth of depression storage on the pervious portion of the subcatchment
(inches or millimeters) (see Section A. 5 for typical values).
Percent of the impervious area with no depression storage.
Choice of internal routing of runoff between pervious and impervious
areas:
IMPERV: runoff from pervious area flows to impervious area,
PERV: runoff from impervious area flows to pervious area,
OUTLET, runoff from both areas flows directly to outlet.
Percent of runoff routed between subareas.
Click the ellipsis button (or press Enter) to edit infiltration parameters for
the subcatchment.
Click the ellipsis button (or press Enter) to edit the use of low impact
development controls in the subcatchment.
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Groundwater
Snow Pack
Land Uses
Initial Buildup
Curb Length
Click the ellipsis button (or press Enter) to edit groundwater flow
parameters for the subcatchment.
Name of snow pack parameter set (if any) assigned to the subcatchment.
Click the ellipsis button (or press Enter) to assign land uses to the
subcatchment. Only needed if pollutant buildup/washoff modeled.
Click the ellipsis button (or press Enter) to specify initial quantities of
pollutant buildup over the subcatchment.
Total length of curbs in the subcatchment (any length units). Used only
when pollutant buildup is normalized to curb length.
1 An initial estimate of the characteristic width is given by the subcatchment area divided by the
average maximum overland flow length. The maximum overland flow length is the length of the
flow path from the furthest drainage point of the subcatchment before the flow becomes
channelized. Maximum lengths from several different possible flow paths should be averaged.
These paths should reflect slow flow, such as over pervious surfaces, more than rapid flow over
pavement, for example. Adjustments should be made to the width parameter to produce good fits
to measured runoff hydrographs.
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B.3 Junction Properties
Name
X-Coordinate
Y-Coordinate
Description
Tag
Inflows
Treatment
Invert El.
Max. Depth
Initial Depth
Surcharge Depth
Ponded Area
User-assigned junction name.
Horizontal location of the junction on the Study Area Map. If left blank then
the junction will not appear on the map.
Vertical location of the junction on the Study Area Map. If left blank then
the junction will not appear on the map.
Click the ellipsis button (or press Enter) to edit an optional description of
the junction.
Optional label used to categorize or classify the junction.
Click the ellipsis button (or press Enter) to assign external direct, dry
weather or RDM inflows to the junction.
Click the ellipsis button (or press Enter) to edit a set of treatment functions
for pollutants entering the node.
Invert elevation of the junction (feet or meters).
Maximum depth of junction (i.e., from ground surface to invert) (feet or
meters). If zero, then the distance from the invert to the top of the highest
connecting link will be used.
Depth of water at the junction at the start of the simulation (feet or
meters).
Additional depth of water beyond the maximum depth that is allowed
before the junction floods (feet or meters). This parameter can be used to
simulate bolted manhole covers or force main connections.
Area occupied by ponded water atop the junction after flooding occurs (sq.
feet or sq. meters). If the Allow Ponding simulation option is turned on, a
non-zero value of this parameter will allow ponded water to be stored and
subsequently returned to the conveyance system when capacity exists.
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B.4 Outfall Properties
Name
X-Coordinate
Y-Coordinate
Description
Tag
Inflows
Treatment
Invert El.
Tide Gate
Route To
Type
Fixed Stage
Tidal Curve Name
Time Series Name
User-assigned outfall name.
Horizontal location of the outfall on the Study Area Map. If left blank then
the outfall will not appear on the map.
Vertical location of the outfall on the Study Area Map. If left blank then the
outfall will not appear on the map.
Click the ellipsis button (or press Enter) to edit an optional description of
the outfall.
Optional label used to categorize or classify the outfall.
Click the ellipsis button (or press Enter) to assign external direct, dry
weather or RDM inflows to the outfall.
Click the ellipsis button (or press Enter) to edit a set of treatment functions
for pollutants entering the node.
Invert elevation of the outfall (feet or meters).
YES - tide gate present to prevent backflow
WO - no tide gate present
Optional name of a subcatchment that receives the outfall's discharge.
Type of outfall boundary condition:
FREE: outfall stage determined by minimum of critical flow depth and
normal flow depth in the connecting conduit
NORMAL: outfall stage based on normal flow depth in connecting conduit
FIXED: outfall stage set to a fixed value
TIDAL: outfall stage given by a table of tide elevation versus time of day
TIMESERIES: outfall stage supplied from a time series of elevations.
Water elevation for a FIXED type of outfall (feet or meters).
Name of the Tidal Curve relating water elevation to hour of the day for a
TIDAL outfall (double-click to edit the curve).
Name of time series containing time history of outfall elevations for a
TIMESERIES outfall (double-click to edit the series).
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B.5 Flow Divider Properties
Name
X-Coordinate
Y-Coordinate
Description
Tag
Inflows
Treatment
Invert El.
Max. Depth
Initial Depth
Surcharge Depth
Ponded Area
Diverted Link
Type
User-assigned divider name.
Horizontal location of the divider on the Study Area Map. If left blank then
the divider will not appear on the map.
Vertical location of the divider on the Study Area Map. If left blank then the
divider will not appear on the map.
Click the ellipsis button (or press Enter) to edit an optional description of
the divider.
Optional label used to categorize or classify the divider.
Click the ellipsis button (or press Enter) to assign external direct, dry
weather or RDM inflows to the divider.
Click the ellipsis button (or press Enter) to edit a set of treatment functions
for pollutants entering the node.
Invert elevation of the divider (feet or meters).
Maximum depth of divider (i.e., from ground surface to invert) (feet or
meters). See description for Junctions.
Depth of water at the divider at the start of the simulation (feet or meters).
Additional depth of water beyond the maximum depth that is allowed
before the divider floods (feet or meters).
Area occupied by ponded water atop the junction after flooding occurs (sq.
feet or sq. meters). See description for Junctions.
Name of link which receives the diverted flow.
Type of flow divider. Choices are:
CUTOFF (diverts all inflow above a defined cutoff value),
OVERFLOW (diverts all inflow above the flow capacity of the non-diverted
link),
TABULAR (uses a Diversion Curve to express diverted flow as a function
of the total inflow),
WEIR (uses a weir equation to compute diverted flow).
CUTOFF DIVIDER
- Cutoff Flow
Cutoff flow value used for a CUTOFF divider (flow units).
TABULAR DIVIDER
- Curve Name
Name of Diversion Curve used with a TABULAR divider (double-click to
edit the curve).
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WEIR DIVIDER
- Min. Flow
- Max. Depth
- Coefficient
Minimum flow at which diversion begins for a WEIR divider (flow units).
Vertical height of WEIR opening (feet or meters)
Product of WEIR's discharge coefficient and its length. Weir coefficients
are typically in the range of 2.65 to 3.10 per foot, for flows in CFS.
Note: Flow dividers are operational only for Steady Flow and Kinematic Wave flow routing. For
Dynamic Wave flow routing they behave as Junction nodes.
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B.6 Storage Unit Properties
Name
X-Coordinate
Y-Coordinate
Description
Tag
Inflows
Treatment
Invert El.
Max. Depth
Initial Depth
Evap. Factor
Seepage Loss
Storage Curve
FUNCTIONAL
Coeff.
Exponent
Constant
User-assigned storage unit name.
Horizontal location of the storage unit on the Study Area Map. If left blank
then the storage unit will not appear on the map.
Vertical location of the storage unit on the Study Area Map. If left blank
then the storage unit will not appear on the map.
Click the ellipsis button (or press Enter) to edit an optional description of
the storage unit.
Optional label used to categorize or classify the storage unit.
Click the ellipsis button (or press Enter) to assign external direct, dry
weather or RDM inflows to the storage unit.
Click the ellipsis button (or press Enter) to edit a set of treatment functions
for pollutants within the storage unit.
Elevation of the bottom of the storage unit (feet or meters).
Maximum depth of the storage unit (feet or meters).
Initial depth of water in the storage unit at the start of the simulation (feet
or meters).
The fraction of the potential evaporation from the storage unit's water
surface that is actually realized.
Click the ellipsis button (or press Enter) to specify optional soil properties
that determine seepage loss through the bottom and sloped sides of the
storage unit.
Method of describing how the surface area of the storage unit varies with
water depth:
FUNCTIONAL uses the function
Area = A*(Depth)B + C
to describe how surface area varies with depth;
TABULAR uses a tabulated area versus depth curve.
In either case, depth is measured in feet (or meters) above the bottom and
surface area in sq. feet (or sq. meters).
A-value in the functional relationship between surface area and storage
depth.
B-value in the functional relationship between surface area and storage
depth.
C-value in the functional relationship between surface area and storage
depth.
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TABULAR
Curve Name
Name of the Storage Curve containing the relationship between surface
area and storage depth (double-click to edit the curve). The curve will be
extrapolated outwards to meet the unit's Max. Depth if need be.
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B.7 Conduit Properties
Name
Inlet Node
Outlet Node
Description
Tag
Shape
Max. Depth
Length
Roughness
Inlet Offset
Outlet Offset
Initial Flow
Maximum Flow
Entry Loss Coeff.
Exit Loss Coeff.
Avg. Loss Coeff.
Flap Gate
Culvert Code
User-assigned conduit name.
Name of node on the inlet end of the conduit (which is normally the end at
higher elevation).
Name of node on the outlet end of the conduit (which is normally the end
at lower elevation).
Click the ellipsis button (or press Enter) to edit an optional description of
the conduit.
Optional label used to categorize or classify the conduit.
Click the ellipsis button (or press Enter) to edit the geometric properties of
the conduit's cross section.
Maximum depth of the conduit's cross section (feet or meters).
Conduit length (feet or meters).
Manning's roughness coefficient (see Section A.7 for closed conduit
values or Section A. 8 for open channel values).
Depth or elevation of the conduit invert above the node invert at the
upstream end of the conduit (feet or meters). See note below.
Depth or elevation of the conduit invert above the node invert at the
downstream end of the conduit (feet or meters). See note below.
Initial flow in the conduit (flow units).
Maximum flow allowed in the conduit (flow units) - use 0 or leave blank if
not applicable.
Head loss coefficient associated with energy losses at the entrance of the
conduit. For culverts, refer to Table A1 1 .
Head loss coefficient associated with energy losses at the exit of the
conduit. For culverts, use a value of 1 .0
Head loss coefficient associated with energy losses along the length of
the conduit.
YES if a flap gate exists that prevents backflow through the conduit, or WO
if no flap gate exists.
Code number of inlet geometry if conduit is a culvert - leave blank
otherwise. Culvert code numbers are listed in Table A10.
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NOTE: Conduits and flow regulators (orifices, weirs,
and outlets) can be offset some distance above the
invert of their connecting end nodes. There are two
different conventions available for specifying the
location of these offsets. The Depth convention uses
the offset distance from the node's invert (distance
between © and © in the figure on the right). The
Elevation convention uses the absolute elevation of the
offset location (the elevation of point © in the figure).
The choice of convention can be made on the Status
Bar of SWMM's main window or on the Node/Link
Properties page of the Project Defaults dialog.
B.8 Pump Properties
Name
Inlet Node
Outlet Node
Description
Tag
Pump Curve
Initial Status
Startup Depth
Shutoff Depth
User-assigned pump name.
Name of node on the inlet side of the pump.
Name of node on the outlet side of the pump.
Click the ellipsis button (or press Enter) to edit an optional description of
the pump.
Optional label used to categorize or classify the pump.
Name of the Pump Curve which contains the pump's operating data
(double-click to edit the curve). Enter* for an Ideal pump.
Status of the pump (ON or OFF) at the start of the simulation.
Depth at inlet node when pump turns on (feet or meters). Enter 0 if not
applicable.
Depth at inlet node when pump shuts off (feet or meters). Enter 0 if not
applicable.
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B.9 Orifice Properties
Name
Inlet Node
Outlet Node
Description
Tag
Type
Shape
Height
Width
Inlet Offset
Discharge Coeff.
Flap Gate
Time to Open /
Close
User-assigned orifice name.
Name of node on the inlet side of the orifice.
Name of node on the outlet side of the orifice.
Click the ellipsis button (or press Enter) to edit an optional description of
the orifice.
Optional label used to categorize or classify the orifice.
Type of orifice (SIDE or BOTTOM).
Orifice shape (CIRCULAR or RECT_ CLOSED).
Height of orifice opening when fully open (feet or meters). Corresponds to
the diameter of a circular orifice or the height of a rectangular orifice.
Width of rectangular orifice when fully opened (feet or meters).
Depth or elevation of bottom of orifice above invert of inlet node (feet or
meters - see note below table of Conduit Properties).
Discharge coefficient (unitless). A typical value is 0.65.
YES if a flap gate exists which prevents backflow through the orifice, or
WO if no flap gate exists.
The time it takes to open a closed (or close an open) gated orifice in
decimal hours. Use 0 or leave blank if timed openings/closings do not
apply. Use Control Rules to adjust gate position.
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B.10 Weir Properties
Name
Inlet Node
Outlet Node
Description
Tag
Type
Height
Length
Side Slope
Inlet Offset
Discharge Coeff.1
Flap Gate
End Coeff.
End Contractions
Can Surcharge
ROADWAY WEIR
Road Width
Road Surface
User-assigned weir name.
Name of node on inlet side of weir.
Name of node on outlet side of weir.
Click the ellipsis button (or press Enter) to edit an optional description of
the weir.
Optional label used to categorize or classify the weir.
Weir type: TRANSVERSE, SIDEFLOW, V-NOTCH, TRAPEZOIDAL or
ROADWAY.
Vertical height of weir opening (feet or meters).
Horizontal length of weir opening (feet or meters).
Slope (width-to-height) of side walls for a V-NOTCH or TRAPEZOIDAL
weir.
Depth or elevation of bottom of weir opening from invert of inlet node
(feet or meters - see note below table of Conduit Properties).
Discharge coefficient for flow through the central portion of the weir (for
flow in CFS when using US units or CMS when using SI units).
YES if the weir has a flap gate that prevents backflow, WO otherwise..
Discharge coefficient for flow through the triangular ends of a
TRAPEZOIDALwe\r. See the recommended values for V-notch weirs.
Number of end contractions for a TRANSVERSE or TRAPEZOIDAL
weir whose length is shorter than the channel it is placed in. Values will
be either 0, 1, or 2 depending if no ends, one end, or both ends are
beveled in from the side walls.
YES if the weir can surcharge (have an upstream water level higher
than the height of the opening) or WO if it cannot.
Width of roadway and shoulders (feet or meters)
Type of road surface: PAVED or GRAVEL.
1 Typical values are: 3.33 US (1.84 SI) for sharp crested transverse weirs, 2.5 - 3.3 US (1.38 -
1.83 SI) for broad crested rectangular weirs, 2.4 - 2.8 US (1.35 - 1.55 SI) for V-notch (triangular)
weirs. Discharge over Roadway weirs with a non-zero road width is computed using the FHWA
HDS-5 method.
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B.11 Outlet Properties
Name
Inlet Node
Outlet Node
Description
Tag
Inlet Offset
Flap Gate
Rating Curve
FUNCTIONAL
- Coefficient
- Exponent
TABULAR
- Curve Name
User-assigned outlet name.
Name of node on inflow side of outlet.
Name of node on discharge side of outlet.
Click the ellipsis button (or press Enter) to edit an optional description of
the outlet.
Optional label used to categorize or classify the outlet.
Depth or elevation of outlet above inlet node invert (feet or meters - see
note below table of Conduit Properties).
YES if a flap gate exists which prevents backflow through the outlet, or
WO if no flap gate exists.
Method of defining flow (Q) as a function of depth or head (y) across the
outlet.
FUNCTIONAL/DEPTH uses a power function (Q = AyB) to describe this
relation where y is the depth of water above the outlet's opening at the
inlet node.
FUNCTIONAL/HEAD uses the same power function except that y is the
difference in head across the outlet's nodes.
TABULAR/DEPTH uses a tabulated curve of flow versus depth of water
above the outlet's opening at the inlet node.
TABULAR/HEAD uses a tabulated curve of flow versus difference in head
across the outlet's nodes.
Coefficient (A) for the functional relationship between depth or head and
flow rate.
Exponent (B) used for the functional relationship between depth or head
and flow rate.
Name of Rating Curve containing the relationship between depth or head
and flow rate (double-click to edit the curve).
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B.12 Map Label Properties
Text
X-Coordinate
Y-Coordinate
Anchor Node
Font
Text of label.
Horizontal location of the upper-left corner of the label on the Study Area
Map.
Vertical location of the upper-left corner of the label on the Study Area
Map.
Name of node (or subcatchment) that anchors the label's position when
the map is zoomed in (i.e., the pixel distance between the node and the
label remains constant). Leave blank if anchoring is not used.
Click the ellipsis button (or press Enter) to modify the font used to draw
the label.
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APPENDIX C - SPECIALIZED PROPERTY EDITORS
C.1 Aquifer Editor
The Aquifer Editor is invoked whenever a new aquifer object is created or an existing aquifer
object is selected for editing. It contains the following data fields:
Aquifer Editor (o)
Property
Aquifer Name
Porosity
Wilting Point
Field Capacity
Conductivity
Conductivity Slope
Tension Slope
Upper Evap. Fraction
Lower Evap. Depth
Lower GW Loss Rate
Bottom Elevation
Water Table Elevation
Unsat. Zone Moisture
Upper Evap. Pattern
Value
Al
0.5
0.15
0.30
5.0
10.0
15.0
0.35
14.0
0.002
0.0
10.0
0.30
User-assigned aquifer name
OK Cancel Help
Name
User-assigned aquifer name.
Porosity
Volume of voids / total soil volume
(volumetric fraction).
Wilting Point
Soil moisture content at which plants
cannot survive (volumetric fraction).
Field Capacity
Soil moisture content after all free
water has drained off (volumetric
fraction).
Conductivity
Soil's saturated hydraulic conductivity
(in/hror mm/hr).
Conductivity Slope
Average slope of log(conductivity)
versus soil moisture deficit (porosity
minus moisture content) curve
(unitless).
Tension Slope
Average slope of soil tension versus soil moisture content curve (inches or mm).
Upper Evaporation Fraction
Fraction of total evaporation available for evapotranspiration in the upper unsaturated zone.
Lower Evaporation Depth
Maximum depth below the surface at which evapotranspiration from the lower saturated zone can
still occur (ft or m).
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Lower Groundwater Loss Rate
Rate of percolation to deep groundwater when the water table reaches the ground surface (in/hr
or mm/hr).
Bottom Elevation
Elevation of the bottom of the aquifer (ft or m).
Water Table Elevation
Elevation of the water table in the aquifer at the start of the simulation (ft or m).
Unsaturated Zone Moisture
Moisture content of the unsaturated upper zone of the aquifer at the start of the simulation
(volumetric fraction) (cannot exceed soil porosity).
Upper Evaporation Pattern
Name of the monthly time pattern of adjustments applied to the upper evaporation fraction
(optional - leave blank if not applicable).
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C.2 Climatology Editor
The Climatology Editor is used to enter values for various climate-related variables required by
certain SWMM simulations. The dialog is divided into six tabbed pages, where each page
provides a separate editor for a specific category of climate data.
Temperature Page
Climatology Editor
Snow Melt
Temperature
Areal Depletion
Evaporation
Adjustments
Wind Speed
Source of Temperature Data:
« No Data
Time Series
External Climate File
tart Reading File at
The Temperature page of the Climatology Editor dialog is used to specify the source of
temperature data used for snowmelt computations. It is also used to select a climate file as a
possible source for evaporation rates. There are three choices available:
No Data: Select this choice if snowmelt is not being simulated and evaporation rates are
not based on data in a climate file.
Time Series: Select this choice if the variation in temperature over the simulation period will be
described by one of the project's time series. Also, enter (or select) the name of
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the time series. Click the
the selected time series.
button to make the Time Series Editor appear for
External
Climate File:
Select this choice if min/max daily temperatures will be read from an external
M.
climate file (see Section 11.4). Also enter the name of the file (or click the «
button to search for the file). If you want to start reading the climate file at a
particular date in time that is different than the start date of the simulation (as
specified in the Simulation Options), check off the "Start Reading File at" box and
enter a starting date (month/day/year) in the date entry field next to it. Use this
choice if you want daily evaporation rates to be estimated from daily
temperatures or be read directly from the file.
Evaporation Page
Climatology Editor
Snow Melt
Temperature
Areal Depletion
Evaporation
Adjustments
Wind Speed
Source of Evaporation Rates Constant Value
Daily Evaporation (in/day)
Constant Value
Time Series
Climate File
Monthly Averages
Temperatures
Monthly Soil Recovery
Pattern (Optional)
^\ Evaporate Only During Dry Periods
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The Evaporation page of the Climatology Editor dialog is used to supply evaporation rates, in
inches/day (or mm/day), for a study area. There are five choices for specifying these rates that
are selected from the Source of Evaporation Rates combo box:
Constant Value:
Use this choice if evaporation remains constant over time. Enter the value in the edit box
provided.
Time Series:
Select this choice if evaporation rates will be specified in a time series. Enter or select the name
of the time series in the dropdown combo box provided. Click the ^ button to bring up the Time
Series editor for the selected series. Note that for each date specified in the time series, the
evaporation rate remains constant at the value supplied for that date until the next date in the
series is reached (i.e., interpolation is not used on the series).
Directly From Climate File:
This choice indicates that daily evaporation rates will be read from the same climate file that was
specified for temperature. Enter values for monthly pan coefficients in the data grid provided.
Monthly Averages:
Use this choice to supply an average rate for each month of the year. Enter the value for each
month in the data grid provided. Note that rates remain constant within each month.
Computed from Temperatures:
The Hargreaves method will be used to compute daily evaporation rates from the daily air
temperature record contained in the external climate file specified on the Temperature page of
the dialog. This method also uses the site's latitude, which can be entered on the Snowmelt page
of the dialog even if snow melt is not being simulated.
Evaporate Only During Dry Periods:
Select this option if evaporation can only occur during periods with no precipitation.
In addition this page allows the user to specify an optional Monthly Soil Recovery Pattern. This
is a time pattern whose factors adjust the rate at which infiltration capacity is recovered during
periods with no precipitation. It applies to all subcatchments for any choice of infiltration method.
For example, if the normal infiltration recovery rate was 1% during a specific time period and a
pattern factor of 0.8 applied to this period, then the actual recovery rate would be 0.8%. The Soil
Recovery Pattern allows one to account for seasonal soil drying rates. In principle, the variation in
pattern factors should mirror the variation in evaporation rates but might be influenced by other
factors such as seasonal groundwater levels. The ^ button is used to launch the Time Pattern
Editor for the selected pattern.
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Wind Speed Page
Climatology Editor
Snow Melt
Areal Depletion
Temperature | Evaporation
Adjustments
Wind Speed
•*' Use Climate File Data (see Temperature Page)
Use Monthly Averages
Monthly Wind Speed (mph)
| Jan
EM
Feb
Mar Apr May Jun
0.0
0.0
0.0
0.0 0.0
Jul
Aug Sep | Oct
Nov Dec
0.0
0.0
0.0
0.0 0.0
The Wind Speed page of the Climatology Editor dialog is used to provide average monthly wind
speeds. These are used when computing snowmelt rates under rainfall conditions. Melt rates
increase with increasing wind speed. Units of wind speed are miles/hour for US units and
km/hour for metric units. There are two choices for specifying wind speeds:
Climate File Data:
Monthly Averages:
Wind speeds will be read from the same climate file that was specified
for temperature.
Wind speed is specified as an average value that remains constant in
each month of the year. Enter a value for each month in the data grid
provided. The default values are all zero.
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Snowmelt Page
Climatology Editor
Temperature Evaporation
Snow Melt
Areal Depletion
Wind Speed
Adjustments
Dividing Temperature
Between Snow and Rain 34
(degrees F)
ATI Weight (fraction) 0.5
Negative Melt Ratio 0,6
(fraction)
Elevation above MSL 0.0
(feet)
Latitude (degrees) 50.0
Longitude Correction 0,0
(+/- minutes)
The Snowmelt page of the Climatology Editor dialog is used to supply values for the following
parameters related to snow melt calculations:
Dividing Temperature Between Snow and Rain
Enter the temperature below which precipitation falls as snow instead of rain. Use degrees F for
US units or degrees C for metric units.
ATI (Antecedent Temperature Index) Weight
This parameter reflects the degree to which heat transfer within a snow pack during non-melt
periods is affected by prior air temperatures. Smaller values reflect a thicker surface layer of snow
which results in reduced rates of heat transfer. Values must be between 0 and 1, and the default
is 0.5.
Negative Melt Ratio
This is the ratio of the heat transfer coefficient of a snow pack during non-melt conditions to the
coefficient during melt conditions. It must be a number between 0 and 1. The default value is 0.6.
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Elevation Above MSL
Enter the average elevation above mean sea level for the study area, in feet or meters. This value
is used to provide a more accurate estimate of atmospheric pressure. The default is 0.0, which
results in a pressure of 29.9 inches Hg. The effect of wind on snow melt rates during rainfall
periods is greater at higher pressures, which occur at lower elevations.
Latitude
Enter the latitude of the study area in degrees North. This number is used when computing the
hours of sunrise and sunset, which in turn are used to extend min/max daily temperatures into
continuous values. It is also used to compute daily evaporation rates from daily temperatures.
The default is 50 degrees North.
Longitude Correction
This is a correction, in minutes of time, between true solar time and the standard clock time. It
depends on a location's longitude (6) and the standard meridian of its time zone (SM) through the
expression 4(6-SM). This correction is used to adjust the hours of sunrise and sunset when
extending daily min/max temperatures into continuous values. The default value is 0.
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Areal Depletion Page
Climatology Editor
Temperature | Evaporation Wind Speed
Snow Melt
Areal Depletion
Adjustments
Fraction of Area Covered by Snow
Depth Ratio
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
OS
Impervious
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1JD
No Depletion
Natural Area
Pervious
1.0
1JO
1JO
IJQ
1JO
in
1JO
in
1JO
in
No Depletion
Natural Area
OK
The Areal Depletion page of the Climatology Editor Dialog is used to specify points on the Areal
Depletion Curves for both impervious and pervious surfaces within a project's study area. These
curves define the relation between the area that remains snow covered and snow pack depth.
Each curve is defined by 10 equal increments of relative depth ratio between 0 and 0.9. (Relative
depth ratio is the ratio of an area's current snow depth to the depth at which there is 100% areal
coverage).
Enter values in the data grid provided for the fraction of each area that remains snow covered at
each specified relative depth ratio. Valid numbers must be between 0 and 1, and be increasing
with increasing depth ratio.
Clicking the Natural Area button fills the grid with values that are typical of natural areas. Clicking
the No Depletion button will fill the grid with all 1's, indicating that no areal depletion occurs. This
is the default for new projects.
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Adjustments Page
Climatology Editor
Temperature | Evaporation | Wind Speed
Snow Melt Areal Depletion Adjustments
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Temp
Evap
Rain
Cond
Temp temperature adjustment (+- deg F or deg C)
Evap evaporation adjustment (+- in/day or mm/day)
Rain rainfall multiplier
Cond soil conductivity multiplier
Clear All
The Adjustments page of the Climatology Editor Dialog is used to supply a set of monthly
adjustments applied to the temperature, evaporation rate, rainfall, and soil hydraulic conductivity
that SWMM uses at each time step of a simulation:
• The monthly Temperature adjustment (plus or minus in either degrees F or C) is added to
the temperature value that SWMM would otherwise use in a specific month of the year.
• The monthly Evaporation adjustment (plus or minus in either in/day or mm/day) is added
to the evaporation rate value that SWMM would otherwise use in a specific month of the
year.
• The monthly Rainfall adjustment is a multiplier applied to the precipitation value that
SWMM would otherwise use in a specific month of the year.
• The monthly Conductivity adjustment is a multiplier applied to the soil hydraulic
conductivity used compute rainfall infiltration, groundwater percolation, and exfiltration
from channels and storage units.
The same adjustment is applied for each time period within a given month and is repeated for that
month in each subsequent year being simulated. Leaving a monthly adjustment blank means that
there is no adjustment made in that month.
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C.3
Control Rules Editor
Control Rules Editor
RULE FUKF1A
IF NODE SU1 DEPTH >= 4
THEN PUMP FUKF1 status = OH
PRIORITY 1
RULE FUMF1B
IF NODE SU1 DEPTH < 1
THEN FUMF FUKF1 status = OFF
PRIORITY 1
OK
Click Help to review the format of Control Rule statements.
The Control Rules Editor is invoked whenever a new control rule is created or an existing rule is
selected for editing. The editor contains a memo field where the entire collection of control rules is
displayed and can be edited.
Control Rule Format
Each control rule is a series of statements of the form:
RULE rulelD
IF
AND
OR
AND
Etc.
condition_l
condition 2
condition 3
condition 4
THEN
AND
Etc.
ELSE
AND
Etc.
action_l
action_2
action_3
action 4
PRIORITY value
where keywords are shown in boldface and ruleio is an ID label assigned to the rule,
condition n is a Condition Clause, action n is an Action Clause, and value is a priority
220
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value (e.g., a number from 1 to 5). The formats used for Condition and Action clauses are
discussed below.
Only the RULE, IF and THEN portions of a rule are required; the ELSE and PRIORITY portions
are optional.
Blank lines between clauses are permitted and any text to the right of a semicolon is considered a
comment.
When mixing AND and OR clauses, the OR operator has higher precedence than AND, i.e.,
IF A or B and C
is equivalent to
IF (A or B) and C.
If the interpretation was meant to be
IF A or (B and C)
then this can be expressed using two rules as in
IF A THEN . . .
IF B and C THEN ...
The PRIORITY value is used to determine which rule applies when two or more rules require that
conflicting actions be taken on a link. A conflicting rule with a higher priority value has precedence
over one with a lower value (e.g., PRIORITY 5 outranks PRIORITY 1). A rule without a priority
value always has a lower priority than one with a value. For two rules with the same priority value,
the rule that appears first is given the higher priority.
Condition Clauses
A Condition Clause of a control rule has the following formats:
object id attribute relation value
object id attribute relation object id attribute
where:
object = a category of object
id = the object's ID label
attribute = an attribute or property of the object
relation = a relational operator (=, <>, <, <=, >, >=)
value = an attribute value
Some examples of condition clauses are:
NODE N23 DEPTH > 10
NODE N23 DEPTH > NODE N25 DEPTH
PUMP P45 STATUS = OFF
SIMULATION CLOCKTIME = 22:45:00
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The objects and attributes that can appear in a condition clause are as follows:
Object
NODE
LINK
CONDUIT
PUMP
ORIFICE
WEIR
OUTLET
SIMULATION
SIMULATION
Attributes
DEPTH
HEAD
VOLUME
INFLOW
FLOW
DEPTH
TIMEOPEN
TIMECLOSED
STATUS
TIMEOPEN
TIMECLOSED
STATUS
SETTING
FLOW
TIMEOPEN
TIMECLOSED
SETTING
TIMEOPEN
TIMECLOSED
SETTING
TIMEOPEN
TIMECLOSED
SETTING
TIMEOPEN
TIMECLOSED
TIME
DATE
MONTH
DAY
CLOCKTIME
Value
numerical value
numerical value
numerical value
numerical value
numerical value
numerical value
decimal hours or hr:min
decimal hours or hr:min
OPEN or CLOSED
decimal hours or hr:min
decimal hours or hr:min
ON or OFF
pump curve multiplier
numerical value
decimal hours or hr:min
decimal hours or hr:min
fraction open
decimal hours or hr:min
decimal hours or hr:min
fraction open
decimal hours or hr:min
decimal hours or hr:min
rating curve multiplier
decimal hours or hr:min
decimal hours or hr:min
elapsed time in decimal hours or
hr:min:sec
month/day/year
month of year (January = 1)
day of week (Sunday = 1)
time of day in hr:min:sec
TIMEOPEN is the duration a link has been in an OPEN or ON state or have its SETTING be greater
than zero; TIMECLOSED is the duration it has remained in a CLOSED or OFF state or have its
SETTING be zero.
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Action Clauses
An Action Clause of a control rule can have one of the following formats:
PUMP id STATUS = ON/OFF
PUMP/ORIFICE/WEIR/OUTLET id SETTING = value
where the meaning of SETTING depends on the object being controlled:
• for Pumps it is a multiplier applied to the flow computed from the pump curve,
• for Orifices it is the fractional amount that the orifice is fully open,
• for Weirs it is the fractional amount of the original freeboard that exists (i.e., weir control
is accomplished by moving the crest height up or down),
• for Outlets it is a multiplier applied to the flow computed from the outlet's rating curve.
Some examples of action clauses are:
PUMP P67 STATUS = OFF
ORIFICE 0212 SETTING =0.5
Modulated Controls
Modulated controls are control rules that provide for a continuous degree of control applied to a
pump or flow regulator as determined by the value of some controller variable, such as water
depth at a node, or by time. The functional relation between the control setting and the controller
variable can be specified by using a Control Curve, a Time Series, or a PID Controller. Some
examples of modulated control rules are:
RULE MCI
IF NODE N2 DEPTH >= 0
THEN WEIR W25 SETTING = CURVE C25
RULE MC2
IF SIMULATION TIME > 0
THEN PUMP P12 SETTING = TIMESERIES TS101
RULE MC3
IF LINK L33 FLOW <> 1.6
THEN ORIFICE 012 SETTING = PID 0.1 0.0 0.0
Note how a modified form of the action clause is used to specify the name of the control curve,
time series or PID parameter set that defines the degree of control. A PID parameter set contains
three values - a proportional gain coefficient, an integral time (in minutes), and a derivative time
(in minutes). Also, by convention the controller variable used in a Control Curve or PID Controller
will always be the object and attribute named in the last condition clause of the rule. As an
example, in rule MC1 above Curve C25 would define how the fractional setting at Weir W25
223
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varied with the water depth at Node N2. In rule MC3, the PID controller adjusts the opening of
Orifice O12 to maintain a flow of 1.6 in Link L33.
PID Controllers
A PID (Proportional-lntegral-Derivative) Controller is a generic closed-loop control scheme that
tries to maintain a desired set-point on some process variable by computing and applying a
corrective action that adjusts the process accordingly. In the context of a hydraulic conveyance
system a PID controller might be used to adjust the opening on a gated orifice to maintain a
target flow rate in a specific conduit or to adjust a variable speed pump to maintain a desired
depth in a storage unit. The classical PID controller has the form:
m(t) = K.
dt
where m(t) = controller output, Kp = proportional coefficient (gain), 7, = integral time, Td =
derivative time, eft) = error (difference between setpoint and observed variable value), and t =
time. The performance of a PID controller is determined by the values assigned to the coefficients
Kp, Ti, and Td.
The controller output m(t) has the same meaning as a link setting used in a rule's Action Clause
while dt is the current flow routing time step in minutes. Because link settings are relative values
(with respect to either a pump's standard operating curve or to the full opening height of an orifice
or weir) the error eft) used by the controller is also a relative value. It is defined as the difference
between the control variable setpoint x* and its value at time t, xft), normalized to the setpoint
va\ue:e(t) = (x*-x(t))/x*.
Note that for direct action control, where an increase in the link setting causes an increase in the
controlled variable, the sign of Kp must be positive. For reverse action control, where the
controlled variable decreases as the link setting increases, the sign of Kp must be negative. The
user must recognize whether the control is direct or reverse action and use the proper sign on Kd
accordingly. For example, adjusting an orifice opening to maintain a desired downstream flow is
direct action. Adjusting it to maintain an upstream water level is reverse action. Controlling a
pump to maintain a fixed wet well water level would be reverse action while using it to maintain a
fixed downstream flow is direct action.
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C.4 Cross-Section Editor
Cross-Section Editor
Rectangular Trapezoidal
Triangular
Parabolic
Power
Irregular
Circular
Force Main
Filled Circular
Standard circular pipe.
Barrels Dimensions
i ~H ^i
Max. Depth
2
OK
The Cross-Section Editor dialog is used to specify the shape and dimensions of a conduit's cross-
section. When a shape is selected from the image list an appropriate set of edit fields appears for
describing the dimensions of that shape. Length dimensions are in units of feet for US units and
meters for SI units. Slope values represent ratios of horizontal to vertical distance. The Barrels
field specifies how many identical parallel conduits exist between its end nodes.
The Force Main shape option is a circular conduit that uses either the Hazen-Williams or Darcy-
Weisbach formulas to compute friction losses for pressurized flow during Dynamic Wave flow
routing. In this case the appropriate C-factor (for Hazen-Williams) or roughness height (for Darcy-
Weisbach) is supplied as a cross-section property. The choice of friction loss equation is made on
the Dynamic Wave Simulation Options dialog. Note that a conduit does not have to be assigned a
Force Main shape for it to pressurize. Any of the other closed cross-section shapes can
potentially pressurize and thus function as force mains using the Manning equation to compute
friction losses.
If a Custom shaped section is chosen, a drop-down edit box will appear where you can enter or
select the name of a Shape Curve that will be used to define the geometry of the section. This
curve specifies how the width of the cross-section varies with height, where both width and height
are scaled relative to the section's maximum depth. This allows the same shape curve to be used
for conduits of differing sizes. Clicking the Edit button & next to the shape curve box will bring
up the Curve Editor where the shape curve's coordinates can be edited.
If an Irregular shaped section is chosen, a drop-down edit box will appear where you can enter or
select the name of a Transect object that describes the cross-section's geometry. Clicking the
Edit button & next to the edit box will bring up the Transect Editor from which you can edit the
transect data.
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C.5
Curve Editor
Pu
mp C
Curve
PUMF
Descri
jrve Editor
Name
_CURVE1
Dtion
Pump Type
TYPE4
H
i
2
3
4
5
6
7
8
9
10
11
Depth
m
Flow
(CFSJ
0 I 0.45
4
4.75
0.45
09
>
T
View...
Load...
Save...
OK
Cancel
Help
The Curve Editor dialog is invoked whenever a new curve object is created or an existing curve
object is selected for editing. The editor adapts itself to the category of curve being edited
(Storage, Tidal, Diversion, Pump, or Rating). To use the Curve Editor:
• Enter values for the following data entry fields:
Name Name of the curve.
Type (Pump Curves Only). Choice of pump curve type as described in
Section 3.2
Description Optional comment or description of what the curve represents. Click
the & button to launch a multi-line comment editor if more than one
line is needed.
Data Grid The curve's X,Y data.
• Click the View button to see a graphical plot of the curve drawn in a separate window.
• If additional rows are needed in the Data Grid, simply press the Enter key when in the
last row.
• Right-clicking over the Data Grid will make a popup Edit menu appear. It contains
commands to cut, copy, insert, and paste selected cells in the grid as well as options to
insert or delete a row.
You can also click the Load button to load in a curve that was previously saved to file or click the
Save button to save the current curve's data to a file.
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C.6
Groundwater Flow Editor
Groundwater Flow Editor
Property
Aquifer Name
Receiving Node
Surface Elevation
Al Coefficient
Bl Exponent
A2 Coefficient
B2 Exponent
A3 Coefficient
Surface Water Depth
Threshold Water Table Elev.
Aquifer Bottom Elevation
Initial Water Table Elev.
Unsat, Zone Moisture
Custom Lateral Flow Equation
Custom Deep Flow Equation
Value
0,1
No
No
Name of Aquifer object that lies below
subcatchment. Leave blank for no groundwater.
The standard equation for lateral groundwater flow is:
QL = Al*(Hgw-Hcb)ABl
-A2*(Hsw-Hcb)AB2
+ A3*Hgw*Hsw
where QL has units of cfs/ac (or cms/ha].
The standard equation for deep groundwater flow is:
QD = LGLR*Hgw/Hgs
where LGLR is the aquifer lower GW loss rate [in/hr or
mm/hr),
OK
Cancel
Help
The Groundwater Flow Editor dialog is invoked when the Groundwater property of a
subcatchment is being edited. It is used to link a subcatchment to both an aquifer and to a node
of the drainage system that exchanges groundwater with the aquifer. It also specifies coefficients
that determine the rate of lateral groundwater flow between the aquifer and the node. These
coefficients (A1, A2, B1, B2, and A3) appear in the following equation that computes groundwater
flow as a function of groundwater and surface water levels:
QL = Al(Hgw -
- A2(HSW -
A3HgwHsw
where:
QL
Hgw
Hsw
Hcb
lateral groundwater flow (cfs per acre or cms per hectare)
height of saturated zone above bottom of aquifer (ft or m)
height of surface water at receiving node above aquifer bottom (ft or m)
height of channel bottom above aquifer bottom (ft or m).
Note that QL can also be expressed in inches/hrfor US units.
The rate of percolation to deep groundwater, QD, in in/hr (or mm/hr) is given by the following
equation:
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QD =LGLR
where LGLR is the lower groundwater loss rate parameter assigned to the subcatchment's
aquifer (in/hr or mm/hr) and HGS is the distance from the ground surface to the aquifer bottom (ft
or m).
In addition to the standard lateral flow equation, the dialog allows one to define a custom equation
whose results will be added onto those of the standard equation. One can also define a custom
equation for deep groundwater flow that will replace the standard one. Finally, the dialog offers
the option to override certain parameters that were specified for the aquifer to which the
subcatchment belongs. The properties listed in the editor are as follows:
Aquifer Name
Name of the aquifer object that describes the subsurface soil properties, thickness, and initial
conditions. Leave this field blank if you want the subcatchment not to generate any groundwater
flow.
Receiving Node
Name of node that receives groundwater from the aquifer.
Surface Elevation
Elevation of ground surface for the subcatchment that lies above the aquifer in feet or meters.
Groundwater Flow Coefficient
Value of A1 in the groundwater flow formula.
Groundwater Flow Exponent
Value of B1 in the groundwater flow formula.
Surface Water Flow Coefficient
Value of A2 in the groundwater flow formula.
Surface Water Flow Exponent
Value of B2 in the groundwater flow formula.
Surface-GW Interaction Coefficient
Value of A3 in the groundwater flow formula.
Surface Water Depth
Fixed depth of surface water above receiving node's invert (feet or meters). Set to zero if surface
water depth will vary as computed by flow routing.
Threshold Water Table Elevation
Minimum water table elevation that must be reached before any flow occurs (feet or meters).
Leave blank to use the receiving node's invert elevation.
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Aquifer Bottom Elevation
Elevation of the bottom of the aquifer below this particular subcatchment (feet or meters). Leave
blank to use the value from the parent aquifer.
Initial Water Table Elevation
Initial water table elevation at the start of the simulation for this particular subcatchment (feet or
meters). Leave blank to use the value from the parent aquifer.
Unsaturated Zone Moisture
Moisture content of the unsaturated upper zone above the water table for this particular
subcatchment at the start of the simulation (volumetric fraction). Leave blank to use the value
from the parent aquifer.
Custom Lateral Flow Equation
Click the ellipsis button (or press Enter) to launch the Custom Groundwater Flow Equation editor
for lateral groundwater flow QL (see section C.7). The equation supplied by this editor will be used
in addition to the standard equation to compute groundwater outflow from the subcatchment.
Custom Deep Flow Equation
Click the ellipsis button (or press Enter) to launch the Custom Groundwater Flow Equation editor
for deep groundwater flow QD. The equation supplied by this editor will be used to replace the
standard equation for deep groundwater flow.
The coefficients supplied to the groundwater flow equations must be in units that are consistent
with the groundwater flow units, which can either be cfs/acre (equivalent to inches/hr) for US units
or cms/ha for SI units.
Note that elevations are used to specify the ground surface, water table height, and
aquifer bottom in the dialog's data entry fields but that the groundwater flow equation
uses depths above the aquifer bottom.
If groundwater flow is simply proportional to the difference in groundwater and surface
water heads, then set the Groundwater and Surface Water Flow Exponents (B1 and B2)
to 1.0, set the Groundwater Flow Coefficient (A1) to the proportionality factor, set the
Surface Water Flow Coefficient (A2) to the same value as A1, and set the Interaction
Coefficient (A3) to zero.
Note that when conditions warrant, the groundwater flux can be negative, simulating flow
into the aquifer from the channel, in the manner of bank storage. An exception occurs
when A3 ^ 0, since the surface water - groundwater interaction term is usually derived
from groundwater flow models that assume unidirectional flow. Otherwise, to ensure that
negative fluxes will not occur, one can make A1 greater than or equal to A2, B1 greater
than or equal to B2, and A3 equal to zero.
To completely replace the standard groundwater flow equation with the custom equation,
set all of the standard equation coefficients to 0.
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C.7 Groundwater Equation Editor
ustom Groundwater Flow Equation Editor
Enter an expression to use in addition to the standard equation for lateral groundwaterflow
(leave blankto use only the standard equation):
0.1*(Hgw-Hcb)*5TEP(Hgw-Hcb)
The Groundwater Equation Editor is used to supply a custom equation for computing
groundwater flow between the saturated sub-surface zone of a subcatchment and either a node
in the conveyance network (lateral flow) or to a deeper groundwater aquifer (deep flow). It is
invoked from the Groundwater Flow Editor form.
For lateral groundwater flow the result of evaluating the custom equation will be added onto the
result of the standard equation. To replace the standard equation completely set all of its
coefficients to 0. Remember that lateral groundwater flow units are cfs/acre (equivalent to
inches/hr) for US units and cms/ha for metric units.
The following symbols can be used in the equation:
Hgw (for height of the groundwater table)
Hsw (for height of the surface water)
Hcb (for height of the channel bottom)
Hgs (for height of the ground surface)
Phi (for porosity of the subsurface soil)
Theta (for moisture content of the upper unsaturated zone)
Ks (for saturated hydraulic conductivity in inches/hr or mm/hr)
K (for hydraulic conductivity at the current moisture content in inches/hr or mm/hr)
Fi (for infiltration rate from the ground surface in inches/hr or mm/hr)
Fu (for percolation rate from the upper unsaturated zone in inches/hr or mm/hr)
A (for subcatchment area in acres or hectares)
where all heights are relative to the aquifer's bottom elevation in feet (or meters).
The STEP function can be used to have flow only when the groundwater level is above a certain
threshold. For example, the expression:
0.001 * (Hgw - 5) * STEP(Hgw - 5)
would generate flow only when Hgw was above 5. See Section C.22 (Treatment Editor) for a list
of additional math functions that can be used in a groundwaterflow expression.
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C.8
Infiltration Editor
Inflation Editor B
Infiltration Method MORTON
Property
Max. Infil. Rate
Min. Infil. Rate
Decay Constant
Drying
Time
Max. Volume
Value
jl.2 |
0.1
2
7
0
Maximum rate on the Morton infiltration curve (in/hr or
mm/hr)
OK C
ancel Help
The Infiltration Editor dialog is used to specify values for the parameters that describe the rate at
which rainfall infiltrates into the upper soil zone in a subcatchment's pervious area. It is invoked
when editing the Infiltration property of a subcatchment. The infiltration parameters depend on
which infiltration model was selected for the project: Morton, Green-Ampt, or Curve Number. The
choice of infiltration model can be made either by editing the project's Simulation Options (see
Section 8.1) or by changing the project's Default Properties (see Section 5.4).
Morton Infiltration Parameters
The following data fields appear in the Infiltration Editor for Morton infiltration:
Max. Infil. Rate
Maximum infiltration rate on the Morton curve (in/hr or mm/hr). Representative values are as
follows:
A. DRY soils (with little or no vegetation):
• Sandy soils: 5 in/hr
• Loam soils: 3 in/hr
• Clay soils: 1 in/hr
B. DRY soils (with dense vegetation):
• Multiply values in A. by 2
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C. MOIST soils:
• Soils which have drained but not dried out (i.e., field capacity):
Divide values from A and B by 3.
• Soils close to saturation:
Choose value close to minimum infiltration rate.
• Soils which have partially dried out:
Divide values from A and B by 1.5 - 2.5.
Min. Infil. Rate
Minimum infiltration rate on the Morton curve (in/hr or mm/hr). Equivalent to the soil's saturated
hydraulic conductivity. See the Soil Characteristics Table in Section A.2 for typical values.
Decay Const.
Infiltration rate decay constant for the Morton curve (1/hours). Typical values range between 2
and 7.
Drying Time
Time in days for a fully saturated soil to dry completely. Typical values range from 2 to 14 days.
Max. Infil. Vol.
Maximum infiltration volume possible (inches or mm, 0 if not applicable). It can be estimated as
the difference between a soil's porosity and its wilting point times the depth of the infiltration zone.
Green-Ampt Infiltration Parameters
The following data fields appear in the Infiltration Editor for Green-Ampt infiltration:
Suction Head
Average value of soil capillary suction along the wetting front (inches or mm).
Conductivity
Soil saturated hydraulic conductivity (in/hr or mm/hr).
Initial Deficit
Fraction of soil volume that is initially dry (i.e., difference between soil porosity and initial moisture
content). For a completely drained soil, it is the difference between the soil's porosity and its field
capacity.
Typical values for all of these parameters can be found in the Soil Characteristics Table in
Section A.2.
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Curve Number Infiltration Parameters
The following data fields appear in the Infiltration Editor for Curve Number infiltration:
Curve Number
This is the SCS curve number which is tabulated in the publication SCS Urban Hydrology for
Small Watersheds, 2nd Ed., (TR-55), June 1986. Consult the Curve Number Table (Section A.4)
for a listing of values by soil group, and the accompanying Soil Group Table (Section A.3) for the
definitions of the various groups.
Conductivity
This property has been deprecated and is no longer used.
Drying Time
The number of days it takes a fully saturated soil to dry. Typical values range between 2 and 14
days.
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C.9
Inflows Editor
The Inflows Editor dialog is used to assign Direct, Dry Weather, and RDM inflow into a node of the
drainage system. It is invoked whenever the Inflows property of a Node object is selected in the
Property Editor. The dialog consists of three tabbed pages that provide a special editor for each
type of inflow.
Direct Inflows Page
Inflows for Node 82309
Direct
Dry Weather RDE
Inflow = (Baseline Value) x (Baseline Pattern) +
[Time Series Value) x (Scale Factor)
Constituent
FLOW
Baseline
Baseline Pattern
Time Series 82309_Inflow
Scale Factor
1.0
If Baseline or Time Series is left blank its value is 0. If
Baseline Pattern is left blank its value isl.O.
Llgj[
The Direct page on the Inflows Editor dialog is used to specify the time history of direct external
flow and water quality entering a node of the drainage system. These inflows are represented by
both a constant and time varying component as follows:
Inflow at time t = (baseline value) * (baseline pattern factor) +
(scale factor) * (time series value at time t)
The page contains the following input fields that define the properties of this relation:
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Constituent
Selects the constituent (FLOW or one of the project's specified pollutants) whose direct inflow will
be described.
Baseline
Specifies the value of the constant baseline component of the constituent's inflow. For FLOW, the
units are the project's flow units. For pollutants, the units are the pollutant's concentration units if
inflow is a concentration, or can be any mass flow units if the inflow is a mass flow (see
Conversion Factor below). If left blank then no baseline inflow is assumed.
Baseline Pattern
An optional Time Pattern whose factors adjust the baseline inflow on either an hourly, daily, or
monthly basis (depending on the type of time pattern specified). Clicking the ^ button will bring
up the Time Pattern Editor dialog for the selected time pattern. If left blank, then no adjustment is
made to the baseline inflow.
Time Series
Specifies the name of the time series that contains inflow data for the selected constituent. If left
blank then no direct inflow will occur for the selected constituent at the node in question. You can
click the -^ button to bring up the Time Series Editor dialog for the selected time series.
Scale Factor
A multiplier used to adjust the values of the constituent's inflow time series. The baseline value is
not adjusted by this factor. The scale factor can have several uses, such as allowing one to easily
change the magnitude of an inflow hydrograph while keeping its shape the same, without having
to re-edit the entries in the hydrograph time series. Or it can allow a group of nodes sharing the
same time series to have their inflows behave in a time-synchronized fashion while letting their
individual magnitudes be different. If left blank the scale factor defaults to 1.0.
Inflow Type
For pollutants, selects the type of inflow data contained in the time series as being either a
concentration (mass/volume) or mass flow rate (mass/time). This field does not appear for FLOW
inflow.
Conversion Factor
A numerical factor used to convert the units of pollutant mass flow rate in the time series data into
concentration mass units per second. For example, if the time series data were in pounds per day
and the pollutant concentration defined in the project was mg/L, then the conversion factor value
would be (453,590 mg/lb) / (86400 sec/day) = 5.25 (mg/sec) per (Ib/day).
More than one constituent can be edited while the dialog is active by simply selecting another
choice for the Constituent property. However, if the Cancel button is clicked then any changes
made to all constituents will be ignored.
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If a pollutant is assigned a direct inflow in terms of concentration, then one must also
assign a direct inflow to flow, otherwise no pollutant inflow will occur. An exception is at
submerged outfalls where pollutant intrusion can occur during periods of reverse flow. If
pollutant inflow is defined in terms of mass, then a flow inflow time series is not required.
Dry Weather Inflows Page
Inflows for Node 82309
Direct Dry Weather RDB
Inflow = (Average Value) x (Pattern 1) x
(Pattern 2) x [Pattern 3) x (Pattern 4)
Constituent
Average Value
(CFS)
Time Patterns
FLOW
12
Monthlyl
Hourlyl
If Average Value is left blank its value is 0. Any Time
Pattern left blank defaults to a constant value of 1.0.
The Dry Weather page of the Inflows Editor dialog is used to specify a continuous source of dry
weather flow entering a node of the drainage system. The page contains the following input fields:
Constituent
Selects the constituent (FLOW or one of the project's specified pollutants) whose dry weather
inflow will be specified.
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Average Value
Specifies the average (or baseline) value of the dry weather inflow of the constituent in the
relevant units (flow units for flow, concentration units for pollutants). Leave blank if there is no dry
weather flow for the selected constituent.
Time Patterns
Specifies the names of the time patterns to be used to allow the dry weather flow to vary in a
periodic fashion by month of the year, by day of the week, and by time of day (for both weekdays
and weekends). One can either type in a name or select a previously defined pattern from the
dropdown list of each combo box. Up to four different types of patterns can be assigned. You can
click the & button next to each Time Pattern field to edit the respective pattern.
More than one constituent can be edited while the dialog is active by simply selecting another
choice for the Constituent property. However, if the Cancel button is clicked then any changes
made to all constituents will be ignored.
RDM Inflow Page
Inflows for Node 82309
Direct | Dry Weather
ROE
Unit Hydrograph Group
UH-1
Sewershed Area
(acres)
20
Leave the Unit Hydrograph Group field blank to remove
any RDE inflow at this node.
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The RDM Inflow page of the Inflows Editor dialog form is used to specify RDM (Rainfall Dependent
Infiltration/Inflow) for the node in question. The page contains the following two input fields:
Unit Hydrograph Group
Enter (or select from the dropdown list) the name of the Unit Hydrograph group that applies to the
node in question. The unit hydrographs in the group are used in combination with the group's
assigned rain gage to develop a time series of RDM inflows per unit area over the period of the
simulation. Leave this field blank to indicate that the node receives no RDM inflow. Clicking the
•^ button will launch the Unit Hydrograph Editor for the UH group specified.
Sewershed Area
Enter the area (in acres or hectares) of the sewershed that contributes RDM to the node in
question. Note this area will typically be only a small, localized portion of the subcatchment area
that contributes surface runoff to the node.
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C.10 Initial Buildup Editor
Property
Infiltration
Groundwater
Snow Pack
LJD Control:
Land Uses
(Initial Buildup
Curb Length
Value |
MORTON *1
NO
0
1
YES ...\\-
0
I I
Initial pollutant buildup on
subcatchment (click to edit)
Initial Buildup Editor
Pollutant Initial Buildup (Ibs/ac)
TSS 10
Lead
Enter initial buildup of pollutants on
subcatchment 1
OK Cancel Help
The Initial Buildup Editor is invoked from the Property Editor when editing the Initial Buildup
property of a subcatchment. It specifies the amount of pollutant buildup existing over the
subcatchment at the start of the simulation. The editor consists of a data entry grid with two
columns. The first column lists the name of each pollutant in the project and the second column
contains edit boxes for entering the initial buildup values. If no buildup value is supplied for a
pollutant, it is assumed to be 0. The units for buildup are either pounds per acre when US units
are in use or kilograms per hectare when SI metric units are in use.
If a non-zero value is specified for the initial buildup of a pollutant, it will override any initial
buildup computed from the Antecedent Dry Days parameter specified on the Dates page of the
Simulation Options dialog.
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C.11 Land Use Editor
The Land Use Editor dialog is used to define a category of land use for the study area and to
define its pollutant buildup and washoff characteristics. The dialog contains three tabbed pages of
land use properties:
• General Page (provides land use name and street sweeping parameters)
• Buildup Page (defines rate at which pollutant buildup occurs)
• Washoff Page (defines rate at which pollutant washoff occurs)
General Page
General Buildup | Washoff
Property
Value
Land Use Name jResidential
Description
STREET SWEEPING
Interval
Availability
Last Swept
User assigned name of land use.
The General page of the Land Use Editor dialog describes the following properties of a particular
land use category:
Land Use Name
The name assigned to the land use.
Description
An optional comment or description of the land use (click the ellipsis button or press Enter to
edit).
Street Sweeping Interval
Days between street sweeping within the land use.
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Street Sweeping Availability
Fraction of the buildup of all pollutants that is available for removal by sweeping.
Last Swept
Number of days since last swept at the start of the simulation.
If street sweeping does not apply to the land use, then the last three properties can be left blank.
Buildup Page
Land Use Editor
General Buildup Washoff
Pollutant
Property
Function
Max, Buildup
Rate Constant
Power/Sat. Constant
Normalizer
TSS
Value
SAT
50
0
2
AREA
Buildup function: ROW = power, EXP =
exponential, SAT = saturation, EXT = external time
series.
The Buildup page of the Land Use Editor dialog describes the properties associated with pollutant
buildup over the land during dry weather periods. These consist of:
Pollutant
Select the pollutant whose buildup properties are being edited.
Function
The type of buildup function to use for the pollutant. The choices are NONE for no buildup, POW
for power function buildup, EXP for exponential function buildup SAT for saturation function
buildup, and EXT for buildup supplied by an external time series. See the discussion of Pollutant
Buildup in Section 3.3.9 Land Uses for explanations of these different functions. Select NONE if no
buildup occurs.
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Max. Buildup
The maximum buildup that can occur, expressed as Ibs (or kg) of the pollutant per unit of the
normalizer variable (see below). This is the same as the C1 coefficient used in the buildup
formulas discussed in Section 3.3.9.
The following two properties apply to the POW, EXP, and SAT buildup functions:
Rate Constant
The time constant that governs the rate of pollutant buildup. This is the C2 coefficient in the
Power and Exponential buildup formulas discussed in Section 3.3.9. For Power buildup its units
are mass / days raised to a power, while for Exponential buildup its units are 1/days.
Power/Sat. Constant
The exponent C3 used in the Power buildup formula, or the half-saturation constant C2 used in
the Saturation buildup formula discussed in Section 3.3.9. For the latter case, its units are days.
The following two properties apply to the EXT (External Time Series) option:
Scaling Factor
A multiplier used to adjust the buildup rates listed in the time series.
Time Series
The name of the Time Series that contains buildup rates (as mass per normalizer per day).
Normalizer
The variable to which buildup is normalized on a per unit basis. The choices are either land area
(in acres or hectares) or curb length. Any units of measure can be used for curb length, as long
as they remain the same for all subcatchments in the project.
When there are multiple pollutants, the user must select each pollutant separately from the
Pollutant dropdown list and specify its pertinent buildup properties.
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Washoff Page
Land Use Editor
General Buildup Washoff
Pollutant
Property
TSS
Value
Function JEXP
Coefficient
Exponent
Cleaning Effic,
BMP Effic.
0.1
1
0
0
Washoff function: EXP = exponential, RC = rating
curve, EMC = event mean concentration.
The Washoff page of the Land Use Editor dialog describes the properties associated with
pollutant washoff over the land use during wet weather events. These consist of:
Pollutant
The name of the pollutant whose washoff properties are being edited.
Function
The choice of washoff function to use for the pollutant. The choices are:
• NONE no washoff
• EXP exponential washoff
• RC rating curve washoff
• EMC event-mean concentration washoff.
The formula for each of these functions is discussed in Section 3.3.9 Land Uses under the
Pollutant Washoff topic.
Coefficient
This is the value of C1 in the exponential and rating curve formulas, or the event-mean
concentration.
Exponent
The exponent used in the exponential and rating curve washoff formulas.
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Cleaning Efficiency
The street cleaning removal efficiency (percent) for the pollutant. It represents the fraction of the
amount that is available for removal on the land use as a whole (set on the General page of the
editor) which is actually removed.
BMP Efficiency
Removal efficiency (percent) associated with any Best Management Practice that might have
been implemented. The washoff load computed at each time step is simply reduced by this
amount.
As with the Buildup page, each pollutant must be selected in turn from the Pollutant dropdown list
and have its pertinent washoff properties defined.
C.12 Land Use Assignment Editor
Sub catchment 2
Property
Infiltration
Ground water
Snow Pack
LJD Controls
ILand Uses
Initial Buildup
Curb Length
1
d
Value |
MORTON
NO
0
i2 ... 1
? \
NONE
0
Assignment of land uses to
subcatchment (click to edit)
Land Use Assignment
Land Use % of Area
Residential 150.00 j
Undeveloped 50.00
OK Cancel Help
The Land Use Assignment editor is invoked from the Property Editor when editing the Land Uses
property of a subcatchment. Its purpose is to assign land uses to the subcatchment for water
quality simulations. The percent of land area in the subcatchment covered by each land use is
entered next to its respective land use category. If the land use is not present its field can be left
blank. The percentages entered do not necessarily have to add up to 100.
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C.13 LID Control Editor
LID Control Editor
Control Name: planters
LID Type;
Bio-Retention Cell
Drain*
Surface Soil
Storage Drain
Thickness
(in, or mm)
Porosity
(volume fraction)
Field Capacity
(volume fraction)
Wilting Point
(volume fraction)
Conductivity
(in/hr or mm/hr)
Conductivity
Slope
Suction Head
(in, or mm)
12
05
10.0
35
The LID Control Editor is used to define a low impact development control that can be deployed
throughout a study area to store, infiltrate, and evaporate subcatchment runoff. The design of the
control is made on a per-unit-area basis so that it can be placed in any number of subcatchments
at different sizes or number of replicates. The editor contains the following data entry fields:
Control Name
A name used to identify the particular LID control.
LID Type
The generic type of LID being defined (bio-retention cell, rain garden, green roof, infiltration
trench, permeable pavement, rain barrel, or vegetative swale).
Process Layers
These are a tabbed set of pages containing data entry fields for the vertical layers and drain
system that comprise an LID control. They include some combination of the following, depending
on the type of LID selected: Surface Layer, Pavement Layer, Soil Layer, Storage Layer, and
Drain System or Drainage Mat.
Surface Layer Properties
The Surface Layer page of the LID Control Editor is used to describe the surface properties of all
types of LID controls except rain barrels. Surface layer properties include:
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Berm Height (or Storage Depth)
When confining walls or berms are present this is the maximum depth to which water can pond
above the surface of the unit before overflow occurs (in inches or mm). For Rooftop
Disconnection it is the roofs depression storage depth, and for Vegetative Swales it is the height
of the trapezoidal cross section.
Vegetative Volume Fraction
The fraction of the volume within the storage depth filled with vegetation. This is the volume
occupied by stems and leaves, not their surface area coverage. Normally this volume can be
ignored, but may be as high as 0.1 to 0.2 for very dense vegetative growth.
Surface Roughness
Manning's n for overland flow over surface soil cover, pavement, roof surface or vegetative swale.
Use 0 for other types of LIDs.
Surface Slope
Slope of a roof surface, pavement surface or vegetative swale (percent). Use 0 for other types of
LIDs.
Swale Side Slope
Slope (run over rise) of the side walls of a vegetative swale's cross section. This value is ignored
for other types of LIDs.
If either Surface Roughness or Surface Slope values are 0 then any ponded water that
exceeds the surface storage depth is assumed to completely overflow the LID control
within a single time step.
Pavement Layer Properties
The Pavement Layer page of the LID Control Editor supplies values for the following properties
of a permeable pavement LID:
Thickness
The thickness of the pavement layer (inches or mm). Typical values are 4 to 6 inches (100 to 150
mm).
Void Ratio
The volume of void space relative to the volume of solids in the pavement for continuous systems
or for the fill material used in modular systems. Typical values for pavements are 0.12 to 0.21.
Note that porosity = void ratio / (1 + void ratio).
Impervious Surface Fraction
Ratio of impervious paver material to total area for modular systems; 0 for continuous porous
pavement systems.
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Permeability
Permeability of the concrete or asphalt used in continuous systems or hydraulic conductivity of
the fill material (gravel or sand) used in modular systems (in/hr or mm/hr). The permeability of
new porous concrete or asphalt is very high (e.g., hundreds of in/hr) but can drop off over time
due to clogging by fine particulates in the runoff (see below).
Clogging Factor
Number of pavement layer void volumes of runoff treated it takes to completely clog the
pavement. Use a value of 0 to ignore clogging. Clogging progressively reduces the pavement's
permeability in direct proportion to the cumulative volume of runoff treated.
If one has an estimate of the number of years it takes to fully clog the system (Yclog), the
Clogging Factor can be computed as: Yclog * Pa * CR * (1 + VR) * (1 - ISF) / (T * VR) where Pa
is the annual rainfall amount over the site, CR is the pavement's capture ratio (area that
contributes runoff to the pavement divided by area of the pavement itself), VR is the system's
Void Ratio, ISF is the Impervious Surface Fraction, and T is the pavement layer Thickness.
As an example, suppose it takes 5 years to clog a continuous porous pavement system that
serves an area where the annual rainfall is 36 inches/year. If the pavement is 6 inches thick, has
a void ratio of 0.2 and captures runoff only from its own surface, then the Clogging Factor is 5 x
36x(1 +0.2)76/0.2 = 180.
Soil Layer properties
The Soil Layer page of the LID Control Editor describes the properties of the engineered soil
mixture used in bio-retention types of LIDs and the optional sand layer beneath permeable
pavement. These properties are:
Thickness
The thickness of the soil layer (inches or mm). Typical values range from 18 to 36 inches (450 to
900 mm) for rain gardens, street planters and other types of land-based bio-retention units, but
only 3 to 6 inches (75 to 150 mm) for green roofs.
Porosity
The volume of pore space relative to total volume of soil (as a fraction).
Field Capacity
Volume of pore water relative to total volume after the soil has been allowed to drain fully (as a
fraction). Below this level, vertical drainage of water through the soil layer does not occur.
Wilting Point
Volume of pore water relative to total volume for a well dried soil where only bound water remains
(as a fraction). The moisture content of the soil cannot fall below this limit.
Conductivity
Hydraulic conductivity for the fully saturated soil (in/hr or mm/hr).
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Conductivity Slope
Slope of the curve of log(conductivity) versus soil moisture content (dimensionless). Typical
values range from 30 to 60. It can be estimated from a standard soil grain size analysis as
0.48(%Sand) + 0.85(%Clay).
Suction Head
The average value of soil capillary suction along the wetting front (inches or mm). This is the
same parameter as used in the Green-Ampt infiltration model.
r,
Porosity, field capacity, conductivity and conductivity slope are the same soil properties
used for Aquifer objects when modeling groundwater, while suction head is the same
parameter used for Green-Ampt infiltration. Except here they apply to the special soil
mixture used in a LID unit rather than the site's naturally occurring soil. See Appendix A.2
Soil Characteristics for typical values of these properties.
Storage Layer Properties
The Storage Layer page of the LID Control Editor describes the properties of the crushed stone
or gravel layer used in bio-retention cells, permeable pavement systems, and infiltration trenches
as a bottom storage/drainage layer. It is also used to specify the height of a rain barrel (or
cistern). The following data fields are displayed:
Thickness (or Barrel Height)
This is the thickness of a gravel layer or the height of a rain barrel (inches or mm). Crushed stone
and gravel layers are typically 6 to 18 inches (150 to 450 mm) thick while single family home rain
barrels range in height from 24 to 36 inches (600 to 900 mm).
The following data fields do not apply to Rain Barrels.
Void Ratio
The volume of void space relative to the volume of solids in the layer. Typical values range from
0.5 to 0.75 for gravel beds. Note that porosity = void ratio / (1 + void ratio).
Seepage Rate
The rate at which water seeps into the native soil below the layer (in inches/hour or
mm/hour).This would typically be the Saturated Hydraulic Conductivity of the surrounding
subcatchment if Green-Ampt infiltration is used or the Minimum Infiltration Rate for Morton
infiltration. If there is an impermeable floor or liner below the layer then use a value of 0.
Clogging Factor
Total volume of treated runoff it takes to completely clog the bottom of the layer divided by the
void volume of the layer. Use a value of 0 to ignore clogging. Clogging progressively reduces the
Infiltration Rate in direct proportion to the cumulative volume of runoff treated and may only be of
concern for infiltration trenches with permeable bottoms and no under drains.
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Storage Drain Properties
LID storage layers can contain an optional drainage system that collects water entering the layer
and conveys it to a conventional storm drain or other location (which can be different than the
outlet of the LID's subcatchment). Drain flow can also be returned it to the pervious area of the
LID's subcatchment. The drain can be offset some distance above the bottom of the storage
layer, to allow some volume of runoff to be stored (and eventually infiltrated) before any excess is
captured by the drain. For Rooftop Disconnection, the drain system consists of the roofs gutters
and downspouts that have some maximum conveyance capacity.
The Drain page of the LID Control Editor describes the properties of this system. It contains the
following data entry fields:
Drain Coefficient and Drain Exponent
The drain coefficient C and exponent n determines the rate of flow through a drain as a function
of the height of stored water above the drain's offset. The following equation is used to compute
this flow rate (per unit area of the LID unit):
q = Chn
where q is outflow (in/hr or mm/hr) and h is the height of saturated media above the drain (inches
or mm). A typical value for n would be 0.5 (making the drain act like an orifice). Note that the units
of C depend on the unit system being used as well as the value assigned to n. If the layer has
no drain then set Cto 0
Drain Offset Height
This is the height of the drain line above the bottom of a storage layer or rain barrel (inches or
mm).
Drain Delay (for Rain Barrels only)
The number of dry weather hours that must elapse before the drain line in a rain barrel is opened
(the line is assumed to be closed once rainfall begins). A value of 0 signifies that the barrel's drain
line is always open and drains continuously. This parameter is ignored for other types of LIDs.
Flow Capacity (for Rooftop Disconnection only)
This is the maximum flow rate that the roofs gutters and downspouts can handle (in inches/hour
or mm/hour) before overflowing. This is the only drain parameter used for Rooftop Disconnection.
There are several things to keep in mind when specifying the parameters of an LID's underdrain:
• If the storage layer that contains the drain has an impermeable bottom then it's best to
place the drain at the bottom with a zero offset. Otherwise, to allow the full storage
volume to fill before draining occurs, one would place the drain at the top of the storage
layer.
• If the storage layer has no drain then set the drain coefficient to 0.
• If the drain can carry whatever flow enters the storage layer up to some specific limit then
set the drain coefficient to the limit and the drain exponent to 0.
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• If the underdrain consists of slotted pipes where the slots act as orifices, then the drain
exponent would be 0.5 and the drain coefficient would be 60,000 times the ratio of total
slot area to LID area. For example, drain pipe with five 1/4" diameter holes per foot
spaced 50 feet apart would have an area ratio of 0.000035 and a drain coefficient of 2.
• If the goal is to drain a fully saturated unit in a specific amount of time then set the drain
exponent to 0.5 (to represent orifice flow) and the drain coefficient to 2D1/2/T where D is
the distance from the drain to the surface plus any berm height (in inches or mm) and T is
the time in hours to drain. For example, to drain a depth of 36 inches in 12 hours requires
a drain coefficient of 1. If this drain consisted of the slotted pipes described in the
previous bullet, whose coefficient was 2, then a flow regulator, such as a cap orifice,
would have to be placed on the drain outlet to achieve the reduced flow rate.
Drainage Mat Properties
Green Roofs usually contain a drainage mat or plate that lies below the soil media and above the
roof structure. Its purpose is to convey any water that drains through the soil layer off of the roof.
The Drainage Mat page of the LID Control Editor for Green Roofs lists the properties of this layer
which include:
Thickness
The thickness of the mat or plate (inches or mm). It typically ranges between 1 to 2 inches.
Void Fraction
The ratio of void volume to total volume in the mat. It typically ranges from 0.5 to 0.6.
Roughness
This is the Manning's n constant used to compute the horizontal flow rate of drained water
through the mat. It is not a standard product specification provided by manufacturers and
therefore must be estimated. Previous modeling studies have suggested using a relatively high
value such as from 0.1 to 0.4.
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C.14 LID Group Editor
LID Controls for Subcatchment SI
Control Name LID Type % of Area %FromImperv Report File
InfilTrench Infil. Trench 1.074 40
RainBarrels Rain Barrel
0.081
17
OK
The LID Group Editor is invoked when the LID Controls property of a Subcatchment is selected
for editing. It is used to identify a group of previously defined LID controls that will be placed
within the Subcatchment, the sizing of each control, and what percent of runoff from the non-LID
portion of the Subcatchment each should treat.
The editor displays the current group of LIDs placed in the Subcatchment along with buttons for
adding an LID unit, editing a selected unit, and deleting a selected unit. These actions can also
be chosen by hitting the Insert key, the Enter key, and the Delete key, respectively. Selecting
Add or Edit will bring up an LID Usage Editor where one can enter values for the data fields
shown in the Group Editor.
Note that the total % of Area for all of the LID units within a Subcatchment must not exceed
100%. The same applies to % From Impervious. Refer to the LID Usage Editor for the meaning
of these parameters.
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C.15 LID Usage Editor
LID Usage Editor
LID Control Name RainBarrels
Detailed Report File (Optional)
D LID Occupies Full Subcatchment
Area of Each Unit (sq ft or sq m)
Number of Units
% of Subcatchment Occupied
Surface Width per Unit (ft or m)
% Initially Saturated
% of Impervious Area Treated
32
0.081
"H
17
Send Drain Flow To:
(Leave blank to use outlet of current Subcatchment)
J Return all Outflow to Pervious Area
OK
Help
The LID Usage Editor is invoked from a subcatchment's LID Group Editor to specify how a
particular LID control will be deployed within the Subcatchment. It contains the following data
entry fields:
Control Name
The name of a previously defined LID control to be used in the Subcatchment. (LID controls are
added to a project by using the Project Browser.)
LID Occupies Full Subcatchment
Select this checkbox option if the LID control occupies the full Subcatchment (i.e., the LID is
placed in its own separate Subcatchment and accepts runoff from upstream subcatchments).
Area of Each Unit
The surface area devoted to each replicate LID unit (sq. ft or sq. m). If the LID Occupies Full
Subcatchment box is checked, then this field becomes disabled and will display the total
Subcatchment area divided by the number of replicate units. (See Section 3.3.14 LID Controls for
options on placing LIDs within subcatchments.) The label below this field indicates how much of
the total Subcatchment area is devoted to the particular LID being deployed and gets updated as
changes are made to the number of units and area of each unit.
Number of Replicate Units
The number of equal size units of the LID practice (e.g., the number of rain barrels) deployed
within the Subcatchment.
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Surface Width Per Unit
The width of the outflow face of each identical LID unit (in ft or m). This parameter applies to
roofs, pavement, trenches, and swales that use overland flow to convey surface runoff off of the
unit. It can be set to 0 for other LID processes, such as bio-retention cells, rain gardens, and rain
barrels that simply spill any excess captured runoff over their berms.
% Initially Saturated
For bio-retention cells, rain gardens, and green roofs this is the degree to which the unit's soil is
initially filled with water (0 % saturation corresponds to the wilting point moisture content, 100 %
saturation has the moisture content equal to the porosity). The storage zone beneath the soil
zone of the cell is assumed to be completely dry. For other types of LIDs it corresponds to the
degree to which their storage zone is initially filled with water.
% of Impervious Area Treated
The percent of the impervious portion of the subcatchment's non-LID area whose runoff is treated
by the LID practice. (E.g., if rain barrels are used to capture roof runoff and roofs represent 60%
of the impervious area, then the impervious area treated is 60%). If the LID unit treats only direct
rainfall, such as with a green roof or roof disconnection, then this value should be 0. If the LID
takes up the entire subcatchment then this field is ignored.
Send Drain Flow To
Provide the name of the Node or Subcatchment that receives any drain flow produced by the LID
unit. This field can be left blank if this flow goes to the same outlet as the LID unit's
subcatchment.
Return All Outflow to Pervious Area
Select this option if outflow from the LID unit should be routed back onto the pervious area of the
subcatchment that contains it. If drain outflow was selected to be routed to a different location
than the subcatchment outlet then only surface outflow will be returned. Otherwise both surface
and drain flow will be returned. Selecting this option would be a common choice to make for Rain
Barrels, Rooftop Disconnection and possibly Green Roofs.
Detailed Report File
The name of an optional file where detailed time series results for the LID will be written. Click the
browse button 4l to select a file using the standard Windows File Save dialog or click the delete
button X to remove any detailed reporting. The detailed report file will be a tab delimited text file
that can be easily opened and viewed with any text editor or spreadsheet program (such as
Microsoft Excel) outside of SWMM.
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C.16 Pollutant Editor
Pollutant Editor |-£3-
Property Value
Name
Units
Rain Concen.
GW Concen.
I&I Concen.
DWF Concen.
Init. Concen.
Decay Coeff.
Snow Only
Co-Pollutant
Co-Fraction
Lead
UG/L
0.0
0.0
0
0
0
0.0
NO
TSS
02
User-assigned name of the pollutant.
| OK i Cancel Help
The Pollutant Editor is invoked when a new pollutant object is created or an existing pollutant is
selected for editing. It contains the following fields:
Name
The name assigned to the pollutant.
Units
The concentration units (mg/L, ug/L, or #/L (counts/L)) in which the pollutant concentration is
expressed.
Rain Concentration
Concentration of the pollutant in rain water (concentration units).
GW Concentration
Concentration of the pollutant in ground water (concentration units).
Initial Concentration
Concentration of the pollutant throughout the conveyance system at the start of the simulation.
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l&l Concentration
Concentration of the pollutant in any Infiltration/Inflow (concentration units).
DWF Concentration
Concentration of the pollutant in any dry weather sanitary flow (concentration units). This value
can be overridden for any specific node of the conveyance system by editing the node's Inflows
property.
Decay Coefficient
First-order decay coefficient of the pollutant (1/days).
Snow Only
YES if pollutant buildup occurs only when there is snow cover, NO otherwise (default is NO).
Co-Pollutant
Name of another pollutant whose runoff concentration contributes to the runoff concentration of
the current pollutant.
Co-Fraction
Fraction of the co-pollutant's runoff concentration that contributes to the runoff concentration of
the current pollutant.
An example of a co-pollutant relationship would be where the runoff concentration of a particular
heavy metal is some fixed fraction of the runoff concentration of suspended solids. In this case
suspended solids would be declared as the co-pollutant for the heavy metal.
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C.17 Snow Pack Editor
The Snow Pack Editor is invoked when a new snow pack object is created or an existing snow
pack is selected for editing. The editor contains a data entry field for the snow pack's name and
two tabbed pages, one for snow pack parameters and one for snow removal parameters.
Snow Pack Editor
Snow Pack Name
SP1
Snow Pack Parameters Snow Removal Parameters
Subcatchment Surface Type
Min. Melt Coeff. (in/hr/deg F)
Max. Melt Coeff. (in/hr/deg F)
Base Temperature (deg F)
Fraction Free Water Capacity
Initial Snow Depth (in)
Initial Free Water (in)
Depth at 100% Cover (in)
Plowable
0.001
0.001
32.0
010
0.00
0,00
Impervious
0.001
0.001
32JO
010
0.00
0.00
0.00
Pervious
0.001
0.001
32.0
0.10
0.00
0.00
0.00
Fraction of Impervious Area That is Plowable:
0.0
Snow Pack Parameters Page
The Parameters page of the Snow Pack Editor dialog provides snow melt parameters and initial
conditions for snow that accumulates over three different types of areas: the impervious area that
is plowable (i.e., subject to snow removal), the remaining impervious area, and the entire
pervious area. The page contains a data entry grid which has a column for each type of area and
a row for each of the following parameters:
Minimum Melt Coefficient
The degree-day snow melt coefficient that occurs on December 21. Units are either in/hr-deg F or
mm/hr-deg C.
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Maximum Melt Coefficient
The degree-day snow melt coefficient that occurs on June 21. Units are either in/hr-deg F or
mm/hr-deg C. For a short term simulation of less than a week or so it is acceptable to use a
single value for both the minimum and maximum melt coefficients.
The minimum and maximum snow melt coefficients are used to estimate a melt coefficient that
varies by day of the year. The latter is used in the following degree-day equation to compute the
melt rate for any particular day:
Melt Rate = (Melt Coefficient) * (Air Temperature - Base Temperature).
Base Temperature
Temperature at which snow begins to melt (degrees F or C).
Fraction Free Water Capacity
The volume of a snow pack's pore space which must fill with melted snow before liquid runoff
from the pack begins, expressed as a fraction of snow pack depth.
Initial Snow Depth
Depth of snow at the start of the simulation (water equivalent depth in inches or millimeters).
Initial Free Water
Depth of melted water held within the pack at the start of the simulation (inches or mm). This
number should be at or below the product of the initial snow depth and the fraction free water
capacity.
Depth at 100% Cover
The depth of snow beyond which the entire area remains completely covered and is not subject
to any areal depletion effect (inches or mm).
Fraction of Impervious Area That is Plowable
The fraction of impervious area that is plowable and therefore is not subject to areal depletion.
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Snow Removal Parameters Page
Snow Pack Editor
Snow Pack Name
SP1
Snow Pack Parameters Snow Removal Parameters
Depth at which snow removal begins (in)
Fraction transferred out of the watershed
Fraction transferred to the impervious area
Fraction transferred to the pervious area
Fraction converted into immediate melt
Fraction moved to another subcatchment
1.0
0,0
0,0
0,0
0,0
0,0
(Subcatchment name)
Note: sum of all fractions must be <= 1.0.
The Snow Removal page of the Snow Pack Editor describes how snow removal occurs within the
Plowable area of a snow pack. The following parameters govern this process:
Depth at which snow removal begins (in or mm)
Depth which must be reached before any snow removal begins.
Fraction transferred out of the watershed
The fraction of snow depth that is removed from the system (and does not become runoff).
Fraction transferred to the impervious area
The fraction of snow depth that is added to snow accumulation on the pack's impervious area.
Fraction transferred to the pervious area
The fraction of snow depth that is added to snow accumulation on the pack's pervious area.
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Fraction converted to immediate melt
The fraction of snow depth that becomes liquid water which runs onto any subcatchment
associated with the snow pack.
Fraction moved to another subcatchment
The fraction of snow depth which is added to the snow accumulation on some other
subcatchment. The name of the subcatchment must also be provided.
The various removal fractions must add up to 1.0 or less. If less than 1.0, then some remaining
fraction of snow depth will be left on the surface after all of the redistribution options are satisfied.
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C.18 Time Pattern Editor
Time Pattern Editor
Name
Type
DWF
HOURLY
Description
Global hourly DWF pattern
Multipliers
12AM
1AM
2AM
BAM
4AM
5AM
6AM
7AM
.0151 N
.01373
.01812
.01098
.01098
.01922
.02773
.03789
The Time Pattern Editor is invoked when a new time pattern object is created or an existing time
pattern is selected for editing. The editor contains that following data entry fields:
Name
Enter the name assigned to the time pattern.
Type
Select the type of time pattern being specified. The choices are Monthly, Daily, Hourly and
Weekend Hourly.
Description
You can provide an optional comment or description for the time pattern. If more than one line is
needed, click the & button to launch a multi-line comment editor.
Multipliers
Enter a value for each multiplier. The number and meaning of the multipliers changes with the
type of time pattern selected:
• MONTHLY One multiplier for each month of the year.
• DAILY One multiplier for each day of the week.
• HOURLY One multiplier for each hour from 12 midnight to 11 PM.
• WEEKEND Same as for HOURLY except applied to weekend days.
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In order to maintain an average dry weather flow or pollutant concentration at its specified
value (as entered on the Inflows Editor), the multipliers for a pattern should average to
1.0.
C.19 Time Series Editor
Time Series Editor
Time Series Name
82309
Description
Direct inflow at Node 82309
Use external data file named below
J Enter time series data in the table below
No dates means times are relative to start of simulation.
Date
(M/D/V)
Time
(H:M)
0
0.25
3JO
325
12JO
Value
0
40
40
0
0
>
T
The Time Series Editor is invoked whenever a new time series object is created or an existing
time series is selected for editing. To use the Time Series Editor:
l. Enter values for the following standard items:
Name Name of the time series.
Description Optional comment or description of what the time series represents.
Click the & button to launch a multi-line comment editor if more than
one line is needed.
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2. Select whether to use an external file as the source of the data or to enter the data
directly into the form's data entry grid.
Cjk
3. If the external file option is selected, click the « button to locate the file's name. The
file's contents must be formatted in the same manner as the direct data entry option
discussed below. See the description of Time Series Files in Section 11.6 Time Series
Files for details.
4. For direct data entry, enter values in the data entry grid as follows:
Date Column Optional date (in month/day/year format) of the time series values (only
needed at points in time where a new date occurs).
Time Column If dates are used, enter the military time of day for each time series value
(as hours:minutes or decimal hours). If dates are not used, enter time as
hours since the start of the simulation.
Value Column The time series' numerical values.
A graphical plot of the data in the grid can be viewed in a separate window by clicking the
View button. Right clicking over the grid will make a popup Edit menu appear. It contains
commands to cut, copy, insert, and paste selected cells in the grid as well as options to
insert or delete a row.
5. Press OK to accept the time series or Cancel to cancel your edits.
Note that there are two methods for describing the occurrence time of time series data:
as calendar date/time of day (which requires that at least one date, at the start of the
series, be entered in the Date column)
as elapsed hours since the start of the simulation (where the Date column remains
empty).
For rainfall time series, it is only necessary to enter periods with non-zero rainfall
amounts. SWMM interprets the rainfall value as a constant value lasting over the
recording interval specified for the rain gage which utilizes the time series. For all other
types of time series, SWMM uses interpolation to estimate values at times that fall in
between the recorded values.
262
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C.20 Title/Notes Editor
gjj Title/Notes Editor
Example 3
Use of Rule-Based Pump Controls
and Dry Weather Flow Patterns
Use title line as header for printing
! OK
Cancel
The Title/Notes editor is invoked when a project's Title/Notes data category is selected for editing.
As shown below, the editor contains a multi-line edit field where a description of a project can be
entered. It also contains a check box used to indicate whether or not the first line of notes should
be used as a header for printing.
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C.21 Transect Editor
Transect Editor
Transect Name
92
Description
1
2
3
4
5
6
7
8
9
10
11
12
13
Station
[ft)
o
55
60
95
115
160
Elevation
(ft)
5
45
0
2
4
6
A
T-
Modifiers:
Stations
Elevations
Meander
The Transect Editor is invoked when a new transect object is created or an existing transect is
selected for editing. It contains the following data entry fields:
Name
The name assigned to the transect.
Description
An optional comment or description of the transect.
Station/Elevation Data Grid
Values of distance from the left side of the channel along with the corresponding elevation of the
channel bottom as one moves across the channel from left to right, looking in the downstream
direction. Up to 1500 data values can be entered.
Roughness
Values of Manning's roughness for the left overbank, right overbank, and main channel portion of
the transect. The overbank roughness values can be zero if no overbank exists.
264
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Bank Stations
The distance values appearing in the Station/Elevation grid that mark the end of the left overbank
and the start of the right overbank. Use 0 to denote the absence of an overbank.
Modifiers
• The Stations modifier is a factor by which the distance between each station will be multiplied
when the transect data is processed by SWMM. Use a value of 0 if no such factor is needed.
• The Elevations modifier is a constant value that will be added to each elevation value.
• The Meander modifier is the ratio of the length of a meandering main channel to the length of
the overbank area that surrounds it. This modifier is applied to all conduits that use this
particular transect for their cross section. It assumes that the length supplied for these
conduits is that of the longer main channel. SWMM will use the shorter overbank length in its
calculations while increasing the main channel roughness to account for its longer length.
The modifier is ignored if it is left blank or set to 0.
Right-clicking over the Data Grid will make a popup Edit menu appear. It contains commands to
cut, copy, insert, and paste selected cells in the grid as well as options to insert or delete a row.
Clicking the View button will bring up a window that illustrates the shape of the transect cross
section.
265
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C.22 Treatment Editor
Treatment Editor for Node 10
Pollutant
TSS
Lead
Treatment Expression
C = 0.523*TSSA0.5*FlowA1.2
Treatment expressions have the general form: *
R = f (P, R_P, V)
or
C = f {P, R_P, V)
where:
R = fractional
remcval,
-
C = outlet concentration,
F = one or more pollutant names,
R P = one or more pollutant removals
{prepend R_ to pollutant name), •*•
OK
The Treatment Editor is invoked whenever the Treatment property of a node is selected from the
Property Editor. It displays a list of the project's pollutants with an edit box next to each as shown
below. Enter a valid treatment expression in the box next to each pollutant which receives
treatment.
A treatment function can be any well-formed mathematical expression involving:
• the pollutant concentration (use the pollutant name to represent its concentration) - for
non-storage nodes this is the mixture concentration of all flow streams entering the node
while for storage nodes it is the pollutant concentration within the node's stored volume
• the removals of other pollutants (use R_ prefixed to the pollutant name to represent
removal)
• any of the following process variables:
- FLOW for flow rate into node (in user-defined flow units)
- DEPTH for water depth above node invert (ft or m)
- AREA for node surface area (ft2 or m2)
- DT for routing time step (sec)
- HRT for hydraulic residence time (hours)
Any of the following math functions (which are case insensitive) can be used in a treatment
expression:
266
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abs(x) for absolute value of x
sgn(x) which is +1 for x >= 0 or -1 otherwise
step(x) which is 0 forx <= 0 and 1 otherwise
sqrt(x) for the square root of x
log(x) for logarithm base e of x
Iog10(x) for logarithm base 10 of x
exp(x) for e raised to the x power
the standard trig functions (sin, cos, tan, and cot)
the inverse trig functions (asin, acos, atan, and acot)
the hyperbolic trig functions (sinh, cosh, tanh, and coth)
along with the standard operators +, -, *, /, A (for exponentiation ) and any level of nested
parentheses.
267
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C.23 Unit Hydrograph Editor
Un
it Hydrograph Editor
Mame of UH Group
^ain Gage Used
Hydrographs For:
Unit
Hydrographs I
Response
Short-Term
Medium -Term
Long -Term
R =
T =
K =
Vlont
UH1
Gagel
All Months
nitial Abstraction Depth
R
0.20
0.10
0.06
T
2
e
12
1^1
T
T
K
2
2
2 !
fraction of rainfall that becomes I&I
time to hydrograph peak (hours)
falling limb duration / rising limb duration
is with UH data have a (*] next to
OK
Cancel
them.
Help
The Unit Hydrograph Editor is invoked whenever a new unit hydrograph object is created or an
existing one is selected for editing. It is used to specify the shape parameters and rain gage for a
group of triangular unit hydrographs. These hydrographs are used to compute rainfall-dependent
infiltration/inflow (RDM) flow at selected nodes of the drainage system. A UH group can contain up
to 12 sets of unit hydrographs (one for each month of the year), and each set can consist of up to
3 individual hydrographs (for short-term, intermediate-term, and long-term responses,
respectively) as well as parameters that describe any initial abstraction losses. The editor
contains the following data entry fields:
Name of UH Group
Enter the name assigned to the UH Group.
Rain Gage Used
Type in (or select from the dropdown list) the name of the rain gage that supplies rainfall data to
the unit hydrographs in the group.
268
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Hydrographs For:
Select a month from the dropdown list box for which hydrograph parameters will be defined.
Select All Months to specify a default set of hydrographs that apply to all months of the year.
Then select specific months that need to have special hydrographs defined. Months listed with a
(*) next to them have had hydrographs assigned to them.
Unit Hydrographs
Select this tab to provide the R-T-K shape parameters for each set of unit hydrographs in
selected months of the year. The first row is used to specify parameters for a short-term response
hydrograph (i.e., small value of T), the second for a medium-term response hydrograph, and the
third for a long-term response hydrograph (largest value of T). It is not required that all three
hydrographs be defined and the sum of the three R-values do not have to equal 1. The shape
parameters for each UH consist of:
• R: the fraction of rainfall volume that enters the sewer system
• 7: the time from the onset of rainfall to the peak of the UH in hours
• K: the ratio of time to recession of the UH to the time to peak
Initial Abstraction Depth
Select this tab to provide parameters that describe how rainfall will be reduced by any initial
abstraction depth available (i.e., interception and depression storage) before it is processed
through the unit hydrographs defined for a specific month of the year. Different initial abstraction
parameters can be assigned to each of the three unit hydrograph responses. These parameters
are:
• D/nax: the maximum depth of initial abstraction available (in rain depth units)
• Dree: the rate at which any utilized initial abstraction is made available again (in rain
depth units per day)
• Do: the amount of initial abstraction that has already been utilized at the start of the
simulation (in rain depth units).
If a grid cell is left empty its corresponding parameter value is assumed to be 0. Right-clicking
over a data entry grid will make a popup Edit menu appear. It contains commands to cut, copy,
and paste text to or from selected cells in the grid.
269
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APPENDIX D - COMMAND LINE SWMM
D.1
General Instructions
EPA SWMM can also be run as a console application from the command line within a DOS
window. In this case the study area data are placed into a text file and results are written to a text
file. The command line for running SWMM in this fashion is:
swmmS inpfile rptfile outfile
where inpfile is the name of the input file, rptfile is the name of the output report file, and
outfile is the name of an optional binary output file. The latter stores all time series results in a
special binary format that will require a separate post-processor program for viewing. If no binary
output file name is supplied then all time series results will appear in the report file. As written, the
above command assumes that you are working in the directory in which EPA SWMM was
installed or that this directory has been added to the PATH variable in your user profile (or the
autoexec.bat file in older versions of Windows). Otherwise full pathnames for the executable
swmm5.exe and the files on the command line must be used.
D.2 Input File Format
The input file for command line SWMM has the same format as the project file used by the
Windows version of the program. Figure D-1 illustrates an example SWMM 5 input file. It is
organized in sections, where each section begins with a keyword enclosed in brackets. The
various keywords are listed below.
[TITLE]
[OPTIONS]
[REPORT]
[FILES]
[RAINGAGES]
[EVAPORATION]
[TEMPERATURE]
[ADJUSTMENTS]
[SUBCATCHMENTS]
[SUBAREAS]
[INFILTRATION]
[LID_CONTROLS]
[LID USAGE]
project title
analysis options
output reporting instructions
interface file options
rain gage information
evaporation data
air temperature and snow melt data
monthly adjustments applied to climate variables
basic subcatchment information
subcatchment impervious/pervious sub-area data
subcatchment infiltration parameters
low impact development control information
assignment of LID controls to subcatchments
270
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[AQUIFERS]
[GROUNDWATER]
[GWF]
[SNOWPACKS]
[JUNCTIONS]
[OUTFALLS]
[DIVIDERS]
[STORAGE]
[CONDUITS]
[PUMPS]
[ORIFICES]
[WEIRS]
[OUTLETS]
[XSECTIONS]
[TRANSECTS]
[LOSSES]
[CONTROLS]
[POLLUTANTS]
[LANDUSES]
[COVERAGES]
[LOADINGS]
[BUILDUP]
[WASHOFF]
[TREATMENT]
[INFLOWS]
[DWF]
[RDII]
[HYDROGRAPHS]
[CURVES]
[TIMESERIES]
[PATTERNS]
groundwater aquifer parameters
subcatchment groundwater parameters
groundwater flow expressions
subcatchment snow pack parameters
junction node information
outfall node information
flow divider node information
storage node information
conduit link information
pump link information
orifice link information
weir link information
outlet link information
conduit, orifice, and weir cross-section geometry
transect geometry for conduits with irregular cross-sections
conduit entrance/exit losses and flap valves
rules that control pump and regulator operation
pollutant information
land use categories
assignment of land uses to subcatchments
initial pollutant loads on subcatchments
buildup functions for pollutants and land uses
washoff functions for pollutants and land uses
pollutant removal functions at conveyance system nodes
external hydrograph/pollutograph inflow at nodes
baseline dry weather sanitary inflow at nodes
rainfall-dependent I/I information at nodes
unit hydrograph data used to construct RDII inflows
x-y tabular data referenced in other sections
time series data referenced in other sections
periodic multipliers referenced in other sections
271
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[TITLE]
Example SWMM Project
[OPTIONS]
FLOWJJNITS
INFILTRATION
FLOW_ROUTING
START_DATE
START_TIME
END_TIME
WET_STEP
DRY_STEP
ROUTING STEP
CFS
GREEN_AMPT
KINWAVE
8/6/2002
10:00
18:00
00:15:00
01:00:00
00:05:00
[RAINGAGES]
;;Name Format Interval SCF DataSource SourceName
r r
GAGE1 INTENSITY 0:15 1.0 TIMESERIES SERIES1
[EVAPORATION]
CONSTANT 0.02
[SUBCATCHMENTS]
;;Name Raingage Outlet Area %Imperv Width Slope
r r
AREA1 GAGE1 NODE1 2 80.0 800.0 1.0
AREA2 GAGE1 NODE2 2 75.0 50.0 1.0
[SUBAREAS]
;;Subcatch N_Imp N_Perv S_Imp S_Perv %ZER RouteTo
r r
AREA1 0.2 0.02 0.02 0.1 20.0 OUTLET
AREA2 0.2 0.02 0.02 0.1 20.0 OUTLET
[INFILTRATION]
;;Subcatch Suction Conduct InitDef
r r
AREA1 4.0 1.0 0.34
AREA2 4.0 1.0 0.34
[JUNCTIONS]
;;Name Elev
r r
NODE1 10.0
NODE2 10.0
NODES 5.0
NODE4 5.0
NODE6 1.0
NODE? 2 . 0
Figure D-1 Example SWMM project file
272
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[DIVIDERS]
;;Name Elev Link Type
r r
Parameters
NODES 3.0 C6 CUTOFF 1.0
[CONDUITS]
;;Name Nodel Node2
r r
Cl NODE1 NODES
C2 NODE2 NODE4
C3 NODES NODES
C4 NODE4 NODES
C5 NODES NODE6
C6 NODES NODE?
[XSECTIONS]
; ;Link Type Gl
f f
Cl RECT OPEN 0.
C2 RECT OPEN 0.
C3 CIRCULAR 1.
C4 RECT OPEN 1.
C5 PARABOLIC 1.
C6 PARABOLIC 1.
[POLLUTANTS]
;;Name Units Cppt Cgw
r r
TSS MG/L 0 0
Lead UG/L 0 0
[LANDUSES]
RESIDENTIAL
UNDEVELOPED
[WASHOFF]
;;Landuse Pollutant
r r
RESIDENTIAL TSS
UNDEVELOPED TSS
[COVERAGES]
; ; Subcatch Landuse
r r
AREA1 RESIDENTIAL
AREA2 RESIDENTIAL
[TIMESERIES]
; Rainfall time series
SERIES1 0:0 0.1 0:
SERIES1 0:45 0.1 1:
Length N Zl Z2 QO
800 0.01 000
800 0.01 000
400 0.01 000
400 0.01 000
600 0.01 000
400 0.01 000
G2 G3 G4
510 0
510 0
000 0
0 1.0 0 0
5 2.0 0 0
5 2.0 0 0
Cii Kd Snow CoPollut CoFract
0 0
0 0 NO TSS 0.20
Type Coeff Expon SweepEff
EMC 23.4 0 0
EMC 12.1 0 0
Pent Landuse Pent
80 UNDEVELOPED 20
55 UNDEVELOPED 45
15 1.0 0:30 0.5
00 0.0 2:00 0.0
BMPEff
0
0
Figure D-1 Example SWMM project file (continued from previous page).
273
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The sections can appear in any arbitrary order in the input file, and not all sections must be
present. Each section can contain one or more lines of data. Blank lines may appear anywhere in
the file. A semicolon (;) can be used to indicate that what follows on the line is a comment, not
data. Data items can appear in any column of a line. Observe how in Figure D-1 these features
were used to create a tabular appearance for the data, complete with column headings.
Section keywords can appear in mixed lower and upper case, and only the first four characters
(plus the open bracket) are used to distinguish one keyword from another (e.g., [DIVIDERS] and
[Divi] are equivalent). An option is available in the [OPTIONS] section to choose flow units from
among cubic feet per second (CFS), gallons per minute (GPM), million gallons per day (MGD),
cubic meters per second (CMS), liters per second, (IPS), or million liters per day (MLD). If cubic
feet or gallons are chosen for flow units, then US units are used for all other quantities. If cubic
meters or liters are chosen, then metric units apply to all other quantities. The default flow units
are CFS.
A detailed description of the data in each section of the input file will now be given. Each section
description begins on a new page. When listing the format of a line of data, mandatory keywords
are shown in boldface while optional items appear in parentheses. A list of keywords separated
by a slash (YES/NO) means that only one of the words should appear in the data line.
274
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Section: [TITLE]
Purpose: Attaches a descriptive title to the problem being analyzed.
Format: Any number of lines may be entered. The first line will be used as a page header in
the output report.
275
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Section: [OPTIONS]
Purpose: Provides values for various analysis options.
Format: FLOW_UNITS
INFILTRATION
FLOW_ROUTING
LINKJDFFSETS
FORCE_MAIN_EQUATION
IGNORE_RAINFALL
IGNORE_SNOWMELT
IGNORE_GROUNDWATER
IGNORE_RDII
IGNORE_ROUTING
IGNORE_QUALITY
ALLOW_PONDING
SKIP_STEADY_STATE
SYS_FLOW_TOL
LAT_FLOW_TOL
START_DATE
START_TIME
END_DATE
END_TIME
REPORT_START_DATE
REPORT_START_TIME
SWEEP_START
SWEEP_END
DRY_DAYS
RE PORT_S TE P
WET_STEP
DRY_STEP
ROUTING_STEP
LENGTHENING_STEP
VARIABLE_STEP
MINIMUM_STEP
INERTIAL_DAMPING
NORMAL FLOW LIMITED
CFS / GPM / MGD / CMS / LPS / MLD
HORTON / MODIFIED_HORTON / GREEN_AMPT
/ MODIFIED_GREEN_AMPT / CURVE_NUMBER
STEADY / KINWAVE / DYNWAVE
DEPTH / ELEVATION
H-W / D-W
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
YES / NO
value
value
month/day/year
hours:minutes
month/day/year
hours:minutes
month/day/year
hours:minutes
month/day
month/day
days
hours:minutes:seconds
hours:minutes:seconds
hours:minutes:seconds
seconds
seconds
value
seconds
NONE / PARTIAL / FULL
SLOPE / FROUDE / BOTH
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MIN_SURFAREA value
MIN_SLOPE value
MAX_TRIALS value
HEAD_TOLERANCE value
THREADS value
TEMPDIR directory
Remarks: FLOW_UNITS makes a choice of flow units. Selecting a US flow unit means that all
other quantities will be expressed in US units, while choosing a metric flow unit will
force all quantities to be expressed in metric units. The default is CFS.
INFILTRATION selects a model for computing infiltration of rainfall into the upper
soil zone of subcatchments. The default model is HORTON.
FLOW_ROUTING determines which method is used to route flows through the
drainage system. STEADY refers to sequential steady state routing (i.e. hydrograph
translation), KINWAVE to kinematic wave routing, DYNWAVE to dynamic wave routing.
The default routing method is KINWAVE.
LINK_OFFSETS determines the convention used to specify the position of a link
offset above the invert of its connecting node. DEPTH indicates that offsets are
expressed as the distance between the node invert and the link while ELEVATION
indicates that the absolute elevation of the offset is used. The default is DEPTH.
FORCE_MAIN_EQUATION establishes whether the Hazen-Williams (H-W) or the
Darcy-Weisbach (D-W) equation will be used to compute friction losses for
pressurized flow in conduits that have been assigned a Circular Force Main cross-
section shape. The default is H-W.
IGNORE_RAINFALL is set to YES if all rainfall data and runoff calculations should be
ignored. In this case SWMM only performs flow and pollutant routing based on user-
supplied direct and dry weather inflows. The default is NO.
IGNORE_SNOWMELT is set to YES if snowmelt calculations should be ignored when a
project file contains snow pack objects. The default is NO.
IGNORE_GROUNDWATER is set to YES if groundwater calculations should be ignored
when a project file contains aquifer objects. The default is NO.
IGNORE_RDII is set to YES if rainfall dependent inflow/infiltration should be ignored
when RDM unit hydrographs and RDM inflows have been supplied to a project file.
The default is NO.
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IGNORE_ROUTING is set to YES if only runoff should be computed even if the project
contains drainage system links and nodes. The default is NO.
IGNORE_QUALITY is set to YES if pollutant washoff, routing, and treatment should be
ignored in a project that has pollutants defined. The default is NO.
ALLOW_PONDING determines whether excess water is allowed to collect atop nodes
and be re-introduced into the system as conditions permit. The default is NO ponding.
In order for ponding to actually occur at a particular node, a non-zero value for its
Ponded Area attribute must be used.
SKIP_STEADY_STATE should be set to YES if flow routing computations should be
skipped during steady state periods of a simulation during which the last set of
computed flows will be used. A time step is considered to be in steady state if the
percent difference between total system inflow and total system outflow is below the
SYS_FLOW_TOL and the percent difference between current and previous lateral
inflows are below the LAT_FLOW_TOL. The default for this option is NO.
SYS_FLOW_TOL is the maximum percent difference between total system inflow and
total system outflow which can occur in order for the SKIP_STEADY_STATE option to
take effect. The default is 5 percent.
LAT_FLOW_TOL is the maximum percent difference between the current and
previous lateral inflow at all nodes in the conveyance system in order for the
SKIP_STEADY_STATE option to take effect. The default is 5 percent.
START_DATE is the date when the simulation begins. If not supplied, a date of
1/1/2002 is used.
START_TIME is the time of day on the starting date when the simulation begins. The
default is 12 midnight (0:00:00).
END_DATE is the date when the simulation is to end. The default is the start date.
END_TIME is the time of day on the ending date when the simulation will end. The
default is 24:00:00.
REPORT_START_DATE is the date when reporting of results is to begin. The default is
the simulation start date.
REPORT_START_TIME is the time of day on the report starting date when reporting is
to begin. The default is the simulation start time of day.
SWEEP_START is the day of the year (month/day) when street sweeping operations
begin. The default is 1/1.
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SWEEP_END is the day of the year (month/day) when street sweeping operations end.
The default is 12/31.
DRY_DAYS is the number of days with no rainfall prior to the start of the simulation.
The default is 0.
REPORT_STEP is the time interval for reporting of computed results. The default is
0:15:00.
WET_STEP is the time step length used to compute runoff from subcatchments
during periods of rainfall or when ponded water still remains on the surface. The
default is 0:05:00.
DRY_STEP is the time step length used for runoff computations (consisting essentially
of pollutant buildup) during periods when there is no rainfall and no ponded water.
The default is 1:00:00.
ROUTING_STEP is the time step length in seconds used for routing flows and water
quality constituents through the conveyance system. The default is 600 sec (5
minutes) which should be reduced if using dynamic wave routing. Fractional values
(e.g., 2.5) are permissible as are values entered in hours:minutes:seconds format.
LENGTHENING_STEP is a time step, in seconds, used to lengthen conduits under
dynamic wave routing, so that they meet the Courant stability criterion under full-flow
conditions (i.e., the travel time of a wave will not be smaller than the specified conduit
lengthening time step). As this value is decreased, fewer conduits will require
lengthening. A value of 0 (the default) means that no conduits will be lengthened.
VARIABLE_STEP is a safety factor applied to a variable time step computed for
each time period under dynamic wave flow routing. The variable time step is
computed so as to satisfy the Courant stability criterion for each conduit and yet not
exceed the ROUTING_STEP value. If the safety factor is 0 (the default), then no
variable time step is used.
MINIMUM_STEP is the smallest time step allowed when variable time steps are used
for dynamic wave flow routing. The default value is 0.5 seconds.
INERTIAL_DAMPING indicates how the inertial terms in the Saint Venant
momentum equation will be handled under dynamic wave flow routing. Choosing
NONE maintains these terms at their full value under all conditions. Selecting
PARTIAL will reduce the terms as flow comes closer to being critical (and ignores
them when flow is supercritical). Choosing FULL will drop the terms altogether.
NORMAL_FLOW_LIMITED specifies which condition is checked to determine if flow in
a conduit is supercritical and should thus be limited to the normal flow. Use SLOPE to
check if the water surface slope is greater than the conduit slope, FROUDE to check if
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the Froude number is greater than 1.0, or BOTH to check both conditions. The default
is BOTH.
MIN_SURFAREA is a minimum surface area used at nodes when computing changes
in water depth under dynamic wave routing. If 0 is entered, then the default value of
12.566 ft2 (i.e., the area of a 4-ft diameter manhole) is used.
MIN_SLOPE is the minimum value allowed for a conduit's slope (%). If zero (the
default) then no minimum is imposed (although SWMM uses a lower limit on
elevation drop of 0.001 ft (0.00035 m) when computing a conduit slope).
MAX_TRIALS is the maximum number of trials allowed during a time step to reach
convergence when updating hydraulic heads at the conveyance system's nodes. The
default value is 8.
HEAD_TOLERANCE is the difference in computed head at each node between
successive trials below which the flow solution for the current time step is assumed to
have converged. The default tolerance is 0.005 ft (0.0015 m).
THREADS is the number of parallel computing threads to use for dynamic wave flow
routing on machines equipped with multi-core processors. The default is 1.
TEMPDIR provides the name of a file directory (or folder) where SWMM writes its
temporary files. If the directory name contains spaces then it should be placed within
double quotes. If no directory is specified, then the temporary files are written to the
current directory that the user is working in.
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Section: [REPORT]
Purpose: Describes the contents of the report file that is produced.
Formats: INPUT YES / NO
CONTINUITY YES / NO
FLOWSTATS YES / NO
CONTROLS YES / NO
SUBCATCHMENTS ALL / NONE /
NODES ALL / NONE /
LINKS ALL / NONE /
LID Name Subcatch Fname
Remarks: INPUT specifies whether or not a summary of the input data should be provided in
the output report. The default is NO.
CONTINUITY specifies whether continuity checks should be reported or not. The
default is YES.
FLOWSTATS specifies whether summary flow statistics should be reported or not. The
default is YES.
CONTROLS specifies whether all control actions taken during a simulation should be
listed or not. The default is NO.
SUBCATCHMENTS gives a list of subcatchments whose results are to be reported. The
default is NONE.
NODES gives a list of nodes whose results are to be reported. The default is NONE.
LINKS gives a list of links whose results are to be reported. The default is NONE.
LID specifies that the LID control Name in subcatchment Subcatch should have a
detailed performance report for it written to file Fname.
The SUBCATCHMENTS, NODES, LINKS, and LID lines can be repeated multiple
times.
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Section: [FILES]
Purpose: Identifies optional interface files used or saved by a run.
Formats: USE / SAVE RAINFALL Fname
USE / SAVE RUNOFF Fname
USE / SAVE HOTSTART Fname
USE / SAVE RDII Fname
USE INFLOWS Fname
SAVE OUTFLOWS Fname
Remarks: Fname is the name of an interface file.
Refer to Section 11.7 Interface Files for a description of interface files. Rainfall, Runoff, and
RDII files can either be used or saved in a run, but not both. A run can both use and save a Hot
Start file (with different names).
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Section: [RAINGAGES]
Purpose: Identifies each rain gage that provides rainfall data for the study area.
Formats: Name Form Intvl SCF TIMESERIES Tseries
Name Form Intvl SCF FILE Fname Sta Units
Remarks: Name name assigned to rain gage.
Form form of recorded rainfall, either INTENSITY , VOLUME or CUMULATIVE.
Intvl time interval between gage readings in decimal hours or hours:minutes
format (e.g., 0:15 for 15-minute readings).
SCF snow catch deficiency correction factor (use 1.0 for no adjustment).
Tseries name of time series in [TIMESERIES] section with rainfall data.
Fname name of external file with rainfall data. Rainfall files are discussed in
Section 11.3 Rainfall Files.
sta name of recording station used in the rain file.
Units rain depth units used in the rain file, either IN (inches) or MM
(millimeters).
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Section: [EVAPORATION]
Purpose: Specifies how daily evaporation rates vary with time for the study area.
Formats: CONSTANT evap
MONTHLY el e2 e3 e4 e5 e6 e7 e8 e9 elO ell e!2
TIMESERIES Tseries
TEMPERATURE
FILE (pi p2 p3 p4 p5 p6 p7 p8 p9 plO pll p!2)
RECOVERY pat tern ID
DRY ONLY NO / YES
Remarks: evap
el
constant evaporation rate (in/day or mm/day).
evaporation rate in January (in/day or mm/day).
e!2 evaporation rate in December (in/day or mm/day).
Tseries name of time series in [TIMESERIES] section with evaporation data.
pi pan coefficient for January.
p!2 pan coefficient for December.
pat ID name of a monthly time pattern.
Use only one of the above formats (CONSTANT, MONTHLY, TIMESERIES,
TEMPERATURE, or FILE). If no [EVAPORATION] section appears, then evaporation is
assumed to be 0.
TEMPERATURE indicates that evaporation rates will be computed from the daily air
temperatures contained in an external climate file whose name is provided in the
[TEMPERATURE] section (see below). This method also uses the site's latitude, which
can also be specified in the [TEMPERATURE] section.
FILE indicates that evaporation data will be read directly from the same external
climate file used for air temperatures as specified in the [TEMPERATURE] section
(see below).
RECOVERY identifies an optional monthly time pattern of multipliers used to modify
infiltration recovery rates during dry periods. For example, if the normal infiltration
recovery rate was 1% during a specific time period and a pattern factor of 0.8 applied
to this period, then the actual recovery rate would be 0.8%.
DRY_ONLY determines if evaporation only occurs during periods with no precipitation.
The default is NO.
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Section: [TEMPERATURE]
Purpose: Specifies daily air temperatures, monthly wind speed, and various snowmelt
parameters for the study area. Required only when snowmelt is being modeled or
when evaporation rates are computed from daily temperatures or are read from an
external climate file.
Formats: TIMESERIES Tseries
FILE Fname (Start)
WINDSPEED MONTHLY si s2 s3 s4 s5 s6 s7 s8 s9 slO sll s!2
WINDSPEED FILE
SNOWMELT Stemp ATIwt RNM Elev Lat DTLong
ADC IMPERVIOUS f.O f.l f.2 f.3 f.4 f.5 f. 6 f. 7 f.8 f.9
ADC PERVIOUS f.O f.l f.2 f.3 f.4 f.5 f.6 f.l f.8 f.9
Remarks: Tseries name of time series in [TIMESERIES] section with temperature data.
Fname name of external Climate file with temperature data.
start date to begin reading from the file in month/day/year format (default is
si
the beginning of the file).
average wind speed in January (mph or km/hr).
s!2 average wind speed in December (mph or km/hr).
stemp air temperature at which precipitation falls as snow (deg F or C).
ATiwt antecedent temperature index weight (default is 0.5).
RNM negative melt ratio (default is 0.6).
Elev average elevation of study area above mean sea level (ft or m) (default is
0).
Lat latitude of the study area in degrees North (default is 50).
DTLong correction, in minutes of time, between true solar time and the standard
clock time (default is 0).
f. o fraction of area covered by snow when ratio of snow depth to depth at
100% cover is 0
f. 9 fraction of area covered by snow when ratio of snow depth to depth at
100% cover is 0.9.
Use the TIMESERIES line to read air temperature from a time series or the FILE line
to read it from an external Climate file. Climate files are discussed in Section 11.4
Climate Files. If neither format is used, then air temperature remains constant at
70 degrees F.
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Wind speed can be specified either by monthly average values or by the same
Climate file used for air temperature. If neither option appears, then wind speed is
assumed to be 0.
Separate Areal Depletion Curves (ADC) can be defined for impervious and pervious
sub-areas. The ADC parameters will default to 1.0 (meaning no depletion) if no data
are supplied for a particular type of sub-area.
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Section: [ADJUSTMENTS]
Purpose: Specifies optional monthly adjustments to be made to temperature, evaporation rate,
rainfall intensity and hydraulic conductivity in each time period of a simulation.
Format:
TEMPERATURE
EVAPORATION
RAINFALL
CONDUCTIVITY
tl t2 t3 t4 t5 t6 t7 t8 t9 tlO til t!2
el e2 e3 e4 e5 e6 el e8 e9 elO ell e!2
rl r2 r3 r4 r5 r6 rl r8 r9 rlO rll r!2
cl c2 c3 c4 c5 c6 c7 c8 c9 clO ell c!2
Remarks: tl. . tl2
el..e!2
rl..r!2
cl..c!2
adjustments to temperature in January, February, etc., as plus or minus
degrees F (degrees C).
adjustments to evaporation rate in January, February, etc., as plus or
minus in/day (mm/day).
multipliers applied to precipitation rate in January, February, etc.
multipliers applied to soil hydraulic conductivity in January, February, etc.
used in either Morton or Green-Ampt infiltration.
The same adjustment is applied for each time period within a given month and is repeated for that
month in each subsequent year being simulated.
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Section: [SUBCATCHMENTS]
Purpose: Identifies each subcatchment within the study area. Subcatchments are land area
units which generate runoff from rainfall.
Format: Name Rgage OutID Area %Imperv Width Slope Clength (Spack)
Remarks: Name
Rgage
OutID
Area
name assigned to subcatchment.
name of rain gage in [RAINGAGES] section assigned to subcatchment.
name of node or subcatchment that receives runoff from subcatchment.
area of subcatchment (acres or hectares).
%imperv percent imperviousness of subcatchment.
width characteristic width of subcatchment (ft or meters).
slope subcatchment slope (percent).
ciength total curb length (any length units). Use 0 if not applicable.
Spack optional name of snow pack object (from [SNOWPACKS] section) that
characterizes snow accumulation and melting over the subcatchment.
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Section: [SUBAREAS]
Purpose: Supplies information about pervious and impervious areas for each subcatchment.
Each subcatchment can consist of a pervious sub-area, an impervious sub-area with
depression storage, and an impervious sub-area without depression storage.
Format: Subcat Nimp Nperv Simp Sperv %Zero RouteTo (%Routed)
Remarks: Subcat
Nimp
Nperv
Simp
Sperv
%Zero
subcatchment name.
Manning's n for overland flow over the impervious sub-area.
Manning's n for overland flow over the pervious sub-area.
depression storage for impervious sub-area (inches or mm).
depression storage for pervious sub-area (inches or mm).
percent of impervious area with no depression storage.
RouteTo IMPERVIOUS if pervious area runoff runs onto impervious area,
PERVIOUS if impervious runoff runs onto pervious area, or OUTLET if
both areas drain to the subcatchment's outlet (default = OUTLET).
%Routed percent of runoff routed from one type of area to another (default = 100).
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Section: [INFILTRATION]
Purpose: Supplies infiltration parameters for each subcatchment. Rainfall lost to infiltration only
occurs over the pervious sub-area of a subcatchment.
Formats: Subcat MaxRate MinRate Decay DryTime Maxlnf
Subcat Psi Ksat IMD
Subcat CurveNo Ksat DryTime
Remarks: Subcat subcatchment name.
For Morton and Modified Morton Infiltration:
MaxRate maximum infiltration rate on Morton curve (in/hr or mm/hr).
MinRate minimum infiltration rate on Morton curve (in/hr or mm/hr).
Decay decay rate constant of Morton curve (1/hr).
DryTime time it takes for fully saturated soil to dry (days).
Maxinf maximum infiltration volume possible (0 if not applicable) (in or mm).
For Green-Ampt and Modified Green-Ampt Infiltration:
Psi soil capillary suction (in or mm).
Ksa t soil saturated hydraulic conductivity (in/hr or mm/hr).
IMD initial soil moisture deficit (volume of voids / total volume).
For Curve-Number Infiltration:
CurveNo SCS Curve Number.
Ksa t soil saturated hydraulic conductivity (in/hr or mm/hr)
(This property has been deprecated and is no longer used.)
DryTime time it takes for fully saturated soil to dry (days).
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Section: [LID_CONTROLS]
Purpose: Defines scale-independent LID controls that can be deployed within subcatchments.
Formats: Name Type
followed by one or more of the following lines depending on Type:
Name SURFACE StorHt VegFrac Rough Slope Xslope
Name SOIL Thick For FC WP Ksat Kcoeff Suet
Name PAVEMENT Thick Vratio Fraclmp Perm Vclog
Name STORAGE Height Vratio Seepage Vclog
Name DRAIN Coeff Expon Offset Delay
Name DRAINMAT Thick Vratio Rough
Remarks: Name
Type
name assigned to LID process.
BC for bio-retention cell; RG for rain garden; GR for green roof; IT for
infiltration trench; PP for permeable pavement; RB for rain barrel; RD for
rooftop disconnection; vs for vegetative swale.
For LIDs with Surface Layers:
storHt when confining walls or berms are present this is the maximum depth to
which water can pond above the surface of the unit before overflow
occurs (in inches or mm). For LIDs that experience overland flow it is the
height of any surface depression storage. For swales, it is the height of
its trapezoidal cross section.
VegFrac fraction of the surface storage volume that is filled with vegetation.
Rough Manning's n for overland flow over surface soil cover, pavement, roof
surface or a vegetative swale. Use 0 for other types of LIDs.
slope slope of a roof surface, pavement surface or vegetative swale (percent).
Use 0 for other types of LIDs.
Xslope slope (run over rise) of the side walls of a vegetative swale's cross
section. Use 0 for other types of LIDs.
If either Rough or slope values are 0 then any ponded water that exceeds the
surface storage depth is assumed to completely overflow the LID control within a
single time step.
For LIDs with Pavement Layers:
Thick thickness of the pavement layer (inches or mm).
Vratio void ratio (volume of void space relative to the volume of solids in the
pavement for continuous systems or for the fill material used in modular
systems). Note that porosity = void ratio / (1 + void ratio).
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Fracimp ratio of impervious paver material to total area for modular systems; 0 for
continuous porous pavement systems.
Perm permeability of the concrete or asphalt used in continuous systems or
hydraulic conductivity of the fill material (gravel or sand) used in modular
systems (in/hr or mm/hr).
vdog number of pavement layer void volumes of runoff treated it takes to
completely clog the pavement. Use a value of 0 to ignore clogging.
For LIDs with Soil Layers:
Thick thickness of the soil layer (inches or mm).
For soil porosity (volume of pore space relative to total volume).
FC soil field capacity (volume of pore water relative to total volume after the
soil has been allowed to drain fully).
WP soil wilting point (volume of pore water relative to total volume for a well
dried soil where only bound water remains).
Ksa t soil's saturated hydraulic conductivity (in/hr or mm/hr).
Kcoeff slope of the curve of log(conductivity) versus soil moisture content
(dimensionless).
Suet soil capillary suction (in or mm).
For LIDs with Storage Layers:
Height thickness of the storage layer or height of a rain barrel (inches or mm).
Vratio void ratio (volume of void space relative to the volume of solids in the
layer). Note that porosity = void ratio / (1 + void ratio).
Seepage the rate at which water seeps from the layer into the underlying native
soil when first constructed (in/hr or mm/hr). If there is an impermeable
floor or liner below the layer then use a value of 0.
vdog number of storage layer void volumes of runoff treated it takes to
completely clog the layer. Use a value of 0 to ignore clogging.
Values for Vratio, Seepage, and vdog are ignored for rain barrels.
For LIDs with Drain Systems:
Coeff coefficient C that determines the rate of flow through the drain as a
function of height of stored water above the drain bottom. For Rooftop
Disconnection it is the maximum flow rate (in inches/hour or mm/hour)
that the roofs gutters and downspouts can handle before overflowing.
Expon exponent n that determines the rate of flow through the drain as a
function of height of stored water above the drain outlet.
offset height of the drain line above the bottom of the storage layer or rain
barrel (inches or mm).
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Delay number of dry weather hours that must elapse before the drain line in a
rain barrel is opened (the line is assumed to be closed once rainfall
begins). A value of 0 signifies that the barrel's drain line is always open
and drains continuously. This parameter is ignored for other types of
LIDs.
For Green Roof LIDs with Drainage Mats:
Thick thickness of the drainage mat (inches or mm).
Vratio ratio of void volume to total volume in the mat.
Rough Manning's n constant used to compute the horizontal flow rate of drained
water through the mat.
The following table shows which layers are required (x) or are optional (o) for each type of LID
process:
LID Type
Bio-Retention Cell
Rain Garden
Green Roof
Infiltration Trench
Permeable
Pavement
Rain Barrel
Rooftop
Disconnection
Vegetative Swale
Surface
X
X
X
X
X
X
X
Pavement
X
Soil
X
X
X
0
Storage
X
X
X
X
Drain
0
0
0
X
X
Drain Mat
X
The equation used to compute flow rate out of the underdrain per unit area of the LID (in in/hr or
mm/hr) is q = C(h-Hd)n where q is outflow, h is height of stored water (inches or mm) and Hd
is the drain offset height. Note that the units of C depend on the unit system being used as well
as the value assigned to n.
The actual dimensions of an LID control are provided in the [LIDJJSAGE] section when it is
placed in a particular subcatchment.
Examples: ;A street planter with no drain
Planter BC
Planter SURFACE 6 0.3 0 0 0
Planter SOIL 24 0.5 0.1 0.05 1.2 2.4
Planter STORAGE 12 0.5 0.5 0
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;A green roof with impermeable bottom
GR1 BC
GR1 SURFACE 3000 0
GR1 SOIL 3 0.5 0.1 0.05 1.2 2.4
GR1 STORAGE 3 0.5 0 0
GR1 DRAIN 5 0.5 0 0
;A rain barrel that drains 6 hours after rainfall ends
RB12 RB
RB12 STORAGE 36 0 00
RB12 DRAIN 10 0.5 0 6
;A grass swale 24 in. high with 5:1 side slope
Swale VS
Swale SURFACE 24 0 0.2 3 5
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Section: [LID_USAGE]
Purpose: Deploys LID controls within specific subcatchment areas.
Format: Subcat LID Number Area Width InitSat Fromlmp ToPerv
(RptFile DrainTo)
Remarks: Subcat name of the subcatchment using the LID process.
LID name of an LID process defined in the [LID_CONTROLS] section.
Number number of replicate LID units deployed.
Area area of each replicate unit (ft2 or m2).
width width of the outflow face of each identical LID unit (in ft or m). This
parameter applies to roofs, pavement, trenches, and swales that use
overland flow to convey surface runoff off of the unit. It can be set to 0 for
other LID processes, such as bio-retention cells, rain gardens, and rain
barrels that simply spill any excess captured runoff over their berms.
initsat for bio-retention cells, rain gardens, and green roofs this is the degree to
which the unit's soil is initially filled with water (0 % saturation
corresponds to the wilting point moisture content, 100 % saturation has
the moisture content equal to the porosity). The storage zone beneath
the soil zone of the cell is assumed to be completely dry. For other types
of LIDs it corresponds to the degree to which their storage zone is
initially filled with water
Fromimp percent of the impervious portion of the subcatchment's non-LID area
whose runoff is treated by the LID practice. (E.g., if rain barrels are used
to capture roof runoff and roofs represent 60% of the impervious area,
then the impervious area treated is 60%). If the LID unit treats only direct
rainfall, such as with a green roof, then this value should be 0. If the LID
takes up the entire subcatchment then this field is ignored.
ToPerv a value of 1 indicates that the surface and drain flow from the LID unit
should be routed back onto the pervious area of the subcatchment that
contains it. This would be a common choice to make for rain barrels,
rooftop disconnection, and possibly green roofs. The default value is 0.
RptFile optional name of a file to which detailed time series results for the LID
will be written. Enclose the name in double quotes if it contains spaces
and include the full path if it is different than the SWMM input file path.
Use '*' if not applicable and an entry for DrainTo follows
DrainTo optional name of subcatchment or node that receives flow from the unit's
drain line, if different from the outlet of the subcatchment that the LID is
placed in.
If ToPerv is set to 1 and DrainTo set to some other outlet, then only the excess
surface flow from the LID unit will be routed back to the subcatchment's pervious
area while the underdrain flow will be sent to DrainTo.
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More than one type of LID process can be deployed within a subcatchment as long
as their total area does not exceed that of the subcatchment and the total percent
impervious area treated does not exceed 100.
Examples: ;34 rain barrels of 12 sq ft each are placed in
;subcatchment SI. They are initially empty and treat 17%
;of the runoff from the subcatchment's impervious area.
;The outflow from the barrels is returned to the
;subcatchment's pervious area.
SI RB14 34 12 0 0 17 1
;Subcatchment S2 consists entirely of a single vegetative
;swale 200 ft long by 50 ft wide.
S2 Swale 1 10000 50 0 0 0 "swale.rpt"
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Section: [AQUIFERS]
Purpose: Supplies parameters for each unconfined groundwater aquifer in the study area.
Aquifers consist of two zones - a lower saturated zone and an upper unsaturated
zone with a moving boundary between the two.
Formats: Name For WP FC Ks Kslp Tslp ETu ETs Seep Ebot Egw Umc (Epat)
Remarks: Name name assigned to aquifer.
Por soil porosity (volumetric fraction).
WP soil wilting point (volumetric fraction).
FC soil field capacity (volumetric fraction).
KS saturated hydraulic conductivity (in/hr or mm/hr).
Kslp slope of the logarithm of hydraulic conductivity versus moisture deficit (i.e.,
porosity minus moisture content) curve (in/hr or mm/hr).
Tslp slope of soil tension versus moisture content curve (inches or mm).
ETU fraction of total evaporation available for evapotranspiration in the upper
unsaturated zone.
ETS maximum depth into the lower saturated zone over which evapotranspiration
can occur (ft or m).
Seep seepage rate from saturated zone to deep groundwater when water table is
at ground surface (in/hr or mm/hr).
Ebot elevation of the bottom of the aquifer (ft or m).
Egw groundwater table elevation at start of simulation (ft or m).
Umc unsaturated zone moisture content at start of simulation (volumetric fraction).
Epa t name of optional monthly time pattern used to adjust the upper zone
evaporation fraction for different months of the year.
Local values for Ebot, Egw, and Umc can be assigned to specific subcatchments in
the [GROUNDWATER] section described below.
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Section: [GROUNDWATER]
Purpose: Supplies parameters that determine the rate of groundwater flow between the aquifer
underneath a subcatchment and a node of the conveyance system.
Format:
Subcat Aquifer Node Esurf Al Bl A2 B2 A3 Dsw (Egwt Ebot Egw Umc)
Remarks: Subcat subcatchment name.
Aquifer name of groundwater aquifer underneath the subcatchment.
Node name of node in conveyance system exchanging groundwater with
aquifer.
Esurf surface elevation of subcatchment (ft or m).
Al groundwater flow coefficient (see below).
Bl groundwater flow exponent (see below).
A2 surface water flow coefficient (see below).
B2 surface water flow exponent (see below).
A3 surface water - groundwater interaction coefficient (see below).
DSW fixed depth of surface water at receiving node (ft or m) (set to zero if
surface water depth will vary as computed by flow routing).
Egwt threshold groundwater table elevation which must be reached before any
flow occurs (ft or m). Leave blank (or enter *) to use the elevation of the
receiving node's invert.
The following optional parameters can be used to override the values supplied for the
subcatchment's aquifer.
Ebot elevation of the bottom of the aquifer (ft or m).
Egw groundwater table elevation at the start of the simulation (ftorm).
Umc unsaturated zone moisture content at start of simulation (volumetric fraction).
The flow coefficients are used in the following equation that determines the lateral groundwater
flow rate based on groundwater and surface water elevations:
QL = A1 (Hgw - Hcb) B1 - A2 (Hs« - Hcb) B2 + A3 Hgw Hsw
where:
QL = lateral groundwater flow (cfs per acre or cms per hectare),
Hgw = height of saturated zone above bottom of aquifer (ft or m),
Hsw = height of surface water at receiving node above aquifer bottom (ft or m),
Hcb = height of channel bottom above aquifer bottom (ft or m).
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Section: [GWF]
Purpose: Defines custom groundwater flow equations for specific subcatchments.
Format: subcat LATERAL/DEEP
Remarks: Subcat
Expr
subcatchment name.
math formula expressing the rate of groundwater flow (in cfs per acre or
cms per hectare for lateral flow or in/hr or mm/hr for deep flow) as a
function of the following variables:
Hgw (for height of the groundwater table)
HSW (for height of the surface water)
Hcb (for height of the channel bottom)
Hgs (for height of ground surface)
where all heights are relative to the aquifer bottom and have
units of either feet or meters;
KS (for saturated hydraulic conductivity in in/hr or mm/hr)
K (for unsaturated hydraulic conductivity in in/hr or mm/hr)
Theta (for moisture content of unsaturated zone)
Phi (for aquifer soil porosity)
Fi (for infiltration rate from the ground surface in in/hr or mm/hr)
FU (for percolation rate from the upper unsaturated zone in in/hr or
mm/hr)
A (for subcatchment area in acres or hectares)
Use LATERAL to designate an expression for lateral groundwater flow (to a node of
the conveyance network) and DEEP for vertical loss to deep groundwater.
See the [TREATMENT] section for a list of built-in math functions that can be used in
Expr. In particular, the STEP (x) function is 1 when x > o and is 0 otherwise.
Examples: ;Two-stage linear reservoir for lateral flow
Subcatchl LATERAL 0.001*Hgw + 0.05*(Hgw-5)*STEP(Hgw-5)
;Constant seepage rate to deep aquifer
Subactchl DEEP 0.002
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Section: [SNOWPACKS]
Purpose: Specifies parameters that govern how snowfall accumulates and melts on the
plowable, impervious and pervious surfaces of subcatchments.
Formats: Name PLOWABLE Cmin Cmax Tbase FWF SDO FWO SNNO
Name IMPERVIOUS Cmin Cmax Tbase FWF SDO FWO SD100
Name PERVIOUS Cmin Cmax Tbase FWF SDO FWO SD100
Name REMOVAL Dplow Fout Fimp Fperv Fimelt (Fsub Scatch)
Remarks: Name name assigned to snowpack parameter set.
Cmin minimum melt coefficient (in/hr-deg F or mm/hr-deg C).
Cmax maximum melt coefficient (in/hr-deg F or mm/hr-deg C).
Tbase snow melt base temperature (deg F or deg C).
FWF ratio of free water holding capacity to snow depth (fraction).
SDO initial snow depth (in or mm water equivalent).
FWO initial free water in pack (in or mm).
SNNO fraction of impervious area that can be plowed.
SDIOO snow depth above which there is 100% cover (in or mm water
equivalent).
Dplow depth of snow on plowable areas at which snow removal begins (in or
mm).
Fout fraction of snow on plowable area transferred out of watershed.
Fimp fraction of snow on plowable area transferred to impervious area by
plowing.
Fperv fraction of snow on plowable area transferred to pervious area by
plowing.
Fimelt fraction of snow on plowable area converted into immediate melt.
Fsub fraction of snow on plowable area transferred to pervious area in
another subcatchment.
Scatch name of subcatchment receiving the Fsub fraction of transferred snow.
Use one set of PLOWABLE, IMPERVIOUS, and PERVIOUS lines for each snow pack
parameter set created. Snow pack parameter sets are associated with specific
subcatchments in the [SUBCATCHMENTS] section. Multiple subcatchments can share
the same set of snow pack parameters.
The PLOWABLE line contains parameters for the impervious area of a subcatchment
that is subject to snow removal by plowing but not to areal depletion. This area is the
fraction SNNO of the total impervious area. The IMPERVIOUS line contains parameter
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values for the remaining impervious area and the PERVIOUS line does the same for
the entire pervious area. Both of the latter two areas are subject to areal depletion.
The REMOVAL line describes how snow removed from the plowable area is
transferred onto other areas. The various transfer fractions should sum to no more
than 1.0. If the line is omitted then no snow removal takes place.
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Section: [JUNCTIONS]
Purpose: Identifies each junction node of the drainage system. Junctions are points in space
where channels and pipes connect together. For sewer systems they can be either
connection fittings or manholes.
Format: Name Elev (Ymax YO Ysur Apond)
Remarks: Name
Elev
Ymax
YO
Ysur
Apond
name assigned to junction node.
elevation of junction invert (ft or m).
depth from ground to invert elevation (ft or m) (default is 0).
water depth at start of simulation (ft or m) (default is 0).
maximum additional head above ground elevation that manhole junction
can sustain under surcharge conditions (ft or m) (default is 0).
area subjected to surface ponding once water depth exceeds Ymax (ft2 or
m2) (default is 0).
If Ymax is 0 then SWMM sets the maximum depth equal to the distance from the
invert to the top of the highest connecting link.
If the junction is part of a force main section of the system then set Ysur to the
maximum pressure that the system can sustain.
Surface ponding can only occur when Apond is non-zero and the ALLOW_PONDING
analysis option is turned on.
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Section: [OUTFALLS]
Purpose:
Formats:
Identifies each outfall node (i.e., final downstream boundary) of the drainage system
and the corresponding water stage elevation. Only one link can be incident on an
outfall node.
Remarks:
Name
Name
Name
Name
Name
Name
Elev
Stage
Tcurve
Tseries
Gated
RouteTo
Elev
Elev
Elev
Elev
Elev
FREE
NORMAL
FIXED
TIDAL
TIMESERIES
(Gated) (RouteTo)
(Gated) (RouteTo)
Stage (Gated) (RouteTo)
Tcurve (Gated) (RouteTo)
Tseries (Gated)
(RouteTo)
name assigned to outfall node.
invert elevation (ft or m).
elevation of fixed stage outfall (ft or m).
name of curve in [CURVES] section containing tidal height (i.e., outfall
stage) v. hour of day over a complete tidal cycle.
name of time series in [TIMESERIES] section that describes how outfall
stage varies with time.
YES or NO depending on whether a flap gate is present that prevents
reverse flow. The default is NO.
optional name of a subcatchment that receives the outfall's discharge.
The default is not to route the outfall's discharge.
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Section: [DIVIDERS]
Purpose: Identifies each flow divider node of the drainage system. Flow dividers are junctions
with exactly two outflow conduits where the total outflow is divided between the two in
a prescribed manner.
Formats: Name Elev DivLink OVERFLOW (Ymax YO Ysur Apond)
Name Elev DivLink CUTOFF Qmin (Ymax YO Ysur Apond)
Name Elev DivLink TABULAR Dcurve (Ymax YO Ysur Apond)
Name Elev DivLink WEIR Qmin Ht Cd (Ymax YO Ysur Apond)
Remarks: Name
Elev
DivLink
Qmin
Dcurve
Ht
Cd
Ymax
YO
Ysur
Apond
name assigned to divider node.
invert elevation (ft or m).
name of link to which flow is diverted.
flow at which diversion begins for either a CUTOFF or WEIR divider (flow
units).
name of curve for TABULAR divider that relates diverted flow to total flow.
height of WEIR divider (ft or m).
discharge coefficient for WEIR divider.
depth from ground to invert elevation (ft or m) (default is 0).
water depth at start of simulation (ft or m) (default is 0).
maximum additional head above ground elevation that node can sustain
under surcharge conditions (ft or m) (default is 0).
area subjected to surface ponding once water depth exceeds Ymax (ft2 or
m2) (default is 0).
If Ymax is 0 then SWMM sets the maximum depth equal to the distance from the
invert to the top of the highest connecting link.
Surface ponding can only occur when Apond is non-zero and the ALLOW_PONDING
analysis option is turned on.
Divider nodes are only active under the Steady Flow or Kinematic Wave analysis
options. For Dynamic Wave flow routing they behave the same as Junction nodes.
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Section: [STORAGE]
Purpose: Identifies each storage node of the drainage system. Storage nodes can have any
shape as specified by a surface area versus water depth relation.
Formats:
Name Elev Ymax YO TABULAR Acurve (Apond Fevap Psi Ksat IMD)
Name Elev Ymax YO FUNCTIONAL Al A2 AO (Apond Fevap Psi Ksat IMD)
Remarks: Name name assigned to storage node.
Elev invert elevation (ft or m).
Ymax maximum water depth possible (ft or m).
YO water depth at the start of the simulation (ft or m).
Acurve name of curve in [CURVES] section with surface area (ft2 or m2) as a
function of depth (ft or m) for TABULAR geometry.
Al coefficient of FUNCTIONAL relation between surface area and depth.
A2 exponent of FUNCTIONAL relation between surface area and depth.
AO constant of FUNCTIONAL relation between surface area and depth.
Apond this parameter has been deprecated - use 0.
Fevap fraction of potential evaporation from surface realized (default is 0).
Psi soil suction head (inches or mm).
Ksa t soil saturated hydraulic conductivity (in/hr or mm/hr).
IMD soil initial moisture deficit (fraction).
Al, A2, and AO are used in the following expression that relates surface area (ft2 or
m2) to water depth (ft or m) for a storage unit with FUNCTIONAL geometry:
Area = AO + AlDepthA2
For TABULAR geometry, the surface area curve will be extrapolated outwards to
meet the unit's maximum depth if need be.
The parameters Psi, Ksat, and IMD need only be supplied if seepage loss through
the soil at the bottom and sloped sides of the storage unit should be considered.
They are the same Green-Ampt infiltration parameters described in the
[INFILTRATION] section. If Ksat is zero then no seepage occurs while if IMD is
zero then seepage occurs at a constant rate equal to Ksat. Otherwise seepage rate
will vary with storage depth.
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Section: [CONDUITS]
Purpose: Identifies each conduit link of the drainage system. Conduits are pipes or channels
that convey water from one node to another.
Format: Name Nodel Node2 Length N Zl Z2 (QO Qmax)
Remarks: Name
Nodel
Node2
Length
N
Zl
Z2
QO
Qmax
name assigned to conduit link.
name of upstream node.
name of downstream node.
conduit length (ft or m).
value of n (i.e., roughness parameter) in Manning's equation.
offset of upstream end of conduit invert above the invert elevation of its
upstream node (ft or m).
offset of downstream end of conduit invert above the invert elevation of
its downstream node (ft or m).
flow in conduit at start of simulation (flow units) (default is 0).
maximum flow allowed in the conduit (flow units) (default is no limit).
The figure below illustrates the meaning of the zi and Z2 parameters.
These offsets are expressed as a relative distance above the node invert if the
LINK_OFFSETS option is set to DEPTH (the default) or as an absolute elevation if it is
Set to ELEVATION.
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Section: [PUMPS]
Purpose: Identifies each pump link of the drainage system.
Format: Name Nodel Node2 Pcurve (Status Startup Shutoff)
Remarks: Name name assigned to pump link.
Nodel name of node on inlet side of pump.
Node2 name of node on outlet side of pump.
Pcurve name of pump curve listed in the [CURVES] section of the input.
status status at start of simulation (either ON or OFF; default is ON).
startup depth at inlet node when pump turns on (ft or m) (default is 0).
shutoff depth at inlet node when pump shuts off (ft or m) (default is 0).
See Section 3.2 for a description of the different types of pumps available.
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Section: [ORIFICES]
Purpose: Identifies each orifice link of the drainage system. An orifice link serves to limit the
flow exiting a node and is often used to model flow diversions and storage node
outlets.
Format: Name Nodel Node2 Type Offset Cd (Gated Orate)
Remarks: Name
Nodel
Node2
Type
Offset
Cd
Flap
Orate
name assigned to orifice link.
name of node on inlet end of orifice.
name of node on outlet end of orifice.
orientation of orifice: either SIDE or BOTTOM.
amount that a Side Orifice's bottom or the position of a Bottom Orifice is
offset above the invert of inlet node (ft or m, expressed as either a depth
or as an elevation, depending on the LINK_OFFSETS option setting).
discharge coefficient (unitless).
YES if flap gate present to prevent reverse flow, NO if not (default is NO).
time in decimal hours to open a fully closed orifice (or close a fully open
one). Use 0 if the orifice can open/close instantaneously.
The geometry of an orifice's opening must be described in the [XSECTIONS] section.
The only allowable shapes are CIRCULAR and RECT CLOSED (closed rectangular).
Regulator
Structure
Orifice
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Section: [WEIRS]
Purpose: Identifies each weir link of the drainage system. Weirs are used to model flow
diversions and storage node outlets.
Format:
Name Nodel Node2 Type CrestHt Cd (Gated EC Cd2 Sur (Width Surface))
Remarks: Name name assigned to weir link.
Nodel name of node on inlet side of wier.
Node2 name of node on outlet side of weir.
Type TRANSVERSE, SIDEFLOW, V-NOTCH, TRAPEZOIDAL Or ROADWAY.
CrestHt amount that the weir's crest is offset above the invert of inlet node (ft or
m, expressed as either a depth or as an elevation, depending on the
LINKJDFFSETS option setting).
cd weir discharge coefficient (for CFS if using US flow units or CMS if using
metric flow units).
Gated YES if flap gate present to prevent reverse flow, NO if not (default is NO).
EC number of end contractions for TRANSVERSE or TRAPEZOIDAL weir
(default is 0).
cd2 discharge coefficient for triangular ends of a TRAPEZOIDAL weir (for
CFS if using US flow units or CMS if using metric flow units) (default is
value of cd).
Sur YES if the weir can surcharge (have an upstream water level higher than
the height of the opening); NO if it cannot (default is YES).
width width of road lanes and shoulders for ROADWAY weir (ft or m).
Surface type of road surface for ROADWAY weir: PAVED or GRAVEL.
The geometry of a weir's opening is described in the [XSECTIONS] section. The
following shapes must be used with each type of weir:
Weir Type
Transverse
Sideflow
V-Notch
Trapezoidal
Roadway
Cross-Section Shape
RECTJDPEN
RECTJDPEN
TRIANGULAR
TRAPEZOIDAL
RECTJDPEN
The ROADWAY weir is a broad crested rectangular weir used model roadway
crossings usually in conjunction with culvert-type conduits. It uses the FHWA HDS-5
method to determine a discharge coefficient as a function of flow depth and roadway
width and surface. If no roadway data are provided then the weir behaves as a
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TRANSVERSE weir with cd as its discharge coefficient. Note that if roadway data are
provided, then values for the other optional weir parameters (NO for Gated, o for
EC, o for cd2, and NO for Sur) must be entered even though they do not apply to
ROADWAY weirs.
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Section: [OUTLETS]
Purpose: Identifies each outlet flow control device of the drainage system. These devices are
used to model outflows from storage units or flow diversions that have a user-defined
relation between flow rate and water depth.
Formats: Name Nodel Node2 Offset TABULAR/DEPTH Qcurve (Gated)
Name Nodel Node2 Offset TABULAR/HEAD Qcurve (Gated)
Name Nodel Node2 Offset FUNCTIONAL/DEPTH Cl C2 (Gated)
Name Nodel Node2 Offset FUNCTIONAL/HEAD Cl C2 (Gated)
Remarks: Name
Nodel
Node2
Offset
Qcurve
Cl, C2
Gated
name assigned to outlet link.
name of node on inlet end of link.
name of node on outflow end of link.
amount that the outlet is offset above the invert of inlet node (ft or m,
expressed as either a depth or as an elevation, depending on the
LINK_OFFSETS option setting).
name of the rating curve listed in the [CURVES] section that describes
outflow rate (flow units) as a function of:
• water depth above the offset elevation at the inlet node (ft or m) for a
TABULAR/DEPTH Outlet
• head difference (ft or m) between the inlet and outflow nodes for a
TABULAR/HEAD Outlet.
coefficient and exponent, respectively, of a power function that relates
outflow (Q) to:
• water depth (ft or m) above the offset elevation at the inlet node for a
FUNCTIONAL/DEPTH Outlet
• head difference (ft or m) between the inlet and outflow nodes for a
FUNCTIONAL/HEAD Outlet.
(i.e., Q = CIHC2 where H is either depth or head).
YES if flap gate present to prevent reverse flow, NO if not (default is NO).
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Section: [XSECTIONS]
Purpose: Provides cross-section geometric data for conduit and regulator links of the drainage
system.
Formats: Link Shape Geoml Geom2 GeomS Geom4 (Barrels Culvert)
Link CUSTOM Geoml Curve (Barrels)
Link IRREGULAR Tsect
Remarks: Link name of the conduit, orifice, or weir.
shape cross-section shape (see Tables D-1 below or 3-1 for available shapes).
Geoml full height of the cross-section (ft or m).
Geom2-4 auxiliary parameters (width, side slopes, etc.) as listed in Table D-1.
Barrels number of barrels (i.e., number of parallel pipes of equal size, slope, and
roughness) associated with a conduit (default is 1).
Culvert code number from Table A.10 for the conduit's inlet geometry if it is a
culvert subject to possible inlet flow control (leave blank otherwise).
Curve name of a Shape Curve in the [CURVES] section that defines how width
varies with depth.
Tsect name of an entry in the [TRANSECTS] section that describes the cross-
section geometry of an irregular channel.
The Culvert code number is used only for conduits that act as culverts and should be
analyzed for inlet control conditions using the FHWA HDS-5 method.
The CUSTOM shape is a closed conduit whose width versus height is described by a
user-supplied Shape Curve.
An IRREGULAR cross-section is used to model an open channel whose geometry is
described by a Transect object.
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Table D-1 Geometric parameters of conduit cross sections
Shape
CIRCULAR
FORCE_MAIN
FILLED_CIRCULAR2
RECT_CLOSED
RECT_OPEN
TRAPEZOIDAL
TRIANGULAR
HORIZ_ELLIPSE
VERT_ELLIPSE
ARCH
PARABOLIC
POWER
RECT_TRIANGULAR
RECT_ROUND
MODBASKETHANDLE
EGG
HORSESHOE
GOTHIC
CATENARY
SEMIELLIPTICAL
BASKETHANDLE
SEMICIRCULAR
Geoml
Diameter
Diameter
Diameter
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Full Height
Geom2
Roughness1
Sediment
Depth
Top Width
Top Width
Base Width
Top Width
Max. Width
Max. Width
Max. Width
Top Width
Top Width
Top Width
Top Width
Base Width
GeomS
Left Slope3
Size Code4
Size Code4
Size Code5
Exponent
Triangle
Height
Bottom
Radius
Top Radius6
Geom4
Right Slope3
1C-factors are used when H-W is the FORCE_MAIN_EQUATION choice in the [OPTIONS]
section while roughness heights (in inches or mm) are used forD-w.
2A circular conduit partially filled with sediment to a specified depth.
3Slopes are horizontal run / vertical rise.
4Size code of a standard shaped elliptical pipe as listed in Appendix A11. Leave blank (or
0) if the pipe has a custom dimensions.
5Size code of a standard arch pipe as listed in Appendix A12. Leave blank (or 0) if the
pipe has custom dimensions).
6Set to zero to use a standard modified baskethandle shape whose top radius is half the
base width.
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Section: [LOSSES]
Purpose: Specifies minor head loss coefficients, flap gates, and seepage rates for conduits.
Formats: Conduit Kentry Kexit Kavg (Flap Seepage)
Remarks: Conduit name of conduit.
Kentry entrance minor head loss coefficient.
Kexit exit minor head loss coefficient.
Kavg average minor head loss coefficient across length of conduit.
Flap YES if conduit has a flap valve that prevents back flow, NO otherwise.
(Default is NO).
Seepage Rate of seepage loss into surrounding soil (in/hr or mm/hr). (Default is 0.)
Minor losses are only computed for the Dynamic Wave flow routing option (see
[OPTIONS] section). They are computed as Kv2/2g where K = minor loss coefficient, v
= velocity, and g = acceleration of gravity. Entrance losses are based on the velocity
at the entrance of the conduit, exit losses on the exit velocity, and average losses on
the average velocity.
Only enter data for conduits that actually have minor losses, flap valves, or seepage
losses.
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Section: [TRANSECTS]
Purpose: Describes the cross-section geometry of natural channels or conduits with irregular
shapes following the HEC-2 data format.
Formats: NC Nleft Nright Nchanl
XI Name Nsta Xleft Xright 000 Lfactor Wfactor Eoffset
GR Elev Station ... Elev Station
Remarks: Nleft Manning's n of right overbank portion of channel (use 0 if no change
from previous NC line).
Nright Manning's n of right overbank portion of channel (use 0 if no change
from previous NC line.
Nchanl Manning's n of main channel portion of channel (use 0 if no change from
previous NC line.
Name name assigned to transect.
Nsta number of stations across cross-section at which elevation data is
supplied.
xieft station position which ends the left overbank portion of the channel (ft or
m).
Xright station position which begins the right overbank portion of the channel (ft
or m).
Lfactor meander modifier that represents the ratio of the length of a meandering
main channel to the length of the overbank area that surrounds it (use 0
if not applicable).
Wfactor factor by which distances between stations should be multiplied to
increase (or decrease) the width of the channel (enter 0 if not
applicable).
Eoffset amount added (or subtracted) from the elevation of each station (ft or m).
Elev elevation of the channel bottom at a cross-section station relative to
some fixed reference (ft or m).
station distance of a cross-section station from some fixed reference (ft or m).
Transect geometry is described as shown below, assuming that one is looking in a
downstream direction:
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Left
Oveibiink
Pi. ilit
Overbiink
Xleft
St.itioii
Xi kjl*
The first line in this section must always be a NC line. After that, the NC line is only
needed when a transect has different Manning's n values than the previous one.
The Manning's n values on the NC line will supersede any roughness value entered
for the conduit which uses the irregular cross-section.
There should be one xi line for each transect. Any number of GR lines may follow,
and each GR line can have any number of Elevation-Station data pairs. (In HEC-2 the
GR line is limited to 5 stations.)
The station that defines the left overbank boundary on the xi line must correspond to
one of the station entries on the GR lines that follow. The same holds true for the right
overbank boundary. If there is no match, a warning will be issued and the program
will assume that no overbank area exists.
The meander modifier is applied to all conduits that use this particular transect for
their cross section. It assumes that the length supplied for these conduits is that of
the longer main channel. SWMM will use the shorter overbank length in its
calculations while increasing the main channel roughness to account for its longer
length.
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Section: [CONTROLS]
Purpose: Determines how pumps and regulators will be adjusted based on simulation time or
conditions at specific nodes and links.
Formats: Each control rule is a series of statements of the form:
rulelD
condition_l
condition 2
condition_3
condition 4
action_l
action 2
action_3
action 4
RULE
IF
AND
OR
AND
Etc.
THEN
AND
Etc.
ELSE
AND _
Etc.
PRIORITY value
Remarks: Rule ID
condition n
action_n
value
an ID label assigned to the rule.
a condition clause.
an action clause.
a priority value (e.g., a number from 1 to 5).
A condition clause of a Control Rule has the following format:
Object Name Attribute Relation Value
where object is a category of object, Name is the object's assigned ID name,
Attribute is the name of an attribute or property of the object, Relation is a
relational operator (=, <>, <, <=, >, >=), and Value is an attribute value.
Some examples of condition clauses are:
NODE N23 DEPTH > 10
PUMP P45 STATUS = OFF
SIMULATION TIME = 12:45:00
The objects and attributes that can appear in a condition clause are as follows:
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Object
NODE
LINK
CONDUIT
PUMP
ORIFICE
WEIR
OUTLET
SIMULATION
SIMULATION
Attributes
DEPTH
HEAD
VOLUME
INFLOW
FLOW
DEPTH
TIMEOPEN
TIMECLOSED
STATUS
TIMEOPEN
TIMECLOSED
STATUS
SETTING
FLOW
TIMEOPEN
TIMECLOSED
SETTING
TIMEOPEN
TIMECLOSED
SETTING
TIMEOPEN
TIMECLOSED
SETTING
TIMEOPEN
TIMECLOSED
TIME
DATE
MONTH
DAY
CLOCKTIME
Value
numerical value
numerical value
numerical value
numerical value
numerical value
numerical value
decimal hours or hr:min
decimal hours or hr:min
OPEN or CLOSED
decimal hours or hr:min
decimal hours or hr:min
ON or OFF
pump curve multiplier
numerical value
decimal hours or hr:min
decimal hours or hr:min
fraction open
decimal hours or hr:min
decimal hours or hr:min
fraction open
decimal hours or hr:min
decimal hours or hr:min
rating curve multiplier
decimal hours or hr:min
decimal hours or hr:min
elapsed time in decimal hours or
hr:min:sec
month/day/year
month of year (January = 1)
day of week (Sunday = 1)
time of day in hr:min:sec
TIMEOPEN is the duration a link has been in an OPEN or ON state or have its
SETTING be greater than zero; TIMECLOSED is the duration it has remained in a
CLOSED or OFF state or have its SETTING be zero.
An action clause of a Control Rule can have one of the following formats:
318
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PUMP id STATUS = ON/OFF
PUMP/ORIFICE/WEIR/OUTLET id SETTING = value
where the meaning of SETTING depends on the object being controlled:
• for Pumps it is a multiplier applied to the flow computed from the pump curve,
• for Orifices it is the fractional amount that the orifice is fully open,
• for Weirs it is the fractional amount of the original freeboard that exists (i.e., weir
control is accomplished by moving the crest height up or down),
• for Outlets it is a multiplier applied to the flow computed from the outlet's rating
curve.
Modulated controls are control rules that provide for a continuous degree of control
applied to a pump or flow regulator as determined by the value of some controller
variable, such as water depth at a node, or by time. The functional relation between
the control setting and the controller variable is specified by using a control curve, a
time series, or a PID controller. To model these types of controls, the value entry on
the right-hand side of the action clause is replaced by the keyword CURVE,
TIMESERIES, or PID and followed by the id name of the respective control curve or
time series or by the gain, integral time (in minutes), and derivative time (in minutes)
of a PID controller. For direct action control the gain is a positive number while for
reverse action control it must be a negative number. By convention, the controller
variable used in a control curve or PID control will always be the object and attribute
named in the last condition clause of the rule. The value specified for this clause will
be the setpoint used in a PID controller.
Some examples of action clauses are:
PUMP P67 STATUS = OFF
ORIFICE 0212 SETTING =0.5
WEIR W25 SETTING = CURVE C25
ORIFICE ORI_23 SETTING = PID 0.1 0.1 0.0
Only the RULE, IF and THEN portions of a rule are required; the other portions are
optional. When mixing AND and OR clauses, the OR operator has higher precedence
than AND, i.e.,
IF A or B and C
is equivalent to
IF (A or B) and C.
If the interpretation was meant to be
IF A or (B and C)
then this can be expressed using two rules as in
319
-------
IF A THEN ...
IF B and C THEN ...
The PRIORITY value is used to determine which rule applies when two or more rules
require that conflicting actions be taken on a link. A conflicting rule with a higher
priority value has precedence over one with a lower value (e.g., PRIORITY 5
outranks PRIORITY l). A rule without a priority value always has a lower priority
than one with a value. For two rules with the same priority value, the rule that
appears first is given the higher priority.
Examples: ; Simple time-based pump control
RULE Rl
IF SIMULATION TIME > 8
THEN PUMP 12 STATUS = ON
ELSE PUMP 12 STATUS = OFF
; Multi-condition orifice gate control
RULE R2A
IF NODE 23 DEPTH > 12
AND LINK 165 FLOW > 100
THEN ORIFICE R55 SETTING =0.5
RULE R2B
IF NODE 23 DEPTH > 12
AND LINK 165 FLOW > 200
THEN ORIFICE R55 SETTING =1.0
RULE R2C
IF NODE 23 DEPTH <= 12
OR LINK 165 FLOW <= 100
THEN ORIFICE R55 SETTING = 0
; PID controller that attempts to keep Node 23's depth at 12:
RULE PID_1
IF NODE 23 DEPTH <> 12
THEN ORIFICE R55 SETTING = PID 0.5 0.1 0.0
; Pump station operation with a main (N1A) and lag (N1B) pump
RULE R3A
IF NODE Nl DEPTH > 5
THEN PUMP N1A STATUS = ON
RULE R3B
IF PUMP N1A TIMEOPEN > 2:30
THEN PUMP NIB STATUS = ON
ELSE PUMP NIB STATUS = OFF
320
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RULE R3C
IF NODE Nl DEPTH <= 0.5
THEN PUMP N1A STATUS = OFF
AND PUMP NIB STATUS = OFF
321
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Section: [POLLUTANTS]
Purpose: Identifies the pollutants being analyzed.
Format:
Name Units Grain Cgw Cii Kd (Sflag CoPoll CoFract Cdwf Cinit)
Remarks: Name name assigned to pollutant.
uni ts concentration units (MG/L for milligrams per liter, UG/L for micrograms
per liter, or #/L for direct count per liter).
Grain concentration of pollutant in rainfall (concentration units).
Cgw concentration of pollutant in groundwater (concentration units).
cii concentration of pollutant in inflow/infiltration (concentration units).
Kdecay first-order decay coefficient (1/days).
sflag YES if pollutant buildup occurs only when there is snow cover, NO
otherwise (default is NO).
CoPoll name of co-pollutant (default is no co-pollutant designated by a *).
CoFract fraction of co-pollutant concentration (default is 0).
cdwf pollutant concentration in dry weather flow (default is 0).
cini t pollutant concentration throughout the conveyance system at the start of
the simulation (default is 0).
FLOW is a reserved word and cannot be used to name a pollutant.
Parameters sflag through cinit can be omitted if they assume their default
values. If there is no co-pollutant but non-default values for cdwf or cinit, then
enter an asterisk (*) for the co-pollutant name.
When pollutant X has a co-pollutant Y, it means that fraction CoFract of pollutant Y's
runoff concentration is added to pollutant X's runoff concentration when wash off from
a subcatchment is computed.
The dry weather flow concentration can be overridden for any specific node of the
conveyance system by editing the node's Inflows property.
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Section: [LANDUSES]
Purpose: Identifies the various categories of land uses within the drainage area. Each
subcatchment area can be assigned a different mix of land uses. Each land use can
be subjected to a different street sweeping schedule.
Format: Name (Sweeplnterval Availability LastSweep)
Remarks: Name land use name.
Sweep interval days between street sweeping.
Availability fraction of pollutant buildup available for removal by street
sweeping.
LastSweep days since last sweeping at start of the simulation.
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Section: [COVERAGES]
Purpose: Specifies the percentage of a subcatchment's area that is covered by each category
of land use.
Format: Subcat Landuse Percent Landuse Percent
Remarks: Subcat subcatchment name.
Landuse land use name.
Percen t percent of subcatchment area.
More than one pair of land use - percentage values can be entered per line. If more
than one line is needed, then the subcatchment name must still be entered first on
the succeeding lines.
If a land use does not pertain to a subcatchment, then it does not have to be entered.
If no land uses are associated with a subcatchment then no contaminants will appear
in the runoff from the subcatchment.
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Section: [LOADINGS]
Purpose: Specifies the pollutant buildup that exists on each subcatchment at the start of a
simulation.
Format:
Subcat Pollut InitBuildup Pollut InitBuildup ...
Remarks: Subcat
Pollut
InitBuildup
name of a subcatchment.
name of a pollutant.
initial buildup of pollutant (Ibs/acre or kg/hectare).
More than one pair of pollutant - buildup values can be entered per line. If more than
one line is needed, then the subcatchment name must still be entered first on the
succeeding lines.
If an initial buildup is not specified for a pollutant, then its initial buildup is computed
by applying the DRY_DAYS option (specified in the [OPTIONS] section) to the
pollutant's buildup function for each land use in the subcatchment.
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Section: [BUILDUP]
Purpose: Specifies the rate at which pollutants build up over different land uses between rain
events.
Format:
Landuse Pollutant FuncType Cl C2 C3 PerUnit
Remarks: Landuse
Pollutant
FuncType
Cl,C2, C3
PerUnit
land use name.
pollutant name.
buildup function type: (POW / EXP / SAT / EXT).
buildup function parameters (see Table D-2).
AREA if buildup is per unit area, CURBLENGTH if per length of curb.
Buildup is measured in pounds (kilograms) per unit of area (or curb length) for
pollutants whose concentration units are either mg/L or ug/L. If the concentration
units are counts/L, then the buildup is expressed as counts per unit of area (or curb
length).
Table D-2 Pollutant buildup functions (t is antecedent dry days)
Name
POW
EXP
SAT
EXT
Function
Power
Exponential
Saturation
External
Equation
Min(C1,C2*tC3)
C1*(1 -exp(-C2*t))
C1*t/(C3 + t)
See below
For the EXT buildup function, C1 is the maximum possible buildup (mass per area or
curb length), C2 is a scaling factor, and C3 is the name of a Time Series that
contains buildup rates (as mass per area or curb length per day) as a function of
time.
326
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Section: [WASHOFF]
Purpose: Specifies the rate at which pollutants are washed off from different land uses during
rain events.
Format: Landuse Pollutant FuncType Cl C2 SweepRmvl BmpRmvl
Remarks: Landuse
Pollutant
FuncType
Cl, C2
SweepRmvl
BmpRmvl
land use name.
pollutant name.
washoff function type: EXP / RC / EMC.
washoff function coefficients(see Table D-3).
street sweeping removal efficiency (percent)
BMP removal efficiency (percent).
Table D-3 Pollutant wash off functions
Name
EXP
RC
EMC
Function
Exponential
Rating Curve
Event Mean
Concentration
Equation
C1 (runoff)02 (buildup)
C1 (runoff)02
C1
Units
Mass/hour
Mass/sec
Mass/Liter
Each washoff function expresses its results in different units.
For the Exponential function the runoff variable is expressed in catchment depth
per unit of time (inches per hour or millimeters per hour), while for the Rating Curve
function it is in whatever flow units were specified in the [OPTIONS] section of the
input file (e.g., CFS, CMS, etc.).
The buildup parameter in the Exponential function is the current total buildup over
the subcatchment's land use area in mass units. The units of ci in the Exponential
function are (in/hr) -°2 per hour (or (mm/hr) ~C2 per hour). For the Rating Curve
function, the units of ci depend on the flow units employed. For the EMC (event
mean concentration) function, ci is always in concentration units.
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Section: [TREATMENT]
Purpose: Specifies the degree of treatment received by pollutants at specific nodes of the
drainage system.
Format: Node Pollut Result = Func
Remarks: Node
Pollut
Result
Func
Name of node where treatment occurs.
Name of pollutant receiving treatment.
Result computed by treatment function. Choices are:
c (function computes effluent concentration)
R (function computes fractional removal).
mathematical function expressing treatment result in terms of pollutant
concentrations, pollutant removals, and other standard variables (see
below).
Treatment functions can be any well-formed mathematical expression involving:
inlet pollutant concentrations (use the pollutant name to represent a
concentration)
removal of other pollutants (use R_ pre-pended to the pollutant name to
represent removal)
process variables which include:
FLOW for flow rate into node (user's flow units)
DEPTH for water depth above node invert (ft or m)
AREA for node surface area (ft2 or m2)
DT for routing time step (seconds)
HRT for hydraulic residence time (hours)
Any of the following math functions can be used in a treatment function:
• abs(x) for absolute value of x
• sgn(x) which is +1 for x >= 0 or -1 otherwise
• step(x) which is 0 forx <= 0 and 1 otherwise
• sqrt(x) for the square root of x
• log(x) for logarithm base e of x
• Iog10(x) for logarithm base 10 of x
• exp(x) for e raised to the x power
• the standard trig functions (sin, cos, tan, and cot)
• the inverse trig functions (asin, acos, atan, and acot)
• the hyperbolic trig functions (sinh, cosh, tanh, and coth)
along with the standard operators +, -, *, /, A (for exponentiation ) and any level of
nested parentheses.
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Examples: ; 1-st order decay of BOD
Node23 BOD C = BOD * exp(-0.05*HRT)
; lead removal is 20% of TSS removal
Node23 Lead R = 0.2 * R TSS
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Section: [INFLOWS]
Purpose: Specifies external hydrographs and pollutographs that enter the drainage system at
specific nodes.
Formats: Node FLOW Tseries (FLOW (1.0 Sfactor Base Pat))
Node Pollut Tseries (Type (Mfactor Sfactor Base Pat))
Remarks: Node
Pollut
Tseries
Type
Mfactor
Sfactor
Base
Pat
name of node where external inflow enters.
name of pollutant.
name of time series in [TIMESERIES] section describing how
external flow or pollutant loading varies with time.
CONCEN if pollutant inflow is described as a concentration, MASS
if it is described as a mass flow rate (default is CONCEN).
the factor that converts the inflow's mass flow rate units into the
project's mass units per second, where the project's mass units
are those specified for the pollutant in the [POLLUTANTS] section
(default is 1.0 - see example below).
scaling factor that multiplies the recorded time series values
(default is 1.0).
constant baseline value added to the time series value (default is
0.0).
name of optional time pattern in [PATTERNS] section used to
adjust the baseline value on a periodic basis.
External inflows are represented by both a constant and time varying component as
follows:
Inflow = (Baseline value) * (Pattern factor) +
(Scaling factor) * (Time series value)
If an external inflow of a pollutant concentration is specified for a node, then there
must also be an external inflow of FLOW provided for the same node, unless the node
is an Outfall. In that case a pollutant can enter the system during periods when the
outfall is submerged and reverse flow occurs.
Examples: NODE2
NODE33
FLOW N2FLOW
TSS N33TSS CONCEN
;Mass inflow of BOD in time series N65BOD given in Ibs/hr
;(126 converts Ibs/hr to mg/sec)
NODE65 BOD N65BOD MASS 126
;Flow inflow with baseline and scaling factor
N176 FLOW FLOW 176 FLOW 1.0 0.5 12.7 FlowPat
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Section: [DWF]
Purpose: Specifies dry weather flow and its quality entering the drainage system at specific
nodes.
Format: Node Type Base (Patl Pat2 Pat3 Pat4)
Remarks: Node name of node where dry weather flow enters.
Type keyword FLOW for flow or pollutant name for quality constituent.
Base average baseline value for corresponding constituent (flow or
concentration units).
Patl,
Pat2,
etc. names of up to four time patterns appearing in the [PATTERNS] section.
The actual dry weather input will equal the product of the baseline value and any
adjustment factors supplied by the specified patterns. (If not supplied, an adjustment
factor defaults to 1.0.)
The patterns can be any combination of monthly, daily, hourly and weekend hourly
patterns, listed in any order. See the [PATTERNS] section for more details.
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Section: [RDII]
Purpose: Specifies the parameters that describe rainfall-dependent infiltration/inflow (RDII)
entering the drainage system at specific nodes.
Format: Node UHgroup SewerArea
Remarks: Node name of a node.
UHgroup name of an RDII unit hydrograph group specified in the
[HYDROGRAPHS] section.
SewerArea area of the sewershed which contributes RDII to the node (acres or
hectares).
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Section: [HYDROGRAPHS]
Purpose: Specifies the shapes of the triangular unit hydrographs that determine the amount of
rainfall-dependent infiltration/inflow (RDM) entering the drainage system.
Formats: Name Raingage
Name Month SHORT/MEDIUM/LONG R T K (Dmax Dree DO)
Remarks: Name
Raingage
Month
R
T
K
Dmax
Dree
DO
name assigned to a unit hydrograph group.
name of the rain gage used by the unit hydrograph group.
month of the year (e.g., JAN, FEE, etc. or ALL for all months).
response ratio for the unit hydrograph.
time to peak (hours) for the unit hydrograph.
recession limb ratio for the unit hydrograph.
maximum initial abstraction depth available (in rain depth units).
initial abstraction recovery rate (in rain depth units per day)
initial abstraction depth already filled at the start of the simulation (in
rain depth units).
For each group of unit hydrographs, use one line to specify its rain gage followed by
as many lines as are needed to define each unit hydrograph used by the group
throughout the year. Three separate unit hydrographs, that represent the short-term,
medium-term, and long-term RDM responses, can be defined for each month (or all
months taken together). Months not listed are assumed to have no RDM.
The response ratio (R) is the fraction of a unit of rainfall depth that becomes RDM.
The sum of the ratios for a set of three hydrographs does not have to equal 1.0.
The recession limb ratio (K) is the ratio of the duration of the hydrograph's recession
limb to the time to peak (T) making the hydrograph time base equal to T*(1+K) hours.
The area under each unit hydrograph is 1 inch (or mm).
The optional initial abstraction parameters determine how much rainfall is lost at the
start of a storm to interception and depression storage. If not supplied then the
default is no initial abstraction.
Examples: ; All three unit hydrographs in this group have the same shapes except those in July,
; which have only a short- and medium-term response and a different shape.
UH101 RG1
UH101 ALL SHORT 0.033 1.0 2.0
UH101 ALL MEDIUM 0.300 3.0 2.0
UH101 ALL LONG 0.033 10.0 2.0
UH101 JUL SHORT 0.033 0.5 2.0
UH101 JUL MEDIUM 0.011 2.0 2.0
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Section: [CURVES]
Purpose: Describes a relationship between two variables in tabular format.
Format: Name Type X-value Y-value . . .
Remarks: JVame name assigned to table
Type STORAGE / SHAPE / DIVERSION / TIDAL / PUMPI / PUMP2 /
PUMPS / PUMP4 / RATING / CONTROL
x-value an x (independent variable) value
r-value the y (dependent variable) value corresponding to x
Multiple pairs of x-y values can appear on a line. If more than one line is needed,
repeat the curve's name (but not the type) on subsequent lines. The x-values must
be entered in increasing order.
Choices for curve type have the following meanings (flows are expressed in the
user's choice of flow units set in the [OPTIONS] section):
STORAGE surface area in ft2 (m2) v. depth in ft (m) for a storage unit node
SHAPE width v. depth for a custom closed cross-section, both
normalized with respect to full depth
DIVERSION diverted outflow v. total inflow for a flow divider node
TIDAL water surface elevation in ft (m) v. hour of the day for an outfall
node
PUMPI pump outflow v. increment of inlet node volume in ft3 (m3)
PUMP2 pump outflow v. increment of inlet node depth in ft (m)
PUMPS pump outflow v. head difference between outlet and inlet nodes
in ft (m)
PUMP4 pump outflow v. continuous depth in ft (m)
RATING outlet flow v. head in ft (m)
CONTROL control setting v. controller variable
See Section 3.2 for illustrations of the different types of pump curves.
Examples: ; Storage curve (x = depth, y = surface area)
AC1 STORAGE 0 1000 2 2000 4 3500 6 4200 8 5000
;Typel pump curve (x = inlet wet well volume, y = flow )
PCI PUMPI
PCI 100 5 300 10 500 20
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Section: [TIMESERIES]
Purpose: Describes how a quantity varies over time.
Formats: Name ( Date ) Hour Value
Name Time Value ...
Name FILE Fname
Remarks: Name
Date
Hour
Time
Value
Fname
name assigned to time series.
date in Month/Day/Year format (e.g., June 15, 2001 would be
6/15/2001).
24-hour military time (e.g., 8:40 pm would be 20:40) relative to the last
date specified (or to midnight of the starting date of the simulation if no
previous date was specified).
hours since the start of the simulation, expressed as a decimal number
or as hours:minutes.
value corresponding to given date and time.
name of a file in which the time series data are stored
There are two options for supplying the data for a time series:
i. directly within this input file section as described by the first two formats
ii. through an external data file named with the third format.
When direct data entry is used, multiple date-time-value or time-value entries can
appear on a line. If more than one line is needed, the table's name must be repeated
as the first entry on subsequent lines.
When an external file is used, each line in the file must use the same formats listed
above, except that only one date-time-value (or time-value) entry is allowed per line.
Any line that begins with a semicolon is considered a comment line and is ignored.
Blank lines are not allowed.
Note that there are two methods for describing the occurrence time of time series
data:
as calendar date/time of day (which requires that at least one date, at the start of
the series, be entered)
as elapsed hours since the start of the simulation.
For the first method, dates need only be entered at points in time when a new day
occurs.
Examples: ; Rainfall time series with dates specified
TS1 6-15-2001 7:00 0.1 8:00 0.2 9:00 0.05 10:00 0
TS1 6-21-2001 4:00 0.2 5:00 0 14:00 0.1 15:00 0
335
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;Inflow hydrograph - time relative to start of simulation
HY1 0 0 1.25 100 2:30 150 3.0 120 4.5 0
HY1 32:10 0 34.0 57 35.33 85 48.67 24 50 0
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Section: [PATTERNS]
Purpose: Specifies time pattern of dry weather flow or quality in the form of adjustment factors
applied as multipliers to baseline values.
Format:
Name MONTHLY
Name DAILY
Name HOURLY
Name WEEKEND
Factorl Factor2
Factorl Factor2
Factorl Factor2
Factorl Factor2
Factorl2
Factor?
Factor24
Factor24
Remarks: Name name used to identify the pattern.
Factorl,
Fact or 2,
etc. multiplier values.
The MONTHLY format is used to set monthly pattern factors for dry weather flow
constituents.
The DAILY format is used to set dry weather pattern factors for each day of the
week, where Sunday is day 1.
The HOURLY format is used to set dry weather factors for each hour of the day
starting from midnight. If these factors are different for weekend days than for
weekday days then the WEEKEND format can be used to specify hourly adjustment
factors just for weekends.
More than one line can be used to enter a pattern's factors by repeating the pattern's
name (but not the pattern type) at the beginning of each additional line.
The pattern factors are applied as multipliers to any baseline dry weather flows or
quality concentrations supplied in the [DWF] section.
Examples: ; Day of week adjustment factors
Dl DAILY 0.5 1.0 1.0 1.0 1.0 1.0 0.5
D2 DAILY 0.8 0.9 1.0 1.1 1.0 0.9 0.8
; Hourly adjustment factors
HI HOURLY 0.5 0.6 0.7 0.8 0.8 0.9
HI 1.1 1.2 1.3 1.5 1.1 1.0
HI 0.90.80.70.60.50.5
HI 0.5 0.5 0.5 0.5 0.5 0.5
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D3. Map Data Section
SWMM's graphical user interface (GUI) can display a schematic map of the drainage area being
analyzed. This map displays subcatchments as polygons, nodes as circles, links as polylines, and
rain gages as bitmap symbols. In addition it can display text labels and a backdrop image, such
as a street map. The GUI has tools for drawing, editing, moving, and displaying these map
elements. The map's coordinate data are stored in the format described below. Normally these
data are simply appended to the SWMM input file by the GUI so users do not have to concern
themselves with it. However it is sometimes more convenient to import map data from some other
source, such as a CAD or CIS file, rather than drawing a map from scratch using the GUI. In this
case the data can be added to the SWMM project file using any text editor or spreadsheet
program. SWMM does not provide any automated facility for converting coordinate data from
other file formats into the SWMM map data format.
SWMM's map data are organized into the following seven sections:
[MAP]
[POLYGONS]
[COORDINATES]
[VERTICES]
[LABELS]
[SYMBOLS]
[BACKDROP]
X,Y coordinates of the map's bounding rectangle
X,Y coordinates for each vertex of subcatchment polygons
X,Y coordinates for nodes
X,Y coordinates for each interior vertex of polyline links
X,Y coordinates and text of labels
X,Y coordinates for rain gages
X,Y coordinates of the bounding rectangle and file name of the backdrop
image.
Figure D-2 displays a sample map and Figure D-3 the data that describes it. Note that only one
link, 3, has interior vertices which give it a curved shape. Also observe that this map's coordinate
system has no units, so that the positions of its objects may not necessarily coincide to their real-
world locations.
Figure D-2 Example study area map
338
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[MAP]
DIMENSIONS
UNITS
[COORDINATES]
;/Node
Nl
N2
N3
N4
[VERTICES]
; /Link
3
3
[SYMBOLS]
;;Gage
Gl
[Polygons]
;;Subcatchment
SI
SI
SI
0.00 0.00
None
X-Coord
4006.62
6953.64
4635.76
8509.93
X-Coord
5430.46
7251.66
X-Coord
5298.01
X-Coord
3708.61
4834.44
3675.50
10000.00 10000.00
Y-Coord
5463.58
4768.21
3443.71
827.81
Y-Coord
2019.87
927.15
Y-Coord
9139.07
Y-Coord
8543.05
7019.87
4834.44
< additional vertices not listed >
S2 6523.18 8079.47
S2 8112.58 8841.06
Figure D-3 Data for example study area map
A detailed description of each map data section will now be given. Remember that map data are
only used as a visualization aid for SWMM's GUI and they play no role in any of the runoff or
routing computations. Map data are not needed for running the command line version of SWMM.
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Section: [MAP]
Purpose: Provides dimensions and distance units for the map.
Formats: DIMENSIONS xi Yl X2 Y2
UNITS FEET / METERS / DEGREES / NONE
Remarks: xi lower-left X coordinate of full map extent
Yl lower-left Y coordinate of full map extent
X2 upper-right X coordinate of full map extent
Y2 upper-right Y coordinate of full map extent
Section: [COORDINATES]
Purpose: Assigns X,Y coordinates to drainage system nodes.
Format: Node Xcoord Ycoord
Remarks: Node name of node.
Xcoord horizontal coordinate relative to origin in lower left of map.
Ycoord vertical coordinate relative to origin in lower left of map.
Section: [VERTICES]
Purpose: Assigns X,Y coordinates to interior vertex points of curved drainage system links.
Format: Link Xcoord Ycoord
Remarks: Link name of link.
Xcoord horizontal coordinate of vertex relative to origin in lower left of map.
Ycoord vertical coordinate of vertex relative to origin in lower left of map.
Include a separate line for each interior vertex of the link, ordered from the inlet node
to the outlet node.
Straight-line links have no interior vertices and therefore are not listed in this section.
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Section: [POLYGONS]
Purpose: Assigns X,Y coordinates to vertex points of polygons that define a subcatchment
boundary.
Format: Subcat Xcoord Ycoord
Remarks: Subcat name of subcatchment.
Xcoord horizontal coordinate of vertex relative to origin in lower left of map.
Ycoord vertical coordinate of vertex relative to origin in lower left of map.
Include a separate line for each vertex of the subcatchment polygon, ordered in a
consistent clockwise or counter-clockwise sequence.
Section: [SYMBOLS]
Purpose: Assigns X,Y coordinates to rain gage symbols.
Format: Gage Xcoord Ycoord
Remarks: Gage name of rain gage.
Xcoord horizontal coordinate relative to origin in lower left of map.
Ycoord vertical coordinate relative to origin in lower left of map.
Section: [LABELS]
Purpose: Assigns X,Y coordinates to user-defined map labels.
Format: Xcoord Ycoord Label (Anchor Font Size Bold Italic)
Remarks: Xcoord horizontal coordinate relative to origin in lower left of map.
Ycoord vertical coordinate relative to origin in lower left of map.
Label text of label surrounded by double quotes.
Anchor name of node or subcatchment that anchors the label on zoom-ins (use
an empty pair of double quotes if there is no anchor).
Font name of label's font (surround by double quotes if the font name includes
spaces).
size font size in points.
Bold YES for bold font, NO otherwise.
italic YES for italic font, NO otherwise.
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Use of the anchor node feature will prevent the label from moving outside the viewing
area when the map is zoomed in on.
If no font information is provided then a default font is used to draw the label.
Section: [BACKDROP]
Purpose: Specifies file name and coordinates of map's backdrop image.
Formats: FILE Fname
DIMENSIONS XI Yl X2 Y2
Remarks: Fname
XI
Yl
X2
Y2
name of file containing backdrop image
lower-left X coordinate of backdrop image
lower-left Y coordinate of backdrop image
upper-right X coordinate of backdrop image
upper-right Y coordinate of backdrop image
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APPENDIX E - ERROR AND WARNING MESSAGES
ERROR 101: memory allocation error.
There is not enough physical memory in the computer to analyze the study area.
ERROR 103: cannot solve KW equations for Link xxx.
The internal solver for Kinematic Wave routing failed to converge for the
specified link at some stage of the simulation.
ERROR 105: cannot open ODE solver.
The system could not open its Ordinary Differential Equation solver.
ERROR 107: cannot compute a valid time step.
A valid time step for runoff or flow routing calculations (i.e., a number greater
than 0) could not be computed at some stage of the simulation.
ERROR 108: ambiguous outlet ID name for Subcatchment xxx.
The name of the element identified as the outlet of a subcatchment belongs to
both a node and a subcatchment in the project's data base.
ERROR 109: invalid parameter values for Aquifer xxx.
The properties entered for an aquifer object were either invalid numbers or were
inconsistent with one another (e.g., the soil field capacity was higher than the
porosity).
ERROR 110: ground elevation is below water table for Subcatchment xxx.
The ground elevation assigned to a subcatchment's groundwater parameters
cannot be below the initial water table elevation of the aquifer object used by the
subcatchment.
ERROR 111: invalid length for Conduit xxx.
Conduits cannot have zero or negative lengths.
ERROR 113: invalid roughness for Conduit xxx.
Conduits cannot have zero or negative roughness values.
ERROR 114: invalid number of barrels for Conduit xxx.
Conduits must consist of one or more barrels.
ERROR 115: adverse slope for Conduit xxx.
Under Steady or Kinematic Wave routing, all conduits must have positive slopes.
This can usually be corrected by reversing the inlet and outlet nodes of the
conduit (i.e., right click on the conduit and select Reverse from the popup menu
that appears). Adverse slopes are permitted under Dynamic Wave routing.
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ERROR 117: no cross section defined for Link xxx.
Cross section geometry was never defined for the specified link.
ERROR 119: invalid cross section for Link xxx.
Either an invalid shape or invalid set of dimensions was specified for a link's
cross section.
ERROR 121: missing or invalid pump curve assigned to Pump xxx.
Either no pump curve or an invalid type of curve was specified for a pump.
ERROR 131: the following links form cyclic loops in the drainage system.
The Steady and Kinematic Wave flow routing methods cannot be applied to
systems where a cyclic loop exists (i.e., a directed path along a set of links that
begins and ends at the same node). Most often the cyclic nature of the loop can
be eliminated by reversing the direction of one of its links (i.e., switching the inlet
and outlet nodes of the link). The names of the links that form the loop will be
listed following this message.
ERROR 133: Node xxx has more than one outlet link.
Under Steady and Kinematic Wave flow routing, a junction node can have only a
single outlet link.
ERROR 134: Node xxx has illegal DUMMY link connections.
Only a single conduit with a DUMMY cross-section or Ideal-type pump can be
directed out of a node; a node with an outgoing Dummy conduit or Ideal pump
cannot have all of its incoming links be Dummy conduits and Ideal pumps; a
Dummy conduit cannot have its upstream end connected to a storage node.
ERROR 135: Divider xxx does not have two outlet links.
Flow divider nodes must have two outlet links connected to them.
ERROR 136: Divider xxx has invalid diversion link.
The link specified as being the one carrying the diverted flow from a flow divider
node was defined with a different inlet node.
ERROR 137: Weir Divider xxx has invalid parameters.
The parameters of a Weir-type divider node either are non-positive numbers or
are inconsistent (i.e., the value of the discharge coefficient times the weir height
raised to the 3/2 power must be greater than the minimum flow parameter).
ERROR 138: Node xxx has initial depth greater than maximum depth.
Self-explanatory.
ERROR 139: Regulator xxx is the outlet of a non-storage node.
Under Steady or Kinematic Wave flow routing, orifices, weirs, and outlet links can
only be used as outflow links from storage nodes.
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ERROR 141: Outfall xxx has more than 1 inlet link or an outlet link.
An outfall node is only permitted to have one link attached to it.
ERROR 143: Regulator xxx has invalid cross-section shape.
An orifice must have either a CIRCULAR or RECT_CLOSED shape, while a weir
must have either a RECTJDPEN, TRAPEZOIDAL, or TRIANGULAR shape.
ERROR 145: Drainage system has no acceptable outlet nodes.
Under Dynamic Wave flow routing, there must be at least one node designated
as an outfall.
ERROR 151: a Unit Hydrograph in set xxx has invalid time base.
The time base of a Unit Hydrograph cannot be negative and if positive, must not
be less than the recording interval for its rain gage.
ERROR 153: a Unit Hydrograph in set xxx has invalid response ratios.
The response ratios for a set of Unit Hydrographs (the short-, medium-, and long-
term response hydrographs) must be between 0 and 1.0 and cannot add up to a
value greater than 1.0
ERROR 155: invalid sewer area for RDM at Node xxx.
The sewer area contributing RDM inflow to a node cannot be a negative number.
ERROR 156: inconsistent data file name for Rain Gage xxx.
If two Rain Gages use files for their data sources and have the same Station IDs
then they must also use the same data files.
ERROR 157: inconsistent rainfall format for Rain Gage xxx.
If two or more rain gages use the same Time Series for their rainfall data then
they must all use the same data format (intensity, volume, or cumulative volume).
ERROR 158: time series for Rain Gage xxx is also used by another object.
A rainfall Time Series associated with a Rain Gage cannot be used by another
object that is not also a Rain Gage.
ERROR 159: recording interval greater than time series interval for Rain Gage xxx.
The recording time interval specified for the rain gage is greater than the smallest
time interval between values in the Time Series used by the gage.
ERROR 161: cyclic dependency in treatment functions at Node xxx.
An example would be where the removal of pollutant 1 is defined as a function of
the removal of pollutant 2 while the removal of pollutant 2 is defined as a function
of the removal of pollutant 1.
ERROR 171: Curve xxx has invalid or out of sequence data.
The X-values of a curve object must be entered in increasing order.
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ERROR 173: Time Series xxx has its data out of sequence.
The time (or date/time) values of a time series must be entered in sequential
order.
ERROR 181: invalid Snow Melt Climatology parameters.
The ATI Weight or Negative Melt Ratio parameters are not between 0 and 1 or
the site latitude is not between -60 and +60 degrees.
ERROR 182: invalid parameters for Snow Pack xxx.
A snow pack's minimum melt coefficient is greater than its maximum coefficient;
the fractions of free water capacity or impervious plowable area are not between
0 and 1; or the snow removal fractions sum to more than 1.0.
ERROR 183: no type specified for LID xxx.
A named LID control has layers defined for it but its LID type was never
specified.
ERROR 184: missing layer for LID xxx.
A required design layer is missing for the specified LID control.
ERROR 185: invalid parameter value for LID xxx.
An invalid value was supplied for an LID control's design parameter.
ERROR 187: LID area exceeds total area for Subcatchment xxx.
The area of the LID controls placed within the subcatchment is greater than that
of the subcatchment itself.
ERROR 188: LID capture area exceeds total impervious area for Subcatchment xxx.
The amount of impervious area assigned to be treated by LID controls in the
subcatchment exceeds the total amount of impervious area available.
ERROR 191: simulation start date comes after ending date.
Self-explanatory.
ERROR 193: report start date comes after ending date.
Self-explanatory.
ERROR 195: reporting time step is less than routing time step.
Self-explanatory.
ERROR 200: one or more errors in input file.
This message appears when one or more input file parsing errors (the 200-series
errors) occur.
ERROR 201: too many characters in input line.
A line in the input file cannot exceed 1024 characters.
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ERROR 203: too few items at line n of input file.
Not enough data items were supplied on a line of the input file.
ERROR 205: invalid keyword at line n of input file.
An unrecognized keyword was encountered when parsing a line of the input file.
ERROR 207: duplicate ID name at line n of input file.
An ID name used for an object was already assigned to an object of the same
category.
ERROR 209: undefined object xxx at line n of input file.
A reference was made to an object that was never defined. An example would be
if node 123 were designated as the outlet point of a subcatchment, yet no such
node was ever defined in the study area.
ERROR 211: invalid number xxx at line n of input file.
Either a string value was encountered where a numerical value was expected or
an invalid number (e.g., a negative value) was supplied.
ERROR 213: invalid date/time xxx at line n of input file.
An invalid format for a date or time was encountered. Dates must be entered as
month/day/year and times as either decimal hours or as hour:minute:second.
ERROR 217: control rule clause out of sequence at line n of input file.
Errors of this nature can occur when the format for writing control rules is not
followed correctly (see Section C.3).
ERROR 219: data provided for unidentified transect at line n of input file.
A GR line with Station-Elevation data was encountered in the [TRANSECTS]
section of the input file after an NC line but before any X1 line that contains the
transect's ID name.
ERROR 221: transect station out of sequence at line n of input file.
The station distances specified for the transect of an irregular cross section must
be in increasing numerical order starting from the left bank.
ERROR 223: Transect xxx has too few stations.
A transect for an irregular cross section must have at least 2 stations defined for
it.
ERROR 225: Transect xxx has too many stations.
A transect cannot have more than 1500 stations defined for it.
ERROR 227: Transect xxx has no Manning's N.
No Manning's N was specified for a transect (i.e., there was no NC line in the
[TRANSECTS] section of the input file.
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ERROR 229: Transect xxx has invalid overbank locations.
The distance values specified for either the left or right overbank locations of a
transect do not match any of the distances listed for the transect's stations.
ERROR 231: Transect xxx has no depth.
All of the stations for a transect were assigned the same elevation.
ERROR 233: invalid treatment function expression at line n of input file.
A treatment function supplied for a pollutant at a specific node is either not a
correctly formed mathematical expression or refers to unknown pollutants,
process variables, or math functions.
ERROR 301: files share same names.
The input, report, and binary output files specified on the command line cannot
have the same names.
ERROR 303: cannot open input file.
The input file either does not exist or cannot be opened (e.g., it might be in use
by another program).
ERROR 305: cannot open report file.
The report file cannot be opened (e.g., it might reside in a directory to which the
user does not have write privileges).
ERROR 307: cannot open binary results file.
The binary output file cannot be opened (e.g., it might reside in a directory to
which the user does not have write privileges).
ERROR 309: error writing to binary results file.
There was an error in trying to write results to the binary output file (e.g., the disk
might be full or the file size exceeds the limit imposed by the operating system).
ERROR 311: error reading from binary results file.
The command line version of SWMM could not read results saved to the binary
output file when writing results to the report file.
ERROR 313: cannot open scratch rainfall interface file.
SWMM could not open the temporary file it uses to collate data together from
external rainfall files.
ERROR 315: cannot open rainfall interface file xxx.
SWMM could not open the specified rainfall interface file, possibly because it
does not exist or because the user does not have write privileges to its directory.
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ERROR 317: cannot open rainfall data file xxx.
An external rainfall data file could not be opened, most likely because it does not
exist.
ERROR 318: date out of sequence in rainfall data file xxx.
An external user-prepared rainfall data file must have its entries appear in
chronological order. The first out-of-order entry will be listed.
ERROR 319: unknown format for rainfall data file.
SWMM could not recognize the format used for a designated rainfall data file.
ERROR 320: invalid format for rainfall interface file.
SWMM was trying to read data from a designated rainfall interface file with the
wrong format (i.e., it may have been created for some other project or actually be
some other type of file).
ERROR 321: no data in rainfall interface file for gage xxx.
This message occurs when a project wants to use a previously saved rainfall
interface file, but cannot find any data for one of its rain gages in the interface
file. It can also occur if the gage uses data from a user-prepared rainfall file and
the station id entered for the gage cannot be found in the file.
ERROR 323: cannot open runoff interface file xxx.
A runoff interface file could not be opened, possibly because it does not exist or
because the user does not have write privileges to its directory.
ERROR 325: incompatible data found in runoff interface file.
SWMM was trying to read data from a designated runoff interface file with the
wrong format (i.e., it may have been created for some other project or actually be
some other type of file).
ERROR 327: attempting to read beyond end of runoff interface file.
This error can occur when a previously saved runoff interface file is being used in
a simulation with a longer duration than the one that created the interface file.
ERROR 329: error in reading from runoff interface file.
A format error was encountered while trying to read data from a previously saved
runoff interface file.
ERROR 331: cannot open hot start interface file xxx.
A hot start interface file could not be opened, possibly because it does not exist
or because the user does not have write privileges to its directory.
ERROR 333: incompatible data found in hot start interface file.
SWMM was trying to read data from a designated hot start interface file with the
wrong format (i.e., it may have been created for some other project or actually be
some other type of file).
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ERROR 335: error in reading from hot start interface file.
A format error was encountered while trying to read data from a previously saved
hot start interface file.
ERROR 336: no climate file specified for evaporation and/or wind speed.
This error occurs when the user specifies that evaporation or wind speed data
will be read from an external climate file, but no name is supplied for the file.
ERROR 337: cannot open climate file xxx.
An external climate data file could not be opened, most likely because it does not
exist.
ERROR 338: error in reading from climate file xxx.
SWMM was trying to read data from an external climate file with the wrong
format.
ERROR 339: attempt to read beyond end of climate file xxx.
The specified external climate does not include data for the period of time being
simulated.
ERROR 341: cannot open scratch RDM interface file.
SWMM could not open the temporary file it uses to store RDM flow data.
ERROR 343: cannot open RDM interface file xxx.
An RDM interface file could not be opened, possibly because it does not exist or
because the user does not have write privileges to its directory.
ERROR 345: invalid format for RDM interface file.
SWMM was trying to read data from a designated RDM interface file with the
wrong format (i.e., it may have been created for some other project or actually be
some other type of file).
ERROR 351: cannot open routing interface file xxx.
A routing interface file could not be opened, possibly because it does not exist or
because the user does not have write privileges to its directory.
ERROR 353: invalid format for routing interface file xxx.
SWMM was trying to read data from a designated routing interface file with the
wrong format (i.e., it may have been created for some other project or actually be
some other type of file).
ERROR 355: mismatched names in routing interface file xxx.
The names of pollutants found in a designated routing interface file do not match
the names used in the current project.
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ERROR 357: inflows and outflows interface files have same name.
In cases where a run uses one routing interface file to provide inflows for a set of
locations and another to save outflow results, the two files cannot both have the
same name.
ERROR 361: could not open external file used for Time Series xxx.
The external file used to provide data for the named time series could not be
opened, most likely because it does not exist.
ERROR 363: invalid data in external file used for used for Time Series xxx.
The external file used to provide data for the named time series has one or more
lines with the wrong format.
WARNING 01: wet weather time step reduced to recording interval for Rain Gage xxx.
The wet weather time step was automatically reduced so that no period with
rainfall would be skipped during a simulation.
WARNING 02: maximum depth increased for Node xxx.
The maximum depth for the node was automatically increased to match the top
of the highest connecting conduit.
WARNING 03: negative offset ignored for Link xxx.
The link's stipulated offset was below the connecting node's invert so its actual
offset was set to 0.
WARNING 04: minimum elevation drop used for Conduit xxx.
The elevation drop between the end nodes of the conduit was below 0.001 ft
(0.00035 m) so the latter value was used instead to calculate its slope.
WARNING 05: minimum slope used for Conduit xxx.
The conduit's computed slope was below the user-specified Minimum Conduit
Slope so the latter value was used instead.
WARNING 06: dry weather time step increased to wet weather time step.
The user-specified time step for computing runoff during dry weather periods was
lower than that set for wet weather periods and was automatically increased to
the wet weather value.
WARNING 07: routing time step reduced to wet weather time step.
The user-specified time step for flow routing was larger than the wet weather
runoff time step and was automatically reduced to the runoff time step to prevent
loss of accuracy.
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WARNING 08: elevation drop exceeds length for Conduit xxx.
The elevation drop across the ends of a conduit exceeds its length. The program
computes the conduit's slope as the elevation drop divided by the length instead
of using the more accurate right triangle method. The user should check for
errors in the length and in both the invert elevations and offsets at the conduit's
upstream and downstream nodes.
WARNING 09: time series interval greater than recording interval for Rain Gage xxx.
The smallest time interval between entries in the precipitation time series used by
the rain gage is greater than the recording time interval specified for the gage. If
this was not actually intended then what appear to be continuous periods of
rainfall in the time series will instead be read with time gaps in between them.
WARNING 10: crest elevation is below downstream invert for regulator Link xxx.
The height of the opening on an orifice, weir, or outlet is below the invert
elevation of its downstream node. Users should check to see if the regulator's
offset height or the downstream node's invert elevation is in error.
WARNING 11: non-matching attributes in Control Rule xxx.
The premise of a control is comparing two different types of attributes to one
another (for example, conduit flow and junction water depth).
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