Evaluation of Three Soil Erosion Models for Small Watersheds

The present study aims at evaluating three soil erosion models; Modified Universal Soil Loss Equation (MUSLE); Unit Sediment graph (USG) and Water Erosion Prediction Project (WEPP). The models were tested on small watersheds within the Pamba River basin of Kerala, India, using the data on observed rainfall-runoff-sediment yield events. Three watersheds are selected with varying land use types, topography and drainage density. Three erosion models were applied for the same rainfall events and the results were compared with the observed sediment yield values. It was seen that the USG predicted the rate of sediment yield better than the other two models. Even though WEPP is a physically distributed model, the large and detailed data requirement, which is impractical in studies of this scale, affected its prediction accuracy. Application MUSLE gives the large errors compared to the observed sediment yield. Therefore, it was found from this study that the Unit Sediment Graph (USG) based approach is having better applicability for the prevailing climatic and geographical setup.