Publications—Scientific Investigations Report 2007-5189
By Christiane I. Mulvihill, Amy Filopowicz, Arthur Coleman, and Barry P. Baldigo
U.S. Geological Survey Scientific Investigations Report 2007-5189
This Report is available Online Only
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) =
|bankfull-channel width (feet) =
21.5 (drainage area (square miles))0.362,
|bankfull-channel depth (feet) =
1.06 (drainage area (square miles))0.329,
|bankfull-channel cross-sectional area (square feet) =
22.3 (drainage area (square miles))0.694.
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 equationsindicate 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.
Purpose and Scope
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
Comparison of Hydrologic Regions 1 and 2 Bankfull-Discharge Equation to Equations for Other Regions in New York State
Limitations of this Study
Summary and Conclusions
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.
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.
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.
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.
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.
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U.S. Geological Survey
New York Water Science Center
425 Jordan Road
Troy, NY 12180
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