NRCS Curve Number Calibration Using USGS Regression Equations NRCS Curve Number Calibration Using USGS Regression Equations
Calibration is ideally accomplished by direct measurement using several rain and stream gauges within a watershed. Gauged data, however, is not always available or easily obtained. A more feasible method of calibration is therefore necessary for broad application of the CN method.
The purpose of this study is to develop a method of CN calibration that can be easily applied to regions where no gauged data is available using the United States Geological Survey (USGS) regression equations. In this study, the peak flow values estimated using the regression equations were used in conjunction with a dimensionless hydrograph to compute runoff volume. The National Oceanic and Atmospheric Administration (NOAA) rainfall grids were used to estimate precipitation. Given the rainfall and runoff, a Curve Number can then calibrated through back-calculation.
The method of CN calibration using the USGS regression equations was applied to nearly 60 watersheds in the state of Utah for this research. The calibration results obtained using the regression equations were compared to other CN calibrations developed using gauged data. Calibrations performed through the use of the regression equations were quite consistent with calibrations obtained using measured data. To ensure the validity of the application of this method in other regions, more comparisons to results obtained using measured data should be further pursued.
School:Brigham Young University
School Location:USA - Utah
Source Type:Master's Thesis
Keywords:cn curve number method calibration usgs regression equations
Date of Publication:02/29/2008