Variable Source Area Contribution to Stream Flow in Southern Coastal Plain Watersheds

摘要

Watershed scale model assessments of stream water quality need accurate estimates of water yield and accounting of the location of runoff generation. Several watershed scale studies performed with a model that calculates runoff by the NRCS curve number (CN) method have shown the tendency to underpredict water yield during wet seasons and overpredict water yield during dry periods. We theorize that alluvial storage in southern Coastal Plain watersheds is not being accurately accounted for in the model. This study develops a construct to improve predictions of storm runoff over those based on the current CN method by accounting for seasonal changes in alluvial storage for low-gradient, riparian-buffered stream systems. The construct uses groundwater elevation readings to calculate the alluvial storage. The form of the CN equation will be used, but the initial abstraction, l_a, and maximum retention, S, parameters will be re-defined. Calculations are planned for 37 single-peak events over a 13-year timeframe to verify the concept