United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
&EFK
Research and Development
EPA-600/S2-81-238 July 1982
Project Summary
5/o
Urban Rainfall-Runoff-Quality
Data Base
Wayne C. Huber, James P. Heaney, Demetrios A. Aggidis, Robert E.
Dickinson, Kevin J. Smolenyak, and Robert W. Wallace
A common and basic need for mathe-
matical models of urban hydrologic pro-
cesses is for adequate data with which
to calibrate and verify them. Such
models are being used in many applica-
tions and the need for relevant data has
intensified. An equally important data
requirement arises from the need to
characterize urban stormwater dis-
charges and combined sewer overflows.
Since 1974 EPA has supported the
urban rainfall-runoff-quality data base
with these needs in mind. The data base
project, conducted by the University of
Florida, was initiated to bring together
in a consistent and accessible format
the many data sources found in unpub-
lished documents widely scattered
throughout various firms, universities,
and government agencies. Urban rain-
fall-runoff-quality data have been as-
sembled on a storm event basis for 48
catchments in 16 urban areas. Urban
hydrologic data without quality data
have been assembled for an additional
25 catchments in 15 urban areas.
Statistical analysis and descriptions of
the catchments, parameters and sam-
pling procedures are provided In the
data base reports. For each storm event,
the clock times, and the duration and
volume of rainfall and runoff are given.
For quality parameters, ranges, flow-
weighted means, standard deviations,
and loadings (i.e., pounds per acre-inch
of runoff) are provided on an average
basis across all events for each catch-
ment. The same statistics are available
for individual storm events on the data
base magnetic tape. Actual data are on
the magnetic tape and on the EPA STO-
RET data retrieval system.
This Project Summary was developed
by EPA's Municipal Environmental Re-
search Laboratory, Cincinnati, OH, to
announce key findings of the research
project that are fully documented in
separate reports (see Project Report
ordering information at back).
Introduction
In an effort to provide useful planning
and design tools for abatement of quan-
tity and quality problems caused by urban
stormwater discharges and combined
sewer overflows, many mathematical
models have been developed to simulate
the various components of urban hydro-
logic processes. These models range
from very simple to very sophisticated,
yet all share a commbn need—adequate
data for development, calibration, and
verification. These data consist of de-
tailed measurements of rainfall, runoff,
and quality parameters taken at frequent
intervals during storms, such that the
full dynamic and spatially variable nature
of the urban runoff may be studied.
Many recent urban hydrologic models
define the complete hydrograph or pol-
lutograph during a storm event; thus,
measurement of only, say, peak flows
or average concentrations is usually
inadequate for calibration of these
models. Other modeling approaches are
based on the statistical and probabilistic
properties of urban hydrology and run-
off quality. Characterization information
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is essential to execute these modeling
approaches. Various examples of char-
acterization needs are as follows:
• determination of rainfall and runoff
volumes, intensities, peaks, dura-
tions, interevent times, and associ-
ated statistics;
• identification of quality parameters
found in urban runoff;
• determination of ranges, arithmetic
and flow-weighted means, medians,
variances, and other statistics of
quality parameters;
• computation of total mass emis-
sions of quality parameters;
• computation of quality "loadings"
such as pounds per acre, pounds
per curb-mile, pounds per inch of
rainfall, pounds per day, etc., and
combinations, and;
• evaluation of causative relationships
among rainfall, runoff, quality, dem-
ographic, and abatement factors.
Several of the above needs require col-
lection of both runoff and quality data;
e.g., calculation of total pollutant loads,
flow-weighted averages, etc., requires
simultaneous measurement of flows and
concentrations. Thus, concentration data
by themselves are insufficient for many
required analyses.
Data collected for characterization
purposes are not always compatible
with needs of detailed models since
infrequent sampling times and/or omis-
sion of key parameters are likely. Data
suitable for model usage, however, are
usually also well suited for characteriza-
tion purposes provided enough of a
sample exists. It is desirable that char-
acterization data be representative of
an entire year or season and thus result
from samplings of many storms since
one group of data may be used for model
calibration and the remaining group may
be used for verification.
This project has obtained data, col-
lected by others, to fulfill both the detail
modeling needs and the characterization
needs. There have been a surprisingly
large number of studies devoted to col-
lection of data useful for modeling,
although collection of good quality data
is more difficult and lags the quantity
data by a considerable degree.
The locations of urban areas incorpo-
rated in the data base are presented in
Figure 1. Urban rainfall-runoff-quality
data have been assembled on a storm
event basis for 48 catchments in the
following cities or counties: San Fran-
cisco, -CA; Broward County, FL; Lin-
coln, NB; Durham, NC; Windsor, ONT;
Lancaster, PA; Seattle, WA; Racine, Wl;
West Lafayette, IN; Greenfield, MA;
Northampton, MA; Burlington, ONT;
Chicago, IL; Denver, CO; Dade County,
FL; and Toronto, ONT. Rainfall-runoff
data have been assembled for 25 more
catchments in 1 5 cities: Baltimore, MD;
Chicago, IL; Champaign-Urbana, IL;
Bucyrus, OH; Falls Church, VA; Los
Angeles, CA; Portland, OR; Houston,
TX; Salt Lake City, UT; Wichita, KS;
Jackson, MS; Winston-Salem, NC^Phil-
adelphia, PA; Westbury, NY; and Denver,
CO.
Data Base Format
At least four types of information are
relatively available for each location
utilized as a data source:
1. physical, demographic etc., de-
scriptions of the sites, plus maps,
parameters, and sampling methods;
2. published reports and other writ-
ten documentation;
3. the rainfall-runoff-quality data
themselves; and
4. associated modeling data, e.g.,
maps, plans, photos, etc.
Item 1 is provided for each location in
the published data base reports. A stand-
ardized tabular format is used for all
sites. Item 2 is handled through a list of
references for each location. Item 3 is
handled separately wherein all data
have been coded and placed on a mag-
netic tape and in the EPA STORET data
retrieval systems. A limited amount of
data needed for model input, item 4, is
available for short-term loan by contact-
ing the EPA Project Officer. The remain-
der of such data will have to be obtained
by contacting individuals at each location.
In addition, input data for the EPA Storm
Water Management Model, SWMM, are
available for several locations.
The emphasis of this project was not
on the formulation of a sophisticated
storage and retrieval system for the
management of the data base. Rather,
it was to obtain and document as much
data as possible. Hence, the "data base"
itself is merely a magnetic tape contain-
ing records of simple card images. Each
quantity and quality parameter is identi-
fied with a relatively unambiguous
STORET code. On the tape, rainfall-run-
off-quality data are grouped by event
and by catchment with one catchment
per tape file. There are a total of 73
catchments for this edition of the data
base.
Data may be used for comparison
with modeling results simply by obtain-
ing a listing via a "dump" utility of the
tape contents. Alternatively, only se-
lected parameters may be utilized for
statistical analyses and characterization
purposes, although in practice such
manipulations will be better served after
having placed the data onto a rapid-
access storage device.
Statistical Analysis
The thousands of data entries assem-
bled as part of the urban rainfall-runoff-
quality data base represent a sample
from the vast population of such data.
As such, they may be used to obtain in-
sight as to the statistical character of
urban runoff through generation of
means, standard deviations, ranges,
loads, etc. These parameters may be
used in turn to develop causative rela-
tionships among water quality param-
eters and hydrologic and demographic
factor (e.g., used in regression analyses).
Data for all catchments subject to
water quality monitoring have been
analyzed statistically for flow and time-
weighted means and standard deviations
as well as ranges of parameters and sur-
face loadings (i.e., pounds of pollutant
per acre-inch of runoff). Summary values
for each catchment and pollutant are
given for each statistical parameter.
Table 1 is an example of the quality
summary information provided in the
data base reports for each catchment.
In addition, hydrologic information such
as rainfall and runoff depth and duration
is given for each storm event. This sta-
tistical summary information is also
available directly on the magnetic tape,
as are voluminous statistical summaries
for each individual storm event for each
catchment.
Summary
A common denominator of mathe-
matical models of urban hydrologic pro-
cesses is the need for adequate data
with which to calibrate and verify model
representations of physical processes.
Such data need to be collected at short
time intervals during several storms and
are typically time consuming and expen-
sive to obtain. However, the data also
serve the very useful purposes of char-
acterization of urban rainfall-runoff-
quality processes in terms of statistics
and loadings (e.g., pounds per acre) and
extrapolation of such characteristics to
ungaged catchments.
The data for 73 catchments in 20
urban areas represent an effort to aggre-
gate available data into one accessible
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Table 1. Example of the quality data statistical summaries.
STATISTICAL SUMMARY
CATCHMEHT FILE : 88
SEATTLE. IMSUX6TOK. CEMTML BUSINESS DISTRICT.
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,
Westbury, R.I.
Lancaster^M Philadelphia
^jf[Baftimore
/in VI
•gnj r Falls Church
v—-' .
Winston Salem
Durham
j • W
Quality cities
Quantity cities
ifBroward County/
Dade County
Figure 1. Location map for urban areas with rainfall-runoff-quality data (quality cities) and rainfall-runoff data (quantity cities).
data base. The data base itself consists
of a magnetic tape with data organized
in a readily accessible format. The
emphasis has been on assembling and
processing of data rather than con-
structing a sophisticated computerized
data storage and retrieval system. The
EPA STORET system is available for the
latter purpose.
The project results are provided in three
forms:
1. The data base reports that include
descriptions and references of data
sources used and pending and sta-
tistical analyses.
2. A magnetic tape containing the
actual rainfall-runoff-quality data
from each source on a storm event
basis. Copies of the tape will be
provided at cost. In addition, all
data are on the EPA STORET data
retrieval system for additional
accessibility.
3. A limited amount of in-house mod-
eling data (maps, plans, photos,
etc.) available for short-term loan
by contacting the EPA Project
Officer.
The full report was submitted in ful-
fillment of Contract No. 68-03-2663
by the University of Florida, Gainesville,
FL, under the sponsorship of the U.S.
Environmental Protection Agency.
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Wayne C. Huber, James P. Heaney, Demetrios A. Aggidis, Robert E. Dickinson,
Kevin J. Smolenyak, and Robert W. Wallace are with the University of Florida,
Gainesville, FL 32611.
Douglas C. Ammon is the EPA Project Officer (see below).
The complete reports, entitled:
"Urban Rainfall-Runoff-Quality Data Base Update with Statistical Analysis,"
(Order No. PB 80-113 384; Cost: $21.00, subject to change)
"Urban Rainfall-Runoff-Quality Data Base," (Order No. PB 82-221 094;
Cost: $37.50, subject to change)
The above reports will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
•(U8QOVERNMENT PRINTING OFFieEr1M2-5M-W2-426
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Environmental Protection Information
Agency Cincinnati OH 45268 Protn
Agency
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