Scientific Investigations Report 2010–5033
Flood-frequency discharges were determined for 290 streamgage stations having a minimum of 9 years of record in West Virginia and surrounding states through the 2006 or 2007 water year. No trend was determined in the annual peaks used to calculate the flood-frequency discharges.
Multiple and simple least-squares regression equations for the 100-year (1-percent annual-occurrence probability) flood discharge with independent variables that describe the basin characteristics were developed for 290 streamgage stations in West Virginia and adjacent states. The regression residuals for the models were evaluated and used to define three regions of the State, designated as Eastern Panhandle, Central Mountains, and Western Plateaus. Exploratory data analysis procedures identified 44 streamgage stations that were excluded from the development of regression equations representative of rural, unregulated streams in West Virginia. Regional equations for the 1.1-, 1.5-, 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year flood discharges were determined by generalized least-squares regression using data from the remaining 246 streamgage stations. Drainage area was the only significant independent variable determined for all equations in all regions.
Procedures developed to estimate flood-frequency discharges on ungaged streams were based on (1) regional equations and (2) drainage-area ratios between gaged and ungaged locations on the same stream. The procedures are applicable only to rural, unregulated streams within the boundaries of West Virginia that have drainage areas within the limits of the stations used to develop the regional equations (from 0.21 to 1,461 square miles in the Eastern Panhandle, from 0.10 to 1,619 square miles in the Central Mountains, and from 0.13 to 1,516 square miles in the Western Plateaus). The accuracy of the equations is quantified by measuring the average prediction error (from 21.7 to 56.3 percent) and equivalent years of record (from 2.0 to 70.9 years).
First posted March 17, 2010
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Wiley, J.B., and Atkins, J.T., Jr., 2010, Estimation of flood-frequency discharges for rural, unregulated streams in West Virginia: U.S. Geological Survey Scientific Investigations Report 2010–5033, 78 p.
Regional Historical Floods
Description of Study Area
Development of Flood-Frequency Discharge Equations
Correlation of Basin Characteristics
West Virginia Skew Coefficients
Regional Regression of Flood-Frequency Discharges
Accuracy of Flood-Frequency Discharge Equations
Procedures For Estimating Flood-Frequency Discharges
At a Streamgage Station
At an Ungaged Location
Upstream From a Streamgage Station
Downstream From a Streamgage Station
Between Streamgage Stations
Hydrologic Conditions Change Linearly between Streamgage Stations
Hydrologic Conditions Change Linearly to the Regional Hydrologic Conditions between Streamgage Stations
Not on the Same Stream as a Streamgage Station
Limitations of Procedures for Estimating Flood-Frequency Discharges
Appendix 1. Matrices Used to Compute Individual Standard Errors of Prediction