Prediction of Sediment Yield in Small Mountainous Watersheds Using by GeoWEPP and Design Rainfall

To predict the sediment yield in small mountainous watersheds Water Erosion Prediction Project (WEPP) based on physics and design rainfall were applied. The result using by GeoWEPP from January, 2004 to January, 2005 was compared with observed total sediment yield over the same period, and the sediment yield computed by GeoWEPP slightly overestimated. To compute design rainfall rainfall data from 1970 to 2004 was used and the rainfalls of reoccurrence periods (20, 50, 100 and 200 years) were analyzed with four probability distributions (Normal, Gamma, Gumbel and Lognormal). The optimum design rainfall(Lognormal) was applied to GeoWEPP and the sediment yields computed by GeoWEPP exhibited a good relationship with rainfall change. However, we suggest that the prudent caution needs to apply the models to real world and the many applications to various area needs to obtain more proper results.