THE WEPP WATERSHED MODEL: III. COMPARISONS TO MEASURED DATA FROM SMALL WATERSHEDS

Abstract

The Water Erosion Prediction Project (WEPP) watershed scale model was developed by the USDA forpurposes of erosion assessment and conservation planning. The purpose of this study was to evaluate the WEPPwatershed model applicability and prediction accuracy for small watersheds (0.34-5.14 ha) under different climate,topography, soil, and management regimes. No calibration was conducted to obtain the results. Only default modelparameters were used. Data from 15 watersheds in six U.S. locations were compared to runoff and sediment yieldestimates using WEPP95. The r2 values between measured and predicted total runoff and sediment yield for the15 watersheds were 0.86 and 0.91, respectively. The r2 between measured and predicted event data for individualwatersheds ranged from 0.01 to 0.85 for runoff and from 0.02 to 0.90 for sediment. Cumulative frequency distributions forpredicted values of event runoff and sediment matched those for measured values with some exceptions. Improvements inthe WEPP model are suggested where limitations were observed.