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Regionalized Equations for Bankfull 

Discharge and Channel Characteristics of 

Streams in New York State—Hydrologic 

Regions 1 and 2 in the Adirondack Region 

of Northern New York

By Christiane I. Mulvihill, Amy Filopowicz, Arthur Coleman, and Barry P. Baldigo

Prepared in cooperation with 

New York State Department of Environmental Conservation

New York State Department of State—Division of Coastal Resources

New York State Department of Transportation

New York City Department of Environmental Protection

Scientific Investigations Report 2007–5189

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

U.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.

Suggested citation:

Mulvihill, C.I., Filopowicz, Amy, Coleman, Arthur, and Baldigo, B P., 2007, Regionalized Equations for Bankfull 

Discharge and Channel Characteristics of Streams in New York State—Hydrologic Regions 1 and 2 in the Adirondack 

Region of Northern New York: U.S. Geological Survey Scientific Investigations Report 2007-5189, 18 p., online only.
iii

Figures

1. Map showing hydrologic regions in New York State: (A) Hydrologic-region 

boundaries as defined by Lumia (1991); and (B) Locations of the 15 active and 1

inactive streamflow-gaging stations used in 2004–05 stream survey in hydrologic 

Regions 1 and 2 in New York State ............................................................................................3

2–5. Graphs showing—

2. Bankfull discharge as a function of drainage area with 95 percent prediction 

limit and 95 percent confidence interval for streams surveyed in hydrologic 

Regions 1 and 2 in New York State ...................................................................................8

3. Bankfull width, depth, and cross-sectional area as a function of drainage 

area with best-fit lines, regression equations, and R2 values for streams 

surveyed in hydrologic Regions 1 and 2 in New York State .......................................12

4. Channel characteristics as a function of drainage area with 95 percent 

prediction limits and 95 percent confidence intervals for streams in hydrologic 

Regions 1 and 2 in New York State: (A) bankfull channel width; (B) bankfull 

channel depth; and (C) bankfull channel cross-sectional area.................................13

5. Bankfull discharge as a function of drainage area for hydrologic Regions 1 

and 2 and published curves for five other regions in New York State......................15

Contents

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

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

Approach................................................................................................................................................2

Purpose and Scope ..............................................................................................................................4

Methods...........................................................................................................................................................4

Site Selection.........................................................................................................................................4

Data Collection......................................................................................................................................5

Data Analysis.........................................................................................................................................5

Regional Equations for Bankfull Discharge and Channel Characteristics of Streams ......................7

Regionalized Relation between Bankfull Discharge and Drainage Area ...................................7

Bankfull-Discharge Recurrence Intervals........................................................................................8

Stream-Channel Characteristics in Relation to Drainage Area ...................................................8

Stream Classification .........................................................................................................................12

Comparison of Hydrologic Regions 1 and 2 Bankfull-Discharge Equation to Equations 

for Other Regions in New York State..................................................................................14

Limitations of this Study..............................................................................................................................15

Summary and Conclusions.........................................................................................................................16

Acknowledgments.......................................................................................................................................17

References Cited..........................................................................................................................................17
iv

Multiply By To obtain

Length

millimeter (mm) 0.03937 inch (in.)

foot (ft) 0.3048 meter (m)

Area

square foot (ft2) 0.09290 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2)

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Conversion Factors and Datum

Tables

1. Characteristics of streamflow-gaging stations surveyed in hydrologic Regions 

1 and 2 in New York State, 2004–05 ...........................................................................................6

2. Stream classification and bankfull channel characteristics for streamflow-gaging 

stations surveyed in hydrologic Regions 1 and 2 in New York State, 2004–05 ..................9

List of Acronyms

NCD Natural channel design

HEC-RAS Hydraulic engineering center river analysis system

HHM Hydrologic and habitat modification

NSCC Nonpoint-source coordinating committeee

NYCDEP-SMP New York City Department of Environmental Protection-Stream 

Management Program

NYSDEC New York State Department of Environmental Conservation

NYSDOS New York State Department of State

NYSDOT New York State Department of Transportation

SUNY-ESF State University of New York College of Environmental Science and Forestry

USGS U.S. Geological Survey
Abstract

Equations that relate drainage area to bankfull discharge 

and channel characteristics (width, depth, and cross-sectional 

area) at gaged sites are needed to define bankfull-discharge 

and channel characteristics at ungaged sites and to provide 

information for watershed assessments, stream-channel 

classification, and design of stream-restoration projects. Such 

equations are most accurate if derived from streams within 

an area of uniform hydrologic, climatic, and physiographic 

conditions and applied only within that region. 

Stream-survey and discharge data from 15 active 

(currently gaged in 2005) streamflow-gaging stations and 

1 inactive (discontinued) streamflow-gaging station in 

hydrologic Regions 1 and 2 were used in linear-regression 

analyses to relate drainage area to bankfull discharge and 

bankfull-channel width, depth, and cross-sectional area. The 

four resulting equations are the following: 

bankfull discharge (cubic feet per second) = 

49.6 (drainage area (square miles))0.849, (1)

bankfull-channel width (feet) = 

21.5 (drainage area (square miles))0.362, (2)

bankfull-channel depth (feet) = 

1.06 (drainage area (square miles))0.329, (3)

bankfull-channel cross-sectional area (square feet) = 

22.3 (drainage area (square miles))0.694. (4)

The coefficients of determination (R2) for these four 

equations are 0.95, 0.89, 0.89, and 0.97, respectively. The 

high coefficients of determination for these equations 

Regionalized Equations for Bankfull Discharge and 

Channel Characteristics of Streams in New York State— 

Hydrologic Regions 1 and 2 in the Adirondack Region 

of Northern New York

By Christiane I. Mulvihill1, Amy Filopowicz2, Arthur Coleman3, and Barry P. Baldigo1

indicate that much variability is explained by drainage area. 

Recurrence intervals for the estimated bankfull discharge 

of each stream ranged from 1.01 to 3.80 years; the mean 

recurrence interval was 2.13 years. The 16 surveyed streams 

were classified by Rosgen stream type; most were B- and 

C-type, with a few E- and F-type cross sections.

The hydrologic Regions 1 and 2 equation for the relation 

between bankfull discharge and drainage area was graphically 

compared to curves developed for 5 other hydrologic regions 

in New York State. The 95-percent confidence interval for 

the hydrologic Regions 1 and 2 curve fully encompassed the 

curves for Regions 4a, 5, and 6, showing that there are very 

few differences in the relation between drainage area and 

bankfull discharge in these four regions. However, the curves 

for Regions 4 and 7 lay outside the 95 percent confidence 

intervals of the Region 3 curve, indicating that these 3 

regions do not have similar bankfull-discharge to drainage 

area relations.

Introduction

Streambank erosion and the resulting sedimentation of 

streams can affect the water quality of reservoirs, endanger 

aquatic life, and jeopardize private and public lands and 

associated infrastructure. Streams throughout New York State 

that have abnormally high rates of erosion and sedimentation 

are undergoing restoration efforts to improve bank and bed 

stability. Stream-restoration procedures have traditionally 

consisted of straightening, widening, and deepening the 

channel, hardening the banks, and imposing static stream 

geometry—all of which can cause permanent ecological 

disruption. Recent stream-restoration projects, in contrast, 

have begun to use an approach that strives toward replication 

of stable-reach characteristics, such as the relation between 

drainage area and bankfull cross-section dimensions and the 

relations among channel characteristics, flow patterns, and 

water-surface profiles. Bankfull discharge and bankfullchannel-characteristics of streams that are ungaged can be 

1

 U.S. Geological Survey, 425 Jordan Rd., Troy, NY 12180.

2

 New York State Department of State, Division of Coastal Resources, 

41 State St., Albany, NY 12231.

3

 Trout Unlimited, 86 Lake Rd., Ballston Lake, NY 12019.
2 Regionalized Equations for Bankfull Discharge and Channel Characteristics of Streams in New York State—Regions 1 and 2

derived from equations (curves) that define these relations; 

such equations are themselves derived using data from nearby 

stable reaches that are gaged. Channel-characteristics data 

from these nearby reference reaches are the foundations 

for Natural Channel Design (NCD) restoration techniques 

to recreate geomorphically1 stable stream reaches. The 

channel characteristics obtained through NCD techniques 

structurally resemble those of natural streams and, thus, can 

slow erosion and sedimentation and allow regeneration of 

aquatic ecosystems that are more diverse and functionally 

complete than those that typically result from the hardening of 

streambeds and banks.

Bankfull discharge is the most useful stream feature for 

determining the relations between drainage area and streamchannel characteristics. Bankfull discharge is the flow that 

reaches the transition between the channel and its flood 

plain and is thus a morphologically significant streamflow 

(Leopold and others, 1964). It may be functionally defined 

and identified as the stage or flow at which the stream is about 

to overtop its banks (Leopold and others, 1964; Leopold, 

1994), and it is reported to occur about every 1 to 2 years, or 

on average about every 1.5 years, for most streams (Rosgen, 

1994). Bankfull discharge is the flow that moves the most 

sediment over time, owing to the combination of its force and 

frequency (Wolman and Miller, 1960; Leopold, 1994). 

Bankfull discharge influences the relation between 

drainage area and stream-channel characteristics in two ways. 

First, bankfull discharge often occurs at a relatively discrete 

and identifiable stage, enabling a system for classifying 

streams to be developed on the basis of channel characteristics 

at bankfull stage (Rosgen, 1996). Second, relations between 

drainage area and discharge and drainage area and channel 

characteristics are relatively constant at bankfull stage in 

stable streams of a given class within a certain hydrologic 

region (Leopold and others, 1964; Rosgen, 1996).

Stable-channel characteristics for an unstable, ungaged 

stream can be estimated from equations that are based on data 

from stable streams that are subject to similar precipitation 

rates and climatic conditions, and whose drainage basins 

have similar soils, recharge patterns, flow patterns, and 

physiographic characteristics as the unstable stream. Deriving 

channel-characteristics equations from stable streams within 

a given hydrologic region can minimize differences in each 

variable and thereby increase the accuracy of the equations.

A statewide cooperative program led by the USGS is 

developing regional hydraulic geometry curves through a 

process established by the New York City Department of 

Environmental Protection Stream Management Program 

(NYCDEP-SMP; Miller and Davis, 2003; Powell and others, 

2004). This program is overseen by the New York State 

Hydrologic and Habitat Modification (HHM) subcommittee of 

the New York State Nonpoint-Source Coordinating Committee 

(NPSCC). Similar efforts are being conducted in other parts 

1

 “Geomorphically”, in the context of this report, refers to channel slope, 

shape, and pattern (Rosgen, 1996).

of the northeastern United States; including, Vermont (Jaquith 

and Kline, 2001), coastal and central Maine (Dudley 2004), 

and the Pennsylvania-Maryland Piedmont area (Chaplin, 

2005). The equations, which reflect local precipitation rates, 

hydrologic conditions, physiographic characteristics, and soil 

properties, are expected to have higher R2 values and lower 

mean square errors--indicating stronger and more accurate 

models--than the currently available equations which represent 

relations over widespread and disparate geographic regions, 

such as those of Dunne and Leopold (1978), which represent 

the Eastern United States.

Approach

In 2001, the U.S. Geological Survey (USGS), in 

cooperation with the New York State Department of 

Environmental Conservation (NYSDEC), the New York 

State Department of Transportation (NYSDOT), and the 

New York City Department of Environmental Protection, 

began a 6-year study to define the relations between drainage 

area and channel characteristics for the eight hydrologic 

regions of New York State (excluding Long Island) that 

were previously established to estimate the magnitude and 

frequency of floods for unregulated streams (Lumia, 1991). 

The New York State Department of State (NYSDOS), 

Division of Coastal Resources became a cooperator in the 

study in 2005. Boundaries of the eight hydrologic regions 

developed by Lumia in 1991 (fig. 1) were used as preliminary 

hydrologic-region boundaries to group streams with similar 

characteristics. This report presents drainage areas and 

associated bankfull characteristics (discharge and channel 

characteristics) for surveyed streams in hydrologic Regions 1 

and 2 in northern New York. Hydrologic Regions 1 and 

2 are combined in this report because (1) there are few 

long-term unregulated (naturally flowing) gaged streams 

in the Adirondack region of northern New York State and 

(2) the most recent flood-frequency report for New York State 

combines hydrologic Regions 1 and 2 into a single hydrologic 

region (Lumia and others, 2006). Previous studies have 

developed bankfull-discharge and channel-characteristics 

equations for Regions 4 and 4a in the Catskills (Miller and 

Davis, 2003), Region 5 in central New York (Westergard and 

others, 2005), Region 6 in southwestern New York (Mulvihill 

and others, 2005), and Region 7 in western New York 

(Mulvihill and others, 2006). 

Objectives of this statewide study are to (1) complete 

bankfull surveys on selected streams in all eight regions 

to verify and (or) redefine these boundaries, (2) assess 

all streams for key features of the Rosgen (1996) streamclassification system; namely, channel-entrenchment ratio 

(ratio of flood plain width to bankfull-channel width), channel 

width-to-depth ratio, water-surface slope, channel materials, 

and channel sinuosity (ratio of stream length to valley length), 

and (3) assess the accuracy of statewide bankfull equations 

by grouping channel-characteristics relations across the eight 
Introduction 3

Figure 1. Hydrologic regions in New York State: (A) Hydrologic-region boundaries as defined by Lumia (1991), and (B) Locations of 

the 15 active and 1 inactive streamflow-gaging stations used in 2004–05 stream survey in hydrologic Regions 1 and 2 in New York State.

Base from U.S. Geological Survey digital data

1

Base from U.S. Geological Survey digital data

Lake Ontario

S andy Cre e k

Boque t R ive r

P ul m Brook

Ausa ble R ive r

Ho osic Rive r Batte n Kill Inde pend e nce Rive r

Mill Cree k

Mill Cree k

Streamflow-gaging stations CLINTON

ST. LAWRENCE

FRANKLIN

JEFFERSON

LEWIS

OSWEGO

ONEIDA

HAMILTON

HERKIMER

WARREN

WASHINGTON

FULTON

MONTGOMERY

SCHENECTADY

SARATOGA

RENSSELAER

ESSEX

0 30 MILES

0 10 20 30 KILOMETERS

10 20

6

5

7

1

2

4

4A 3

EXPLANATION

1 Hydrologic-region identifier

Hydrologic-region boundary

New York

80° 78° 76° 74° 72°

41°

43°

0 30 60 90 120 MILES

0 30 60 90 120 KILOMETERS

PENNSYLVANIA

NEW JERSEY

LONG ISLAND

CANADA

VERMONT

MASSACHUSETTS

CONNECTICUT

ATLANTIC

OCEAN

A. ACTIVE SITES

INACTIVE SITES

77° 76° 75° 74° 73°

45°

44°

43°

1 2

EXPLANATION

Hydrologic flood-region boundary and identifier

Inactive, crest stage

Active, continuous record

Active, crest stage

CANADA

B.

County boundary 04268200

04268720

04275000

04276500

04274000

04256040

04250750 04253296

04256000 04254500

01342797

01348420

01330000

01329490

01333500

Archer

VERMONT

Region 7

Region 5

Region 4

Region 3 MASSACHUSETTS

04268200 Plum Brook near Grantville

04268720 Hopkinton Brook at Hopkinton

04275000 East Branch Au Sable River at Au Sable Forks

04276500 Bouquet River at Willsboro

04274000 West Branch Au Sable River near Lake Placid

04256040 Tributary to Mill Creek Tributary near Lowville

04253296 Buck Creek near Inlet

04250750 Sandy Creek near Adams

04256000 Independence River at Donnattsburg

04254500 Moose River at McKeever

01342797 Vly Brook near Morehouseville

01348420 North Creek near Ephratah

01330000 Glowegee Creek at West Milton

01329490 Batten Kill below Mill at Battenville

01333500 Little Hoosic River at Petersburg

No USGS

site ID

Archer Creek above Arbutus Pond
4 Regionalized Equations for Bankfull Discharge and Channel Characteristics of Streams in New York State—Regions 1 and 2

regions by stream type in accordance with the Rosgen streamclassification system (Miller and Davis, 2003).

Rosgen’s stream-classification system (1996) was 

created to provide stream descriptions for use in evaluations 

of channel stability and in the design and simulation of stable 

conditions for ungaged stream reaches. The geomorphic 

characteristics defined by Rosgen (1996) that correspond 

to bankfull stage were chosen for their consistency among 

streams with similar physiographic characteristics for a given 

drainage-basin size and among streams subject to similar 

climatic conditions (Rosgen, 1994, 1996). 

Hydrologic Regions 1 and 2 (fig. 1A) are the sixth 

and seventh of the eight regions examined in this study. 

Hydrologic Regions 1 and 2 encompass an area bounded by 

Vermont to the east, Canada to the north and northwest, Lake 

Ontario to the west, and the Tug Hill Plateau and foothills of 

the Adirondack Mountains to the south (Lumia, 1991). As 

mentioned earlier, these hydrologic regions do not contain 

many actively gaged streams that are unregulated and have 

at least 10 years of peak-flow record; therefore, one inactive 

streamflow-gaging station and one streamflow-gaging station 

with less then 10 years of record were included in the database 

for development of the bankfull-discharge and channelcharacteristics equations. 

The hydrologic regions defined by Lumia (1991) were 

based on multiple linear-regression analyses that related 

the 50-year peak discharge to basin characteristics such as 

drainage area, main-channel slope, basin storage, mean annual 

precipitation, percentage of basin covered by forest area, mean 

main-channel elevation, and a basin-shape index (ratio of 

basin length to basin width). One of the assumptions tested 

in this investigation is that stratifying bankfull-discharge 

and channel-characteristics data by hydrologic region 

creates individual models that are more accurate than one 

comprehensive statewide model.

Purpose and Scope

This report (1) describes the methods of site selection and 

data collection and analysis (2) presents the relations between 

drainage area and bankfull width, depth, cross-sectional area, 

and discharge and (3) graphically compares bankfull-discharge 

equations developed for hydrologic Regions 1 and 2 with 

equations developed in previous studies for Regions 4, 4a, 5, 

6, and 7 in New York State.

Methods

Sixteen reaches at streamflow-gaging stations in 

hydrologic Regions 1 and 2 were surveyed during 2004–05. 

The methods used to collect and analyze the data in this report 

are described in detail in Powell and others (2004).

Site Selection

The streams were selected to represent a wide range 

of drainage areas so that the resulting equations would be 

applicable to most streams within the hydrologic regions. 

Other selection criteria (Miller and Davis, 2003) for study 

reaches are listed below: 

•	 All must contain a USGS streamflow-gaging station with 

at least 10 years of annual peak-discharge data, if possible. 

Both crest-stage gages, which record only the annual peak 

stage, and continuous record stream-flow gaging stations 

can be used. 

•	 All must be primarily alluvial and unregulated (naturally 

flowing) and must consist of a single channel at 

bankfull stage.

•	 All must either include at least two sequences of a pool and 

a riffle or be at least 20 bankfull widths long.

•	 All must have readily identifiable bankfull indicators 

(defined in the following section).

•	 All must meet the minimum requirements for slope-area 

calculation of discharge (uniform channel characteristics; 

flow confined to a single, trapezoidal channel; and watersurface-elevation drop of at least 0.50 ft within the reach 

(Dalrymple and Benson, 1967)) so that surveyed data can 

be used reliably in hydraulic analysis and calculation of 

bankfull discharge.

•	 All should represent a single Rosgen stream type (1996), 

if possible.

USGS streamflow-gaging stations are not always on 

geomorphically stable stream reaches because landowner 

permission, access to the station, and the need for the safe 

measurement of high flows often dictate where a station is 

located. As a result, most streamflow-gaging stations are near 

bridges and other structures that may cause localized channel 

instability of stream reaches near gages. To assess channel 

stability at streamflow-gaging stations used in this study, 

two methods were employed. At active streamflow-gaging 

stations, stability was assessed through inspection of the 

most recent analysis of flow-measurement data for evidence 

of scour, deposition, and frequent shifting of bed material. 

At the discontinued streamflow-gaging station (Hopkinton 

Brook at Hopkinton (04268720)) (fig. 1B and table 1), three 

discharge measurements (low to medium stage) were made 

during the study period to define the stage-discharge relation, 

which was compared with the last known relation from 

when the streamflow-gaging station was active. Significant 

discrepancies between the two relations would have been 

indicative of channel instability.

The selected stream sites were referred to as calibration 

sites because they were used to develop, or calibrate, the 

channel-characteristics equations. Hydrologic Regions 1 

and 2 contain 20 active streamflow-gaging stations with 

10 or more years of peak-flow record. Thirteen of the 20 
Methods 5

streamflow-gaging stations were determined to be suitable for 

calibration surveys. To ensure that the regional curves were 

as representative as possible, three streamflow-gaging stations 

were added: Hopkinton Brook at Hopkinton (04268720), 

which had been discontinued in 1986; Buck Creek near Inlet 

(04253296), which has only 7 years of peak-flow record; 

and Archer Creek above Arbutus Pond, which is operated by 

the State University of New York College of Environmental 

Science and Forestry (SUNY-ESF). Figure 1B shows the 

location of the 16 streamflow-gaging stations surveyed in 

hydrologic Regions 1 and 2

Data Collection

Preliminary reconnaissance of all sites entailed marking 

bankfull indicators, cross-section locations, and reach 

boundaries. Bankfull indicators consisted of (1) topographic 

break from vertical bank to flat flood plain; (2) topographic 

break from steep slope to gentle slope; (3) change in 

vegetation (for example, from treeless to trees); (4) textural 

change in sediment; (5) scour break, or elevation below which 

no fine debris (needles, leaves, cones, seeds) occurs; and 

(6) back of point bar, lateral bar, or low bench (Castro and 

Jackson, 2001; Miller and Davis, 2003).

The upstream and downstream ends of the reach and the 

locations of cross sections were marked with a rebar driven 

into the streambank above bankfull stage on one bank. Three 

to five cross sections at each site were placed in riffles or runs, 

away from channel-constricting structures such as bridges 

and culverts.

After the preliminary reconnaissance, each reach 

was surveyed by methods described in Powell and others 

(2004). Longitudinal-profile and cross-sectional surveys 

were done. The longitudinal-profile survey consisted of 

elevation measurements of the rebar markers at the upstream 

and downstream reach limits; all bankfull indicators; and 

the thalweg and water surface at each bankfull indicator, 

cross section, and pool-to-riffle transition. The cross-section 

surveys consisted of measurements of bed and bank elevations, 

bankfull indicators, rebars that marked cross sections, and 

flood-plain width. The reference elevation for all surveys was 

the elevation used to define the stage-to-discharge relation. 

Channel material at each reach was characterized using a 

modification of the transect pebble count procedure described 

in Powell and others (2004).

Data Analysis

All field data were compiled for graphical analysis. At 

most sites, a bankfull-elevation profile along the study reach 

was constructed by plotting a best-fit linear-regression line 

through the surveyed bankfull-stage indicators. Bankfull 

water-surface elevation (stage) and discharge at these sites 

were derived from these best-fit lines, rather than from 

surveyed bankfull indicators, to smooth local variations in 

slope that can result from intermittent disruptions such as 

debris piles or bedrock outcrops. Bankfull stage and discharge 

at one site (Vly Brook near Morehouseville (01342797)) 

(fig. 1B and table 1) were obtained through a nonlinear 

regression technique called a LOWESS smooth (Locally 

Weighted Scatterplot Smoother; Ott and Longnecker, 2001), 

because steep slopes upstream and downstream from the gage 

pool resulted in the best-fit line of bankfull elevation being 

considerably lower then true bankfull elevation (table 1).

The bankfull stage at the gaging station or staff gage at 

active stations was calculated as described previously, and 

the corresponding bankfull discharge was obtained from the 

most current stage-discharge relation. Bankfull discharge at 

the inactive station was interpolated from the newly developed 

stage-discharge relation that was extended to bankfull stage 

by use of the Johnson method (Kennedy, 1984). Estimates 

of bankfull discharges for all sites were verified through a 

hydraulic analysis of the bankfull geomorphic data collected 

during the gage-calibration survey, as follows. Additional 

details are given in Powell and others (2004).

1. The computer program NCALC (Jarrett and Petsch, 

1985) was used to compute Manning’s n, the roughness 

coefficient for the reach. Data required for this 

computation were discharge from the stage-discharge 

relation, channel-bed and bankfull water-surface 

elevations at each cross section, and distance along the 

thalweg between cross sections (Jarrett and Petsch, 1985). 

2. The computer program HEC-RAS (U.S. Army Corps of 

Engineer’s Hydraulic Engineering Center River Analysis 

System) (Brunner, 1997) was used to calculate bankfull 

discharge from the water-surface elevation, as follows. 

First, the reference elevation for the survey was entered as 

the starting elevation, and Manning’s n (from the NCALC 

analysis), channel-bed elevations at each cross section, 

the distance along the thalweg between cross sections, 

and several estimated discharges were input for each cross 

section. Next, the discharge at the water-surface elevation 

calculated by HEC-RAS that most closely approximated 

the surveyed bankfull water-surface elevation was chosen 

as the bankfull discharge at each cross section. Finally, 

the average of these discharges from all cross sections in 

the reach was used as the bankfull discharge for the reach. 

3. The bankfull discharge obtained from the stage-discharge 

relation was compared with the bankfull discharge 

obtained from the HEC-RAS analysis. If the two 

discharges differed by 10 percent or less, the discharge 

obtained from the stage-discharge relation was then used 

as the bankfull discharge, and the recurrence interval 

of this discharge was calculated. If the two bankfull 

discharges differed by more than 10 percent, the stream 

and reach selection, discharge measurements, elevation of 

bankfull indicators, and the stage-discharge relation were 

reviewed for potential sources of error. If no errors were 

found, the discharge that more closely fit the expected 

1- to 2-year bankfull recurrence interval was chosen.
6 Regionalized Equations for Bankfull Discharge and Channel Characteristics of Streams in New York State—Regions 1 and 2

Table 1. Characteristics of streamflow-gaging stations surveyed in hydrologic Regions 1 and 2 in New York State, 

2004–05.—Continued

[mi2, square miles; ft3/s, cubic feet per second. Streamflow-gaging station locations are shown in fig. 1B]

Site name 

and 

USGS

station number

Period(s)

of 

record

Drainage 

area 

(mi2)

Bankfull 

discharge1

(ft3/s)

Recurrence 

interval of 

bankfull 

discharge

(years)

Reach 

stream 

type2

Archer Creek above Arbutus Pond3 1995–present 0.52 26.5 1.95 B3a, C3b

Buck Creek near Inlet (04253296) 1989–90, 

2001–present

1.28 79 1.904 B4, E4b

Tributary to Mill Creek Tributary 

near Lowville (04256040)

1976–86

1993–present

1.66 1505 2.80 B4, C4b 

Vly Brook near Morehouseville 

(01342797)

1993–present 3.28 1336 1.40 B3, C3b

North Creek near Ephratah 

(01348420)

1975–present 6.52 100 1.01 B4c ,C4

Hopkinton Brook at Hopkinton 

(04268720)

1962–86 20.0 5505 3.00 C3

Glowegee Creek at West Milton 

(01330000)

1948–63,

1990–present

26.0 507 1.22 C5

Plum Brook near Grantville 

(04268200) 

1959–63,

1964–present

43.9 678 1.95 C4

Little Hoosic River at Petersburg 

(01333500)

1949, 1951–96,

1997–present

56.1 2,5005 3.00 C3

Independence River at 

Donnattsburg (04256000)

1942–present 88.7 2,420 2.80 C3

West Branch Au Sable River near 

Lake Placid (04274000)

1920–27, 1928–68, 

1983–present

116 3,100 1.70 C5cSandy Creek near Adams 

(04250750)

1957–present 137 5,030 1.80 C3

East Branch Ausable River at 

Au Sable Forks (04275000)

1925–present 198 6,440 2.10 C4, F4

Bouquet River at Willsboro 

(04276500)

1904–08, 1923–68, 

1980, 1985, 1987–89, 

1990–present

270 6,2005 3.80 B3c

Moose River at McKeever 

(04254500)

1869, 1901–22, 

1923–70, 1982, 

1985, 1987–present

363 6,440 1.40 C4cBatten Kill below Mill at 

Battenville (01329490)7

1923–68, 1998–present 396 6,320 2.30 B4c, C4
Regional Equations for Bankfull Discharge and Channel Characteristics of Streams 7

At four sites (Tributary to Mill Creek Tributary near 

Lowville (04256040), Hopkinton Brook at Hopkinton 

(04268720), Little Hoosic River at Petersburg (01333500), and 

Bouquet River at Willsboro (04276500) (fig. 1B and table 1), 

the bankfull discharges from the stage-discharge relation did 

not agree with the bankfull-discharge from the HEC-RAS 

analysis. At these sites it was assumed that localized channel 

constrictions at the streamflow-gaging station (bridges and 

culverts) and (or) significant flattening of the water-surface 

slope at the streamflow-gaging station distorted the true 

elevation of bankfull stage. Therefore, the bankfull discharge 

from the HEC-RAS analysis, calculated at cross sections not 

affected by channel-constricting influences, was assumed to be 

the best estimate of bankfull discharge.

Regional Equations for Bankfull 

Discharge and Channel 

Characteristics of Streams

The relations between bankfull-discharge, depth, width, 

and cross-sectional area and drainage area for hydrologic 

Regions 1 and 2 are presented in the following sections. 

The period of record, drainage area, bankfull discharge and 

associated recurrence intervals, and Rosgen (1994) stream 

type for each site are summarized in table 1.

Regionalized Relation between Bankfull 

Discharge and Drainage Area 

The estimated bankfull discharges and drainage areas 

for the 16 stream sites used to develop the relation between 

bankfull discharge and drainage area are in table 1. The 

bankfull-discharge equation for streams in hydrologic Regions 

1 and 2 (fig. 2) is:

bankfull discharge (ft3/s) = 49.6 (drainage area(mi2))0.849, (5)

and the coefficient of determination (R2) is 0.95. The 

95-percent confidence and prediction intervals for the equation 

are shown in figure 2. The 95-percent confidence interval 

defines the range within which streamflows based on data 

collected on a different set of streams in the same region 

would have a 95-percent probability of occurring, whereas the 

wider 95-percent prediction interval defines the range within 

which the bankfull discharge estimated for a single stream of 

a given drainage area in the region would have a 95-percent 

probability of occurring. 

Table 1. Characteristics of streamflow-gaging stations surveyed in hydrologic Regions 1 and 2 in New York State, 

2004–05.—Continued

[mi2, square miles; ft3/s, cubic feet per second. Streamflow-gaging station locations are shown in fig. 1B]

1

 From stage-discharge relation. 

2

 From Rosgen (1994): 

B3: average-gradient, moderately entrenched, riffle-dominated channel with cobbles;

B3a: high-gradient, moderately entrenched, riffle-dominated channel with cobbles;

B3c: very low-gradient, moderately entrenched, riffle-dominated channel with cobbles; 

B4: average-gradient, moderately entrenched, riffle-dominated channel with gravel;

B4c: very low-gradient, moderately entrenched, riffle-dominated channel with gravel; 

C3: low-gradient, cobble-dominated channel with well defined flood plains;

C3b: high-gradient, cobble-dominated channel with well defined flood plains;

C4: low-gradient, gravel-dominated channel with well defined flood plains;

C4b: high-gradient, gravel-dominated channel with well defined flood plains;

C4c-: very low-gradient, gravel-dominated channel with well defined flood plains;

C5: low-gradient, sand-dominated channel with well defined flood plains;

C5c-: very low-gradient, sand-dominated channel with well defined flood plains;

E4b: sinuous, high-gradient channel with gravel;

F4: sinuous, low-gradient, highly entrenched gravel-dominated channel;

Channel materials from longitudinal-profile pebble count (table 2). 3

 Station operated by Adirondack Ecological Center (SUNY-ESF).

4

 Recurrence interval estimated from 7 years of record.

5

 Bankfull discharge from HEC-RAS analysis.

6

 Bankfull gage height from LOWESS smooth.

7

 Survey data collected at former streamflow-gaging-station location 0.76 miles downstream.
8 Regionalized Equations for Bankfull Discharge and Channel Characteristics of Streams in New York State—Regions 1 and 2

Bankfull-Discharge Recurrence Intervals

The recurrence interval for the estimated bankfull 

discharge of each stream was obtained from dischargefrequency relations for each study site that were developed 

by fitting the logarithms of the annual peak-discharges 

to a Pearson type III distribution according to guidelines 

recommended by the U.S. Water Resources Council (1981); 

resulting data were analyzed by means of U.S. Geological 

Survey flood-frequency programs (Kirby, 1981). Other 

studies have reported that the average recurrence interval for 

bankfull discharge typically ranges from about 1 to 2 years 

(Dunne and Leopold, 1978; Rosgen, 1996; Harman and 

Jennings, 1999). The bankfull-discharge recurrence interval 

for streams surveyed in hydrologic Regions 1 and 2 ranged 

from 1.01 to 3.80 years and averaged 2.13 years (table 1). 

Previous bankfull studies in New York State determined an 

average bankfull-discharge recurrence interval of 1.54 years 

and a range of 1.2 to 2.7 years in hydrologic Regions 4 and 4a 

(fig.1A; Miller and Davis, 2003), an average of 1.51 years and 

a range of 1.11 to 3.40 years in hydrologic Region 5 (fig. 1A; 

Westergard and others, 2005), an average of 1.54 years and a 

range of 1.01 to 2.35 years in hydrologic Region 6 (fig. 1A; 

Mulvihill and others, 2005), and an average of 2.13 years and 

a range of 1.05 to 3.60 years in hydrologic Region 7 (fig. 1A; 

Mulvihill and others, 2006). 

Stream-Channel Characteristics in Relation to 

Drainage Area 

Bankfull-channel width, depth, and cross-sectional area 

for 16 streams in hydrologic Regions 1 and 2 are listed in 

table 2. Data were collected at three or four cross sections at 

each stream, and these data were used to develop the bankfull 

width, depth, and cross-sectional area regression equations. 

The equations are as follows: 

bankfull-channel width (ft) = 21.5 (drainage area(mi2))0.362, (6)

bankfull-channel depth (ft) = 1.06 (drainage area(mi2))0.329, (7)

bankfull-channel cross-sectional area (ft2) = 22.3 (drainage 

area(mi2))0.694. (8)

Results are plotted in figure 3; coefficients of 

determination (R2) for the equations are 0.89, 0.89, and 0.97, 

respectively. The high coefficients of determination (R2) 

indicate that much of the range in these variables is explained 

by drainage area.

The raw data for Regions 1 and 2 equations and the 

corresponding 95-percent confidence and prediction intervals 

are plotted for bankfull width, depth, and cross-sectional 

Figure 2. Bankfull discharge as a function of drainage area with 95 percent 

prediction limit and 95 percent confidence interval for streams surveyed in 

hydrologic Regions 1 and 2 in New York State.

y = 49.6x0.849

R2 = 0.95

1

10

100

1,000

10,000

100,000

0 1 10 100 1,000

DRAINAGE AREA, IN SQUARE MILES

95-percent prediction interval

95-percent confidence interval

BANKFULL DISCHARGE, IN CUBIC FEET PER SECOND
Regional Equations for Bankfull Discharge and Channel Characteristics of Streams 9

Table 2. Stream classification and bankfull-channel characteristics for streamflow-gaging stations surveyed in hydrologic Regions 1 and 2 in New York State, 2004–05.[ft, feet; ft2, square feet; mi2, square miles; mm, millimeters; na, not available. Streamflow-gaging station locations are shown in fig. 1B]

Site name and 

station-identification 

number

Drainage 

area 

(mi2

)

Crosssection 

downstream 

stationing 

(ft)

Bankfull 

width 

(ft)

Bankfull 

depth 

(ft)

Bankfull 

crosssectional 

area 

(ft2

)

Width 

of 

flood-plain 

(ft)

Entrenchment 

ratio1

Width-todepth ratio Water surface slope D50 (mm)2 Sinuosity3 Cross- section stream type4

Archer Creek

above ArbutusPond

0.52 63 19.6 1.1 21.4 41.7 2.1 17.8 0.074 245 1.25 B3a

135 29.0 0.7 19.7 53.1 1.8 41.4 B3a153 11.6 1.2 13.9 33.3 2.9 9.7 C3b162 16.9 .9 14.7 53.2 3.1 18.8 C3b

Buck Creek

near Inlet(04253296)

1.28 138 14.2 1.8 24.9 41.0 2.9 7.9 .033 47.2 1.11 E4b

166 15.4 1.2 18.2 28.0 1.8 12.8 B4193 17.9 1.8 31.3 42.0 2.3 9.9 E4b

Tributary to Mill 

Creek Tributarynear Lowville(04256040)

1.66 0 27.6 .9 24.2 47.8 1.7 30.7 .023 26.0 1.14 B4

57 30.5 1.1 33.0 36.5 1.2 27.7 B4

121 28.6 .8 21.6 36.0 1.3 35.8 B4153 46.7 .8 37.1 202 4.3 58.4 C4b

Vly Brook near

Morehouseville(01342797)

3.28 35 34.5 1.5 50.6 50.5 1.5 23.0 .025 147 1.17 B3

78 34.3 1.2 42.3 66.0 1.9 28.6 B3

139 41.3 1.4 56.4 57.0 1.4 29.5 B3382 30.4 1.8 53.5 173 5.7 16.9

C3b

North Creek near

Ephratah(01348420)

6.52 81 37.4 2.1 78.4 340 9.1 17.8 .019 32.2 1.22 C4

507 51.5 1.8 93.6 90.0 1.7 28.6 B4c562 62.3 1.8 111 107 1.7 34.6 B4c594 74.8 1.5 115 104 1.4 49.9

B4c

Hopkinton Brook 

at Hopkinton(04268720

20.0 97 72.3 2.1 154 190 2.6 34.4 .014 68.4 1.24 C3

146 61.5 2.0 125 180 2.9 30.8 C3226 67.5 3.3 220 149 2.2 20.5 C3

Glowegee Creek 

at West Milton(01330000)

26.0 242 51.6 3.9 199 310 6.0 13.2 .001 .2 1.73 C5

316 49.6 4.1 201 215 4.3 12.1 C5350 48.0 4.0 193 223 4.6 12.0 C5
10 Regionalized Equations for Bankfull Discharge and Channel Characteristics of Streams in New York State—Regions 1 and 2 Table 2. Stream classification and bankfull-channel characteristics for streamflow-gaging stations surveyed in hydrologic Regions 1 and 2 in New York State, 2004–05.—Continued [ft, feet; ft2, square feet; mi2, square miles; mm, millimeters; na, not available. Streamflow-gaging station locations are shown in fig. 1B] Site name and station- identification number Drainage area (mi2

)

Crosssection 

downstream 

stationing 

(ft)

Bankfull 

width 

(ft)

Bankfull 

depth 

(ft)

Bankfull 

crosssectional 

area 

(ft2

)

Width 

of 

flood-plain 

(ft)

Entrenchment 

ratio1

Widthtodepth 

ratio

Water 

surface 

slope

D50

(mm)2 Sinuosity3

Crosssection 

stream 

type4

Plum Brook 

nearGrantville(04268200)

43.9 250 58.5 4.9 287 269 4.6 11.9 0.002 45.8 1.62 C4

337 55.5 4.6 257 144 2.6 12.1 C4487 56.6 3.2 180 213 3.8 17.7 C4732 69.0 3.1 215 226 3.3 22.3 C4

Little Hoosic

River atPetersburg(01333500)

56.1 1044 94.1 3.5 330 367 3.9 26.9 .004 65.6 1.19 C3

1172 66.1 4.7 309 420 6.4 14.1 C31264 96.4 3.7 356 408 4.2 26.1 C31424 78.2 4.5 354 505 6.5 17.4 C3

Independence

River at Donnattsburg(04256000)

88.7 1385 129 4.1 531 330 2.6 31.4 .005 86.5 1.90 C3

1500 131 4.2 554 300 2.3 31.2 C31723 88.2 4.9 434 245 2.8 18.0 C3

West Branch 

Au Sable River near Lake Placid(04274000)

116 406 114 7.6 859 410 3.6 14.9 <.001 2.0 1.35 C5c731 123 6.8 830 445 3.6 18.0 C5c843 113 6.5 737 392 3.5 17.3 C5cSandy Creek near 

Adams(04250750)

137 1137 116 5.8 671 na na 20.1 .002 77.0 1.55 na

1421 108 5.6 608 3450 31.9 19.3 C31572 108 5.6 606 3450 31.9 19.3 C3

East Branch

Au Sable River at Au SableForks(04275000)

198 647 179 5.1 912 230 1.3 35.1 .002 55.4 1.23 F4

892 176 6.4 1132 1160 6.6 27.5 C4

1102 323 3.5 1134 1252 3.9 92.4 C4

Bouquet River

at Willsboro(04276500)

270 746 172 5.6 969 272 1.6 30.8 .003 122.3 1.69 B3c

877 182 5.5 1006 265 1.5 33.1 B3c

1008 146 6.1 886 261 1.8 23.9 B3c1155 145 5.2 761 268 1.8 27.9 B3c
Regional Equations for Bankfull Discharge and Channel Characteristics of Streams 11

Table 2. Stream classification and bankfull-channel characteristics for streamflow-gaging stations surveyed in hydrologic Regions 1 and 2 in New York State, 2004–05.—Continued[ft, feet; ft2, square feet; mi2, square miles; mm, millimeters; na, not available. Streamflow-gaging station locations are shown in fig. 1B]

Site 

name 

and stationidentification 

number

Drainage 

area 

(mi2

)

Crosssection 

downstream 

stationing 

(ft)

Bankfull 

width 

(ft)

Bankfull 

depth 

(ft)

Bankfull 

crosssectional 

area 

(ft2

)

Width 

of 

flood-plain 

(ft)

Entrenchment 

ratio1

Widthtodepth 

ratio

Water 

surface 

slope

D50

(mm)2 Sinuosity3

Crosssection 

stream 

type4

Moose River

at McKeever (04254500)

363 1497 229 9.6 2208 560 2.4 23.9 <.001 19.9 1.04 C4c1828 222 8.6 1901 na na 25.8 na

2074 228 9.3 2108 600 2.6 24.5 C4cBatten Kill

below Millat Battenville (01329490)

396 1865 197 8.0 1584 572 2.9 24.7 .001 39.1 1.46 C4

2057 193 5.5 1074 328 1.7 35.2 B4c3227 151 7.4 1117 449 3.0 20.5 C4

1 Entrenchment ratio: flood-plain width divided by bankfull width (Harman and Jennings, 1999).2 D50: median particle size, the diameter that exceeds that of 50 percent of all streambed particles in the reach.3 Sinuosity: ratio of stream length to valley length (Harman and Jennings, 1999).4 from Rosgen (1994): 

B3: average-gradient, moderately entrenched, riffle-dominated channel with cobbles,B3a: high-gradient, moderately entrenched, riffle-dominated channel with cobbles,B3c: very low-gradient, moderately entrenched, riffle-dominated channel with cobbles, B4: average-gradient, moderately entrenched, riffle-dominated channel with gravel,B4c: very low-gradient, moderately entrenched, riffle-dominated channel with gravel, C3: low-gradient, cobble-dominated channel with well defined flood plains,C3b: high-gradient, cobble-dominated channel with well defined flood plains,C4: low-gradient, gravel dominated channel with well defined flood plains,C4b: high-gradient, gravel-dominated channel with well defined flood plains,C4c-: very low-gradient, gravel-dominated channel with well defined flood plains,C5: low-gradient, sand-dominated channel with well defined flood plains,C5c-: very low-gradient, sand-dominated channel with well defined flood plains,E4b: sinuous, high-gradient channel with gravel,F4: sinuous, low-gradient, highly entrenched gravel-dominated channe.
12 Regionalized Equations for Bankfull Discharge and Channel Characteristics of Streams in New York State—Regions 1 and 2

area as a function of drainage area in figures 4A , B and C, 

respectively. The confidence and prediction intervals shown 

on these graphs were calculated using all available crosssection data; these bands are narrower than they would have 

been if only the mean values for each parameter at each site 

had been used.

Stream Classification

The Rosgen classification system (Rosgen, 1996) 

categorizes streams on the basis of channel morphology 

to provide consistent, quantitative descriptions of stream 

condition (Harman and Jennings, 1999). This study used the 

following criteria and measurements to classify streams; the 

values obtained are listed in table 2.

•	 Entrenchment ratio: a field measurement of channel 

incision, defined as the flood-plain width divided by 

the bankfull width (Harman and Jennings, 1999). The 

flood-plain width is measured at the elevation of twice 

the maximum depth at bankfull.

•	 Width-to-Depth ratio: the bankfull width divided by 

the mean bankfull depth (Harman and Jennings, 1999).

•	 Water-surface slope: the difference between the watersurface elevation at the upstream end of a riffle to 

the upstream end of another riffle at least 20 bankfull 

widths downstream, divided by the distance between 

the riffles along the thalweg (Harman and Jennings, 

1999).

•	 Median size (D50) of bed material: the median particle 

size, or the diameter that exceeds the diameter of 

50 percent of all streambed particles (Harman and 

Jennings, 1999). D50 values were obtained through a 

modified Wolman pebble count (modified to account 

for bank and within-channel material, sand and smaller 

particle sizes, and bedrock (Rosgen 1996)).

•	 Sinuosity: stream length divided by valley length 

(Harman and Jennings, 1999).

Each reach was classified by Rosgen stream type(s) 

(table 1) on the basis of the stream-channel measures taken 

at each cross section. Each cross section was also classified 

Figure 3. Bankfull width, depth, and cross-sectional area as a function of drainage area with best-fit lines, 

regression equations, and R2 values for streams surveyed in hydrologic Regions 1 and 2 in New York State.

y = 22.3x0.694

R2 = 0.97

y = 21.5x0.362

R2 = 0.89

y = 1.06x0.329

R2 = 0.89

0.1

1

10

100

1,000

10,000

0.1 1 10 100 1,000

DRAINAGE AREA, IN SQUARE MILES

Bankfull channel width

Bankfull channel depth

Bankfull channel cross-sectional area

BANKFULL CHANNEL WIDTH AND DEPTH, IN FEET,

 AND CROSS-SECTIONAL AREA, IN SQUARE FEET
Regional Equations for Bankfull Discharge and Channel Characteristics of Streams 13

Figure 4. Channel characteristics as a function of drainage area with 95 percent prediction limits 

and 95 percent confidence intervals for streams in hydrologic Regions 1 and 2 in New York State: 

(A) bankfull-channel width, (B) bankfull-channel depth, and 

(C) bankfull-channel cross-sectional area. 

y = 1.06x0.329

R2 = 0.89

0.1

1

10

100

0 1 10 100 1,000

DRAINAGE AREA, IN SQUARE MILES

95-percent prediction interval

95-percent confidence interval

BANKFULL CHANNEL DEPTH, IN FEET

B. BANKFULL CHANNEL DEPTH

y = 21.5x0.362

R2 = 0.89

1

10

100

1,000

0 1 10 100 1,000

DRAINAGE AREA, IN SQUARE MILES 

95-percent prediction interval

95-percent confidence interval

BANKFULL CHANNEL WIDTH, IN FEET

A. BANKFULL CHANNEL WIDTH
14 Regionalized Equations for Bankfull Discharge and Channel Characteristics of Streams in New York State—Regions 1 and 2

individually by Rosgen stream type (table 2). Stream types A 

through G represent seven major stream categories that differ 

in entrenchment, gradient, width-to-depth ratio, and sinuosity 

(Rosgen, 1996). Within each major category, the numbers 1 

through 6 are assigned to delineate dominant channel material 

ranging from bedrock to silt and clay (Rosgen, 1996). 

For 9 of the 16 streams surveyed, the stream type in all 

cross sections was the same (table 2). For 6 of the 16 streams 

surveyed, one cross section was classified as a different 

stream type: Buck Creek near Inlet (04253296), Tributary 

to Mill Creek Tributary near Lowville (04256040), Vly 

Brook near Morehouseville (01342797), North Creek near 

Ephratah (01348420), East Branch Au Sable River at Au Sable 

Forks (0427500), and Batten Kill below Mill at Battenville 

(01329490) (fig. 1 and table 2). One stream, Archer Creek 

above Arbutus Pond, had two B cross sections and two C cross 

sections (table 2). 

In all streams surveyed, almost all cross sections were 

classified as type B or C. Exceptions were Buck Creek near 

Inlet (04253296), which had two E cross sections, and the 

East Branch Au Sable River at Au Sable Forks (04275000), 

which had one F cross section (table 2). The majority of the 

streams surveyed differed from one another only in the degree 

of vertical containment of the river channel (Rosgen, 1994) 

because the only difference between B and C streams is the 

entrenchment ratio. 

Comparison of Hydrologic Regions 1 and 2 

Bankfull-Discharge Equation to Equations 

for Other Regions in New York State

The hydrologic Regions 1 and 2 equation for the relation 

between bankfull discharge and drainage-area was graphically 

compared to curves developed for 5 other regions in New York 

State to evaluate region-to-region differences and the ability of 

regional curves to produce results that are more accurate than 

what would be obtained from one comprehensive statewide 

model (fig. 5). The 95-percent confidence interval for the 

hydrologic Regions 1 and 2 curve fully encompasses the 

curves for Regions 4a, 5, and 6 (fig. 5), showing that there 

are very few differences in the relation between drainage 

area and bankfull discharge in these four regions. However, 

the curves for Regions 4 and 7 lay outside the 95-percent 

confidence intervals of the Region 3 curve (fig 5), indicating 

that these 3 regions do not have similar bankfull discharge to 

drainage-area relations. For example, a stream with a drainage 

area of 10 mi2 would have an estimated bankfull discharge 

of 200 ft3/s in Region 7, 350 ft3/s in Regions 1 and 2, and 

700 ft3/s in Region 4 (fig. 5). These differences demonstrate 

that streams fairly close to one another do not always have 

similar flow regimes and that regional equations designed for a 

specific geographic area are valuable tools for anyone involved 

in local watershed management and planning. 

Figure 4. Channel characteristics as a function of drainage area with 95 percent prediction limits and 

95 percent confidence intervals for streams in hydrologic Regions 1 and 2 in New York State: (A) bankfullchannel width, (B) bankfull-channel depth, and (C) bankfull-channel cross-sectional area.—Continued

y = 22.3x0.694

R2 = 0.97

1

10

100

1,000

10,000

0.1 1 10 100 1,000

DRAINAGE AREA, IN SQUARE MILES

95-percent prediction interval

95-percent confidence interval

BANKFULL CHANNEL CROSS-SECTIONAL AREA,

IN SQUARE FEET 

C. BANKFULL CHANNEL CROSS-SECTIONAL AREA
Limitations of this Study 15

Limitations of this Study

An assumption made in this study—that the bankfull 

discharge was within the 1- to 2-year recurrence-interval 

range—may be an oversimplification (Thorne and others, 

1997), even though similar recurrence intervals have been 

found in other studies (Harman and Jennings, 1999; Rosgen, 

1994). Channel characteristics associated with a 1- to 2-year 

recurrence interval were used to aid in the identification of 

bankfull indicators during initial site inspections; but if the 

Figure 5. Bankfull discharge as a function of drainage area for hydrologic Regions 1 and 2 and published curves for five other 

regions in New York State.

bankfull recurrence interval at a site were longer or shorter 

than that frequency, the bankfull channel could be incorrectly 

identified (White, 2001). The average bankfull recurrence 

interval for streams surveyed in hydrologic Regions 1 and 2 

was 2.13 years, higher than the average 1.5-year frequency 

reported by Rosgen (1996) but still within the 1- to 2.5-year 

range reported by Leopold (1994). 

The relatively few active USGS streamflow-gaging 

stations in hydrologic Regions 1 and 2 that met selection 

criteria also limited this investigation. To ensure that the 

10

100

1,000

10,000

100,000

0.1 1 10 100 1,000

DRAINAGE AREA, IN SQUARE MILES

Region 1 and 2

Region 1 and 2 − 95-percent confidence interval

Region 41

Region 4a1

Region 52

Region 63

Region 74

BANKFULL DISCHARGE, IN CUBIC FEET PER SECOND

EXPLANATION

Sources:

1

 Miller and Davis, 2003

2

 Westergard and others, 2005

3

 Mulvihill and others, 2005

4

 Mulvihill and others, 2006
16 Regionalized Equations for Bankfull Discharge and Channel Characteristics of Streams in New York State—Regions 1 and 2

equations were as representative as possible, three additional 

gages were added; one that had been inactive since 1986 

(Hopkinton Brook at Hopkinton (04268720)), one that had 

only 7 years of peak-flow record (Buck Creek near Inlet 

(04253296)), and one that was operated by SUNY-ESF 

(Archer Creek above Arbutus Pond). 

The use of one site that had been inactive since 1986 

and seven sites in which more than one stream type were 

included in the study reach necessitated several assumptions. 

In analyzing data from the inactive streamflow-gaging station, 

it was assumed that (1) the recurrence interval of bankfull 

discharge had not changed since the site was last active; 

(2) the flow pattern at the site had not been significantly 

altered by floods, diversions, ground-water recharge, or 

changes in land use since the site was discontinued; and 

(3) three low- to medium-flow discharge measurements 

were sufficient to define a stage-discharge relation that could 

reliably be extended to bankfull stage. In data analysis for 

the sites representing several stream types, it was assumed 

that averaging measurements from cross sections of differing 

types was an accurate measure of overall reach characteristics. 

Also, the recurrence interval at Buck Creek near Inlet was 

estimated from 7 years of peak-flow record, though 10 years 

of peak-flow record is generally thought to be the minimum 

for recurrence-interval calculations. The recurrence interval at 

this streamflow-gaging station will be updated when additional 

data become available. 

At four other sites it was assumed that localized channel 

constrictions at the streamflow-gaging station (bridges 

and culverts) and (or) a significant flattening of the watersurface slope at the streamflow-gaging station distorted the 

true elevation of bankfull stage. In these cases, the bankfull 

discharge from HEC-RAS analysis, calculated at cross 

sections not affected by channel-constricting influences, 

was assumed to be the best estimate of bankfull discharge 

(table 1). At one site, bankfull stage and discharge were 

obtained through a regression technique called a LOWESS 

smooth (Locally Weighted Scatterplot Smoother) (Ott and 

Longnecker, 2001) because steep slopes upstream and 

downstream from the gage pool resulted in the best-fit 

bankfull elevation being considerably lower then true bankfull.

Regional channel-characteristics equations can be more 

accurate than those representing an entire state or larger area 

in the design of stream-restoration projects, enhancement of 

fish habitat, and adjustment of instream and riparian structures 

(Castro and Jackson, 2001). Users of these regional relations 

must recognize their limitations, however, and must accept 

that these regression equations (curves) are designed only 

to provide estimates of bankfull-channel characteristics and 

discharges; the equations are not intended to substitute for 

the field measurement and verification of bankfull-channel 

characteristics and streamflow (White, 2001).

Summary and Conclusions

Equations relating bankfull discharge and channel 

characteristics (width, depth, and cross-sectional area) to 

the size of the drainage area at gaged streams are needed to 

estimate bankfull discharge and channel characteristics at 

ungaged streams and to provide information used in the design 

of stream-restoration projects. The USGS, in cooperation with 

the New York City Department of Environmental Protection, 

New York State Department of Environmental Conservation, 

New York State Department of Transportation, and the New 

York State Department of State, undertook a study to develop 

these equations for streams in the Adirondack region of New 

York State (hydrologic Regions 1 and 2). Fifteen active 

and one inactive streamflow-gaging stations were chosen in 

accordance with established guidelines. Stream-survey data 

and discharge records from these sites were used in linearregression analyses to relate bankfull discharge and bankfullchannel width, depth, and cross-sectional area to drainage 

area. The resulting equations are the following: 

bankfull discharge (ft3/s) = 49.6 (drainage area (mi2))0.849, (9)

bankfull-channel width (ft) = 21.5 (drainage area (mi2))0.362, (10)

bankfull-channel depth (ft) = 1.06 (drainage area (mi2))0.329, (11)

bankfull-channel cross-sectional area (ft2) = 22.3 (drainage 

area (mi2))0.694. (12)

The high coefficients of determination (R2) for the four 

regression equations (0.95, 0.89, 0.89 and 0.97, respectively) 

indicate that much of the variation in these factors is explained 

by the size of the drainage area. 

Recurrence intervals of bankfull discharges were 

calculated for each stream by means of regression equations 

that relate measured discharges to known recurrence intervals. 

The recurrence intervals for bankfull discharge of the 16 

surveyed streams in hydrologic Regions 1 and 2 ranged from 

1.01 to 3.80 years, with a mean recurrence interval of 2.13 

years. Streams were classified by Rosgen stream type on the 

basis of specific channel characteristics at each surveyed cross 

section. Most streams were B- and C-type, with a few E- and 

F-type cross-sections. 

The hydrologic Regions 1 and 2 equation for the relation 

between bankfull discharge and size of drainage area was 

compared with equations developed for five other regions in 

New York State. The hydrologic Regions 1 and 2 equation 

was found to be similar to three of the five other regions. 

Large differences between the hydrologic Regions 1 and 2 

curve and curves for two other hydrologic regions indicate a 

need to develop equations by region for greatest accuracy.
References Cited 17

Acknowledgments

Thanks are extended to Daniel Davis, Sarah Miller, and 

Elizabeth Reichheld (NYCDEP) for geomorphology training 

and for advice on survey and data analysis and methods of 

interpretation. Thanks are also extended to the Adirondack 

Ecological Center (SUNY-ESF) for allowing access to their 

streamflow-gaging station and sharing peak-flow data; to 

Richard Lumia (USGS) for calculating recurrence intervals; 

and to Bethany Boisvert and Marshall Thomas, both of 

Cornell University, for assistance in the field. 

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For additional information write to: 

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U.S. Geological Survey

425 Jordan Road 

Troy, NY 12180

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or visit our Web site at:

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Mulvihill and others—Regionalized Equations for Streams in New York State—Hydrologic Regions 1 and 2—Scientific Investigations Report 2007–5189