EVALUATION OF WEPP AND ITS COMPARISON WITH USLE AND RUSLE

Abstract

The USDA-Water Erosion Prediction Project (WEPP) demonstrates a new generation of water erosionprediction technology for use in soil and water conservation planning and assessment. The WEPP computer model isbased on various interacting natural processes in hydrology, plant sciences, soil physics, and erosion mechanics. Themodel offers several advantages over existing erosion prediction technology and has the capability of accommodatingspatial and temporal variability in topography, soil properties, cropping and management, and sediment detachment anddeposition. The model has a wider range of applicability as it accounts for most of the variables affecting runoff anderosion processes. However, considerable validation is required to assess the reliability of predictions obtained from themodel. Sixteen-hundred plot years of natural runoff plot data were used for verification and validation of WEPP,including most of data used to develop Universal Soil Loss Equation (USLE). WEPP predictions of soil loss from naturalrunoff plots at 20 different locations were compared to measured data and existing technology (i.e., USLE and RUSLE).WEPP recorded a model efficiency of 0.71 compared to 0.80 and 0.72 for the USLE and RUSLE respectively. While theUSLE and RUSLE did exhibit better model efficiency than WEPP this could be attributed to availability of more refinedand site specific input parameters for the empirical models.