Estimation of sediment yield and runoff from small watersheds using WEPP model - A research report by National Institute of Hydrology

The study uses Water Erosion Prediction Project (WEPP) model of the United States Department of Agriculture (USDA) to simulate the flow and erosion processes in Sallopat watershed of Mahi river basin in Banswara, Rajasthan. The WEPP model is a distributed, continuous, small agricultural watershed erosion model. It can simulate the effects of management practices and land use changes on the spatial and temporal variability of the erosion processes within a watershed system. The major features of this model are the ability to –

• Delineate areas of detachment and deposition on a hill slope or along a channel reach
• Account for the effects of management and land use changes on the erosion process
• Account for the effects of backwater on detachment, transport and deposition processes within channels

An attempt has been made to utilize the hill slope and watershed versions of the WEPP model. Since there were no runoff or sediment yield observations available for the watershed, the results could not be compared with measured values. However, Durbude (1997) calculated the average runoff from the watershed using the SCS method. The result from the study shows that the average runoff from the watershed is 362 mm. This compares well with the average value obtained from the model application.

The study establishes that WEPP is capable of simulating erosion and deposition processes in hill slope or along a channel course. It gives precise locations of erosion and deposition so that proper management strategies can be taken up to tackle the problems.

Using the various components of the WEPP, a great amount of detail can be obtained about the watershed behavior for a set of climatological, soil, slope and management factors. Since it gives an idea of the overland flow over hill slopes and progress of these outflows from the hill slopes through the channels, it can also be used as a rainfall-runoff model for small watersheds.

Download the report here: