Soil erosion prediction and sediment yield estimation: the Taiwan experience

Estimating watershed erosion using geographic information systems coupled with the universal soil loss equation (USLE) or agricultural non-point source pollution model (AGNPS) has become a recent trend. However, errors in over-estimation often occur due to the misapplication of parameters in the equation and/or model. Because of poor slope length calculation definitions for entire watersheds, the slope length factor is the parameter most commonly misused in watershed soil loss estimation. This paper develops a WinGrid system that can be used to calculate the slope length factor from each cell for reasonable watershed soil loss and sediment yield estimation.