^USGS
science for a changing world
Prepared in cooperation with the *%. || \
U.S. Environmental Protection Agency
Pre-Restoration Geomorphic Characteristics of
Minebank Run, Baltimore County, Maryland, 2002-04
Scientific Investigations Report 2007-5127
U.S. Department of the Interior
U.S. Geological Survey
-------
Cover. Top photograph taken in June 2004 at station 0158397967, Minebank Run near Glen Arm, Maryland. View is looking upstream
at the stream channel from the station location. Bottom photograph taken in October 2004 at the same location and same view after the
stream restoration was completed in this area. (Photographs by Edward J. Doheny, U.S. Geological Survey.)
-------
Pre-Restoration Geomorphic
Characteristics of Minebank Run,
Baltimore County, Maryland,
2002-04
By Edward J. Doheny1, Roger J. Starsoneck2, Paul M. Mayer3, and Elise A. Striz4
3 U.S. Geological Survey, Baltimore, Maryland.
2 Formerly of U.S. Geological Survey, Baltimore, Maryland.
3 U.S. Environmental Protection Agency. Office of Research and Development, Ada, Oklahoma.
4 Formerly of U.S. Environmental Protection Agency, Office of Research and Development. Ada, Oklahoma.
Prepared in cooperation with the
U.S. Environmental Protection Agency
Scientific Investigations Report 2007-5127
U.S. Department of the Interior
U.S. Geological Survey
-------
U.S. Department of the Interior
DIRK KEMPTHORNE, Secretary
U.S. Geological Survey
Mark D. Myers, Director
LJ.S, Geological Survey, Reston, Virginia: 2007
For more information on the USGS-the Federal source for science about the Earth, its natural and living resources,
natural hazards, and the environment:
World Wide Web: http://www.usgs.gov
Telephone: 1-888-ASK-USGS
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the
U.S. Government.
Although this report is in the public domain, permission must be secured from the individual copyright owners to
reproduce any copyrighted materials contained within this report.
The U.S. Environmental Protection Agency (USEPA), through its Office of Research and Development, partially funded
and collaborated in the research described here under an interagency agreement fDW-14-93944801-0) with the Water
Science Center of the U.S. Geological Survey (USGSJ in Baltimore, Md. The research described here has not been
subjected to USEPA review and therefore does not necessarily reflect the views of USEPA, and no official endorse-
ment should be inferred.
Suggested citation:
Doheny, E.J., Starsoneck, R.J., Mayer, P.M., and Striz, E.A., 2007, Pre-restoration geomorphic characteristics of
Minebank Run, Baltimore County, Maryland, 2002-04: U.S. Geological Survey Scientific Investigations Report
2007-5127, 49 p.
-------
iii
Contents
Abstract 1
Introduction 1
Description of Minebank Run Watershed 2
Description of Study Area 4
Methods of Data Collection 6
Streamflow 6
Longitudinal Profiles 8
Cross Sections 8
Bank Erosion Pins 8
Scour Chains 8
Channel Materials 9
Bed-Elevation Measurements 11
High-Water Marks 11
Geomorphic Characteristics 12
Longitudinal Profiles 12
Cross-Section Geometry 18
Grain-Size Analysis 22
Net Changes in Bed Elevation 26
Stream-Channel Classification 29
Shear-Stress Analysis 31
Data Limitations 34
Summary and Conclusions 35
Acknowledgments 36
References Cited 36
Glossary 39
Appendix 1. Changes in Cross-Section Geometry at Permanent Cross Sections in the
Minebank Run Study Reach, 2002 through 2004 42
Figures
1, Map showing location of Minebank Run watershed and study area, Baltimore
County, Maryland 3
2, Photograph showing view looking upstream at restored section of Minebank Run,
just upstream of the Baltimore Beltway (I-695), 2001 4
3, Map showing detailed view of Minebank Run watershed and study reach, Baltimore
County, Maryland 5
4, Photograph showing view looking upstream at unrestored section of Minebank
Run in Cromwell Valley Park, downstream of the Baltimore Beltway (I-695), 2002 6
5-6. Maps showing—
5, Location of continuous-record streamflow-gaging stations, crest-stage
partial-record stations, and well transects along the Minebank Run study
reach, Baltimore County, Maryland 7
-------
iv
6. Locations of permanent cross sections that were established in the
Minebank Run study reach at Cromwell Valley Park, 2002 10
7-9. Diagrams showing—
7, Example of bank-erosion pin placement and monitoring 12
8. Example of scour chain placement and monitoring 12
9, Examples of longest, intermediate, and shortest axes for measuring median
particle diameter of pebbles during pebble counts 12
10, Plot of grain-size distribution developed from the pebble count at cross section Ff,
Minebank Run study reach, June 6,2003 13
11, Graph showing example of locations within cross section Gg that were selected
for sediment-sample collection, Minebank Run study reach, November 2002 14
12, Diagram showing technique used for tracking of net channel-bed elevations by
use of instream piezometers, Minebank Run study reach, December 2002 through
July 2004 14
13, Photograph showing crest-stage gage for obtaining high-water marks in the
Minebank Run study reach 14
14, Aerial photograph of Minebank Run study reach in Cromwell Valley Park prior to
channel restoration 15
15, Longitudinal profile of channel features in the Minebank Run study reach from
field survey conducted on March 31 and April 1,2003 15
16, Graphs showing variation in point bar and channel bed elevation between 2002
and 2004 longitudinal surveys in the Minebank Run study reach 16
17, Comparison of riffle, pool, and run distribution in the Minebank Run study reach
prior to channel restoration, 2002 through 2004 17
18--26. Graphs showing pre-restoration cross-section geometry at—
18, Permanent cross section Aa, December 2002 through February 2004 19
19, Permanent cross section Bb, December 2002 through February 2004 19
20, Permanent cross section Cc, December 2002 through February 2004 19
21, Permanent cross section Dd, December 2002 through February 2004 20
22, Permanent cross section Ee, December 2002 through January 2004 20
23, Permanent cross section Ff, December 2002 through February 2004 20
24, Permanent cross section Gg, December 2002 through January 2004 21
25, Permanent cross section Hh, December 2002 through January 2004 21
26, Permanent cross section li, December 2002 through January 2004 21
27, Map showing summary of pre-restoration geomorphic conditions in the
Minebank Run study reach, 2002 through 2004 25
28, Graph showing composite pebble countfor Minebank Run study reach above
Sherwood Bridge prior to channel restoration, 2003 28
29—31. Graphs showing comparison of particle-size distributions at—
29, Cross section Ee, 2002 and 2003 29
30, Cross section Ff, 2002 and 2003 29
31, Cross section Gg, 2002 and 2003 29
32-34. Graphs showing net changes in bed elevation over time at—
32, Cross section Ee, January 2. 2003 through July 13,2004 30
33, Cross section Ff, December 3,2002 through July 14,2004 30
34, Cross section Gg, January 2,2003 through July 14, 2004 30
35, Key for the Rosgen classification of natural rivers 32
-------
¥
36-38. Graphs showing—
36, Boundary shear stress versus peak discharge in the Minebank Run study
reach, November 2001 through September 2004 35
37, Boundary shear stress versus mean velocity at the peak discharge during
storm events in the Minebank Run study reach, November 2001 through
September 2004 35
38, Boundary shear stress versus mean velocity at the peak discharge during
storm events in the Minebank Run study reach, November 2001 through
September 2004, and relations developed by Rosgen stream type for
non-urban stream channels 35
Tables
1. Summary of streamflow statistics for station 0158397967, Minebank Run near
Glen Arm, Maryland, water years 2002-04 8
2. Dates, locations, and longitudinal stationing used for the longitudinal-profile
surveys in the Minebank Run study reach, 2002-04 9
3. Basic station information for permanent cross sections located in and near the
Minebank Run study reach 11
4. Grain-size distribution and computation of percent finerfrom pebble count at
Cross Section Ff, Minebank Run study reach, June 6,2003 13
5. Slopes of channel features in the Minebank Run study reach from longitudinal-
profile surveys, 2002-04 16
6. Percentage of riffles, pools, and runs in the Minebank Run study reach from
longitudinal-profile surveys, 2002-04 17
7 Approximate extent of lateral erosion, maximum scour, and maximum depths of
deposition for each permanent cross section in the Minebank Run study reach,
2003-04 22
8, Changes in cross-section geometry at permanent cross-section Hh, Minebank
Run study reach, 2002 through 2004 23
9. Summary of variability of cross-sectional characteristics in the Minebank Run
study reach, 2002 through 2004 24
10. Cumulative distribution of grain sizes, in percent finer, for surficial bed material at
permanent cross section locations in the Minebank Run study reach, 2003 27
11. Median particle diameter from pebble counts and sampling locations associated
with each permanent cross section in the Minebank Run study reach, 2002
and 2003 27
12. Grain-size distribution and computation of percent finerfrom composite pebble
count at all permanent cross sections, Minebank Run study reach, 2003 28
13. Data variables describing the bankfull channel at cross section Hh that were
used for Rosgen classification of the stream channel, 2002-04 33
14. Data variables and boundary shear stress computations for 21 storm runoff
events in the Minebank Run study reach, November 2001 through September 2004 34
-------
vi
Conversion Factors, Vertical Datum, and Abbreviations
Multiply
By
To obtain
Length
inch (in.)
2.54
centimeter
inch (in.)
25.4
millimeter
foot (ft)
0.3048
meter
mile (mi)
1.609
kilometer
Area
acre
4,047
square meter
acre
0.004047
square kilometer
square mile (mi2)
259
hectare
square mile (mi2)
2.59
square kilometer
Volume
cubic foot (ft')
0.000023
acre-feet
Flow Rate
cubic foot per second (ft3/s)
0.02832
cubic meter per second
Mass
pound, avoirdupois (lb)
0.4536
kilogram (kg)
ton, short (2,000 lb)
907.2
kilogram (kg)
Temperatures in degrees Celsius (°C) can be converted to degrees Fahrenheit (°Fj by using the
following equation:
°F = 1.8 (°C) + 32
Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929
(NGVD 29).
Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L)
or micrograms per liter (pg/L).
Water year is defined as the 12-month period beginning October 1 and ending September 30.
The water year is designated by the calendaryear in which it ends. For example, the year
beginning October 1,2003 and ending September 30,2004 is called "water year 2004."
-------
vii
List of Abbreviations
D.C, District of Columbia
DEPRM Department of Environmental Protection and Resource Management
d50 Median particle diameter
IES Institute of Ecosystem Studies
1-695 Interstate 695, Baltimore Beltway
NGVD National Geodetic Vertical Datum of 1929
R2 Coefficient of determination
USEPA U.S. Environmental Protection Agency
USGS U.S. Geological Survey
-------
-------
Pre-Restoration Geomorphic Characteristics of Minebank
Run, Baltimore County, Maryland, 2002-04
By Edward J. Doheny, Roger J. Starsoneck, Paul M. Mayer, and Elise A. Striz
Abstract
Data collected from 2002 through 2004 were used
to assess geomorphic characteristics and geomorphic
changes over time in a selected reach of Minebank Run, a
small urban watershed near Towson, Maryland, prior to its
physical restoration in 2004 and 2005. Longitudinal profdes
of the channel bed, water surface, and bank features were
developed from field surveys. Changes in cross-section
geometry between field surveys were documented. Grain-size
distributions for the channel bed and banks were developed
from pebble counts and laboratory analyses. Net changes in
the elevation of the channel bed over time were documented at
selected locations.
Rosgen Stream Classification was used to classify the
stream channel according to morphological measurements of
slope, entrenchment ratio, width-to-depth ratio, sinuosity, and
median-particle diameter of the channel materials. An analysis
of boundary shear stress in the vicinity of the stream flow-
gaging station was conducted by use of hydraulic variables
computed from cross-section surveys and slope measurements
derived from crest-stage gages in the study reach.
Analysis of the longitudinal profiles indicated noticeable
changes in the percentage and distribution of riffles, pools, and
runs through the study reach between 2002 and 2004. Despite
major changes to the channel profile as a result of storm runoff
events, the overall slope of the channel bed, water surface, and
bank features remained constant at about 1 percent.
The cross-sectional surveys showed net increases in
cross-sectional area, mean depth, and channel width at several
locations between 2002 and 2004, which indicate channel
degradation and widening. Two locations were identified
where significant amounts of sediment were being stored in
the study reach. Data from scour chains identified several
locations where maximum scour ranged from 1.0-1.4 feet
during storm events. Bank retreat varied widely throughout the
study reach and ranged from 0.2 feet to as much as 7.9 feet.
Sequential measurements of bed elevation in selected locations
indicated as much as 2 feet of channel degradation in one
location during a storm event in May 2004 and identified
pulses of sediment that were gradually transported through the
study reach during the monitoring period.
Particle-size analyses of channel bed materials indicated
a median particle diameter of 20.5 millimeters (coarse gravel)
for the study reach, with more than 24 percent being sand
particles (greater than 0.062 millimeters). Analyses of bank
samples showed finer-grained material composing the channel
banks, predominantly silt/clay or a mixture of silt/clay (less
than 0.062 millimeters) and very fine to coarse sand.
The Minebank Run stream channel was classified as a
R4c channel, based on morphological descriptions from the
Rosgen Stream Classification System. The B4c classification
describes a single-thread stream channel with a moderate
entrenchment ratio of 1.4 to 2.2; a width-to-depth ratio greater
than 12; moderate sinuosity of 1.2 or greater; a water-surface
slope of less than 2 percent; and a median-particle diameter in
the gravel range of 2 to 64 millimeters.
Analysis of boundary shear stress indicated larger mean
velocities and boundary shear stress values for Minebank
Run when compared to relations for non-urban B channel
types developed by Rosgen. The slope of the regression line
for mean velocity versus boundary shear stress at Minebank
Run was considerably less than slopes developed by Rosgen
for non-urban channel types. This indicates that relatively
small increases in mean velocity can result in large increases
in boundary shear stress in stream channels with highly
developed watersheds, such as Minebank Run.
Introduction
Minebank Run, a small urban stream in Baltimore
County, Maryland, is a tributary of the Gunpowder River in
the Chesapeake Bay watershed that drains approximately
3.27 mi2 (square miles). Since the late 1990s, Minebank
Run has been the focus of physical restoration efforts by the
Baltimore County Department of Environmental Protection
and Resource Management (DEPRM). One of the primary
goals of physical restoration is to re-establish geomorphic
stability1 of the stream channel.
Urban streams, such as Minebank Run, commonly
display flashy streamflow due to rapid runoff from impervious
surfaces. The flashy streamflow can alter the bed and banks of
'Words in bold are defined in the glossary section of the report.
-------
2 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
the stream channel considerably over time. The erosive power
that is generated in urban streams often leads to degradation
and widening of stream channels, bank failure, increased
sediment supply, and instability of riffle and pool features
along the channel profile (Paul and Meyer, 2001).
In April 2001, the U.S. Environmental Protection Agency
(USEPA) began investigating opportunities in the Baltimore
metropolitan area to study streams that were targeted for
restoration to improve physical function and habitat. Baltimore
was a focus area for stream restoration research because of a
large number of projects that had been carried out since the
early 1990s. Minebank Run was selected for study because
of the opportunity to collect and interpret several different
types of data before and after the channel restoration. The
restoration of Minebank Run has provided an opportunity to
study potential water-quality benefits from implementation of
specific restoration practices, such as re-planting vegetation
in riparian zones, reconfiguring of meanders and point bars,
reconstruction of flood plains, and physical movement of
sections of the channel within the valley. In October 2001,
the U.S. Geological Survey (USGS), the USEPA, and the
Institute of Ecosystem Studies (IES) jointly initiated a study
to investigate the effects of stream restoration on stream
hydrology, denitrification, and overall water quality in a
selected reach of Minebank Run (Doheny and others, 2006). In
response to rapid changes in channel geometry, elevations of
channel features, and the rate of lateral migration of the stream
channel observed during the first yea- of the study, the USGS
was additionally tasked with measuring and documenting the
geomorphic changes within the Minebank Run study reach
prior to physical restoration.
This report describes conventional techniques that were
used for collection of geomorphic data in a study reach in the
Minebank Run watershed during water years 2002 through
2004. Continuous-record streamflow data were collected in the
study reach. Geomorphic data collected in the reach included
surveyed elevations of the channel bed, water surface, and
bank features; surveyed cross sections; measurements of
bank erosion and maximum scour by use of bank pins and
scour chains; pebble counts and samples of material from the
channel bed and banks for grain-size analyses; measurements
of bed elevations over time in selected locations; and high-
water marks from storm runoff events in the watershed.
Data collected during this study were used to assess
pre-restoration geomorphic characteristics and pre-restoration
geomorphic changes over time in the Minebank Run study
reach. Analyses conducted for this report included (1) a
comparison of changes in longitudinal profiles of the channel
bed, water surface, and bank features over time; (2) a
comparison of changes in cross-section geometry due to
aggradation, degradation, and lateral erosion; (3) grain-size
distribution of the channel bed and banks; (4) net changes
in the elevation of the channel bed at selected locations
over time; (5) classification of selected sections of the reach
according to the Rosgen system of stream classification
(Rosgen, 1994, 1996); and (6) boundary shear stress based
on cross-section geometry and water-surface slope in the
vicinity of the streamflow-gaging station.
Description of Minebank Run
Watershed
Minebank Run is a 3.27 mi2 sub-watershed of the
Gunpowder Falls located in the south-central section of
Baltimore County, Maryland, approximately 4.7 mi (miles)
northwest of the Fall Line in the Piedmont Physiographic
Province (fig. 1). The watershed lies between 39° 23' 34"
and 39° 25' 26" north latitude, and between 76° 32' 07" and
76° 35' 40" west longitude. The headwaters are located on the
cast side of Towson, Maryland. The stream flows roughly in
a northeasterly direction and confluences with Gunpowder
Falls near the town of Loch Raven, approximately 0.30 mi
downstream of the lower dam on Loch Raven Reservoir
(Doheny and others, 2006).
The Minebank Run watershed is bounded by 2 ridges
that are oriented approximately from southwest to northeast,
with a broad, lightly sloping valley in between. The valley
width ranges from approximately 0.6 mi near the headwater
and outlet areas, to about 1.5 mi near the mid-point: of the
watershed. The watershed ranges in elevation from about 400
to 500 ft (feet) above sea level at the drainage boundaries, to
about 150 to 400 ft above sea level in the stream valley. Relief
ranges from 100 to 300 ft in most areas of the watershed
(Doheny and others, 2006).
As of 2004, the Minebank Run watershed consisted of a
restored section and an unrestored section. The upper 0.80 mi2
of the watershed, which is upstream of the Baltimore Beltway
(1-695) (fig. 1), was restored in 1998 and 1999. Restoration
was initiated in the lower 2.47 mi2 of the watershed during
2004 and was completed in 2005 (Doheny and others, 2006).
In the section of the watershed that was restored during
1998 and '1999, the dimension, pattern, and profile of the
stream channel were reconstructed for purposes of improving
stability. Riffle and pool sequences were re-created by
selective placement of rock weirs (Rosgen, 1993), which were
also intended to control sediment supply in the watershed.
Where possible, flood plains were created to allow flood flows
to spread out in the valley and reduce the energy directed at
the channel bed. Channel-bank slopes were reduced in many
locations and natural vegetation was planted on the banks.
Low to moderate channel sinuosity was maintained throughout
the restored reaches to reduce the potential for lateral bank
erosion and failure (fig. 2). Similar techniques were used in
the unrestored section of the watershed during 2004 and 2005
to reconstruct what had been a degraded and over-widened
stream channel (Doheny and others, 2006).
-------
Description of Minebank Run Watershed 3
77°00' 76°30' 76°00'
39°30'
39°00'
0 5 10 15 MILES
1 1 h H 1
0 5 10 15 KILOMETERS
MAPAREA
' NEW
JERSEY
WASHINGTON,
D.C. /
VIRGINIA
MARYLAND
Prettyboy
Reservoir
Westminster
Loch Raven
Reservoir
Minebank Run
watershed
-x- boundary^
Refer to figure 3
for enlarged—
map area
Liberty Lake
>wson
BALTIMORE
Triadelphia
\ Reservoir
LANCASTER /
<£\ \ V \ J
YORK
PENNSYLVANIA
CARROL
Minebank Run
PENNSYLVANIA
WEST
VIRGINIA
Figure 1. Location of Minebank Run watershed and study area, Baltimore County, Maryland.
-------
4 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
Figure 2. View looking upstream at restored section of Minebank Run, just upstream of the
Baltimore Beltway (1-695), 2001. (Photograph by Robert J. Shedlock, U.S. Geological Survey).
Description of Study Area
The Minebank Run study reach drains 2.06 mi2 in the
unrestored section of the watershed (fig. 3). The length of the
study reach is approximately 1,800 ft. At this location, land
use in the watershed is approximately 80.6 percent urban
and 16.9 percent forested or open space (Baltimore County
Department of Environmental Protection and Resource
Management, 2000). The largest percentages of urban land
use and impervious surfaces are in the headwaters of the
watershed, upstream of 1-695. Most of these highly impervious
areas are at higher elevations near the southern section of the
drainage boundary. These areas, in combination with direct
runoff from 1-695, are the likely sources of increased storm
runoff that cause the stream stage and corresponding discharge
to increase and decrease very quickly during storm events
(Doheny and others, 2006).
Prior to restoration in 2004 and 2005, much of the
unrestored section of Minebank Run was entrenched and
over-widened (Doheny and others, 2006). Most of the stream
energy was being directed at the channel bed and banks, with
little or no ability for the streamflow to overtop the channel
banks and spread out onto the flood plain. The channel
banks were steeply sloped in many locations with numerous
occurrences of bank failure and lateral erosion. The channel
sinuosity in the study reach was fairly low, but several
locations in the reach had large meanders that coincided with
very unstable channel banks and a highly mobile and unstable
channel bed (fig. 4) (Doheny and others, 2006).
Bed material in the study reach consists of a mixture
of sand, gravel, cobbles, and a few small boulders. In this
section of the watershed, much of the flood plain and channel
bed lie within deposits of alluvium and colluvium mapped
by Crowley and Cleaves (1974). Bew bedrock outcrops are
visible in the study reach because of the deposits of alluvium
and colluvium. Bank material includes some deposits of sand
and gravel, with greater percentages of silt and clay than in the
channel bed.
The study reach selected for geomorphic investigation
overlapped a study reach where shallow ground water
and water quality have been monitored since 2001 (fig. 5)
(Mayer and others, 2003). The study design for ground-water
and water-quality monitoring included nests of three 1-in.
(inch)-diameter piezometers that were installed 2 to 6 ft
below the surface of the channel bed, and 3.75 to 11.85 ft
below the surface of the channel banks in three selected
locations along Minebank Run (fig. 5) (Doheny and others,
2006). These piezometers in the channel bed also were used in
the geomorphic investigation as measuring points for tracking
channel-bed elevations over time.
-------
Description of Study Area 5
76°35'00" 76°32'30"
Loch Raven
Dam
Lower Dam
o GUNPOWDER FALLS
\ STATE PARK
Refer to figure 5 for
detail of this area
(146
CROMWELL /
VALLEY /
PARK \\ / J
25'00"
PARK OFFICE
Notre
Dame
Prep
STUDY
REACH
Cromwell
Bridge
Pumping
GOUCHER COLLEGE
567
Run
Minebank,
Minebank Run
watershed
boundary
ROAD
12-foot-diameter Loch Raven-Montebellp Tunn<
(Loch Raven Reservoir to Montebello Filtration Plant)
0
0.5
1 MILE
0 0.5 1 KILOMETER
Figure 3. Detailed view of Minebank Run watershed and study reach, Baltimore County, Maryland.
-------
6 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
Figure 4. View looking upstream at unrestored section of Minebank Run in Cromwell Valley
Park, downstream of the Baltimore Beltway (1-695), 2002. (Photograph by Robert J. Shedlock,
U.S. Geological Survey.)
Methods of Data Collection
Geomorphic data were collected in and near the
Minebank Run study reach to quantify pre-restoration
stream-channel characteristics, and to assess changes to
the stream channel prior to restoration. A continuous-
record streamflow-gaging station (USGS station number
0158397967, Minebank Run near Glen Arm, Maryland)
(fig. 5) has provided 5-minute, unit-value stage and discharge
data in the Minebank Run study reach since October 2001.
Surveys were conducted to document existing cross-section
geometry and changes in channel geometry over time. Scour
chains and bank pins were installed at the cross section
locations to quantify physical changes occurring between
storm events; Measuring point elevations from instream
piezometers were used as the elevation control in selected
cross-section locations to determine the net change in channel-
bed elevation over time. Surveys of the longitudinal profile
were conducted to determine the elevations of channel features
throughout the study reach. Pebble counts were conducted to
detennine grain-size distributions of the surficial bed material.
Samples of the underlying channel bed material and channel
banks were collected to detennine grain-size distributions for
selected areas. High-water marks were measured at the gaging
station and at other selected locations in the study reach to
determine the water-surface slope during storm events.
Streamflow
Since October 2001, continuous-record streamflow
data have been collected at USGS station 0158397967 in the
Minebank Run study reach using standard USGS stream-
gaging techniques (Carter and Davidian, 1968; Buchanan and
Somers, 1968). Periodic measurements of streamflow were
made at a range of gage heights to develop a stage-discharge
rating for the stream. The stage-discharge rating was used
with the continuous record of gage heights from the station
to detennine the discharge of the stream continuously at
5-minute intervals. Daily mean discharges were detennined
for each day of the water year. Streamflow statistics for station
0158397967, Minebank Run near Glen Ann, Maryland for
water years 2002 through 2004 are presented in table 1 (Saffer
and others, 2005).
Geomorphic monitoring occuned during a relatively wet
hydrologic period as the Baltimore region was recovering from
severe drought conditions in the spring and summer of 2002.
The long-tenn average for the Baltimore region is about 42 in.
of precipitation (James, 1986). On the basis of precipitation
data collected in the vicinity of the Minebank Run study reach,
over 64 in. of total precipitation were recorded during the
2003 water year, and nearly 52 in. were recorded during the
2004 water year (Doheny and others, 2006).
-------
Methods of Data Collection 7
76 33'30" 76 33'00"
39 25'00"
39 24'30"
0 500 1,000 1,500 FEET
1 1 1 1 f 1 1
0 100 200 300 400 METERS
EXPLANATION
0158397967^ C0NT|NU0US.REC0RD STREAMFLOW-GAGING STATION • • WELL TF1ANSECT (consisting of 2-inch monitoring wells on
AND IDENTIFICATION NUMBER each flood plain, and 1-inch piezometer nests in the channel
bed and on each channel bank)
CREST-STAGE PARTIAL-RECORD STATION WITH STAFF
GAGE AND IDENTIFICATION NUMBER — MINEBANK RUN STUDY REACH
boundary
Merrick Bridge,
Station 0158397975
Station ^
\ 0158397973.
Sherwood Bridge
Station j \
0158397967 \
(MinebankRun
near Glen Arm, MD),
STUDY REACH
Minebank
Minebank Run
watershed
Refer to figure 6 for
detail of the study reach
Well transect No. 1
(Station 0158397971)
Well transect No. 2
(Station 0158397969)
Well transect No. 3
(Station 0158397968)
CROMWELL VALLEY PARK
Station 01583980
(Minebank Run
at Loch Raven, MD)~
PARK OFFICE
Station
392449076331100
(Minebank Run
Rain Gage)
<$>
0
Loch Raven
High School
Cromwell Bridge
Pumping Station
12-foot-diameter Loch Raven-Montebello Tunnel
(Loch Raven Reservoir to Montebello Filtration Plant)
Figure 5. Location of continuous-record streamflow-gaging stations, crest-stage partial-record stations, and well transects
along the Minebank Run study reach, Baltimore County, Maryland.
-------
8 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
Table 1. Summary of streamflow statistics for station
0158397967, Minebank Run near Glen Arm, Maryland, water
years 2002-04.
[mi2, square mile; ft3/s, cubic foot per second; [(ft3/s)/mi2], cubic foot per
second per square mile]
Station 0158397967,
Minebank Run near
Glen Ami, Md.
2.06
3.25
4.34
(2004)
1.15
{2002}
61
(Oci. 27. 2003)
(Aug. 17, 2002)
I ..WO
(.Inn. i 2. 2003)
0.04
(Aug. 17, 2002)
2.1.46
1.58
and distribution of riffles, pools, and runs in the reach.
Point bar surfaces, terraces, and top of bank elevations were
also surveyed in selected locations along the reach where
these features were clearly identifiable. Dates, locations,
and longitudinal stationing used for the longitudinal-profile
surveys in the Minebank Run study reach are summarized in
table 2.
Cross Sections
Permanent cross sections were established in and near
the Minebank Run study reach to assess physical changes to
the stream channel prior to restoration. Nine cross sections
were established with monumented endpoints over a distance
of approximately 1,300 ft (fig. 6) within the study reach. The
reach contained the continuous-record streamflow-gaging
station, and the three transects of wells and piezometers that
were established for other technical aspects of the study
(fig. 5). The cross sections were established in straight sections
of the channel, or in straight sections between meanders, and
were aligned perpendicular to the direction of streamflow. The
cross sections were vertically referenced to mean sea level
datum and were initially surveyed in December 2002. The
cross sections were re-surveyed during June and July of 2003
in the aftermath of a major storm event that occurred in the
watershed on June 12, 2003 (table 1). The cross sections were
surveyed again during January and February of 2004, just
prior to the start of the channel restoration work that began in
June 2004. Basic station information for the nine permanent
cross sections in and near the Minebank Run study reach is
summarized in table 3.
Bank Erosion Pins
I damage area
(mi2)
Annual Mean I >ischavge
(I'l 7s}
Highest aniiiicil mean discharge
(I'l 7s)
l.owesi annual mean discharge
(I'l 7s)
I Iighesi daily mean discharge
(I'l 7s)
l.owesi dally mean discharge
(i'l 7s)
Maximum insianlaneous peak flow
discharge
(I'l 7s)
Minimum instantaneous low flow
discharge
(ftVs)
Annual runolT
(inches)
Annual runoff
[(ft3/s)/mi2]
Longitudinal Profiles
The longitudinal profile of the Minebank Run study
reach was surveyed during April 2002, March 2003, and April
2004 to determine the relative elevations and consistency of
channel features. The methods used are described in Leopold
(1994). The reach where the longitudinal profile surveys were
conducted was located between the Sherwood Bridge and just
downstream of the confluence of Harts Run and Minebank
Run (fig. 5). Channel-bed and water-surface elevations were
surveyed along the study reach, as were channel features such
as point bar surfaces, terraces, and top of bank elevations.
All surveys were conducted using the same starting point
and longitudinal stationing so that comparisons of profiles
from different years would be possible. Survey elevations
were measured at break points between riffles, pools, and
runs in order to define these features individually. Distances
were measured along the thalweg between surveyed points
on the streambed, which allowed for definition of the lengths
Changes in bank erosion and deposition over time were
measured at each surveyed cross section using a series of
bank erosion pins (Harrelson and others, 1994). Metal pins,
approximately Vi-in. thick and 2-4 ft in length, were inserted
horizontally at different elevations into shear and heavily-
eroded banks, with a measured length that was left exposed.
At each pin. an elevation was determined by use of a rod and
level. During periodic visits to each cross section, exposure of
each pin was measured. If the bank had been severely eroded
between site visits, the exposed pin was driven back into the
bank and re-measured before leaving the site. Pin loss was
documented and another pin was installed at approximately
the same elevation. A sample diagram of the placement of
bank erosion pins at a cross section is shown in figure 7.
Scour Chains
Scour chains were used to measure the aggradation or
degradation in the thalweg of the streambed at each surveyed
cross section (Harrelson and others, 1994). A known length
-------
Methods of Data Collection 9
Table 2. Dates, locations, and longitudinal stationing used for the longitudinal-profile surveys in the Minebank Run study reach,
2002-04.
[ft, feet]
Date
of
survey
Starting
station
(ft)
Starting
location
Ending
station
(ft)
Ending
location
Reach
length
(ft)
April 16-17. 2002
March 31-April 1, 2003
April 23. 2004
5.000
5,000
5.000
IIpslream side of
Sherwood Bridge
Upstream side of
Sherwood Bridge
I ipslrcairi side of
Sherwood Bridie
3,358 In meander bend.
approximalely
330 fl npsiream
of gage
3,283 In meander bend,
approximately
290 ft upstream
of gage
3.337 In meander bend.
approximalely
2.80 fl npsiream
of «ace
! ,642
1,717
1.663
of chain was installed vertically into the unconsolidated bed
material and anchored at the bottom by a horizontal pin. At
the loose end, a measured length of chain was left exposed
and laid over the surface of the channel bed. The number of
chain links exposed on the bed was recorded as well as the
measured length of exposed chain. The chains were located
and excavated approximately once a month or after large
storm events. The depth of fill overlying the chains was also
recorded. The number of horizontal chain links and measured
length of horizontal chain was recorded. If additional chain
links were bent over and exposed horizontally in between
site visits, this indicated scour on the channel bed. The depth
of material covering the chain is indicative of subsequent
deposition of channel materials that occurs on the recession of
a storm event (fig. 8).
Channel Materials
The channel materials composing the bed and banks of
the study reach were characterized using (1) pebble counts of
the surficial channel-bed sediments at each cross section, and
(2) grain-size analysis of sediment samples collected from the
channel banks and the subsurface of the channel bed at each
cross section.
One-hundred-particle pebble counts were conducted in
the main channel at each of the nine permanent cross sections
during May and June of 2003. Pebble counts were also
conducted in May 2002 at the three well transects in the study
reach that correspond to cross sections Ee, I T, and Gg. The
pebble counts were made by randomly picking up particles
from the channel bed throughout the entire length of the main
channel at an interval of about 1 particle per foot of cross
section, and measuring the intermediate axis of the particle
that is picked up (fig. 9) (Leopold, 1994; Harrelson and others,
1994). The particle sizes were tallied according to size class
(silt, sand, gravel, or cobbles) and used to directly determine
grain-size distributions for the surface of the channel bed at
each cross section and for the study reach. An example of a
grain-size distribution and computation of percent finer from
a pebble count at cross section Ff in the Minebank Run study
reach on June 6, 2003 is shown in table 4. A plot of the grain-
size distribution developed from the pebble count is shown in
figure 10.
Sediment samples were collected from the channel bed
subsurface and banks at each cross section during November
2002 and shipped to the USGS sediment laboratory in
Vancouver, Washington for grain-size analysis. Channel-bed
samples were collected in the left, center, and right side of
each cross section by (1) removing the top 2-3 in. of bed
material in the location of the sample, and (2) shoveling about
6-8 in. into the bed, and filling a standard cloth sediment bag
with material from the subsurface of the bed. Bank samples
were collected from both channel banks. If the bank was
lightly sloped, the sample was taken from the top of the bank
by shoveling 6-8 in. down from the surface. If the bank was
shear or severely undercut, a sample was taken from the
top of the bank, and also from within the shear part of the
bank (fig. 11). Samples were quantified using a standard
sieve analysis for the channel-bed material and sedigraph
analysis for the bank samples (Daniel I. Gooding, USGS,
written commun., 2002). Sedigraph analysis was necessary to
determine grain-size distributions of the bank samples due to
significant percentages of fine material such as silt and clay
that compose the channel banks at Minebank Run.
-------
10 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
76 33'24"
76 33'18"
76 33'12"
39 24'30"
Station
0158397975
Sherwood
STUDY REACH
Station
0158397973
Well transect No. 1
(Station 0158397971)
Well transect No. 2
(Station 0158397969)
Well transect No. 3
(Station 0158397968)
Station
0158397967
(Minebank Run
near Glen Arm, MD)
CROMWELL VALLEY PARK
100
200
300
~~r~
20
~~r~
40
~r~
60
400 FEET
_1
T
80 100 METERS
EXPLANATION
0158397967
~ CONTINUOUS-RECORD STREAMFLOW-GAGING STATION
AND IDENTIFICATION NUMBER
0158397973
A CREST-STAGE PARTIAL-RECORD STATION WITH STAFF
GAGE AND IDENTIFICATION NUMBER
Hh-
WELL TRANSECT (consisting of 2-inch monitoring wells on
each flood plain, and 1-inch piezometer nests in the channel
bed and on each channel bank)
PERMANENT CROSS SECTION
MINEBANK RUN STUDY REACH
Figure 6. Locations of permanent cross sections that were established in the Minebank Run study reach at Cromwell
Valley Park, 2002.
-------
Methods of Data Collection
11
Table 3. Basic station information for permanent cross sections located in and nearthe Minebank Run
study reach.
[Lat, Latitude; Long, Longitude; ft. feet; °, degrees;minutes; seconds]
Left
Right
Cross
Longitudinal
Description of
cross section
cross section
section
station
cross section
endpoint
endpoint
name
(ft)
location
lat long
("•"»
lat long
Aa
4,777.0
Downstream of meander
39 24 42.6
39 24 41.1
76 33 14.8
76 33 13.5
Bb
4,703.0
Upstream of meander
39 24 42.1
39 24 42.4
76 33 15.8
76 33 13.8
Cc
4,563.0
Straight
39 24 41.1
39 24 40.4
76 33 16.7
76 33 14.5
Dd
4,399.0
Downstream of meander
39 24 40.2
39 24 39.0
76 33 18.0
76 33 17.0
Ee
4,210.0
Upstream of meander
39 24 38.8
39 24 38.5
76 33 19.6
76 33 18.8
Ff
3,990.0
Straight
39 24 37.8
39 24 36.5
76 33 20.4
76 33 19.4
Gg
3,838.0
Straight
39 24 37.0
39 24 36.3
76 33 22.3
76 33 21.3
Hh
3,678.0
Downstream of meander
39 24 35.8
39 24 35.1
76 33 24.0
76 33 23.3
li
3,462.0
Between two meanders
39 24 35.3
39 24 34.6
76 33 25.8
76 33 26.1
Bed-Elevation Measurements
Net changes in bed elevation were determined over
time at three locations in the study reach where instream
piezometers had been installed to monitor shallow ground
water (Mayer and others, 2003). These locations closely
coincide with locations of permanent cross sections Ee, Ff,
and Gg (fig. 6). The distance from the top of the piezometer
to the channel bed was measured every 1-2 months and after
major storm events between December 2002 and July 2004.
Since the measuring point elevations were surveyed and
related to mean sea level datum, net bed elevations could be
determined over time at the piezometer location by making
these periodic measurements. The tracking of bed elevations
by use of an instream piezometer with a surveyed measuring
point elevation is illustrated in figure 12.
High-Water Marks
High-water marks were obtained along the study reach
during water years 2002 through 2004 from crest-stage
gages that were installed at selected locations (Buchanan
and Somers, 1968). These marks were used along with data
from the continuous-record streamflow-gaging station to
determine peak water-surface elevations that occurred in the
study reach between site visits. The crest-stage gages were
serviced every 1-2 months and after major storm events. All
high-water marks that were registered on each crest-stage
gage were documented and logged. The hydrographs from the
continuous-record streamflow-gaging station were referenced
to determine the date of the storm that left the high-water mark
and the discharge associated with that storm.
The distance between crest-stage gages along the thalweg
of the stream channel was measured so that water-surface
slopes could be determined at a range of stages and discharges
by use of the high-water marks. Since the reach in the vicinity
of the streamflow-gaging station was the most linear section
of the study reach, the streamflow-gaging station and the
crest-stage gage immediately downstream of this station were
predominantly used for determination of water-surface slopes.
A crest-stage gage that was used for obtaining high-water
marks in the Minebank Run study reach is shown in figure 13.
-------
12 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
CONTOUR
LOST PIN
BURIED PINS
PRESENT BANK
CONTOUR\
PREVIOUS BANK
Geomorphic Characteristics
Figure 7. Example of bank-erosion pin placement and
monitoring (modified from Harrelson and others, 1994).
^pa\
0 a 9,
~.°i
*6 f
* * i
O ij!
Qoq"
* A
% 1
r^rr
*1
Q W
•fc-
CI
«¦
V
^ ^ 1
t * *
| o ^ ^
°° * 4
°o
O
^ *
DEPTH OF
SCOUR
DEPTH
OF FILL
BEFORE
AFTER SCOUR AND FILL
Figure 8. Example of scour chain placement and monitoring
(modified from Harrelson and others, 1994).
A = LONGEST AXIS (LENGTH)
B = INTERMEDIATE AXIS (WIDTH)
C = SHORTEST AXIS (THICKNESS)
Figure 9. Examples of
longest, intermediate,
and shortest axes for
measuring median
particle diameter of
pebbles during pebble
counts (modified
from Harrelson and
others, 1994).
Geomorphic data collected during water years
2002 through 2004 were used to assess pre-restoration
geomorphic characteristics and pre-restoration geomorphic
changes occurring over time in the Minebank Run study
reach. Geomorphic characteristics that were assessed
included (1) longitudinal profiles of the channel bed, water
surface, and bank features; (2) changes in cross-section
geometry; (3) grain-size analyses of the channel bed and
banks; (4) net changes in the elevation of the channel
bed at selected locations over time; (5) classification of
selected sections of the reach according to the Rosgen
system of stream classification (Rosgen, 1994, 1996); and
(6) analysis of boundary shear stress based on cross-section
geometry and water-surface slope in the vicinity of the
streamflow-gaging station.
Longitudinal Profiles
Longitudinal profiles of the channel bed, water surface,
point bar, terrace, and top of bank elevations were developed
for the Minebank Run study reach on the basis of field surveys
that were conducted in April 2002, April 2003, and April
2004. Slopes of the different channel features were determined
by use of simple linear regression. Percentages of riffles,
pools, and runs were determined for each profile based on
the stream length of each feature relative to the length of the
surveyed reach. The profiles also were analyzed to determine
differences in the distribution and location of riffles, pools,
and runs throughout the study reach over time. An aerial view
of the study reach used for the longitudinal surveys is shown
in figure 14 (Baltimore County Department of Environmental
Protection and Resource Management, 2000). An example
plot of the longitudinal profile that was developed from the
March 31-April 1, 2003 survey is shown in figure 15.
A distinct and extensive series of point bar and terrace
features in the main channel along the study reach is shown
in figure 15. The presence of these features indicates that
the channel bed has degraded over time and that the stream
channel may have abandoned its flood plain at least twice due
to degradation. The field evidence indicates that the stream
channel may have initially degraded from the top of the
topographic banks to form a new flood plain at the level of the
terrace feature that was surveyed throughout the study reach.
Additional degradation likely caused the stream channel to
abandon this flood plain and establish an active flood plain at
the approximate elevation of the top of point bar features that
were surveyed throughout the study reach.
Slopes were computed for the channel bed, water surface,
point bar surface, terrace, and top of topographic bank
elevations for each of the three longitudinal profiles surveyed
between April 2002 and April 2004. The results are shown in
table 5.
-------
Geomorphic Characteristics 13
Table 4. Grain-size distribution and computation of percent finer from pebble count at Cross
Section Ff, Minebank Run study reach, June 6, 2003.
[mm, millimeter; %, percent; —, not applicable]
Particle
description
Particle
size limit
(mm)
Item
count
Cumulative
percent finer
(%)
Silt
0.062
0
0
Sand
2
18
18.0
Very fine gravel
4
0
18.0
Fine gravel
8
2
20.0
Medium gravel
16
12
32.0
Coarse gravel
32
14
46.0
Very coarse gravel
64
22
68.0
Small cobbles
128
20
88.0
Large cobbles
256
12
100.0
Small boulders
512
0
100.0
Medium boulders
1,024
0
100.0
Large boulders
2,048
0
100.0
Very large boulders
4,096
0
100.0
TOTAL
--
100
--
1,000
100
CC
LU
LU
O
CC
LU
0_
10 100
GRAIN SIZE, IN MILLIMETERS
Figure 10. Plot of grain-size distribution developed from the
pebble count at cross section Ff, Minebank Run study reach,
June 6, 2003.
Slopes for all channel features were approximately
1 percent (table 5). Except for the top of bank slope, all
channel features showed a slight decrease in slope between
2002 and 2003, and a slight increase between 2003 and 2004.
Over the 2-year period, the slopes of all features showed
changes that were within 10 percent or less. A small amount
of variation in these numbers was expected, however, due to
inherent inaccuracies associated with conventional surveying.
The slope of the point bar surface showed the most variation
in the re-surveys, likely because the point bars are within the
active flood plain and subject to frequent adjustments from
higher flows (fig. 16). The slopes of these channel features
also are consistent with low-flow and high-flow water-surface
slopes that were determined in the Minebank Run study
reach from staff gage readings and high-water marks between
January 2002 and August 2004 (Doheny and others, 2006).
-------
14 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
LU
>
LU
_l
<
LU
C/3
2
LU
>
o
CO
<
i—
LU
LU
§
LU
Cross Section Gg
(Samples were collected on November 8, 2002.
Channel survey was done on December 6, 2002.)
4 Location where sediment
samples were collected
for grain-size analysis
10 20 30 40 50 60
STATION, IN FEET
70
80
90
100
Figure 11. Example of locations within cross section Gg that were selected for sediment-sample collection,
Minebank Run study reach, November 2002.
Measuring point elevation -
Streamflow
Channel bed
Well screen
J Distance to channel
bed from measuring
point elevation
Figure 12. Technique used for tracking of
net channel-bed elevations by use of instream
piezometers, Minebank Run study reach,
December 2002 through July 2004.
I'
mi
Figure 13. Crest-stage gage
for obtaining high-water marks
in the Minebank Run study reach.
(Photograph by Edward J. Doheny,
U.S. Geological Survey.)
-------
Geomorphic Characteristics
Aerial photograph by Vargis, LLC., Herndon, VA, 2000
Modified from Baltimore County Department of Environmental
Protection and Resource Management
300 METERS
Figure 14. Aerial photograph of Minebank Run study reach in Cromwell Valley Park priorto channel restoration.
LU
>
UJ
<
LXJ
w
z
<
lli
UJ
>
O
<
I—
LU
LLI
Li.
$
Lli
POINT BAR
WATER
SURFACE
CHANNEL
BED
STATION
0158397967
TRANSECT
NO. 2
TRANSECT
BELOW
TRANSECT
NO. 1
205
3,000
3,500
4,000
STATION, IN FEET
4,500
5,000
-| , r 1 1 1 1 | , r [-
Longitudinal profile upstream of Sherwood Bridge,
Minebank Run, March 31 and April 1,2003.
TOP OF
TOPOGRAPHIC
BANK
TERRACE
Figure 15. Longitudinal profile of channel features in the Minebank Run study reach from field survey conducted
on March 31 and April 1, 2003.
-------
16 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
Table 5. Slopes of channel features in the Minebank Run study reach from longitudinal-profile surveys, 2002-04.
Date
of
survey
Channel
bed
Water
surface
Point
bar
surface
Terrace
surface
Top
of
bank
April 16, 2002
0.0101
0.0100
0.0101
0.0099
0.0091
March 31-April 1, 2003
0.0093
0.0092
0.0092
0.0091
0.0089
April 23, 2004
0.0095
0.0095
0.0107
0.0097
0.0088
LU
>
LU
<
LU
C/)
Z
<
LU
LU
>
o
CD
<
H
LU
LU
§
LU
226
224
222
220
218
216
214
212
210
208
3,200
j ^
1 1 1 | 1 1 1 1 | 1 1 1 1 | 1 1 1 1 | 1 1 1 1 | 1 1 1 1 | 1 1 1 1 _
:
Point Bar Profile
2002 to 2004
j
:
-
~—» 2002
:
¦—¦ 2003
:
*—* 2004
1
:
:
=
i i i iii
1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
3,400
3,600
3,800 4,000 4,200
STATION, IN FEET
Channel Bed Profile
2002 to 2004
4,400
4,600
4,800
5,000
3,200
3,400
3,600
3,800
4,000 4,200
STATION, IN FEET
4,400
4,600
4,800
5,000
Figure 16. Variation in point bar and channel bed elevation between 2002 and 2004 longitudinal surveys in the
Minebank Run study reach.
-------
Geomorphic Characteristics 17
The data indicate that despite major geomorphic changes
to the stream channel from storms, the overall slope of the
channel bed and other channel features remained at about
1 percent.
Data from the longitudinal-profile surveys also were used
to determine the percentages of riffles, pools, and runs in the
study reach and whether these percentages and distribution
remain consistent over time. The percentages of riffles,
pools, and runs in the Minebank Run study reach that were
determined from the longitudinal-profile surveys between
2002 and 2004 are shown in table 6. The distribution of riffles,
pools, and runs that were determined from the longitudinal-
profile surveys between 2002 and 2004 are shown in figure 17.
Noticeable changes are evident in the percentages of
riffles, pools, and runs in the study reach between April 2002
and April 2004 (table 6). The large changes in percentages
of pools over time indicate that different sections of the
stream channel go through alternating periods of scour and
fill over time. The increase in riffle and run percentages with
the corresponding decrease in pool percentages between
2002 and 2003 indicates that, on average, the channel in the
study reach is storing more sediment during this period. The
increase in pool percentages and corresponding decrease
in run percentages between 2003 and 2004 indicates that,
on average, the channel in the study reach is storing less
sediment during this period. Some distinct variations in the
distribution and location of riffles, pools, and runs in many
sections of the study reach are also evident (fig. 17). Despite
these changes in riffle, pool, and run percentages and changes
in the distribution and location of these features, this analysis
indicated that, on average, the stream is roughly maintaining
the overall slope of its channel features.
Table 6. Percentage of riffles, pools, and runs in the Minebank Run study reach from
longitudinal-profile surveys, 2002-04.
[%, percent]
Date
of
survey
Riffle
Pool
Run
(%)
(%)
(%)
April 16, 2002
42.2
42.3
15.5
March 31-April 1, 2003
52.2
27.5
20.3
April 23, 2004
52.4
39.9
7.7
APRIL
2002
H MARCH
§ 2003
APRIL
2004
3,000 3,100 3,200 3,300 3,400 3,500 3,600 3,700 3,800 3,900 4,000 4,100 4,200 4,300 4,400 4,500 4,600 4,700 4,800 4,900 5,000
STATION, IN FEET
EXPLANATION
RIFFLE POOL RUN
Figure 17. Comparison of riffle, pool, and run distribution in the Minebank Run study reach prior to channel restoration, 2002
through 2004.
-------
18 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Mary land, 2002-04
Cross-Section Geometry
Pre-restoration channel geometry at the nine permanent
cross sections was determined on the basis of field surveys
conducted in December 2002, June-July 2003, and in January-
February 2004. Each cross section was plotted for the three
surveys to determine changes in bed elevation and channel
alignment over time. Bank-pin data collected in locations with
cut banks were used to investigate bank retreat. Data collected
from the scour chains were used to measure, or reasonably
approximate, depths of maximum scour as well as depths of
deposition that occurred on the recession of storm events.
Cross-sectional area, wetted perimeter, hydraulic radius,
channel width, and mean channel depth were determined
for each cross section at a range of water-surface elevations,
and compared to document changes occurring between
field surveys.
Plots of the nine permanent cross sections are shown in
figures 18-26. Varying degrees of aggradation and degradation
of the channel bed are evident, as well as lateral erosion along
the study reach. A summary of lateral erosion, maximum
scour, and depths of maximum deposition that were directly
measured, or reasonably approximated, based on field
conditions during site visits at or near each permanent cross
section in the study reach during the pre-restoration period is
provided in table 7.
Data from the bank-pin measurements, as well as
measurements made after bank collapses in some of the
cross-section locations, indicate a range of 0.21 to 7.88 ft
of lateral erosion from January 2003 through August 2004.
individual bank-pin measurements during site visits indicate
that lateral bank erosion of 1-2 ft was possible dining large
storm events that occurred from January 2003 through July
2004. Data from scour chains at the cross sections indicate that
maximum bed scour ranging from 0.1 to 1.4 ft was possible in
the thalweg of the channel during large storm events occurring
between January 2003 and July 2004. Maximum deposition
on the channel bed at the location of the scour- chains ranged
from approximately 0.30 to 1.50 ft. Due to the dynamic
and unstable nature of the unrestored channel at Minebank
Run, scour chains and bank pins were sometimes lost during
large storm events. When this occurred, estimates of bank
retreat and maximum scour were made on the basis of known
conditions from the previous site visit. If a known length of a
bank pin or a scour chain was exposed during a site visit, for
example, and the total length of the pin or chain was known, a
rough estimate of erosion on the bank or bed could be made if
the pin or chain was washed away during a storm event prior
to the next site visit. Data from the resurveyed cross sections
were also used to aid in estimating bank retreat during periods
when bank pins had been lost.
Cross-section geometry was determined at a range
of stages for the three different field surveys at all nine
permanent cross-section locations. Hydraulic variables
that were determined include cross-sectional area, wetted
perimeter, hydraulic radius, channel width, and mean channel
depth. A comparison of cross-section geometry for cross-
section Hh during the three field surveys conducted during
2002 through 2004 is shown in table 8. Comparisons for each
of the other eight permanent cross sections in the Minebank
Run study reach are included in Appendix 1.
A net increase in cross-sectional area, hydraulic radius,
and mean depth over time is evident at cross-section Hh
(table 8). Channel width and wetted perimeter show net
increases at low- to mid-range water-surface elevations over
time. These changes in channel width occur mainly within the
active channel, due to the net effects of erosion and deposition
of the point bar on the right side of the channel. At higher
elevations, the channel width did not change significantly
over time. The cross-section surveys also indicate alternating
increases and decreases in cross-sectional area and mean depth
between field surveys, which indicates alternating aggradation
and degradation of the channel bed resulting from temporary
storage and removal of sand and gravel during storm events.
These analyses were performed for all permanent cross
sections in the Minebank Run study reach, and were used to
develop an overall assessment of channel geometry changes
in the study reach that occurred between 2002 and 2004. The
results are summarized in table 9.
Net increases in cross-sectional area, channel width,
and mean depth for most elevations at cross sections Aa, Dd,
Ff, and li are indicated in table 9. These changes indicate
an overall trend of bed degradation, bank instability, and
channel widening over time. Cross section Aa, however, shows
alternating increases and decreases in mean depth between
field surveys. This indicates that, like cross section Hh, sand
and gravel could be temporarily stored in this location after
certain storm events despite overall degradation during the
monitoring period. Considerable lateral bank erosion is also
a likely factor in the increases in cross-sectional area and
channel width at these locations.
A net decrease in cross-sectional area and mean depth
over time at cross section Bb is evident (table 9). Channel
width shows a net decrease at lower elevations, with relatively
minor increases and decreases at higher elevations. The
surveys and bank pin information also indicate that lateral
erosion was relatively minor over time. The decrease in
cross-sectional area and mean depth with little lateral erosion
indicates an aggrading channel bed at cross section Bb with a
net increase in storage of sediment that is transported during
storm events.
Cross section Cc shows approximately the same channel-
geometry characteristics that were documented at cross section
Hh. The cross-sectional surveys indicate a net increase in
cross-sectional area, hydraulic radius, and mean depth over
time. Channel width shows a net increase at lower to mid-
range elevations over time. These changes in channel width
occur mainly within the active channel, due to the net effects
of erosion at the base of the terrace on the left side of the
channel. At most higher elevations, the channel width did not
change considerably over time. The cross-section surveys
also indicate alternating increases and decreases in cross-
-------
Geomorphic Characteristics
Cross Section Aa
December 12. 2002
July 31,2003
February 19, 2004
STATION, IN FEET
Figure 18. Pre-restoration cross-section geometry at permanent cross section Aa, December 2002 through
February 2004.
Cross Section Bb
December 12, 2002
July 31, 2003
February 19, 2004
100 110 120 130 140 150 160 170 180 190 200
STATION, IN FEET
Figure 19. Pre-restoration cross-section geometry at permanent cross section Bb, December 2002 through
February 2004.
Cross Section Cc
~—» December 12, 2002
¦ July 31, 2003
a—± February 13, 2004
STATION, IN FEET
Figure 20. Pre-restoration cross-section geometry at permanent cross section Cc, December 2002 through
February 2004.
-------
Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
LD
>
LD
_l
<
LD
03
Z
<
LD
LD
>
o
CD
<
H
LD
LD
219
218
217
216
215
214
213
Cross Section Dd
December 12, 2002
July 8, 2003
February 13, 2004
STATION, IN FEET
Figure 21. Pre-restoration cross-section geometry at permanent cross section Dd, December 2002 through
February 2004.
LD
>
LD
_l
<
LD
C/5
Z
<
LD
LD
>
o
CD
<
I—
LD
LD
221
220
219
218
217
216
215
214
Cross Section Ee
December 6, 2002
July 8, 2003
January 13, 2004
40 50
STATION, IN FEET
Figure 22. Pre-restoration cross-section geometry at permanent cross section Ee, December 2002 through
January 2004.
LD
>
LD
_l
<
LD
OT
Z
<
LD
2
LD
>
o
m
<
224
223
222
221
220
219
218
217
216
Cross Section Ff
December 3, 2002
July 8, 2003
February 13, 2004
70 80 90 100
STATION, IN FEET
170
Figure 23. Pre-restoration cross-section geometry at permanent cross section Ff, December 2002 through
February 2004.
-------
Geomorphic Characteristics
—I
227
LD
>
LD
_l
226
<
LD
0)
225
z
s
224
LD
>
223
o
CD
<
I—
222
LD
LD
LL
221
Z
z"
220
o
H
§
219
LD
_l
LD
218
Cross Section Gg
*—» December 6, 2002
:
\ \
¦—¦ June 16, 2003
po
«o
5 9 -
\ \
*—* January 13, 2004
V.
.Q ffl m i T -
§ " 1
\ 0)
^ \\ 1
WJ
•S
OS
if
\ \ N
\ \ .®
A \ Q-
.E
8 /
:
\_JSfo | ± .
1 /
!
:
10
20
30
40
50
60
70
80
90
100
Figure 24. Pre-restoration cross-section geometry at permanent cross section Gg, December 2002 through
January 2004.
LD
>
LD
_l
<
LD
C0
z
<
LD
LD
>
o
CO
<
I—
LD
LD
U_
z
z~
o
§
LD
227
226
225
223
Cross Section Hh
~—» December 10, 2002
¦—¦ June 16, 2003
*—* January 13, 2004
10
20
30 40
STATION, IN FEET
50
60
70
Figure 25. Pre-restoration cross-section geometry at permanent cross section Hh, December 2002 through
January 2004.
229
228
226
225
223
LD
>
LD
_l
<
LD
03
Z
<
LD
2
LD
>
o
CD
<
5
LD
Cross Section li
December 10, 2002
July 8, 2003
January 13, 2004
10
20
30
40 50
STATION, IN FEET
60
70
80
90
Figure 26. Pre-restoration cross-section geometry at permanent cross section li, December 2002 through
January 2004.
-------
22 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Mary land, 2002-04
Table 7. Approximate extent of lateral erosion, maximum scour, and maximum depths of deposition for each permanent cross
section in the Minebank Run study reach, 2003-04.
[e = includes estimates due to loss of pins from bank collapse or loss of scour chain during large storm event.]
Cross section
Period of
bank pin
monitoring
(month/year)
Total
lateral
erosion
of cut bank
(feet)
Period of
scour chain
monitoring
(month/year)
Maximum
scour depth
between
site visits
(feet)
Maximum bed
deposition
between
site visits
(feet)
Aa
1/2003-8/2004
3.71e
2/2003-12/2003
0.60
1.50e
Bb
1/2003-7/2004
0.95
2/2003-6/2004
1.19e
0.50
Cc
1/2003-7/2004
0.83
2/2003-7/2004
0.10
0.60
Dd
1/2003-7/2004
7.88e
2/2003-6/2004
1.44e
0.80e
He
1 /2003-7/2004
0.611
2/2003-12/2003
1.22e
0.96e
Ff
1/2003-12/2003
4.86e
2/2003-12/2003
0.40e
0.60
Gg
1/2003-12/2003
4.68e
2/2003-6/2004
l.OOe
0.30
Hh
1 /2003-7/2004
0.21
2/2003-12/2003
0.42
0.60
Ii
1/2003-7/2004
4.96c
2/2003-6/2004
0.88c
1.25
1 Lateral erosion for cross section Ec was measured along the left bank, approximately 25 feet downstream of the cross-section location because of a nearby
meander bend.
sectional area and mean depth between field surveys. As with
cross section lit), this condition indicates temporary storage
and removal of sand and gravel during storm events with net
degradation of the channel bed over time.
Cross-section Ee shows a net increase in cross-sectional
area at lower elevations and a net decrease at higher elevations.
Mean depth shows a net decrease at most elevations, but
alternates between increasing depth and decreasing depth
between channel surveys. Changes in channel width are
considerable and vary between increases and decreases
over the range of elevations analyzed. The cross-section
surveys indicate major vertical and lateral instability of the
stream channel in this location, with alternating periods of
considerable sediment storage and removal.
Cross section Gg shows net increases in cross-sectional
area and channel width over time. Mean depths show a small
net decrease at lower elevations, and a net increase at higher
elevations. The cross-section surveys indicate greater lateral
instability of the stream channel than vertical instability in this
location. Lateral migration of the right bank, and adjustment
of the terrace and point bar features on the left side of the
channel are the main cause of the net increases in cross-
sectional area and mean depth over time.
A summary of the pre-restoration geomorphic conditions
that were interpreted from changes in the cross sections during
the monitoring period is shown in figure 27. Cross sections
Bb and Ee appear- to be primary areas for sediment storage
within the study reach. Cross section Ee appears to store large
volumes of sediment for short periods of lime and is vertically
and laterally unstable. Cross section Bb shows net aggradation
of the channel bed over time with small amounts of lateral
erosion. Cross sections Aa, Cc, and Hh also show indications
of temporary sediment storage and removal over time. Cross
sections Aa, Dd, Ee, Ff, and li appear to be the most unstable
cross sections in the study reach, due to either considerable
lateral erosion, erosion of the channel bed, or both. Cross
section Gg appears to be laterally unstable with a lesser
degree of vertical instability. On the basis of the locations of
cut banks and lateral erosion in the study reach, the stream
channel was actively adjusting its meander pattern and trying
to increase its sinuosity prior to restoration.
Grain-Size Analysis
Grain-size distributions were determined for sediment
in the channel bed and banks in the study reach during 2002
and 2003 by use of (1) pebble counts of the surficial channel-
bed sediments at each cross section (Wolman, 1954), and
(2) sediment samples that were collected from the channel
banks and the subsurface of the channel bed at each cross
section. Cumulative frequency distributions of percent liner
were developed for the surficial bed material based on the
pebble count data. The median particle diameter, or particle
diameter associated with 50 percent of the material being finer,
was determined for each pebble count and sample location.
Grain-size distributions from the pebble counts also were
combined to develop a composite analysis of the surficial
bed material for the entire study reach. The 2003 grain-size
distributions also were compared to selected pebble counts
-------
Geomorphic Characteristics
c s.«
«B & —~
S S. S
«5 © —-
C € ~
s a ^
«5 & —-
—
C *5
s -o
£ s
s *
c *5
3 *
B *
© 3d
gE|
S S
s ® —.
S.i£
5 ®
£, ® —.
i .i £
5 ®
¦S £ «
O ?B ^
¦s St
U «5
i w
C/5 5 00 05
O C >
_Q CO 05
CO 05
E
CM
00
s
CM
CM
CM
CM
00
CM
s
CM
CM
m
5
o
re,
4
in
•n
CM
m
•n
OC
«n
re
a\
CM
O)
r-.
00
ns
cm
Tt
>n
m
r.
A
¦'¦
+
in
o\
r^,
in
•¦r,
00
r^-
CM
ON
-t
00
-------
24 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
Table 9. Summary of variability of cross-sectional characteristics in the Minebank Run study reach, 2002 through 2004.
Cross
section
Lateral
Cross-
sectional
area
Channel
width
Mean
channel
depth
Comments
An Considerable on
ieli bunk
Bb Slight on left bank
Cc Sonic on base of
iei'i terrace
Dd
Considerable on
right bank
Nel increase
Net decrease
Nel increase
Net increase
Nel increase
Slight increases
and decreases
at range of
elevations.
Slight increase in
main channel
ai lower
eievalions.
Slighl decrease
ai higher
eievalions.
Net increase
Nel increase Considerable laleriil and vertical
changes in seclion. Channel
migrating to left side of valley.
Net decrease Small lateral changes in section,
at most Channel bed aggrading over
elevations. time.
Nel increase Considerable vertical changes
al mosi in seclion. Some lateral
eievalions. adjustment of left bank lerra.ee.
Overall, lateral location of
seclion is maintained over time.
Net increase Considerable lateral/vertical
changes in section. Channel
migrating to right side of valley.
C.s
Hh
Considerable on
risiht bank
onsKieranie ¦
left bank
Considerable on
risiht bank
Slight on both
banks
Increasing from
2002 to 2003.
I )ccreasing from
2003 So 2004. Nel
increase al lower
eievalions. Nel
decrease ai higher
eievalions.
Nel increase in main
channel.
Nel increase
Increasing from
2002 to 2003.
Decreasing from
2003 to 2004. Net
increase at most
elevations during
2002-04.
Nel increase al
mosi eievalions.
Nel increase al
most elevations.
Nel increase al
mosi eievalions.
Net increase at
low elevations.
Slight increases
and decreases
at higher
elevations.
Nel decrease
al mosi
eievalions.
Net increase in
main channel.
Sliglu nel
decrease
al lower
eievalions.
Sliglu net
increase
at higher
eievalions.
Net increase
at most
elevations.
Major lateral and vertical changes
in seclion. Channel migrating to
right side of valley.
Considerable lateral changes in
section. Some vertical changes
on channel bed in main channel.
Channel migrating to left side
of valley.
Significant lateral changes in
section. Sliglu vertical changes
on channel bed. Channel
migrating lo right side of valley.
Considerable vertical changes
to channel bed and point bar.
Slight lateral changes in section
over time.
Considerable on
left bank
Nel increase
Nei increase
Nel increase Considerable iaierai and verlicai
changes in seclion. Channel
migrating to left side of valley.
-------
Geomorphic Characteristics
25
76°33'24" 76°33'18" 76°33
w
Sherwood
XBridge
STUDY REACH
Aa
Bb.
Cc
Dd
Ee
Hh
39 24'30"
CROMWELL VALLEY PARK
400 FEET
0
100
200
300
0 20 40 60 80 100 METERS
„ EXPLANATION
Gg
+ LOCATION OF LATERAL BANK
EROSION AT CROSS SECTION
OVERALL DEGRADATION/WIDENING
AGGRADING BED, LATERALLY STABLE
AGGRADATION/DEGRADATION OF CHANNEL BED, LATERALLY UNSTABLE
MINOR AGGRADATION/DEGRADATION OF CHANNEL BED, LATERALLY UNSTABLE
AGGRADATION/DEGRADATION OF CHANNEL BED, OVERALL LATERALLY STABLE
Figure 27. Summary of pre-restoration geomorphic conditions in the Minebank Run study reach, 2002 through 2004.
-------
26 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Mary land, 2002-04
that were made in 2002 at the three ground-water transect
locations, corresponding to permanent cross sections Ee, Ff,
and Gg respectively.
Pebble count data that were collected during May and
June 2003 were used to develop grain-size distributions of
percent finer for the surlicial bed material. The distributions
were developed for each cross section based on the
percentages of counted pebbles that fall within 12 particle-size
ranges of sand, gravel, cobbles, and boulders. The results are
shown in table 10.
A wide range of grain sizes is present within the
Minebank Run study reach (table 10). Several locations in the
study reach had considerable percentages of sand, including
cross sections Bb, Ee, Gg, Hh, and li. Cross sections Gg,
Hh, and li collectively represent approximately the upper
28 percent of the study reach. Cross sections Bb, Ee, and li are
located near meanders in the stream channel, which indicates
that finer material may be temporarily stored in these locations
and transported during storm events. The cross-section
geometry at cross section Bb also indicates a net aggradation
of the channel bed over time in this location. Cross section Hh,
which is in a fairly straight reach, is also a location where finer
material can be stored because of a braided sand and gravel
bar that was acting as a grade control at the start of the study.
Cross sections Cc, Dd, and Ff had the coarsest
distribution of grain sizes, including a higher percentage of
gravel and cobbles than the other locations. Cross section Aa
had a considerable amount of gravel and some sand, but fewer
cobbles. Cross sections Aa, Cc, and Ff are in fairly straight
reaches, which indicates that finer material may be transported
through these locations during storms with relatively small
amounts of net storage. The cross-section geometry at cross
sections Aa, Dd, and Ff also indicated lateral erosion of at
least one of the channel banks, which may have exposed
coarser bed material as the channel migrated. Only a few
boulders were present in the entire study reach.
The median particle diameter (d50), or particle diameter
associated with 50 percent of the material being finer, was
determined for each surficial pebble count and for all bank and
subsurface sample locations at each cross section. The results
are shown in table 11.
The data listed in tabic 11 indicate a wide variation of
d50 values throughout the study reach. Most sample locations
on the banks indicated a d50 in the silt/clay range or in the
range of very fine to coarse sand. The subsurface material
in the channel bed is coarser than the channel banks in most
locations. In cross sections Bb, Cc, Dd, and Ff, parts of
the channel subsurface were coarser than the surficial bed
material, based on the pebble count data. The subsurface
samples also confirmed that cross sections Cc, Dd, and Ff are
the coarsest locations in the study reach.
Data from the pebble counts at each of the nine cross
sections also were combined to develop a composite grain-size
distribution of the surficial bed material for the entire study
reach. This distribution was developed using over 900 pebbles
that were collected in the cross sections during May and
June of 2003. The grain-size distribution and computation of
percent finer for the composite pebble count in the Minebank
Run study reach is shown in table 12. These results are
presented graphically in figure 28.
The data in table 12 show that the majority of particle
sizes in the Minebank Run study reach falls between medium
gravel and small cobbles. The analysis also indicates that over
24 percent of the pebbles counted throughout the study reach
were sand. As shown in figure 28, the d50 for this analysis is
approximately 20.5 mm, which falls within the range of coarse
gravel. The analysis also indicates that less than 20 percent of
the surficial particles were in the cobble range. The abundance
of relatively small bed material sizes in combination with
the flashy streamflow from urban and suburban runoff likely
contributes to the considerable geomorphic changes that
have been observed during this investigation (Doheny and
others, 2006).
The grain-size distributions that were developed from
pebble count data collected in 2003 were compared to
distributions from selected pebble counts that were made
in 2002 at the three ground-water transect locations, which
correspond to permanent cross sections Ee, Ff, and Gg
respectively. Grain-size distributions at these locations for
2002 and 2003 are shown in figures 29-31. An overall shift
to larger grain-size distributions, or coarsening, can be seen at
all three locations between 2002 and 2003. For cross section
Ee, the median particle diameter increased from 18 mm in
2002 to 30 mm in 2003. For cross section Ff, the median
particle diameter increased from approximately 31.5 mm in
2002 to 36 mm in 2003. For cross section Gg, the median
particle diameter increased from 10 mm in 2002 to 14 mm
in 2003. For cross section Ee, there was a slight decrease
in the percentage of sand particles between 2002 and 2003,
whereas there were slight increases in the percentages of sand
particles at cross sections Ff and Gg between 2002 and 2003.
These data indicate that from May 2002 through June 2003,
the changes in grain-size distribution appear to be largely
due to changes in the percentages and distribution of gravel
on the surface of the channel bed. Coarsening of the channel
bed could be the result of large storms that are transporting
and re-distributing sand, gravel, and cobbles within the
stream channel.
Net Changes in Bed Elevation
Net changes in bed elevation were monitored in selected
locations of the study reach by use of the stream piezometers
that had been installed for monitoring shallow ground water
under the channel bed. The locations of these piezometers
correspond very closely to the locations of cross sections
Ee, Ff, and Gg. The net changes in bed elevation at these
three locations were tracked over a period of about 1.5 years,
starting in December 2002 and January 2003, and ending in
July 2004. The net changes in bed elevation during this period
at these locations are shown in figures 32-34.
-------
Geomorphic Characteristics 27
Table 10. Cumulative distribution of grain sizes, in percent finer, for surficial bed material at permanent cross section locations in the
Minebank Run study reach, 2003.
[Values represent the percentage of total particles that are finer than the particle size indicated in the second column of each row of values, mm, millimeters;
%, percent]
Particle
description
Particle
size
limit
(mm)
Aa
(%)
Bb
(%)
Cc
(%)
Dd
(%)
Ee
(%)
Ff
(%)
Gg
(%)
Hh
(%)
li
<%)
Sill
0.062
0
0
0
0
0
0
0
0
0
Sand
2
1 !.!)
30.0
3.9
4.0
30.0
18.0
25.0
61.4
35.0
Very fine
4
13.0
33.0
3.9
4.0
30.0
! 8.0
26.0
62.4
36.0
gravel
Fine
gravel
8
23.0
48.0
6.8
6.0
31.0
20.0
34.0
67.3
45.0
Medium
i 6
43.0
56.0
17.5
26.0
36.0
32.0
52.0
78.2
59.0
gravel
Coarse
gravel
32
61.0
64.0
29.1
46.0
51.0
46.0
68.0
86.1
76.0
Very
64
86.0
80.0
6!.2
74.0
80.0
68.0
88.0
97.0
91.0
coarse
gravel
Small
cobbles
128
99.0
97.0
87.4
94.0
100.0
88.0
99.0
100.0
97.0
|f
256
100.0
99.0
100.0
ioo.o
100.0
100.0
100.0
100.0
100.0
Small
boulders
512
100.0
99.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
Medium
boulders
1.024
100.0
99.0
100.0
ioo.o
100.0
100.0
100.0
100.0
ioo.o
Large
boulders
2,048
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
Table 11. Median particle diameter from pebble counts and sampling locations associated with each permanent cross section in the
Minebank Run study reach, 2002 and 2003.
[mm, millimeters; —, not applicable; <, less than]
Cross
section
Surficial
pebble
count
(mm)
Top of
left bank
(mm)
Left
cut
bank
(mm)
Subsurface
main channel
left
(mm)
Subsurface
main channel
middle
(mm)
Subsurface
main channel
right
(mm)
Right
cut
bank
(mm)
Top of
right bank
(mm)
Aa
2.0.5
0.06
0.03
6.0
i 6.0
0.13
--
0.20
Bb
9.0
0.008
0.014
20.0
19.0
0.3!
--
!).! !
Cc
5o.o
0.026
O.I 1
31.0
70.0
70.0
10.0
0.20
IX!
36.0
!).!!)
--
20.0
55.0
25.0
0.2.0
0.05
lie
30.0
0.09
--
0.43
6.5
8.7
-
0.19
IT
36.0
0. i 2
!).!!)
40.0
14.0
0.27
0.04
0.05
Gg
14.0
0.60
0.60
4.0
20.0
9.5
0.35
0.35
< 2.0
--
0.19
0.82
2.5
1.0
0.15
--
li
J 0.2
O.J 5
0.04
9.0
4.5
0.20
0.20
-------
28 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
Table 12. Grain-size distribution and computation of percent finer from composite pebble count at
all permanent cross sections, Minebank Run study reach, 2003.
[mm, millimeters; %, percent; —, not applicable]
Particle
Cumulative
Particle
size limit
Item
percent finer
description
(mm)
count
(%)
Silt
0.062
0
0
Sand
2
219
24.2
Very fine gravel
4
8
25.1
Fine gravel
8
48
30.4
Medium gravel
16
126
44.4
Coarse gravel
32
128
58.5
Very coarse gravel
64
199
80.5
Small cobbles
128
137
95.7
Large cobbles
256
38
99.9
Small boulders
512
0
99.9
Medium boulders
1,024
0
99.9
Large boulders
2,048
1
100.0
Very large boulders
4,096
0
100.0
TOTAL
--
904
--
TTT
I I r
10,000
Figure 28. Composite pebble count for Minebank Run study
reach above Sherwood Bridge prior to channel restoration, 2003.
DC
HI
LLI
o
DC
LLI
CL
10 100 1,000
GRAIN SIZE, IN MILLIMETERS
Rapid aggradation and degradation of the channel bed
at cross section Ee between January 2003 and July 2004 is
evident (fig. 32). Large storm events on June 12-13, 2003
caused the channel bed to degrade by nearly 1 ft in this
location. From June 2003 to May 2004, the net aggradation
of the channel bed in this location was nearly 1.2 ft. A large
storm event on May 17, 2004 caused the channel bed to
degrade by over 2 ft in this location. The bed began to aggrade
in the aftermath of this storm, but then degraded again during
a large storm event on July 7, 2004. Analysis of the net
changes in bed elevations indicate that (1) pulses of sediment
are gradually transported into this section of the channel, and
(2) the channel is undergoing alternating periods of storage
and extreme erosion of sand and gravel at this location.
-------
Geomorphic Characteristics 29
cc
LU
o
tr
B
O
U
L
D
E
R
S
1,000
Figure 29. Comparison of particle-size distributions at cross
section Ee, 2002 and 2003.
100
90
80
70
60
50
40
30
20
10
0
2
mm
64
mm
256
mm
E
I I I I I I I | I I I I I I I I |
Cross Section [ jr
an—i—~ i i u
E
Ff S
| yV
E
E
B
Q
2002—/'
//
r u
0
u
L
- o
= A
//
A //
B
L
E N
Jr
D
E
i
L^-2003
e
E
R
i
9
S
E
' I
I I I I I
1
10 100
GRAIN SIZE, IN MILLIMETERS
1,000
Figure 30. Comparison of particle-size distributions at cross
section Ff, 2002 and 2003.
100
90
80
70
60
50
40
30
20
10
0
2
mm
64
mm
256
mm
= i
1 1 1 1 1 1 1 1
G
i i i i i i
* i i i i i i i_
E I
R
A
/ / 1
E
E i
V
/ / i
/ / i
c
0
B
L /
/ 1
O
U ^
L =
l! !
2002—/>
/ I
I
B
B
L
E N I
2003
D
c
E
I
i
E
s
R
f—
i
I
S
E |
i
Cross Section i
E
= i
bg |
11 i
1
10 100
GRAIN SIZE, IN MILLIMETERS
1,000
Figure 31. Comparison of particle-size distributions at cross
section Gg, 2002 and 2003.
Alternating periods of aggradation and degradation of
the channel bed at cross section Ff from December 2002 to
July 2004 were observed (fig. 33), however, the range of net
bed elevations measured during this period was approximately
0.62 ft at this location. The three storms that caused
considerable degradation of the channel at cross section Ee,
which is located 220 ft downstream, resulted in aggradation
of the channel at cross section Ff. Overall, the channel bed
showed slight aggradation during the monitoring period, with
a few periods of slight degradation over time. Analysis of
the net bed elevations over time indicated (1) some pulsing
of sediment through the cross section, but with considerably
smaller amounts of storage in this location than at cross
section Ee, and (2) that channel migration could also be a
contributing factor to the net aggradation observed at this
location, due to considerable lateral erosion on the left bank
and extension of a point bar into the channel.
Relatively small net changes in bed elevation were
observed at cross section Gg during most of the period from
January 2003 to July 2004. The range of net bed elevations
measured during this period was approximately 0.61 ft at cross
section Gg, however, the range was only about 0.20 ft from
January 2003 to April 2004. The storm of May 17, 2004
caused the channel bed to degrade by 0.26 ft, and the storm
of July 7, 2004 caused the channel bed to degrade by an
additional 0.34 ft. Analysis of the net bed elevations over
time indicated that (1) the channel cross section was relatively
stable with some pulsing of sediment through the cross
section, but with considerably smaller amounts of storage in
this location than at either cross section Ee or Ff, and (2) the
channel bed became increasingly unstable during the last
3 months of the monitoring period from May to July 2004.
Stream-Channel Classification
Rosgen (1994) developed a classification system for
natural rivers that groups different types of rivers according
to quantitative measurements of dimension, pattern, profile,
and composition of the bankfull channel. Stream channels
are grouped according to single- or multiple-thread channels,
and then divided into stream types according to their degree of
entrenchment, bankfull width/depth ratio, sinuosity, water-
surface slope, and type of channel materials (Rosgen, 1994,
1996). The Rosgen system can be used to describe landforms
and channel dimensions within a river valley, and is widely
used as a tool for investigations of sediment supply, stream
sensitivity to disturbances, recovery potential of natural
channels, channel response to changes in flow regime, fish-
habitat potential, and river-restoration designs (Rosgen, 1994,
1996; Anderson and others, 2002).
The stream channel in the Minebank Run study
reach was classified according to Level II of the Rosgen
stream-classification system, which is used to determine a
morphological description of a given natural stream reach
(fig. 35). Data from cross-sectional and longitudinal-profile
2
mm
64
mm
Cross Section
Ee
10 100
GRAIN SIZE, IN MILLIMETERS
-------
Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
cc
LU
m Ej
o £
N —'
LU <
£L LU
¦-2
OZ
o <
IJL LU
CD ^
|_ LU
to
gti
LU Z
Q —
LU
m
1/2/2003 4/12/2003 7/21/2003 10/29/2003 2/6/2004 5/16/2004
DATE
Figure 32. Net changes in bed elevation overtime at cross section Ee, January 2, 2003 through July 13, 2004.
Figure 33. Net changes in bed elevation overtime at cross section Ff, December 3,2002 through July 14, 2004.
GC
LU
UJ
N -I
LU <
Q_ LU
O z
o <
LL LU
CD ^
i_ LU
Is
9<
Q
LU
m
o o
216.9
216.8
216.7
216.6
216.5
216.4
216.3
216.2
216.1
12/3/2002
3/13/2003
6/21/2003
9/29/2003
DATE
1/7/2004
4/16/2004
7/25/2004
219.5
219.4
219.3
219.2
219.1
219.0
, - 218.9
218.8
i i Cross Section i r i i
k ! A Gfl ^ • \
/ K : \ i i:
\ -
;
S5 '
0 I
01
CVJ 1
)rm of June 12,2003
o 1
o 1
°VJ I
£1
o 1
-------
Geomorphic Characteristics 31
surveys collected in the study reach from 2002 to 2004 were
used to determine entrenchment, width/depth ratio, and water-
surface slope. Sinuosity was calculated on the basis of stteam
lengths that were determined from the longitudinal-profile
surveys, and valley length that was measured from an aerial
photo as a nearly straight-line distance between the upper and
lower ends of the study reach (Baltimore County Department
of Environmental Protection and Resource Management,
2000). Pebble-count data collected during 2003 were used to
classify the channel materials in the study reach.
The reach containing cross section Hh was selected for
classification. This reach of stream was selected because
it was generally straight, and because bankfull indicators
were clearly visible and easy to identify (Leopold, 1994;
Harrelson and others, 1994). Cross section Hh is located
28 ft downstream of the continuous-record streamflow-gaging
station. As a result, bankfull indicators were easily related to a
gage height at the station and associated with a discharge from
the stage-discharge rating that is representative of bankfull.
The data variables that describe the bankfull channel at cross-
section Hh during 2002 to 2004 are summarized in table 13.
On the basis of data variables shown in table 13, the
Minebank Run stream channel was classified as a B stream
type, indicating moderate entrenchment, a moderate width-to-
depth ratio, and moderate sinuosity. Since the water-surface
slope is consistently less than 2 percent in the study reach and
the composite pebble count for the reach indicated a d50 of
21 mm, the stream channel was classified as a B4c channel
based on the Level II Rosgen morphological descriptions
(fig. 35).
The Rosgen system incorporates an entrenchment, ratio
variance of +/- 0.2 dimensionless units, therefore, the data
in table 13 indicate that the Minebank Run stream channel
could have been in transition between a B and F channel
type between the 2002 and 2003 channel surveys. The
entrenchment ratio then increased between the 2003 and
2004 surveys, however, indicating that the stream channel fell
within the B classification at the end of the study period.
The bankfull indicators near the streamflow-gaging
station and cross section Hh corresponded to the profile of
point bar- elevations that were surveyed during the longitudinal
surveys during 2002-04. The stage-discharge rating at the
streamflow-gaging station indicated a bankfull discharge
of approximately 244 ft3/s (cubic feet per second). The
recurrence interval for this discharge is about a 1.0 year flood
(Doheny and others, 2006). Leopold (1994) suggested that for
many streams, the bankfull discharge is the flow that occurs
at an average recurrence interval of approximately 1.5 years.
For watersheds with large percentages of urban and suburban
development, however, the bankfull discharge likely occurs
more frequently and for very short durations due to the flashy
nature of these streams. A flow-duration analysis using
data from the streamflow-gaging station in the Minebank
Run study reach indicated that the point bar elevation was
exceeded by flows 0.014 percent of the time during water year
2002, 0.040 percent of the time during water year 2003, and
0.032 percent of the time during water year 2004 (Doheny
and others, 2006). On average, the point bar elevation was
exceeded 0.029 percent of the time during the study period.
Results of the Rosgen stream classification and associated
bankfull flow characteristics indicate that Minebank Run has
more frequent bankfull events than typical non-urban steams
on the basis of recurrence interval (Doheny and others,
2006), but the amount of time the stream stage exceeded this
elevation was as little as 1.2 to 3.5 cumulative hours dining a
given water year due to the flashiness of the stream.
Shear-Stress Analysis
Boundary shear stress, in relation to stream flow and
natural channels, is the force that flowing water imposes on
the channel bed and banks of the stream. Shear stress was first
described by Shields (1936) as follows:
T=URS (1)
where
T = boundary shear stress (pounds/ft2),
U = unit weight of water (pounds/ft:3),
R = hydraulic radius (ft),
S = water-surface slope (ft/ft).
Rosgen (1996) used this relation along with different
stream types that were determined from various field surveys
and corresponding data on mean velocity and stream discharge
to develop a logarithmic relation of mean velocity versus
boundary shear stress according to various stream types.
Boundary shear stresses were computed for the peak discharge
of 21 storms that occurred in the Minebank Run watershed
from November 2001 to September 2004. Hydraulic radius
was determined by use of the geometry characteristics
surveyed at cross section Hh, or from channel surveys that
were done for indirect measurements of peak discharge at
the streamflow-gaging station. Peak water-surface slopes
were computed using high-water mark elevations that were
surveyed at and near the streamflow-gaging station, or from
crest-stage gages that are located at the streamflow-gaging
station, and approximately 180 ft downstream in the vicinity
of cross section Gg and the transect of wells and piezometers
farthest upstream in the study reach. Corresponding mean
velocities were computed for each storm event using the peak
discharge for the storm and the corresponding cross-sectional
area at cross section Hh. The results are summarized in
table 14.
The computed boundary shear stress values were plotted
against the peak discharge for each storm (fig. 36) and
against corresponding mean velocity (fig. 37). Simple linear
regression was used to determine logarithmic relations for both
boundary shear stress versus peak discharge and boundary
shear stress versus mean velocity. The following equations
-------
32 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
£-£oc
CJ) r~
LU CO CN
CO cm
JL JL JL
o
cc
o
"a
"a
o
o
cc
k—
3
OJ
-------
Geomorphic Characteristics 33
Table 13. Data variables describing the bankfull channel at cross section Hh that were used for
Rosgen classification of the stream channel, 2002-04.
[ft, feet; ft2, square feet]
Data variable
2002
2003
2004
I in ilk I'll II elevalion
(i'l above moan sea level)
Cross-sectional area
(ft2)
Welled jieriineler
(I'D
Hydraulic radius
(ft)
Mean deplh
(I'D
Maximum depth
(ft)
Top width
(I'D
Entrenchment width
(in ft, at twice maximum
Imnkfiiii depth)
Hiiirenchirieiil ralio
(I'l/I'D
Width/depth ratio
(ft/ft)
Simiosily
(I'i/I'D
Water-surface slope
(ft/ft)
222.58
50.6
3 I.9
1.58
1.68
2.80
30.0
50.9
1.70
17.9
I.! 6
0.0100
222.56
62.9
42.0
1.51
1.60
3.12
.19.7
53.4
i .35
24.8
1.16
0.0092
222.74
66.3
37.6
1.76
1.87
2.99
35.5
54.0
1.52
19.0
1.16
0.0095
were developed based on the data from the Minebank Run
study reach:
where
and
Q
ss
where
and
Q = 385(55)1418
: peak discharge in ft3/s,
: boundary shear stress in lb/ft2.
V = 4.715 (SS)0533
(2)
(3)
55
: mean velocity at the peak discharge in ft/s,
: boundary shear stress in lb/ft2.
The equation for boundary shear stress versus peak
discharge indicated a coefficient of determination (R2) of
0.84. The residual standard error (RSE) was 0.127 log units,
or approximately 33 percent. The equation for boundary shear
stress versus mean velocity indicated an R2 of 0.83. The RSE
was 0.051 log units, or approximately 31.8 percent.
The relation for boundary shear stress versus mean
velocity was also plotted on the relation developed by Rosgen
(1996) for boundary shear stress versus mean velocity by
stream type (fig. 38). Most boundary shear stress and mean
velocity values for Minebank Run are larger than non-urban
B channel types that were classified and plotted by Rosgen
(1996). The slope of the regression line for Minebank Run is
considerably flatter than the relations developed by Rosgen
(fig. 38). This indicates that for Minebank Run, small changes
in mean velocity result in larger changes in boundary shear
-------
34 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04
Table 14. Data variables and boundary shear stress computations for 21 storm runoff events in the Minebank Run study reach,
November 2001 through September 2004.
[ft3/s, cubic feet per second; ft2, square feet; ft/s, feet per second; ft, feet; lb/ft2, pound per square foot]
Date
of
storm
event
Peak
discharge
(ff/s)
Cross-
sectional
area
(ft2)
Mean
velocity
(ft/s)
Hydraulic
radius
(ft)
Water-
surface
slope
(ft/ft)
Boundary
shear
stress
(lb/ft2)
1 1/25/2001
367
76.7
4.78
! .92
0.0097
1.16
3/3/2002
OS
30.3
3.14
! .05
0.009!
0.60
3/26/2002
! 33
38.0
3.50
1.15
0.0093
0.67
4/! 9/2002
40!
81.7
4.9!
2..0!)
0.0098
! .2.2
5/2/2002
247
61.3
4.03
1.59
0.0077
0.76
6/6/2002
466
88.3
5.28
2.! 2
0.0103
! .36
8/3/2002
725
i 14
6.34
2.38
0.0080
1.19
2/22/2003
253
59.6
4.24
! .42
0.0063
0.56
6/1 2/2003
i .390
150
9.29
2.97
0.01 12
2.08
9/23/2003
834
14!
5.9!
2.74
0.0095
! .62
10/14/2003
4i 1
99.4
4.! 3
2.19
0.0081
I • 1 I
10/27/201 >3
234
60.6
3.86
! .75
0.0063
0.69
! 1/19/2003
700
126
5.54
2,49
0.0! 01
1.57
12/1 1/2003
194
53.3
3.64
! .62
0.0055
0.56
5/17/2004
720
130
5.56
2.54
0.0091
1.44
5/25/2004
266
71.1
3.73
! .64
0.0054
0.55
6/25/2004
295
78.8
3.74
1.79
0.0062.
0.69
7/7/2004
945
148
6.37
2.84
0.0103
1.82
7/2.7/2004
919
146
6.30
2.80
0.0109
1.90
9/1 8/2004
190
5!.2
3.7!
! .58
0.0067
0.66
9/28/2004
21 I
56.5
3.73
1.68
0.0058
0.6!
stress when compared to the non-urban stream channels
plotted by Rosgen (1996). Rapid increases in boundary shear
stress indicate rapidly increasing forces that the flowing water
imposes on the channel bed and banks of the stream channel,
and thus a greater ability for the stream to transport sediment.
Data Limitations
The geomorphic data collected during this study are
representative of approximately 11.5 years in the long-term
geomorphic evolution of the stream channel. Data collection
over longer periods could provide a longer term perspective on
the geomorphic form and processes of the stream channel.
Longitudinal profiles and cross-sectional data were
collected by use of conventional leveling techniques. Although
permanent monuments were used to identify and re-survey
cross sections, there is a degree of difficulty in maintaining
the same stations from survey to survey, and conventional
leveling includes a small degree of human error in interpreting
readings from the survey rod. Due to geomorphic changes in
the stream channel over time, there is also a small degree of
error in maintaining exact longitudinal stationing from survey
to survey.
Pebble count data represent a random sampling of
particle sizes from the channel bed. As a result, small
differences in particle-size distribution may, in some cases, be
explained by random variability of the samples taken from the
channel bed.
-------
Summary and Conclusions 35
10,000
o
o
HI
iii 2 1.°00
Qo
m
o
z
100 =
R = 0.84
Q = 385(SS)
1.418
¦|Q I I I I I I I I I I I I I L
0.1 1 10
SHEAR STRESS, IN POUNDS PER SQUARE FOOT
Figure 36. Boundary shear stress versus peak discharge
in the Minebank Run study reach, November 2001 through
September 2004.
10
£:°
h o
o LU
o «
wE
> Q.
Zh
< LU
LU LU
V = 4.715(SS)
R2= 0.83
0.533
0.1
0.1
1
SHEAR STRESS, IN POUNDS PER SQUARE FOOT
10
Figure 37. Boundary shear stress versus mean velocity at the
peak discharge during storm events in the Minebank Run study
reach, November 2001 through September 2004.
10
o
b o
O LU
o®
> 0.
Z i_
< ~
LU K
0.1
C3^—
E3/
v = 4.715(SS)0-533
R2= 0.83
•—F3
/B3
\s
I I I i\ I I I
A3-F3 = ROSGEN STREAM
TYPES
I I I
0.1 1
SHEAR STRESS, IN POUNDS PER SQUARE FOOT
10
Figure 38. Boundary shear stress versus mean velocity at the
peak discharge during storm events in the Minebank Run study
reach, November 2001 through September 2004, and relations
developed by Rosgen stream type for non-urban stream channels
(modified from Rosgen, 1996).
Summary and Conclusions
This report describes the methods used to collect pre-
restoration geomorphic data in a selected study reach of
Minebank Run near Towson, Maryland. Data collected
from 2002 to 2004 include continuous-record streamflow;
surveyed elevations of the channel bed, water surface, and
bank features; surveyed cross sections; measurements of bank
erosion and maximum scour by use of bank pins and scour
chains; pebble counts and samples of the channel bed and
banks for determination of grain-size analyses; measurements
of bed elevations over time in selected locations; and
high-water mark elevations from storm runoff events in
the watershed.
These data were used to assess pre-restoration
geomorphic characteristics and pre-restoration geomorphic
changes over time in the Minebank Run study reach.
Longitudinal profiles of the channel bed, water surface, and
bank features were developed from field surveys. Changes
in cross-section geometry were documented. Grain-size
distributions of the channel bed and banks were developed
from pebble counts and laboratory sediment analysis. Net
changes in the elevation of the channel bed over time were
documented at selected locations. The stream channel was
classified according to morphological descriptions using
measurements of slope, entrenchment ratio, width-to-depth
ratio, sinuosity, and median particle diameter of the channel
materials. Boundary shear stress was analyzed in the vicinity
of the streamflow-gaging station by use of hydraulic variables
that were computed from the cross-section surveys, and slope
measurements that were made by use of crest-stage gages in
the study reach.
Comparison of the longitudinal profiles showed
considerable changes in the percentage and distribution of
riffles, pools, and runs in the study reach between 2002 and
2004. In spite of major geomorphic changes to sections of
the channel profile from storm events, the overall slope of the
channel bed and other features remained constant at about
1 percent.
The cross-sectional surveys indicated net increases in
cross-sectional area, mean depth, and channel width over time
at several locations, which indicate channel degradation and
widening. Large amounts of sediment were being stored in
the study reach at two locations. Data from the scour chains
indicated maximum scour of 1.4 feet, and several cross
sections where maximum scour exceeded 1.0 feet during
storm events. Lateral migration of the banks varied widely
throughout the study reach and ranged from 0.2 feet to as
much as 7.9 feet. Changes in net bed elevation measured at
selected locations indicated a maximum aggradation of nearly
1.2 feet in one location over time, degradation of the channel
bed of nearly 2 feet in one location during a storm event
in May 2004, and pulses of sediment that were transported
through the study reach over time.
-------
36 Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Mary land, 2002-04
Particle-size analyses of the channel bed from
pebble counts indicated a median particle diameter of
20.5 millimeters for the study reach with over 24 percent
of the total count consisting of sand particles. Laboratory
analyses of bank samples indicated that the material in the
channel banks was predominantly silt/clay, or a mixture of
silt/clay and very fine to coarse sand.
The Minebank Run stream channel was classified as a
B4c channel on the basis of morphological descriptions in the
Rosgen Stream Classification System. The B4c classification
describes a single-thread stream channel with a moderate
entrenchment ratio of 1.4 to 2.2; a width-to-depth ratio greater
than 12; moderate sinuosity of 1.2 or greater; a water-surface
slope of less than 2 percent; and a median particle diameter in
the gravel range (2-64 millimeters).
The analysis of boundary shear stress showed larger mean
velocities and boundary shear stress values for Minebank Run
when compared to the relation for non-urban B channel types
plotted by Rosgen. The slope of the regression line for mean
velocity versus boundary shear stress at Minebank Run was
noticeably smaller than the relations developed by Rosgen
for non-urban channel types. This indicates that relatively
small increases in mean velocity can result in large increases
in boundary shear stress in stream channels with highly
developed watersheds, such as Minebank Run.
Acknowledgments
The authors would like to thank Kenneth Jewell, Russell
Neill, and Brad Scoggins of the USEPA National Risk
Management Laboratory, Ada, Oklahoma, for extensive
assistance in planning and implementation of the study design.
Special thanks are extended to Donald Outen, Karen
Ogle, Robert Ryan, Steven Stewart, Candice Croswell, and
Nancy Pent/ of the Baltimore County DEPRM for planning
assistance and technical input about the stream-restoration
project at Minebank Run.
The authors would like to thank Leo Rebetsky of the
Baltimore County Department of Recreation and Parks.
As park manager of Cromwell Valley Park, Mr. Rebetsky's
support, cooperation, and assistance have been critical to
successful completion of the work to date.
Thanks are extended to Joseph Fisher and Michael
Hansen, formerly of the IJSGS Mary land-Delaware-D.C.
Water Science Center, for their assistance with data-
collection efforts.
Thanks are also extended to John Brakebill, Gary Fisher,
and Robert Shedlock of the USGS Maryland-Delaware-D.C.
Water Science Center, and Robert W. James, Jr., formerly of
the USGS Maryland-Delaware-D.C. Water Science Center,
for their assistance and support with technical issues and
data interpretation.
Finally, the authors thank the staff of the USGS Cascades
Volcano Observatory Sediment Laboratory in Vancouver,
Washington, for their assistance in determining grain-
size distributions of channel bed and bank samples from
Minebank Run.
References Cited
Anderson, A.L., Miller, C.V., Olsen, L.D., Doheny, E.J., and
Phelan, D.J., 2002, Water quality, sediment quality, and
stream-channel classification of Rock Creek, Washington,
D.C., 1999-2000: U.S. Geological Survey Water-Resources
Investigations Report 02-4067, 91 p.
Baltimore County Department of Environmental Protection
and Resource Management, 2000, aerial photograph of
Minebank Run watershed: Baltimore County, MD, 1 sheet,
scale 1:4,800.
Buchanan, T.J., and Somers, W.P., 1968, Stage measurement
at gaging stations: U.S. Geological Survey Techniques of
Water-Resources Investigations, book 3, chap. A7, 28 p.
Carter, R.W. and Davidian, J., 1968, General procedure for
gaging streams: U.S. Geological Survey Techniques of
Water-Resources Investigations, book 3, chap. A6, 13 p.
Crowley, W.P., and Cleaves, E.T., 1974, Geologic map of
the Towson quadrangle, Maryland: Maryland Geological
Survey, 1 sheet, scale '1:24,000.
Doheny, E.J., Starsoneck, R.J., Striz, E.A., and Mayer, P.M.,
2006, Watershed characteristics and pre-restoration surface-
water hydrology of Minebank Run, Baltimore County,
Maryland, water years 2002-04: U.S. Geological Survey
Scientific-Investigations Report 2006-5179, 42 p.
Harrelson, C.C., Rawlins, C.L., and Potyondy, J.P., 1994,
Stream channel reference sites—An illustrated guide to
field technique: Fort Collins, CO, U.S. Department of
Agriculture, Forest Service, Rocky Mountain Forest and
Range Experiment Station, General Technical Report
RM-245, 61 p.
James, R.W., 1986, Maryland and the District of Columbia
surface-water resources, in National water summary 1985—
Hydrologic events and surface-water resources: U.S.
Geological Survey Water-Supply Paper 2300, p. 265-270.
Leopold, L.B., 1994, A view of the river: Cambridge, MA,
Harvard University Press, 298 p.
-------
References Cited 37
Mayer, P.M., Striz, E.A., Shedlock, R.J., Doheny, E.J., and
Groffman, P., 2003, The effects of ecosystem restoration
on nitrogen processing in an urban, mid-Atlantic Piedmont
stream, in Renard, K.G., McEIroy, S.A., Gburek, W.J.,
Canfield, H.E., and Scott, R.L., eds., Proceedings of
the First Interagency Conference on Research in the
Watersheds, Tucson, Arizona, October 27-30, 2003, U.S.
Department of Agriculture, Agricultural Research Service,
p. 536-541. (Available online at http://www.tucson.ars.
ag. gov/icrw/Proceedings/Mayer. pdf)
Paul, M J., and Meyer, J.L., 2001, Streams in the urban
landscape: Annual Review of Ecology and Systematica,
v. 32, p. 333-365.
Rosgen, 13.1.., 1993, Applied fluvial geomorphology, training
manual, river short course: Pagosa Springs, CO, Wildland
Hydrology, 450 p.
Rosgen, D.I... 1994, A classification of natural rivers: Catena,
v. 22, p. 169-199.
Rosgen, D.L., 1996, Applied river morphology: Pagosa
Springs, CO, Wildland Hydrology, 365 p.
Saffer, R.W., Pentz, R.H., and Tallman, A.J., 2005, Water
resources data, Maryland and Delaware, water year 2004,
Volume 1. Surface-water data: U.S. Geological Survey
Water-Data Report MD-DE-DC-04-1, 540 p.
Shields, A., 1936, Application of similarity principles and
turbulence research to bedload movement, translated by
W.P. Ott and J.C. Uchelen: Pasadena, CA, California
Institute of Technology Report No. '167, 43 p.
Wolman, M.G., 1954, A method of sampling coarse river-bed
material: Transactions of the American Geophysical Union,
v. 35, no. 6, p. 951-956.
-------
-------
Glossary 39
Glossary
A
Alluvium Sedimentary material that was
deposited by flowing water. Examples of
alluvial deposits include deltas, point bars,
and sand in the flood-plain areas of rivers
or streams.
B
Bankfull (stage or discharge) Bankfull
stage refers to the water-surface elevation
at the level of the active flood plain in a
stream channel. Bankfull discharge refers
to the stream discharge at the level of the
active flood plain. It is also the discharge
that, over time, transports the largest volumes
of sediment, and forms and maintains the
morphological features in the stream channel.
Bankfull indicator(s) Geomorphic features
in a stream channel that define the elevation
of the active flood plain. These features might
include the top of point bar surfaces and
depositional features, breaks or changes in
bank vegetation, changes or breaks in bank
slope, changes in channel-material sizes or
distribution on the channel banks, the upper
extent of bank undercuts, and stain lines
on rocks.
Boundary shear stress The force, in pounds
per square foot, that flowing water applies to
the channel bed and banks of a stream.
C
Coefficient of determination (R2) The
fraction of the variation in the dependent
variable that is explained by the explanatory
variable(s). R2 ranges between 0 and 1. The
closer R2 is to 1, the better the explanation
of variation in the dependent variable with
changes in the explanatory variable(s).
Colluvium Loose deposits of collapsed rock
debris that accumulate at the base of a cliff or
sloping valley.
Continuous-record streamflow-gaging
station Location where a water-stage
recorder is used to collect continuous
time-series stage data that are related to
systematic discharge measurements at the
station. Continuous-record streamflow-
gaging stations are often operated for the
purpose of long-term monitoring or as part of
hydrologic investigations.
Crest-stage gage A device that will register
the peak stage of the stream occurring
between inspections of the gage. Crest-stage
gages arc typically used as a supplement to
a water-stage recorder since the peak stage
of a storm can occur in between recorded
stage values. Crest-stage gages can be
used to obtain high-water marks at a given
location during a flood, or to determine
water-surface slopes at different stream
stages if placed in multiple locations along a
reach of stream. A stage-discharge relation
for the location of a crest-stage gage can be
developed using discharge data obtained by
indirect measurements of peak flow, or direct
measurement of a range of discharges by use
of a current meter.
D
Daily mean discharge Discharge that is
computed as the arithmetic mean of the
instantaneous discharge values for a given day
of the water year.
F
Fall Line The line marking the point on each
stream where the flow descends from the
eastern section of the Piedmont Physiographic
Province to the western section of the Coastal
Plain Physiographic Province in Maryland.
The Fall Line is characterized by an abrupt
decrease in channel slope in transition
between the Piedmont and the Coastal Plain
Physiographic Provinces.
Flashy A stream or watershed that tends
to produce narrow, steeply peaked storm
hydrographs that rise and fall very quickly.
H
Hydraulic radius The cross-sectional area of
a channel divided by the wetted perimeter.
-------
Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Mary land, 2002-04
L
Lateral erosion Erosion in which the
removal of bank material extends laterally
from the toe of the bank.
P
Percent finer A cumulative percentage,
associated with a particular particle size
or diameter, that represents how much of
the material that composes the channel
bed or banks is smaller, or finer, than that
particle diameter.
Piezometer An open-ended vertical pipe
that, is used for measurement, of pressure and
changes in pressure at a selected depth within
an aquifer,
R
Relief The variation between the highest
and lowest elevations at any location in a
watershed, using a common elevation datum.
Residual standard error (RSE) The square
root of the mean square error, which is the
sum of the squared differences between the
observed and predicted values divided by the
number of observations minus 2. Residual
standard error is also commonly known as the
standard error of estimate.
Run A longitudinal section of stream
channel that has a moderate current, moderate
depth, and a relatively smooth water surface.
S
Sinuosity The ratio of stream length
to valley length. The minimum value for
sinuosity is 1.0 for a straight channel,
and increases depending on the level of
meandering in the reach of interest.
Stability The ability of a stream or river
to transport its flow and sediment while
maintaining its dimension, pattern, and
profile with no net change in aggradation
or degradation.
Stage-discharge rating A logarithmic
curve of stream stage versus stream discharge
that is developed from a series of discharge
measurements made in a particular location.
A stage-discharge rating can also be presented
as a table that is prepared from the curve.
T
Terrace An abandoned flood plain in a
river or stream . A flood plain may become
abandoned when a stream channel degrades
and forms new channel features that are
indicative of the active flood plain.
Thalweg The lowest elevation along a cross
section in a stream channel.
Top of topographic bank The topographic
break in elevation that separates the stream
valley from the over-bank area.
W
Water year The 12-month period beginning
October 1 and ending September 30. The
water year is designated by the calendar
year in which it ends and includes 9 of the
12 months. For example, the year beginning
October 1, 2003 and ending September 30,
2004, is called "water year 2004."
Wetted perimeter The length along the
cross-sectional boundary of a channel that
is contacted by water. In an open channel,
such as a stream or river, the cross-sectional
boundary is the channel bed and banks.
-------
Appendix 41
Appendix 1
-------
Appendix 1. Changes in cross-section geometry at permanent cross section Aa, Minebank Run study reach, 2002 through 2004.
[ft, feet; ft2, square feet; Hyd., Hydraulic; %„ percent]
Elevation
(ft
above
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Channel
width
(ft)
Channel
width
(ft)
Channel
width
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
mean
sea level)
2002
'003
2004
2002
'003
2004
2002
9003
2004
2002
'003
2004
2002
'003
2004
2! 2.00
48.4
47.1
(-2.1%)
57.9
(+19.6'/;)
3 i .5
32.6
35.9
1.54
1.44
1.61
29.5
30.4
32.5
1.65
1.55
1.78
2! 2. SO
63.4
62.5
(-1.4%)
¦"! A -¦1
'+1lA'/i)
33.5
34.!
3 "7 A
1.89
1.84
1.99
30.7
31.3
33.3
2.06
2.00
2.23
2 i .¦!.00
79.1
78.4
(-0.9v<)
91.3
{+15 A'/()
35.5
35.5
39.5
:
2.21
2.31
32.2
32.2
34.9
2.46
2.44
2.62
213.SO
95.6
95.!
i'-0.5vv)
109.2
'+J-!?'/,)
37.6
38.5
41.9
2.54
2.47
2.6!
33. i
34.8
36.8
2.83
2.73
2.97
214.00
1 1 2.9
1 13.2.
{+0.3'/( )
128.0
(+13.4V,)
39.7
41.8
44.3
2.84
2.71
2.89
35.3
37.6
38.7
3.20
3.0!
3.31
214.50
165.2
165.9
(+0.4%)
184.1
(+11.4%)
78.0
81.7
82.3
2.12
2.03
2.24
72.6
76.4
75.7
2.28
2.17
2.43
2 3 5.00
20i .7
204.2.
(+I.2V)
222.2
(+10.2V)
79.7
82.9
84.0
2.53
2.46
2.65
73.7
77.0
76.9
2.74
2.89
215.50
238.9
242.9
(+1.7%)
261.0
(+9.3%)
81.4
84.1
85.8
2.93
2.89
3.04
74.9
77.7
78.1
3.19
3.13
3.34
216.00
276.6
282.0
(+2.0% )
300.3
(+8.6V )
83.7
86.3
87.8
3.30
3.27
3.42
76.7
79.3
79.6
3.61
3.56
3.77
216.15
288.2
293.9
(+2.0%)
312.4
(+8.4%)
85.3
87.1
90.1
3.38
3.38
3.47
78.2
80.0
81.9
3.68
3.68
3.82
7
CP
!
33
CP
SI
n
CP
o
2
o
%
o"
o
o
s
1°
n
a
w
23
3
O
3
o
o
c
#
3
-3
Note: Percentages shown in parentheses under cross-sectional areas represent the percent change in area from the original survey in 2002.
§
-------
Appendix 1. Changes in cross-section geometry at permanent cross section Bb, Minebank Run study reach, 2002 through 2004.—Continued
[ft, feet; ft2, square feet; Hyd., Hydraulic; %, percent]
Elevation
(ft
above
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Channel
width
(ft)
Channel
width
(ft)
Channel
width
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
mean
sea level)
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
21 2.17
50.!
33.4
(-33.3'/
33.9
28.1
28.8
1.48
1.19
1.11
32.2
27.3
28.0
1.56
1.22
1.14
212.50
62.2
44.5
(-28.5%)
42.8
(-31.2%)
41.7
38.4
38.6
1.49
1.16
1.11
39.7
37.6
37.7
1.57
1.18
1.13
213.00
82.7
64.2
(-22.4'/,)
62.3
(-24.7%)
44.6
42.0
41.7
1.85
1.53
1.49
42.2
41.0
40.4
1.96
1.57
1.54
213.50
104.2
85.8
(-17.7%)
83.3
(-20.1%)
46.7
46.6
44.9
2.23
1.84
1.86
43.8
45.4
43.2
2.38
1.89
1.93
214.00
1 26.5
108.5
(-14.2'/,)
105.5
(-16.6'/,)
48.9
48.7
47.5
2.59
2.24
45.5
47.0
45.7
2.78
2.32
2.31
214.50
149.9
132.9
(-11.3%)
129.0
(-13.9%)
52.0
51.1
50.5
2.89
2.60
2.56
48.2
48.9
48.4
3.11
2.72
2.66
2 i 5.00
178.2
160.6
(-9.9'/;)
156.6
(-12.1'/,)
66.5
61.7
64.1
2.68
2.60
2.44
62.3
59.0
61.5
2.86
2.72
2.55
2! 5.50
210.4
191.5
(-9.0%)
188.7
(-10.3%)
7! ).4
67.6
70.2
2.99
2.83
2.69
65.8
{V"! A
67.1
3.20
2.97
2.81
216.00
243.9
224.0
(-8.2'/, i
222.9
(-8.6'/,)
74.0
69.5
73.6
3.30
3.22
3.03
68.9
65.8
70.0
3.54
3.41
3.18
216.50
280.0
259.2
(-7.4'/,)
259.2
(-7.4'/,)
82.8
80.0
81.6
3.38
3.24
3.17
/ I .J
75.8
77.6
3.62
3.42
3.34
216.54
283.1
262.2
(-7.4'* )
262.3
(-7.3'/,)
83.6
81.3
82.3
3,39
3.22.
3.19
78.1
77.1
78.2
3.63
3.40
3.36
Nolo: Poivoiilagos shown In paronlhosos undor eross-soelionai aroas ivprosonl iho poreonl diango In aroa ironi iho original surwy In 2002.
-------
Appendix 1. Changes in cross-section geometry at permanent cross section Cc, Minebank Run study reach, 2002 through 2004..
[ft, feet; ft2, square feet; Hyd., Hydraulic; %, percent]
Elevation
(ft
above
mean
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Channel
width
(ft)
Channel
width
(ft)
Channel
width
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
sea level)
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
214.05
40.0
50.5
(+26.3'4)
46.4
( + l6.0';O
45.3
46.6
46.9
0.88
1.08
0.99
43.7
44.5
43.8
0.92
1.14
1.06
214.50
59.9
70 7
( + i 8,!)vv)
fsfs A.
(+10.9%)
46.7
47.8
48.6
1.28
1.48
1.37
44.8
45.3
45.2
1.34
1.56
1.47
215.00
82.5
9.1.5
( + 13.3%)
89.4
(+8.4'/,)
48.0
49. i
50.5
1.72
1.91
1.77
45.5
46.1
46.9
1.81
2.03
1.91
2! 5.50
105.4
! ! 6.7
(+1 < ).7vv )
1 13.3
(+7.5vv)
49.1
50.2
52.7
2.15
2.32
2.! 5
46.0
46.6
48.7
2.29
2.51
2.33
215.95
12.6.1
137.8
(+9.3'/,)
150.7
( + 19.5'/;)
50. i
51.6
86.0
2.52.
2.67
1.75
46.5
47.5
81.6
:
2.90
1.85
216.50
188.8
200.1
(+6.0%)
196.4
(+4.0%)
88.1
90.8
89.9
2.14
2.20
2.18
83.8
85.9
85.1
2.25
2.33
2.31
217.00
2.3 1.5
243.3
(+5.1 V,)
2.39.8
(+3.6'/<)
92.9
92.5
93.8
2.49
2.63
2.56
88.3
87.1
88.7
2.62
217.50
276.7
287.6
(+3.9%)
285.0
(+3.0%)
98.2
95.9
97.3
2.82
3.00
2.93
93.3
90.1
92.0
2.97
3.19
3.10
218.00
324.8
335.0
(+3.1 V,)
332.0
(+2.2VO
106.3
107.0
103.7
3.06
3.13
3.20
101.2
101.1
98.3
3.21
3.31
3.38
218.18
343.4
353.8
(+3.0%)
350.3
(+2.0%)
111.0
114.7
110.2
3.09
3.09
3.18
106.0
108.8
104.8
3.24
3.25
3.34
Note: Percentages shown in parentheses under cross-sectional
areas represent the percent change in area
from the original survey
in 2002.
7
CP
!
33
CP
SI
n
CP
o
2
o
%
o"
o
o
s
1°
n
a
w
3
©
3
o
o
c
#
3
-3
§
-------
Appendix 1. Changes in cross-section geometry at permanent cross section Dd, Minebank Run study reach, 2002 through 2004.—Continued
[ft, feet; ft2, square feet; Hyd., Hydraulic; %, percent]
Elevation
(ft
above
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Channel
width
(ft)
Channel
width
(ft)
Channel
width
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
sea level)
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
215.00
23.6
30.0
(+27.1'/,)
31.2
(+32.2%)
23.9
26.5
30.9
0.99
1.13
1.01
23.1
25.0
29.4
1.02
1.20
1.06
215.50
35.4
42.7
(+20.6%)
46.1
(+30.2%)
25.7
27.9
32.3
1.38
1.53
1.43
24.5
26.0
30.2
1.45
1.64
1.53
2.16.00
49.4
56.1
( + 13.67,)
61.4
(+24.3'/,)
;: -
30.0
33.8
1.51
1.87
1.82
31.1
31.1
1.59
2.02
1.97
216.50
65.4
72.3
(+10.6%)
78.3
(+19.7%)
35.2
36.7
39.6
1.86
1.97
1.98
33.2
34.1
36.5
1.97
2.12
2.14
2! 7.00
83.3
90.7
(+8.97,)
97.9
( + 17.57;)
40.0
42.0
44.8
2.08
2.16
2. i 8
37.7
38.9
41.4
2.21
2.33
2.36
217.50
104.5
! 1 ! .9
i'+ 7. i vv)
! 19.9
f + J -1.7'/,)
48.6
48.8
51.6
2.! 5
2.29
2.32
45.9
45.4
47.8
2.27
2.46
2.51
218.00
i 28.5
136.1
(+5.9%)
145.8
( + 13.5'/,)
55.4
58.5
6 i .9
2.32.
2.33
2.36
52.4
54.7
57.7
2.45
2.49
2.53
218.38
182.7
190.1
(+4.1%)
200.0
(+9.5%)
94.6
96.5
98.0
1.93
1,97
2.04
90.8
91.8
92.7
2.01
2.07
2.16
Note: Percentages shown in parentheses under cross-sectional
areas represent the percent change in area
from the original survey
in 2002.
-------
Appendix 1. Changes in cross-section geometry at permanent cross section Ee, Minebank Run study reach, 2002 through 2004.—Continued
[ft, feet; ft2, square feet; Hyd., Hydraulic; %, percent]
Elevation
(ft
above
mean
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Channel
width
(ft)
Channel
width
(ft)
Channel
width
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
sea level)
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
216.00
2.1.1
29.6
(440.3V,)
23.5
(41 1.4 V)
21.5
28.0
29.5
0.98
1.06
0.80
20.9
27.3
28.4
1.01
1.08
0.83
216.SO
32.1
44.0
(437.1V)
38.0
(418.4 V)
24.9
30.7
31.1
1.29
1.43
1.22
24.1
29.9
29.5
1.33
1.47
1.29
217.00
56.6
62.. 1
(49.7V )
53.1
(-6.2V )
42.4
45.0
33.1
1.33
i .38
1.61
41.3
43.9
31.2.
1.37
1.42
1.70
217. SO
78.6
85.1
(48.3V )
72.3
(-8,0V )
47.7
51.4
50.5
1.65
1.66
1.43
46.2
50.0
48.3
1.70
1.70
1.50
218.00
102.2
i 10.5
(48.1V)
97.4
(-4.7V )
49.6
53.2
53.8
2.06
2.08
1.81
47.8
51.4
51.4
2.14
2.15
1.90
218.SO
127.6
136.6
¦'47.1V )
123.6
(-3.1%)
54.1
55.2
56.2
2.36
2.47
2.20
52.0
53.2
53.6
2.45
2.57
2.31
2 i 9.00
154.1
i 63.7
(46.2V)
150.8
(-2.1 V)
57.5
57.3
58.3
2.68
2.86
2.59
55.2
55.0
55.4
2.79
2.97
: ~
219.38
175.9
184,8
(45.1%)
172.1
(-2.2%)
62.0
58.6
59.8
2.84
3.15
2.88
59.4
56.1
56.7
2.96
3.29
3.04
Note: Percentages shown in parentheses under cross-sectional
areas represent the percent change in area
from the original survey
in 2002.
Ǥ?
7
CP
!
33
CP
SI
n
CP
o
2
o
%
o"
o
o
s
1°
n
a
w
23
3
©
3
o
o
c
#
3
23
-a
§
-------
Appendix 1. Changes in cross-section geometry at permanent cross section Ft, Minebank Run study reach, 2002 through 2004.—Continued
[ft, feet; ft2, square feet; Hyd., Hydraulic; %, percent]
Elevation
(ft
above
mean
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Channel
width
(ft)
Channel
width
(ft)
Channel
width
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
sea level)
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
219.00
.>0.6
39.1
(+27.8'.--;)
41.8
(+36.6'/,)
2.5.4
26.1
26.0
1.2.0
1.50
1.60
23.6
25.0
24.5
1.29
1.56
1.70
219.50
44.4
53.6
(+20.7%)
54.6
(+23.0%)
34.7
34.2
28.6
1.28
1.57
1.91
32.6
32.8
26.7
1.36
1.63
2.04
220.00
62.0
72.0
( + 16.1 )
71.9
( + 16.0'/,)
39.6
40.9
41.0
1.57
1.76
1.76
37.3
39.1
38.7
1.66
1.84
1.86
220.50
81.2
92.2
(+13.5%)
92.1
(+13.4%)
42.0
43.7
44.5
1.93
2.11
2.07
39.3
41.5
42.1
2.07
2.22
2.19
221.00
101.3
II 3.5
! + l 2.0'/,)
1 13.9
( + 12.4%)
44.7
46.8
47.8
2.27
2.42
2.38
41.6
44.2
45.1
2.43
2.57
2.53
221.50
123.5
136.9
(+10.9%)
137.3
( + 1 1.2'/,)
54.3
56.2
53.7
2.27
2.43
2.56
50.9
53.2
50.7
2.43
2.57
2.71
222.00
31 2.8
323.6
(+3.5'/,)
324.0
(+3.6%)
i 37.2
i 41.8
I42..8
2.28
2.28
132.5
137.6
138.7
2.36
2.35
2.34
222.34
358.1
370.6
(+3.5%)
371.4
(+3.7%)
138.6
143.7
147.0
2.58
2.58
2.53
133. /
139.3
142.6
2.68
2.66
2.60
Note: Percentages shown in parentheses under cross-sectional areas represent the percent change in area from the original survey in 2002.
-------
Appendix 1. Changes in cross-section geometry at permanent cross section Gg, Minebank Run study reach, 2002 through 2004.—Continued
[ft, feet; ft2, square feet; Hyd., Hydraulic; %, percent]
Elevation
(ft
above
mean
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Wetted
perimeter
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Channel
width
(ft)
Channel
width
(ft)
Channel
width
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
sea level)
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
22.0.80
39. i
41.9
(+7.2'/,)
42.8
(+9.5'/,)
34.8
36.8
37.9
1.12
1.14
1.13
33.4
36.0
37.1
1.17
1.17
1.15
221.!!!)
45.8
49.2
(+7.4'/,)
50.4
( + 10.0'/,)
35.4
3 / .'/
39.2
1.29
1.30
1.29
3 3.8
37.0
38.2
1.36
1.33
1.32
2.21.50
62.9
68.2
(+8.4<;o
ov.7
(+10.8'/,)
36.7
411.1
411.7
1.71
1.70
1.72
.•>4./
38.9
39.3
1.81
1.75
1.78
22? 00
80.8
88.1
(+9.0%)
89.6
(+10.9%)
39.8
42.0
42.1
2.03
2.10
2.13
37.5
40.5
40.3
2.! 5
2.! 8
2.22
22.2.50
100.6
108.8
(+8.2'4)
1 10.2
(+9.5'/,)
44.0
44.9
44.6
2.2.9
2.43
2.47
41.6
43.1
42.4
2.42
2.52
2.60
223.00
122.3
X j j, j
(+9.0%)
(+8.0%)
48.2
56,4
47.5
2.54
2.36
2.78
45,7
54.6
44.9
2.68
2.44
2.94
223.48
149.7
160.6
(+7.3'/,)
162.2
(+8.4'/,)
62.0
61.3
66.5
2.4 i
2.62.
2.44
59.2
59.3
63.7
2.53
2.71
2.55
Note: Percentages shown in parentheses under cross-sectional
areas represent the percent
change in area
from the original survey
in 2002.
Si
7
CP
!
33
CP
SI
n
CP
o
2
o
%
o"
o
o
s
1°
n
a
w
23
3
©
3
o
o
c
#
3
23
-a
§
-------
Appendix 1. Changes in cross-section geometry at permanent cross section li, Minebank Run study reach, 2002 through 2004.—Continued
[ft, feet; ft2, square feet; Hyd., Hydraulic; %, percent]
Elevation
(ft
above
mean
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Cross-
sectional
area
(ft2)
Wetted Wetted Wetted
perimeter perimeter perimeter
(ft) (ft) (ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Hyd.
radius
(ft)
Channel
width
(ft)
Channel
width
(ft)
Channel
width
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
Mean
channel
depth
(ft)
sea level)
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
2002
2003
2004
224.0!)
39.8
45.5
( + I4.W
60.1
(+51 .()'/<)
37.9
34.4
45.2
1.05
1.32
1.33
35.8
32.7
43.3
1.11
1.39
1.39
224.50
58.6
66.3
(+13.1%)
82.2
(+40.3%)
43.2
46.5
47.4
1.36
1.43
1.73
40.3
44.2
45.1
1.45
1.50
1.82
225.00
82.1
90.6
( + 10.4'/;)
106.9
(+30.2'/<)
51.2
52.7
54.4
i .60
1.72
1.97
47.6
49.9
51.6
1.73
1.82
2.07
225.50
108.5
117.1
(+7.9%)
134.1
(+23.6%)
61.6
61.1
63.6
1.76
1.92
2.11
57.6
57.9
60.3
1.88
2.03
2.22
226.00
137.7
146.7
(+6.5'/<}
164.8
( + 19.7% )
64.1
64.0
65.9
2.15
2.29
2.50
59.7
60.3
62.2
2.31
2.43
2.65
226.50
168.0
177.3
(+5.5'/f)
196.2
{ + 16.8vv )
66.1
66.1
68.0
2.54
2.68
2.89
61.2
62.0
63.7
2.74
2.86
3.08
227.00
199.0
208.7
(+4.9'/f )
228.4
( + 14.8% j
67.9
68.3
69.8
2.93
3.05
3.27
62.8
63.9
65.1
3.17
3.51
227.50
230.6
241.2
(+4.6%)
261.4
(+13.4%)
69.3
71.1
72.1
3.33
3.39
3.63
63.7
66.4
66.7
3.62
3.63
3.91
227.H.i
252.0
263.5
74.2
75.7
3.47
3.55
3.75
67.0
69.5
70.4
3.76
3.79
4.03
(44.6'/,) ( + (2.6'*)
Nolo: Poreonlagos shown In paronlhosos undor cross-sodlonal aroas ivprosonl iho poreonl chango In aroa ironi iho original surwy In 2002.
-------
-------
-------
-------
Prepared by Publishing Service Centers 3 and 1,
Edited by Valerie M. Gaine.
Graphics byTimothy W, Auer.
Layout by Mary P. Lee,
For additional information, contact:
Director, MD-DE-DC Water Science Center
U.S. Geological Survey
5522 Research Park Drive
Baltimore, MD 21228
or visit our Web site at:
http://md.water.usgs,gov
-------
c/>
a
C/3
3
0)
¦2
O
o
3"
CD
B)
3
3
¦<
a
m
ro
C—
g
GO
r+
I
03
o
-Fh
Q3
CO*
09
a_
t—h
CO
o
3
CO
m"
33
m
CD
"D
>
O
i
7X
N>
O
CD
©
-J
30
1
CD
CJl
C/J
ro
o
3
F+
o"
3
o
CD
O
3
o
¦a
s;
o"
0
0)
n>
a
CD
g
O
c/>
0
3
3*
CD
03
3
30
C
3
03
2L
3"
0
CD
O
O
e
3
------- |