Effects of curve number modification on runoff estimation using WSR-88D rainfall data in Texas watersheds
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abstract
The purpose of this study was to evaluate variations of the Natural Resources Conservation Service (NRCS) curve number method for estimating near real-time runoff for naturalized flow, using high resolution radar rainfall data in Texas watersheds. This study was undertaken in an attempt to provide more accurate runoff estimates to watershed and water resource managers for planning purposes. Stage III Weather Surveillance Radar 1988 Doppler (WSR-88D) precipitation data, obtained from the West Gulf River Forecast Center, was used as the precipitation input for runoff estimates in this study. The study areas consisted of dominant or homogenous land use and were characterized by naturalized flow. Findings indicate that the use of a dry antecedent soil moisture condition curve number value and a reduced initial abstraction coefficient (I0) in the NRCS curve number equation produced the most statistically significant comparison between observed and estimated runoff in nine out of ten watersheds. The combined comparison for all events in these nine watersheds produced a coefficient of efficiency (COE) of 0.70, with a slope of 0.78 and an r2 of 0.77. Overall, the results of this research suggest that, although further improvements can be made for improved runoff estimation, the use of modified inputs to the NRCS curve number equation in conjunction with WSR-88D radar rainfall data could be useful in producing runoff estimates for Texas in real-time.
