U.S. Department of the Interior

U.S. Geological Survey

Development of Regional Curves of

Bankfull-Channel Geometry and Discharge

for Streams in the Non-Urban,

Piedmont Physiographic Province,

Pennsylvania and Maryland

by Peter J. Cinotto

Water-Resources Investigations Report 03-4014

In cooperation with the

PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION

New Cumberland, Pennsylvania

2003
ii

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

For additional information, write to: Copies of this report may be

purchased from:

District Chief U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

215 Limekiln Road Box 25286

New Cumberland, Pennsylvania 17070-2424 Denver, Colorado 80225-0286

Email: dc_pa@usgs.gov Telephone: 1-888-ASK-USGS

Internet Address: http://pa.water.usgs.gov
iii

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Description of the study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Study design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Regional-curve development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Characteristics of assessed stream reaches and streamflow-measurement stations . . . . . . . . . . . . . . 8

Evaluation of regional curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Comparison of estimates from Piedmont Physiographic Province regional curves and

Dunne and Leopold regional curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Limitations of the investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Summary and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

References cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

ILLUSTRATIONS

Figure 1. Map showing locations of the Piedmont Physiographic Province, Sections, and

U.S. Geological Survey streamflow-measurement stations selected for

regional-curve development, Pennsylvania and Maryland . . . . . . . . . . . . . . . . . . . . . . 3

2-15. Photographs showing:

2. View looking upstream at reach for Manatawny Creek near Pottstown,

Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3. View looking downstream at reach for French Creek near Phoenixville,

Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4. View looking downstream at reach for Perkiomen Creek at East Greenville,

Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5. View looking upstream at reach for West Branch Perkiomen Creek at

Hillegas, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

6. View looking downstream at reach for Crum Creek near Newtown, Pennsylvania. . 13

7. View looking downstream at reach for Chester Creek near Chester, Pennsylvania . . 13

8. View looking upstream at reach for West Branch Brandywine Creek

near Honey Brook, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

9. View looking downstream at reach for West Branch Brandywine

Creek at Coatesville, Pennsylvania. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

10. View looking downstream at reach for Sucker Run near Coatesville,

Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

11. View looking upstream at reach for West Branch Brandywine Creek

at Modena, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

12. View looking upstream at reach for Conowingo Creek near Buck, Pennsylvania. . . . 19

13. View looking upstream at reach for Beaver Run near Finksburg, Maryland. . . . . . . . 19

CONTENTS

Page
iv

Figure 2-15. Photographs showing—Continued:

14. View looking downstream at reach for Morgan Run near Louisville, Maryland . . . . 21

15. View looking upstream at reach for Big Pipe Creek at Bruceville, Maryland . . . . . . . 21

16-19. Graphs showing:

16. Regional curve representing relation between bankfull cross-sectional area and

drainage area in non-urban, Piedmont Physiographic Province, Pennsylvania

and Maryland. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

17. Regional curve representing relation between bankfull discharge and drainage

area in non-urban, Piedmont Physiographic Province, Pennsylvania and

Maryland. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

18. Regional curve representing relation between bankfull cross-sectional width

and drainage area in non-urban, Piedmont Physiographic Province,

Pennsylvania and Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

19. Regional curve representing relation between bankfull cross-sectional mean

depth and drainage area in non-urban, Piedmont Physiographic Province,

Pennsylvania and Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

TABLES

Table 1. Streamflow-measurement stations used for regional-curve development in the

Piedmont Physiographic Province, Pennsylvania and Maryland . . . . . . . . . . . . . . . . . 5

2. Data collected during assessment of the stream reaches at the streamflow-measurement

stations used for regional-curve development in the Piedmont Physiographic

Province, Pennsylvania and Maryland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3. Comparison of estimates from Piedmont Physiographic Province Regional Curves,

Piedmont Lowlands Regional Curves, and Dunne and Leopold

Regional Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

CONVERSION FACTORS AND DATUMS

Multiply By To obtain

Length

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

Area

square foot (ft2) 0.09290 square meter

square mile (mi2) 2.590 square kilometer

Flow

cubic foot per second (ft3/s) 0.02832 cubic meter per second

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29);

horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).

ILLUSTRATIONS—Continued

Page
v

The terms in this glossary were compiled from numerous sources. Some definitions have been modified

for use within this report.

Bankfull channel—The active stream channel during the bankfull discharge.

Bankfull cross-sectional area—The cross-sectional area of the bankfull channel measured perpendicular

to the streamflow.

Bankfull discharge—The most effective streamflow for moving sediment, forming or removing bars,

forming or changing bends and meanders, and generally doing work that results in the average

morphological characteristics of channels (Dunne and Leopold, 1978).

Bankfull mean depth—The mean depth of the bankfull channel measured perpendicular to the

streamflow.

Bankfull stage—The elevation of the water surface during bankfull discharge.

Bankfull width—The width of the bankfull channel measured perpendicular to the streamflow.

Drainage area—That area, measured in a horizontal plane, enclosed by a topographic divide from which

direct surface runoff from precipitation normally drains by gravity into the stream above the specified

point.

Gage height—Water-surface elevation referred to some arbitrary station datum. Gage height commonly is

used interchangeably with the more general term “stage.”

Physiographic province—A region of which all parts are similar in geologic structure and climate and

which has consequently had a unified geomorphic history; a region whose pattern of relief features or

landforms differs significantly from that of adjacent regions.

Regional curve—A regression of the relations among drainage area, selected cross-sectional parameters,

and streamflow.

Regulation—A condition where streamflow is controlled by an upstream human-made feature.

Stream reach—A section of stream extending between 10 and 20 bankfull widths in length.

Stream restoration—For this report, adjusting stream dimensions, pattern, and profile to a condition

where it effectively accommodates a range of streamflow and sediment and supports diverse habitat.

Watershed—For this report, used interchangeably with drainage area.

GLOSSARY
vi
1

ABSTRACT

Stream-restoration projects utilizing naturalstream designs frequently are based on the bankfull-channel characteristics of stream reaches that

can accommodate streamflow and sediment transport without excessive erosion or deposition and

lie within a watershed that has similar runoff characteristics. The bankfull channel at an ungaged

impaired site or reference reach is identified by use

of field indicators and is confirmed with tools such

as regional curves. Channel dimensions were surveyed at 14 streamflow-measurement stations

operated by the U.S. Geological Survey (USGS) in

the Gettysburg-Newark Lowland Section, Piedmont Lowland Section, and the Piedmont Upland

Section of the Piedmont Physiographic Province1

in Pennsylvania and Maryland. From the surveyed

channel dimensions, regional curves were developed from regression analyses of the relations

between drainage area and the cross-sectional area,

mean depth, width, and streamflow of the bankfull

channel at these sites.

Bankfull cross-sectional area and bankfull

discharge have the strongest relation to drainage

area as evidenced by R2 values of 0.94 and 0.93,

respectively. The relation between bankfull crosssectional area and drainage area has a p-value of

less than 0.001; no p-value is presented for the relation between bankfull discharge and drainage area

because of a non-normal residual distribution. The

relation between bankfull width and drainage area

has an R2 value of 0.80 and a p-value of less than

0.001 indicating a moderate linear relation between

all stations. The relation between bankfull mean

depth and drainage area, with an R2 value of 0.72

and a p-value of less than 0.001, also indicates a

moderate linear relation between all stations.

The concept of regional curves can be a valuable tool to support efforts in stream restoration.

Practitioners of stream restoration need to recognize it as such and realize the limitations. The

small number of USGS streamflow-measurement

stations available for analysis is a major limiting

factor in the strength of the results of this investigation, as is the inherent problem of directly associating streamflow-measurement station data to

geomorphic analysis of a stream reach. Subjective

selection criteria may have unnecessarily eliminated streamflow-measurement stations that could

have been included in the regional curves and (or)

added those that may belong within a different

region. A bankfull discharge with a recurrence

interval within the 1- to 2-year range commonly is

used as a criterion for the confirmation of the bankfull stage at each streamflow-measurement station.

Many researchers accept this range for recurrence

interval of the bankfull discharge; however, literature provides contradictory evidence.

INTRODUCTION

Restoration of stream channels with excessive erosion, deposition, or degraded habitat is

proposed and is implemented by federal, state,

local, and private organizations in an effort to

return the impaired streams to more stable and

biologically productive conditions. Traditional

engineering practices for stream stabilization frequently rely on hardening the stream channel in

sections that are affected by erosive forces. Recent

stream-restoration projects propose to utilize a

natural-stream design approach that emphasizes

working in concert with natural-stream processes

as opposed to combating them. For the purposes of

this study, natural-stream design is defined as a

design intended to restore an impaired stream

reach to a state such that the stream can transport

the current sediment load and runoff provided to it

from upstream without excessive aggradation or

degradation while maintaining habitat and aesthetics consistent with that found in an unimpaired

reach within an area of similar physiography.

The bankfull discharge is considered to be

the most effective flow for moving sediment, forming or removing bars, forming or changing bends

and meanders, and generally doing work that

results in the average morphological characteristics of channels (Dunne and Leopold, 1978). The

bankfull discharge is, therefore, the channel-form1 Words that are in bold are found in the Glossary

section of this report.

DEVELOPMENT OF REGIONAL CURVES OF BANKFULL-CHANNEL GEOMETRY AND

DISCHARGE FOR STREAMS IN THE NON-URBAN, PIEDMONT PHYSIOGRAPHIC PROVINCE,

PENNSYLVANIA AND MARYLAND

by Peter J. Cinotto
2

ing discharge and is responsible for the formation

of the bankfull channel. As the basis of the restoration design, the bankfull channel is defined and

verified by field reconnaissance and direct measurement of channel features. In addition to identifying the bankfull channel on the basis of field

indicators, an independent source of information is

required to support the findings, such as data

obtained from a U.S. Geological Survey (USGS)

streamflow-measurement station. According to

Leopold (1994), the bankfull discharge has an average recurrence interval of 1.5 years. The recurrence

interval for bankfull discharge for this study

ranged from the 1-year to 1.5-year event, with an

average of 1.3 years.

Some of the more common tools available

for supporting the selection of the bankfull channel

are regional curves. Several studies have

attempted to create regional curves for various

parts of the United States; one set of regional

curves, developed by Dunne and Leopold (1978),

is intended to be representative of the bankfullchannel dimensions throughout the eastern United

States. The applicability of one set of regional

curves to multiple physiographic provinces and

(or) other bounding conditions has not been verified.

Characteristics of the bankfull channel are

quantified using parameters such as bankfull

cross-sectional area, bankfull width, bankfull

mean depth, and streamflow. These characteristics

are correlated strongly with drainage area (Dunne

and Leopold, 1978). Regional curves are developed

by regression analysis of the bankfull characteristics and drainage area, and provide estimated

bankfull channel dimensions and streamflow

when drainage area is known. Estimates of bankfull dimensions are helpful for confirming field

identification of the bankfull channel.

Background

In 1999, the Pennsylvania Department of

Environmental Protection (PaDEP) proposed a

study to develop regional curves representative of

channel geometry in the Piedmont Lowland and

Gettysburg-Newark Lowland Sections of the Piedmont Physiographic Province and to quantify

channel characteristics of a stream reach for use as

a template in a stream-restoration design. The initial field work was completed in 2000 and the

report “Regional Curve Development and Selection of a Reference Reach in the Non-Urban, Lowland Sections of the Piedmont Physiographic

Province, Pennsylvania and Maryland” by K.E.

White (2001) was published. This report builds

upon the previous work by White (2001) by adding

data from eight additional streamflow-measurement stations, predominantly within the Piedmont

Upland Section, and completing a regional curve

for the entire Piedmont Physiographic Province

that is thought to provide a better representation of

the province as a whole. PaDEP and the USGS conducted this study as a cooperative effort.

Purpose and Scope

This report describes the methods used, data

collected, and the application of regional curves

developed for the Piedmont Physiographic Province. Regional curves developed from channelcharacteristic data collected from December 1999

to April 2002 that represent channel dimensions in

the Piedmont Physiographic Province within

Pennsylvania and Maryland are presented. This

report is intended to present regional curves that

either confirm the findings of, or more accurately

represent, the Piedmont Physiographic Province

than existing curves by White (2001) and (or)

Dunne and Leopold (1978).

Description of the Study Area

The Piedmont Physiographic Province

(fig. 1) is separated into three sections on the basis

of changes in physiography within the province:

the Piedmont Upland Section, the Piedmont Lowland Section, and the Gettysburg-Newark Lowland

Section. Locations of USGS streamflow-measurement stations used in this study are shown in

figure 1.

The Piedmont Lowland Section study area in

Pennsylvania consists of broad, moderately dissected valleys separated by broad low hills. The

section is developed primarily on limestone and

dolomite rock. Karst topography is common. Local

relief in the section generally is less than 100 ft but

may be as high as 300 ft. Land-surface altitudes in

the section range from 170 to 630 ft. Drainage is

basically dendritic in pattern, but some areas

within the section have virtually no pattern

because of the well-developed subsurface drainage

(Sevon, 2000).

The Gettysburg-Newark Lowland Section

study area in Pennsylvania and Maryland consists

mainly of rolling hills and valleys developed on

sedimentary rocks. There are also isolated higher

hills developed on diabase, baked sedimentary
3

Figure 1. Locations of the Piedmont Physiographic Province, Sections, and U.S. Geological Survey

streamflow-measurement stations selected for regional-curve development, Pennsylvania and Maryland.
4

rock, and conglomerates. Almost all the underlying sedimentary rock dips to the north or northwest, and many smaller drainage ways are oriented normal to the direction of dip so that some of

the topography has a northeast-southwest linearity. The basic drainage pattern is dendritic. Relief is

generally 100 to 200 ft but locally is up to 600 ft on

some of the isolated hills. Altitude in the section

ranges from 40 to 1,335 ft (Sevon, 2000).

The Piedmont Upland Section study area in

Pennsylvania and Maryland consists mainly of

broad, rounded to flat-topped hills and shallow

valleys developed on schist, gneiss, and quartzite

with some saprolite. The local relief is low to moderate with the lowest altitude approximately 100 ft

and the highest point approximately 1,220 ft. The

rocks in this section are intensely folded and

faulted and the resulting drainage pattern is primarily dendritic (Sevon, 2000).

STUDY DESIGN

This study builds on the previous work by

White (2001). Data from eight new USGS streamflow-measurement stations were added to complete regional curves for the entire Piedmont

Physiographic Province. Data from USGS streamflow-measurement stations within the Piedmont

Physiographic Province (Sevon, 2000) were used to

develop the regional curves for this study. Data

from stations outside of the Piedmont Physiographic Province were omitted from the study;

however, three streamflow-measurement stations

used in this study had some part of the watershed

draining to them outside of the Piedmont Physiographic Province. Subjective filtering criteria utilizing Geographic Information System (GIS) land-use

(U.S. Geological Survey, 1996) and stream coverages (Pennsylvania Department of Transportation,

1997; Alexander and others, 1999), and additional

station-information criteria, were used to identify

streamflow-measurement stations with potentially

similar runoff characteristics in Pennsylvania. The

range of gaged-watershed size used in the regional

curves is required to be large enough to provide

confidence in the relation over a range of drainage

areas; this range is limited, however, by the existing number of streamflow-measurement stations.

The filtering criteria used for selecting streamflowmeasurement stations in Pennsylvania used in the

analyses in this study are listed below:

• The station is within the boundaries of the

Piedmont Physiographic Province; however,

a significant percentage of the watershed

draining to the station may be outside of the

Piedmont Physiographic Province.

• The station has at least 10 years of record.

• If the station has been discontinued, the station must have been operational until at least

1985 to minimize the extent to which any

changes in land use may have affected the

channel since the station was active.

• No more than 25 percent of the upstream

watershed is classified as “urban” land use.

• Streamflow at the station is subjected to no

greater than approximately 20 percent

regulation. No greater than approximately

20 percent of the flowpath in the upstream

watershed is subject to regulation.

• The stream must be wadeable.

The filtering criteria above were applied to a

comprehensive listing of active and discontinued

continuous- and partial-record streamflow-measurement stations operated by the USGS in Pennsylvania. Stations meeting all criteria were

considered for inclusion in the analysis. Streams

included in this analysis may be subject to anthropogenic influences, such as the sporadic placement

of rip rap; however, they must not be channelized,

such as concrete-lined or trapezoidal channels.

This analysis also did not exclude streams with

bedrock outcrops appearing in, or near, the channel. Station descriptions, describing flow conditions and site characteristics, from records in USGS

offices and, in some instances, field reconnaissance

were used to finalize the list of stations included in

the formulation of the regional curves. Streamflowmeasurement stations within Maryland were not

subjected to the same filtering criteria applied to

stations within Pennsylvania because of limited

GIS data. The stations in Maryland were, therefore,

selected only on the basis of location, land use, and

drainage area as per written and oral communications from USGS personnel in the Maryland District Office. On the basis of the listed criteria,

14 streamflow-measurement stations were selected

for inclusion in the regional-curves development

(table 1). Ancillary descriptors such as land use,

percentage of regulation, percentage of the basin

underlain by carbonate rocks, and others also are

presented in table 1 to assist in the interpretation of

the regional curves. For example, the presence of
5

Table 1. Streamflow-measurement stations used for regional-curve development in the Piedmont Physiographic Province, Pennsylvania [<, less than]

U.S.

Geological

Survey

station

identification

number

(see fig. 1)

Station name Latitude/ longitude

Drainage

area

(square

miles)

Land use

(percentage

of basin)

Percentage of flowpath in the

Piedmont Physiographic

Province1,2

Percentage 

flowpath out

the Piedmo

Physiograp

Province

Urban Forest

Gettysburg

Newark

Lowland

Piedmont

Lowland

Piedmont

Upland

301471980 Manatawny Creek near Pottstown, Pa. Lat 40°16′22′′

Long 75°40′49′′

85.5 <2 56 15 — — 85 

301472157 French Creek near Phoenixville, Pa. Lat 40°09′05′′

Long 75°36′06′′

59.1 <1 64 38 — 62 — 

301472198 Perkiomen Creek at East Greenville, Pa. Lat 40°23′38′′

Long 75°30′57′′

38.0 2 54 51 — — 49 

301472199 West Branch Perkiomen Creek at

Hillegas, Pa.

Lat 40°22′26′′

Long 75°31′22′′

23.0 2 61 43 — — 57 

01475850 Crum Creek near Newtown Square, Pa. Lat 39°58′35′′

Long 75°26′13′′

15.8 16 61 — — 100 — 

01477000 Chester Creek near Chester, Pa. Lat 39°52′10′′

Long 75°24′30′′

61.1 23 50 — — 100 — 

01480300 West Branch Brandywine Creek near

Honey Brook, Pa.

Lat 40°04′22′′

Long 75°51′40′′

18.7 1.5 27 — — 100 — 

01480500 West Branch Brandywine Creek at

Coatesville, Pa.

Lat 39°59′08′′

Long 75°49′40′′

45.8 2.1 42 — — 100 — 

301480610 Sucker Run near Coatesville, Pa. Lat 39°58′20′′

Long 75°51′03′′

2.57 11.6 45 — 53 47 — 

01480617 West Branch Brandywine Creek at

Modena, Pa.

Lat 39°57′42′′

Long 75°48′06′′

55.0 6 42 — 7 93 — 

01578200 Conowingo Creek near Buck, Pa. Lat 39°50′35′′

Long 76°11′45′′

8.7 .9 20 — — 100 — 

01586210 Beaver Run near Finksburg, Md.4 Lat 39°29′22′′

Long 76°54′12′′

14.0 — 28 — — 100 — 

01586610 Morgan Run near Louisville, Md.4 Lat 39°27′07′′

Long 76°57′20′′

28.0 — 29 — — 100 — 

301639500 Big Pipe Creek at Bruceville, Md.4 Lat 39°36′45′′

Long 77°14′10′′

102 — 17 32 — 68 — 

1 Pennsylvania Department of Transportation, 1997; Sevon, 2000.2 Percentage is based on flowpath and not total basin area.3 Field assessment data previously published in White, 2001.4 Data provided by R.W. James, Jr., U.S. Geological Survey, oral commun., 2001.
6

carbonate rocks within the watershed leads to the

possibility of significant, undetected, underground

flow that may alter surficial runoff patterns and

affect the regional curves.

Procedures for measurements of hydraulic

geometry and stream-type assessment, outlined by

Leopold (1994) and Rosgen (1996), were followed

for the data collection at each station. Deviations

from the established procedure, warranted because

of site conditions, are discussed along with the specific details describing the characteristics of each

stream reach. Surveyed altitudes are recorded to

the hundredth of a foot as per the accuracy of the

equipment and survey techniques; however,

stream slope data are presented to the thousandth

of a foot to provide the user with relative differences between stream slopes and sufficient data for

rounding purposes.

REGIONAL-CURVE DEVELOPMENT

Many restoration designs have been developed on the basis of bankfull-channel dimensions

because the bankfull channel has the correct pattern, profile, and dimension to accommodate the

streamflow and sediment load provided from

upstream without excessive erosion or deposition.

According to Dunne and Leopold (1978), the bankfull-channel dimensions of width, mean depth,

and cross-sectional area are highly correlated with

the size of the basin (drainage area) in a given

region. A regional curve is a regression of the relation of bankfull-channel dimensions and bankfull

discharge to drainage area and provides estimated

bankfull-channel dimensions and streamflow for

the bankfull channel when drainage area is known.

Regional curves are, therefore, useful for verifying

the correct bankfull stage in the field, and subsequently, for confirming the correct bankfull-channel dimensions and streamflow within regions

having similar runoff characteristics.

USGS streamflow-measurement stations

provide a source of readily available and reliable

information from which regional curves can be

developed. The drainage area has been determined

accurately for each station, and discharge measurements at each station provide a long-term record of

channel dimensions over a broad range of flows.

Analysis of station records provides the frequencies of occurrence for a range of streamflows. By

identifying the bankfull stage at a streamflow-measurement station, the investigator can determine

the recurrence interval of the associated flow. Use

of the USGS streamflow-measurement data does

not necessarily provide absolute confirmation of

the bankfull channel but does support the identification of the bankfull channel when used along

with other field indicators. Caution should be

observed when using data from a USGS streamflow-measurement station for geomorphic analysis

because the measurement section is selected by

USGS personnel to provide accurate velocity and

area determinations for the computation of streamflow only. These measuring sections may be in

slow-velocity, pool-dominated sections and not in

riffles as required by most computations involved

in fluvial geomorphology. Therefore, the user of

these data should review the station descriptions

carefully before use and be sure of whether the

measurement section used by USGS personnel is a

riffle, run, pool, or glide.

Field indicators used in development of the

regional curves include longitudinal-profile survey

data, cross-section survey data collected in one or

more riffle sections, and particle distribution data

for each cross section. From these data, the crosssectional dimensions were determined, the stream

reach was classified according to the Rosgen classification system (Rosgen, 1996), and bankfull discharge was calculated and, if possible, also

recorded directly from the USGS streamflowmeasurement station. Regression of the bankfullchannel dimensions and streamflow for each

streamflow-measurement station in relation to its

drainage area provided the data necessary for

defining the regional-curve relation.

Field data collected during the site assessments are included in table 2. Rosgen stream type

and Rosgen valley type refer to a stream and valley

classification system based on the morphological

characteristics (Rosgen, 1996). When two different

stream types are listed for the same streamflowmeasurement station (table 2), the stream type

changed over the length of the study reach.

A change in stream type could possibly lead to

increased variance within the associated regional

curves. Particle-distribution data, as presented in

table 2, are required for classification purposes. In

certain cases, dams, or other anthropogenic influences, prevented the stream slope from being computed for the entire study reach; in these cases,

stream slope was computed from a smaller, representative reach of unaffected channel. Characteristics of the 14 stream reaches and the data collected

are discussed in the following sections.
7

Table 2. Data collected during assessment of the stream reaches at the streamflow-measurement stations used for

regional-curve development in the Piedmont Physiographic Province, Pennsylvania and Maryland

[WY, water year; mi2, square miles; ft, feet; ft2, square feet; ft3/s, cubic feet per second; ft/ft, feet per foot; mm,

millimeter; D50, particle size larger than 50 percent of the cumulative sample; D84, particle size larger than 84 percent

of the cumulative sample]

U.S.

Geological

Survey

station

identification

number

(see fig. 1)

Period of record used for analysis

(WY)

Rosgen stream type1

Rosgen valley type1

Bankfull cross-sectional area

(ft2)

Bankfull width

(ft)

Bankfull mean depth

(ft)

Estimated bankfull stage

(ft)

Estimated bankfull discharge (ft3/s)

Recurrence interval (years)

Stream slope

(ft/ft)

Average

D50

(mm)

Average

D84

(mm)

2

01471980 1974–2000 C4 VIII 468 90.1 5.19 6.26 2,340 1.3 0.001 27.7 103

2

01472157 1969–2000 C3 VIII 316 87.1 3.63 7.78 1,440 1.3 .004 89.4 311

2

01472198 1982–2000 C4 VIII 304 117 2.65 3.83 1,190 1.4 .002 3.80 42.4

2

01472199 1982–2000 C4 VIII 202 96.5 1.94 4.79 1,000 1.5 .004 .80 70.4

01475850 1970-2001 3C4/C5 VIII 161 57.5 2.79 5.62 601 1.2 .002 3.20 38.9

01477000 1931-2001 B4c VI 303 69.6 4.35 7.02 1,772 1.2 .002 48.1 153

01480300 1960-2001 C4 VIII 128 57.4 2.24 4.91 333 1.0 .001 7.33 35.2

01480500 1969-2001 F4/B4c VI 179 77.6 2.33 5.60 1,097 1.3 .009 42.2 140

2

01480610 1964–2000 B5c VI 24.0 17.8 1.36 4.83 143 1.2 .009 .25 55.7

01480617 1969-2001 C4 VIII 268 97 2.77 6.40 1,643 1.3 .004 24.3 82.4

01578200 1962-2002 E4/C4 VIII 63.7 29.2 2.22 5.44 260 1.3 .004 43.6 146

01586210 1982-2001 B4c VI 106 44.4 2.38 3.60 559 1.4 .006 25.3 114

01586610 1982-2001 C4/B4c VI 189 68.2 2.77 4.71 970 1.4 .004 27.0 78.9

2

01639500 1948–2000 C4 VIII 616 101 6.12 7.93 3,060 1.5 .001 22.4 95.8

1 Rosgen, 1996.

2 Field assessment data previously published in White, 2001.

3 If two stream types are listed, the first is for the upstream-most cross section.
8

Characteristics of Assessed Stream Reaches

and Streamflow-Measurement Stations

Manatawny Creek near Pottstown -

01471980.—The continuous streamflow-measurement station is about 180 ft upstream from a

bridge. The bridge does not appear to constrict or

redirect the bankfull discharge. Discharge measurements at this station usually are made while

wading in the approximate location of the crosssection survey. High-water measurements are

made from the bridge.

The bankfull channel was defined clearly

throughout most of the reach by field indicators

such as riparian vegetation, abrupt change in bank

angle, and change in depositional material. Four

riffles were present within the study reach; however, the cross-section survey was limited to one

cross section in a “run” (an area of intermediate

relative velocity) because of the presence of a

divided channel throughout the upstream half of

the reach. A view of the study reach is shown in

figure 2. The elevation of the bankfull stage was

surveyed to the outside vertical staff gage from

which the gage height and associated bankfull discharge were determined. The measured geometry

of the channel within the estimated range of bankfull discharge, as taken from streamflow-measurement data in the USGS database, was used to assist

with confirmation of bankfull selection (White,

2001).

French Creek near Phoenixville -

01472157.—The continuous streamflow-measurement station is about 70 ft downstream from a

bridge. The bridge may have a slight effect on the

bankfull discharge due to constriction of higher

flows and the subsequent hydraulic jump upon

exiting the bridge structure. Discharge measurements usually are made while wading in the vicinity of the station. High-water measurements are

made from the bridge.

The bankfull channel, in the vicinity of the

streamflow-measurement station, was defined

poorly because of excessive bank erosion. Directly

across from the streamflow-measurement shelter is

an auxiliary channel, separated from the main

channel by a berm that extends 500 ft downstream.

This auxiliary channel is a component of the bankfull channel and contains flowing water during

moderate and high streamflow events. Riffles

within this area were not surveyed because of the

resulting divided channel at the bankfull discharge. Excellent bankfull indicators were identified on a point bar beginning about 700 ft downstream from the station. Two cross sections were

surveyed at riffles within this downstream reach.

A view of the study reach is shown in figure 3. The

bankfull widths, mean depths, and cross-sectional

areas of the two cross sections were averaged to

determine the input for the regional curves. The

bankfull elevation was extended upstream to the

streamflow-measurement station to determine the

gage height and streamflow associated with the

bankfull stage. The measured geometry of the

channel within the estimated range of bankfull discharge, as taken from streamflow-measurement

data in the USGS database, was used to assist with

confirmation of bankfull selection (White, 2001).
9

Figure 2. View looking upstream at reach for Manatawny Creek near

Pottstown, Pennsylvania (From White, 2001).

Figure 3. View looking downstream at reach for French Creek near

Phoenixville, Pennsylvania (From White, 2001).
10

Perkiomen Creek at East Greenville -

01472198.—The continuous streamflow-measurement station is adjacent to a pool created by a weir

immediately downstream from the shelter.

A multi-span bridge is 100 ft downstream from the

weir and does not appear to constrict the bankfull

discharge. Discharge measurements usually are

made while wading downstream from the weir

and the bridge. High-water measurements are

made from the bridge.

The bankfull channel throughout the entire

study reach was defined fairly well by an abrupt

change in bank angle and intermittent depositional

features. Two cross sections were surveyed at

riffles within the reach. A section of the stream

reach was stabilized previously; however, the surveyed cross sections were beyond the affected

stream section. A view of the study reach is shown

in figure 4. The bankfull widths, mean depths, and

cross-sectional areas of the two cross sections were

averaged to determine the input for the development of the regional curves. The bankfull watersurface elevation could not be extended upstream

to the streamflow-measurement station because of

the relatively high-profile weir. The measured

geometry of the channel within the estimated

range of bankfull discharge, as taken from streamflow-measurement data in the USGS database, was

used to assist with confirmation of bankfull selection (White, 2001).

West Branch Perkiomen Creek at Hillegas -

01472199.—The continuous streamflow-measurement station is adjacent to a pool created by a weir

immediately downstream from the shelter. The rating is considered to be poorly defined above

560 ft3/s because of the lack of a good location

from which to make high-water measurements.

Discharge measurements are conducted throughout the stream reach while wading both upstream

and downstream from the weir.

The assessed reach was separated from the

streamflow-measurement station by a high-profile

rock outcrop approximately 300 ft upstream. The

bankfull channel was defined clearly throughout

most of the assessed reach by riparian vegetation,

abrupt changes in bank angle, and depositional

features. Two cross sections were surveyed at riffles within the assessed reach. A view of the study

reach is shown in figure 5. The bankfull widths,

mean depths, and cross-sectional areas of the two

cross sections were averaged to determine the

input for the development of the regional curves.

Despite the presence of the rock outcrop, the bankfull elevation could be extended to the outside vertical staff gage adjacent to the streamflowmeasurement station to determine the gage height

and streamflow associated with the bankfull stage.

The measured geometry of the channel within the

estimated range of bankfull discharge, as taken

from streamflow-measurement data in the USGS

database, was used to assist with confirmation of

bankfull selection (White, 2001).
11

Figure 4. View looking downstream at reach for Perkiomen Creek at East

Greenville, Pennsylvania (From White, 2001).

Figure 5. View looking upstream at reach for West Branch Perkiomen Creek

at Hillegas, Pennsylvania (From White, 2001).
12

Crum Creek near Newtown Square -

01475850.—The continuous streamflow-measurement station is approximately 120 ft upstream

from a bridge that may have a slight effect on the

bankfull discharge due to constriction of higher

flows and the associated backwater effect. Discharge measurements usually are made while

wading in the vicinity of the station. High-water

measurements are made from the bridge.

The bankfull channel was defined clearly

throughout most of the reach by field indicators

such as riparian vegetation and depositional features. Two cross sections were surveyed at riffles

within the reach. A view of the study reach is

shown in figure 6. The lower third of the stream

reach was affected by fill on the right bank due to

development, but both cross sections were

upstream and beyond the immediate effect of this

fill. The bankfull widths, mean depths, and crosssectional areas were averaged to determine the

input for the development of the regional curves.

The elevation of the bankfull stage was surveyed

to the outside vertical staff gage from which the

gage height and streamflow associated with the

bankfull discharge were determined. The measured geometry of the channel within the estimated range of bankfull discharge, as taken from

streamflow-measurement data in the USGS database, was used to assist with confirmation of bankfull selection.

Chester Creek near Chester - 01477000.—The

continuous streamflow-measurement station is

about 30 ft downstream from a bridge that appears

to have little or no effect on the bankfull discharge.

Discharge measurements usually are made while

wading in the vicinity of the station. High-water

measurements are made from the bridge. The

bankfull channel, in the vicinity of the streamflowmeasurement station and throughout the reach,

was defined poorly because of heavy bank erosion.

The left bank is affected throughout the reach by a

road that parallels the stream, and sporadic riprap

is present along that bank. Two cross sections were

surveyed at riffles within the reach. A view of the

study reach is shown in figure 7. The bankfull

widths, mean depths, and cross-sectional areas of

the two cross sections were averaged to determine

the input for the development of the regional

curves. The elevation of the bankfull stage was

extended to the outside vertical staff gage from

which the gage height and streamflow associated

with the bankfull discharge were determined. The

measured geometry of the channel within the

estimated range of bankfull discharge, as taken

from streamflow-measurement data in the USGS

database, was used to assist with confirmation of

bankfull selection.
13

Figure 6. View looking downstream at reach for Crum Creek near Newtown

Square, Pennsylvania.

Figure 7. View looking downstream at reach for Chester Creek near Chester,

Pennsylvania.
14

West Branch Brandywine Creek near Honey

Brook - 01480300.—The continuous streamflowmeasurement station is about 100 ft upstream from

a bridge that appears to have a slight effect on the

bankfull discharge due to constriction of higher

flows and the associated backwater effect. Discharge measurements usually are made while

wading in the vicinity of the station. High-water

measurements are made from the bridge.

The bankfull channel throughout the reach

was well defined by changes in riparian vegetation, depositional features, and a well-defined

flood plain above which no features were present.

Two cross sections were surveyed at riffles within

the reach. A view of the study reach is shown in

figure 8. A road is directly adjacent to the right

bank along the upper third of the study reach and

sporadic riprap alters the natural channel within

this area; however, surveyed cross sections were

downstream and beyond the effects of this stream

reach. The bankfull widths, mean depths, and

cross-sectional areas of the two cross sections were

averaged to determine the input for the development of the regional curves. The bankfull elevation

was extended to the outside vertical staff gage

from which the gage height and streamflow associated with the bankfull discharge were determined.

The measured channel geometry at the estimated bankfull discharge, as indicated by streamflow-measurement data in the USGS database, was

problematic in the confirmation of bankfull at this

station. The recurrence interval of the bankfull discharge at this site (1-year flood event) was at the

lower boundary of the 1- to 2-year flood-event

range commonly associated with the bankfull discharge. This 1-year recurrence interval was also

lower than had been noted at all other sites within

this study (table 2). However, throughout the

entire reach, there are no higher geomorphic features above the well-developed flood plain and the

bankfull stage could be extended clearly, without

obstruction, to the outside vertical staff gage at the

USGS streamflow-measurement station. These

findings confirm the association of the bankfull

channel to the 1-year flood event.

West Branch Brandywine Creek at

Coatesville - 01480500.—The continuous streamflow-measurement station is within the impoundment area of a small dam approximately 150 ft

downstream from the gage. Several bridges cross

the stream within the range of 400 ft upstream to

1,200 ft downstream from the station. All of these

bridges appear to have an effect on the bankfull

discharge either by redirecting or constricting

flows. The confluence of Rock Run into the West

Branch of the Brandywine Creek is approximately

0.6 mi upstream from the gage. Discharge measurements usually are made while wading either

1,000 ft upstream or 600 ft downstream from the

gage. High-water measurements are made from

the bridge 400 ft upstream from the gage.

The bankfull channel in the vicinity of the

gage was defined poorly because of excessive

width caused by the dam; therefore, the study

reach was downstream and below the dam. The

dam currently is filled with sediment and has very

little storage or regulation effect on the bankfull

discharge. The bankfull channel throughout the

study reach was moderately well defined by depositional features, riparian vegetation, and a subtle

change in bank angle. Two cross sections were surveyed at riffles within the reach. A view of the

study reach is shown in figure 9. The bankfull

widths, mean depths, and cross-sectional areas of

the two cross sections were averaged to determine

the input for the development of the regional

curves. The bankfull elevation could not be

extended to the outside vertical staff gage because

of the dam, and calculated values for bankfull discharge subsequently were used to determine the

bankfull recurrence interval (1.3-year flood event).

The channel geometry at the estimated bankfull

discharge, as indicated by streamflow-measurement data in the USGS database, proved not to be

effective with bankfull confirmation at this station

because discharge measurements commonly are

made while wading within a pool-dominated

reach. Measurements of streamflow within a pool

result in a slightly higher area than an equivalent

streamflow in a riffle.
15

Figure 8. View looking upstream at reach for West Branch Brandywine

Creek near Honey Brook, Pennsylvania.

Figure 9. View looking downstream at reach for West Branch Brandywine

Creek at Coatesville, Pennsylvania.
16

Sucker Run near Coatesville - 01480610.—

The crest-stage, partial-record station does not

collect continuous data but is operated primarily to

document peak streamflow. Discharge measurements are made while wading approximately 50 ft

downstream of the streamflow-measurement

station; cross-section surveys were conducted in

this same reach. High-water measurements are

made from the bridge immediately upstream from

the station. Two bridges, which are 227 ft apart,

bound the reach and may constrict the bankfull

discharge slightly.

Definition of the bankfull channel, in the

vicinity of the streamflow-measurement station,

was fair, as evidenced by a subtle change in bank

angle. Two cross sections were surveyed at riffles

within the reach. A view of the study reach is

shown in figure 10. The bankfull widths, mean

depths, and cross-sectional areas of the two cross

sections were averaged to determine the input for

the development of the regional curves. The bankfull water-surface elevation was extrapolated to

the outside vertical staff gage to determine the

gage height and streamflow associated with the

bankfull stage. The measured geometry of the

channel within the estimated range of bankfull discharge, as taken from streamflow-measurement

data in the USGS database, was used to assist with

confirmation of bankfull selection (White, 2001).

West Branch Brandywine Creek at Modena -

01480617.—The continuous streamflow-measurement station is approximately 15 ft downstream

from a multi-span bridge and approximately 300 ft

upstream from a small tributary (Dennis Run). The

bridge appears to have a slight effect on the bankfull discharge as indicated by a mid-channel bar

that forms directly downstream from the bridge.

Discharge measurements commonly are made

while wading in the vicinity of the station. Highwater measurements are made from the bridge.

The bankfull channel in the vicinity of the

gage was moderately well defined by changes in

riparian vegetation and depositional features. Two

cross sections were surveyed at riffles within the

reach. A view of the study reach is shown in

figure 11. The cross sections were at 146 and 242 ft

downstream from the bridge, respectively, in order

to be above the confluence of Dennis Run and also

above the effects of fill from an industrial complex

on the left streambank approximately 275 ft downstream. The bankfull widths, mean depths, and

cross-sectional areas of the two cross sections were

averaged to determine the input for the development of the regional curves. The elevation of the

bankfull stage was extended to surveyed reference

marks at the streamflow-measurement station

from which the gage height and streamflow associated with the bankfull discharge were determined.

The channel geometry at the estimated bankfull

discharge, as indicated by streamflow-measurement data in the USGS database, proved not to be

effective with bankfull confirmation at this station

because wading measurements of streamflow are

made within a pool-dominated reach adjacent to

the station.
17

Figure 10. View looking downstream at reach for Sucker Run near

Coatesville, Pennsylvania (From White, 2001).

Figure 11. View looking upstream at reach for West Branch Brandywine

Creek at Modena, Pennsylvania.
18

Conowingo Creek near Buck - 01578200.—

The crest-stage partial-record station consists of

two crest-stage gages mounted approximately 70 ft

upstream of a bridge on the left bank and on the

downstream left wingwall of the bridge. The

bridge appears to have very little effect on bankfull

discharge. Discharge measurements commonly are

made while wading in the vicinity of the station.

High-water measurements are made from the

bridge.

The bankfull channel throughout the reach

was well defined by riparian vegetation, both subtle and abrupt changes in bank angle, and depositional features. Two cross sections were surveyed

at riffles within the study reach approximately

200 ft upstream and 400 ft downstream of the

bridge. A view of the study reach is shown in

figure 12. The bankfull widths, mean depths, and

cross-sectional areas of the two cross sections were

averaged to determine the input for the development of the regional curves. The elevation of the

bankfull stage was extended to surveyed reference

marks at the streamflow-measurement station

from which the gage height and streamflow associated with the bankfull discharge were determined.

The study reach was bounded on the upstream end

by the confluence of a small tributary and downstream by a large evulsion indicative of accelerated

bank erosion. Approximately half of the study

reach, upstream from the bridge, was well vegetated and bounded on the left overbank by a large

farm pond that appeared to be well above the

bankfull stage. The remainder of the study reach,

or that part downstream from the bridge, exhibited

very little vegetation on the banks and (or) floodplain and showed evidence, in the form of meander scars, of extensive lateral movement of the

channel. The measured geometry of the channel

within the estimated range of bankfull discharge,

as taken from streamflow-measurement data in the

USGS database, was used to assist with confirmation of bankfull selection.

Beaver Run near Finksburg - 01586210.—The

continuous streamflow-measurement station is

mounted directly to the downstream face of a

multi-span bridge and approximately 250 ft

upstream of a small stone dam. Both the bridge

and dam appear to effect the bankfull discharge.

The dam increases resistance to streamflow that, in

turn, causes increased an flood stage during periods of high flows and an increased bank erosion

rate directly adjacent to the structure. The bridge

constricts flow and causes both scour and the associated deposition of sediment downstream from

the bridge structure.

The bankfull channel in the vicinity of the

gage was defined poorly because of the effects of

the bridge and dam; however, the bankfull channel

was well defined farther downstream by riparian

vegetation, subtle changes in bank angle, and depositional features. Two cross sections were surveyed at riffles within the study reach approximately 400 and 600 ft downstream from the gage.

A view of the study reach is shown in figure 13.

The cross sections were downstream of the small

stone dam that has been bypassed along the right

bank by bank erosion. This dam, while small and

largely filled with sediment, appears to have a significant effect on the bankfull discharge. A farm

pond lies in the flood plain beyond the left bank of

the stream for almost the entire study reach. The

berm around this pond obstructs the floodplain

but is above the bankfull channel and has no effect

at less-than flood stage. The bankfull widths, mean

depths, and cross-sectional areas of the two cross

sections were averaged to determine the input for

the development of the regional curves. The bankfull elevation could not be extended to the outside

vertical staff gage because of the dam, and calculated values for bankfull discharge subsequently

were used to determine the bankfull recurrence

interval (1.4-year flood event). The channel geometry at the estimated bankfull discharge, as indicated by streamflow-measurement data in the

USGS database, proved not to be effective with

bankfull confirmation because wading measurements of streamflow are made within a pool-dominated reach slightly downstream of the bride.
19

Figure 12. View looking upstream at reach for Conowingo Creek near Buck,

Pennsylvania.

Figure 13. View looking upstream at reach for Beaver Run near Finksburg,

Maryland.
20

Morgan Run near Louisville - 01586610.—The

continuous streamflow-measurement station is

30 ft downstream from the face of a bridge on the

right bank. The outside vertical staff gage is

mounted directly to the downstream-right wingwall of the bridge. The bridge appears to both constrict and redirect flows that affect the bankfull

discharge in the vicinity of the bridge.

The bankfull channel upstream and downstream of the gage was moderately well defined by

riparian vegetation and depositional features;

however, because of the effect of the bridge, the

bankfull channel was not well defined within the

bridge right-of-way. Two cross sections were surveyed at riffles within the reach. A view of the

study reach is shown in figure 14. The cross sections were at 600 ft upstream and 450 ft downstream of the gage because of irregular banks in the

vicinity of the bridge. This irregularity appears to

be caused by deflected flow through the bridge

structure and runoff from the adjacent roadway.

The bankfull widths, mean depths, and cross-sectional areas of the two cross sections were averaged to determine the input for the development

of the regional curves. The bankfull elevation

could not be extended to the outside vertical staff

gage because of the bridge, and calculated values

for bankfull discharge subsequently were used to

determine the bankfull recurrence interval

(1.4-year flood event). The measured geometry of

the channel within the estimated range of bankfull

discharge, as taken from streamflow-measurement

data in the USGS database, was used to assist with

confirmation of bankfull selection.

Big Pipe Creek at Bruceville - 01639500.—The

continuous streamflow-measurement station is

adjacent to a pool created by a low-profile weir

25 ft downstream from the shelter. A multi-span

bridge is 300 ft upstream from the station and does

not appear to constrict the bankfull discharge. Discharge measurements usually are made while

wading upstream from the station. High-water

measurements are made from the bridge.

The site assessment was limited to one crosssection survey within the reach because of a storm

event and resulting elevated streamflow midway

through the assessment. A view of the study reach

is shown in figure 15. The bankfull channel was

defined clearly throughout most of the reach, with

the exception of within the bridge right-of-way, by

riparian vegetation and a subtle change in bank

angle. The bankfull water-surface elevation passed

the outside vertical staff gage from which the gage

height and streamflow associated with the bankfull stage were determined. The measured geometry of the channel within the estimated range of

bankfull discharge, as taken from streamflow-measurement data in the USGS database, was used to

assist with confirmation of bankfull selection

(White, 2001).
21

Figure 14. View looking downstream at reach for Morgan Run near Louisville,

Maryland.

Figure 15. View looking upstream at reach for Big Pipe Creek at Bruceville,

Maryland (From White, 2001).
22

Evaluation of Regional Curves

The regional curves presented in figures 16

through 19 show the relation between drainage

area and bankfull cross-sectional area, bankfull

discharge, bankfull width, and bankfull mean

depth, respectively. The 95-percent confidence

interval indicates a band within which there is a

95-percent probability that estimates of the mean

bankfull-channel geometry or bankfull-channel

flow for that particular drainage area will occur.

The coefficient of determination, R2, is a measure

of variability accounted for by the regression relations in the observed channel-geometry, and (or)

discharge compared to the drainage area. The

p-value measures the “believability” of the level of

significance of the statistical test. If the p-value is

less than 0.05, the test is considered significant and

the trend, as represented by the regression line, can

be assumed to be real.

Bankfull cross-sectional area (fig. 16) and

bankfull discharge (fig. 17) have the strongest relation to drainage area as evidenced by R2 values of

0.94 and 0.93, respectively. The relation between

bankfull cross-sectional area and drainage area has

a p-value of less than 0.001. The p-value for the

relation between bankfull discharge and drainage

area could not be presented because of a non-normal distribution of residuals within this data set

and is discussed later. The relation between bankfull width and drainage area (fig. 18) has an R2

value of 0.80 and a p-value of less than 0.001, indicating a moderate linear relation between all stations. The relation between bankfull mean depth

and drainage area (fig. 19), with an R2 value of 0.72

and a p-value of less than 0.001, also indicates a

moderate linear relation between all stations. The

moderate relation indicated by the bankfull mean

depth and bankfull width regional curves may be

due, in part, to variation in Rosgen stream type as

noted in table 2. The Cook’s Distance statistic is a

measure of the influence a particular point has on

the regression relations of observed channel-geometry, and (or) discharge compared to the drainage

area. Analysis of the Cook’s Distance statistic for

each regional curve yielded no values greater than

1; therefore, none of the 14 data points has significant influence, or leverage effect, in any regionalcurve data set.

Figure 16. Regional curve representing relation between bankfull cross-sectional area and

drainage area in non-urban, Piedmont Physiographic Province, Pennsylvania and

Maryland.
23

Figure 17. Regional curve representing relation between bankfull discharge and drainage area

in non-urban, Piedmont Physiographic Province, Pennsylvania and Maryland.

Figure 18. Regional curve representing relation between bankfull cross-sectional width

and drainage area in non-urban, Piedmont Physiographic Province, Pennsylvania and

Maryland.
24

Statistical tests for the normality of residuals

by analysis of the p-value statistic obtained from

the Kolmogorov-Smirnov Goodness-of-fit (GOF)

test yielded a value of 0.003 for the relation

between bankfull discharge and drainage area.

P-values from the Kolmogorov-Smirnov GOF test

equal to or less than 0.05 indicate the residuals

from the data set should be considered not normal.

All other relations reported values above this limit.

Non-normal residuals do not necessarily indicate a

poor relation; however, they do result in incorrect

p-values because the residual distribution does not

fit the normal t-distribution used to compute the

p-value. For this reason, no p-value is presented

for the relation between bankfull discharge and

drainage area, and the curve should be used with

caution. This non-normality also causes the 95-percent confidence bands presented in figure 17 to be

questionable because they are constructed using

the assumption of a normal distribution. The

95-percent confidence bands are shown in figure 17

for reference but also should be used with caution.

On the basis of regression diagnostics and visual

evaluation, users of the bankfull cross-sectional

area and bankfull discharge regional curves would

expect to obtain better estimates than those of

bankfull width and bankfull mean depth.

COMPARISON OF ESTIMATES FROM

PIEDMONT PHYSIOGRAPHIC PROVINCE

REGIONAL CURVES AND DUNNE AND

LEOPOLD REGIONAL CURVES

Bankfull-channel dimensions and streamflows determined from the relations discussed previously herein, those determined from White

(2001), and those estimated from Dunne and

Leopold (1978) for drainage areas of 5, 25, 50, 75,

100, and 200 mi2 are shown in table 3. Comparison

of estimates computed from regional curves presented by White (2001) and Dunne and Leopold

(1978) to those computed from the Piedmont Physiographic Province regional curves yield differences for bankfull cross-sectional area ranging

from 29 to -7.2 percent, differences for bankfull

mean-depth ranging from 30 to -6.7 percent, differences for bankfull width ranging from 9.1 to

-33 percent, and differences for bankfull discharge

ranging from 16 to -4.0 percent.

Figure 19. Regional curve representing relation between bankfull cross-sectional

mean depth and drainage area in non-urban, Piedmont Physiographic Province,

Pennsylvania and Maryland.
25

LIMITATIONS OF THE INVESTIGATION

Subjective filtering criteria may have eliminated, unnecessarily, streamflow-measurement

stations that could have been included in the

development of the regional curves. Conversely,

land-use percentages characterizing the watershed

may affect runoff characteristics at a much lower

percentage than the criteria would indicate. For

example, numerous studies suggest channel stability may be affected by urban land use and regulation at percentages lower than the 20 percent used

in this report. While this study has added eight

additional data points to the previous work by

White (2001), this data set is still statistically small.

The continued addition of data from streamflowmeasurement stations in this and other physiographic provinces may provide better estimates of

the relation of channel characteristics to drainage

area in all provinces by increasing the size of the

data set.

Physiography is used in this study as one

way to categorically analyze the assessment of

streamflow-measurement stations. This approach

may, or may not, be a significant factor in determining the regional relation of runoff characteristics of a watershed to the geomorphic characteristics at a specific station; for example, large percentages of the drainage areas to some streamflowmeasurement stations are in a different physiographic section or province than the station itself.

Table 3. Comparison of estimates from Piedmont Physiographic Province Regional Curves, Piedmont Lowlands

Regional Curves, and Dunne and Leopold Regional Curves

[mi2, square miles; ft3/s, cubic feet per second; ft2, square feet; ft, feet]

Drainage

area Channel characteristics

Piedmont

Physiographic

Province

regional

curves—

Values

computed from

equations

Piedmont

Lowlands

regional curves

from White,

2001—Values

computed from

equations

Dunne and

Leopold

Regional Curves

for southeast

Pennsylvania

and eastern

United States—

Values from

graphs

Comparison of

estimates from

White (2001) to

Piedmont

Physiographic

Province curves

in percent

difference

Comparison of

estimates from

Dunne and

Leopold (1978)

to Piedmont

Physiographic

Province curves

in percent

difference

5 - mi2 Bankfull discharge - ft3/s 210 250 220 16 4.5

5 - mi2 Bankfull cross-sectional area - ft2 46 46 65 0.0 29

5 - mi2 Bankfull mean depth - ft 1.6 1.5 2.3 -6.7 30

5 - mi2 Bankfull width - ft 29 31 30 6.5 3.3

25 - mi2 Bankfull discharge - ft3/s 800 890 800 10 0.0

25 - mi2 Bankfull cross-sectional area - ft2 170 180 180 5.6 5.6

25 - mi2 Bankfull mean depth - ft 2.7 2.8 3.8 3.6 29

25 - mi2 Bankfull width - ft 62 65 50 4.6 -24

50 - mi2 Bankfull discharge - ft3/s 1,400 1,500 1,500 6.7 6.7

50 - mi2 Bankfull cross-sectional area - ft2 300 330 320 9.1 6.3

50 - mi2 Bankfull mean depth - ft 3.4 3.6 4.5 5.6 24

50 - mi2 Bankfull width - ft 85 90 70 5.6 -21

75 - mi2 Bankfull discharge - ft3/s 2,000 2,100 2,000 4.8 0.0

75 - mi2 Bankfull cross-sectional area - ft2 410 460 400 11 -2.5

75 - mi2 Bankfull mean depth - ft 4.0 4.2 4.9 4.8 18

75 - mi2 Bankfull width - ft 100 110 80 9.1 -25

100 - mi2 Bankfull discharge - ft3/s 2,600 2,700 2,500 3.7 -4.0

100 - mi2 Bankfull cross-sectional area - ft2 510 590 500 14 -2.0

100 - mi2 Bankfull mean depth - ft 4.4 4.7 5.5 6.4 20

100 - mi2 Bankfull width - ft 120 120 90 0.0 -33

200 - mi2 Bankfull discharge - ft3/s 4,600 4,600 4,500 0.0 -2.2

200 - mi2 Bankfull cross-sectional area - ft2 890 1,100 830 19 -7.2

200 - mi2 Bankfull mean depth - ft 5.5 6.2 7.0 11 21

200 - mi2 Bankfull width - ft 160 170 130 6 -23
26

The regional curves presented in this report

should be used only for the confirmation of the

bankfull channel conditions in non-urban streams

of the Piedmont Physiographic Province. Due to

the variation inherent in hydrologic data, regional

curves should not be used for direct computation

of channel dimensions in steam restoration

designs. The assumption made for this investigation is that the bankfull discharge is within the

1- to 2-year recurrence range. Thorne and others

(1997) state, “The widely reported assertion that

bankfull discharge occurs on average once every

1 to 2 years is now seen as an oversimplification.”

If runoff patterns at a streamflow-measurement

station are such that the bankfull discharge may

occur more, or less, often than this 1- to 2-year frequency, the recurrence-interval criteria did not

substantiate identification of the bankfull channel

as it was intended. In addition, land use and other

basin characteristics upstream from the reach

where regional curves are to be applied should be

similar to those used for the selection criteria in

this assessment.

The stability of the reaches included in this

study—in terms of sediment transport, hydraulic

conveyance, and degradation and (or) aggradation

of the stream reaches—has not been confirmed,

and long-term monitoring of the reaches has not

been completed. Stream channels in transitional

states may have introduced increased variance into

the regional curves, especially the bankfull width

and bankfull mean depth curves. Stream-restoration projects must rely on reference reaches indicative on long-term stability for design criteria and

use regional-curve data only to initially confirm or

refute the field identification of the bankfull channel conditions.

SUMMARY AND CONCLUSIONS

The U.S. Geological Survey (USGS), in cooperation with the Pennsylvania Department of Environmental Protection, conducted a study to

develop regional curves of bankfull-channel geometry and discharge for use in support of stream-restoration efforts. This study took place from 1999 to

2000 in the Lowland Sections of the Piedmont

Physiographic Province and continued into 2002 to

complete the Upland Section and, therefore, the

entire Piedmont Physiographic Province within

Pennsylvania and Maryland. Those regional

curves were developed from channel-geometry

and streamflow data collected at 14 USGS streamflow-measurement stations in the Piedmont

Physiographic Province. These streamflow-measurement stations included six from the previous

study of the Piedmont Lowland Sections and eight

additional streamflow-measurement stations in the

Piedmont Upland Section. The watersheds range

in size from 2.57 to 102 mi2. The bankfull channel

was identified at each station by use of field indicators and confirmed by use of historical streamflowmeasurement data when possible. Width, mean

depth, cross-sectional area and discharge of the

bankfull channel were plotted as a function of

drainage area and a “best fit” regression line was

applied to the data. The resulting regression line,

and the corresponding equation defining that line,

can be used to confirm field identification of bankfull-channel conditions at non-urban stream sites

having similar runoff characteristics throughout

the Piedmont Physiographic Province given a

known drainage area. On the basis of regression

diagnostics and visual evaluation, bankfull area

and bankfull discharge have a stronger relation to

drainage area than do bankfull width and bankfull

mean depth.

Regional-curve sets that provide an estimate

of bankfull-channel dimensions and streamflow

can be a valuable tool to support efforts in stream

restoration by assisting in identification of the

bankfull channel; however, practitioners of stream

restoration need to realize their limitations. The

curves developed for this study are based on limited, highly variable data. The small number of

streamflow-measurement stations used to create

these regressions limits the strength of the regional

curves presented.
27

REFERENCES CITED

Alexander, R.B., Brakebill, J.W., Brew, R.E., Smith,

R.A., 1999, ERF1-Enhanced River Reach File

1.2: U.S. Geological Survey Open-File

Report 99-457, accessed May 17, 2001, at

http://water.usgs.gov/GIS/metadata/

usgswrd/erf1.html.

Dunne, T., and Leopold, L.B., 1978, Water in environmental planning: San Francisco, Calif.,

W.H. Freeman, 818 p.

Leopold, L.B., 1994, A view of the river:

Cambridge, Mass., Harvard University

Press, 298 p.

Pennsylvania Department of Transportation, 1997,

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information: Harrisburg, Pa., Bureau of

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Rosgen, D., 1996, Applied river morphology:

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Sevon, W.D., comp., 2000, Physiographic provinces

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Applied fluvial geomorphology for river

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May 17, 2001, at http://edcwww.cr.usgs.gov/

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White, K.E., 2001, Regional curve development

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20 p.