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Scientific Investigations Report 2007–5227

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

Regionalized Equations for Bankfull-Discharge and Channel Characteristics of Streams in New York State—Hydrologic Region 3 East of the Hudson River

By Christiane I. Mulvihill and Barry P. Baldigo

U.S. Geological Survey Scientific Investigations Report 2007–5227


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Equations that relate drainage area to bankfull discharge and channel characteristics (such as width, depth, and cross-sectional area) at gaged sites are needed to define bankfull discharge and channel characteristics at ungaged sites and can be used for stream-restoration and protection projects, stream-channel classification, and channel assessments. These equations are intended to serve as a guide for streams in areas of similar hydrologic, climatic, and physiographic conditions. New York State contains eight hydrologic regions that were previously delineated on the basis of high-flow (flood) characteristics. This report presents predictive equations for bankfull characteristics (discharge and channel characteristics) for streams east of the Hudson River, referred to as Hydrologic Region 3.


Stream-survey data and discharge records from 12 streamflow-gaging stations were used in regression analyses to relate drainage area to bankfull discharge and bankfull channel width, depth, and cross-sectional area. The four predictive equations are:


bankfull discharge (cubic feet per second) =
83.8 (drainage area (square miles))0.679,



bankfull-channel width (feet) =
24.0 (drainage area (square miles))0.292,



bankfull-channel depth (feet) =
1.66 (drainage area (square miles))0.210,


bankfull-channel cross-sectional area (square feet) =
39.8 (drainage area (square miles))0.503.


The coefficients of determination (R2) for these four equations are 0.93, 0.85, 0.77, and 0.92, respectively. The high coefficients of determination for bankfull discharge and cross-sectional area indicate that much of the range in the variables is explained by the size of the drainage area; the smaller correlation coefficients for bankfull channel width and depth indicate that other factors also affect these relations. Recurrence intervals for the estimated bankfull discharge of each stream ranged from 1.16 to 3.35 years; the mean recurrence interval was 2.08 years. The 12 surveyed streams were classified by Rosgen stream type; most were B and C type, with occasional E- and F-type cross sections. The Region 3 equation (curve) for bankfull discharge was compared with those previously obtained for seven other hydrologic regions in New York State. The differences confirm that the hydraulic geometry of streams is affected by local climatic and physiographic conditions.





Purpose and Scope


Site Selection

Data Collection

Data Analysis

Regional Equations for Bankfull Discharge and Channel Characteristics of Streams

Regionalized Relation between Bankfull Discharge and Drainage Area

Bankfull-Discharge Recurrence Intervals

Stream-Channel Characteristics in Relation to Drainage Area

Stream Classification

Comparison of Region 3 Equations to Equations for Other Regions in New York State

Limitations of this Study

Summary and Conclusions


References Cited


1. Map showing hydrologic regions of New York State: (A) hydrologic-region boundaries as defined by Lumia (1991) and (B) locations of the 12 streamflow- gaging stations used in 2005–06 stream survey in Region 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 Region 3, in New York State.

3. Bankfull width, depth, and cross-sectional area as a function of drainage area with best-fit lines, regression equations, and R 2 values for all streams surveyed in Region 3 in New York State.

4. Selected channel characteristics as a function of drainage area with 95-percent prediction limits and 95-percent confidence intervals for streams in Region 3 in New York State: (A) bankfull channel width, (B) bankfull channel depth, and (C) bankfull channel cross-sectional area.

5. Bankfull discharge as a function of drainage area for Region 3 and published curves for six other regions in New York State


  1. Characteristics of streamflow-gaging stations surveyed in Region 3 of New York, 2005–06.
  2. Stream classification and bankfull-channel characteristics for cross sections at the 12 streamflow-gaging stations surveyed in Region 3 in New York State.

Suggested Citation

Mulvihill, C.I., and Baldigo, B. P., 2007, Regionalized equations for bankfull-discharge and channel characteristics of streams in New York State—Hydrologic region 3 east of the Hudson River: U.S. Geological Survey Scientific Investigations Report 2007–5227, 15 p., online only.

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