Evaluation of WEPP and its comparison with USLE and RUSLE

The USDA-Water Erosion Prediction Project (WEPP) demonstrates a new generat ion of water erosion prediction technology for use in soil and water conser vation planning and assessment. The WEPP computer model is based on various interacting natural processes in hydrology, plant sciences, soil physics, and erosion mechanics. The model offers several advantages over existing er osion prediction technology and has the capability of accommodating spatial and temporal variability in topography, soil properties, cropping and mana gement and sediment detachment and deposition. The model has a wider range of applicability as it accounts for most of the variables affecting runoff and erosion processes. However considerable validation is required to asses s the reliability of predictions obtained from the model. Sixteen-hundred p lot years of natural runoff plot data were used for verification and valida tion of WEPP including most of data used to develop Universal Soil Loss Equ ation (USLE). WEPP predictions of soil loss from natural runoff 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 the USLE and RUS LE did exhibit better model efficiency than WEPP this could be attributed t o availability of more refined and site specific input parameters for the e mpirical models.