Assessment of soil erosion at large watershed scale using RUSLE and GIS:: A case study in the Loess Plateau of China

Soil erosion is a serious problem in the Loess Plateau of China, and assessment of soil erosion at large watershed scale is urgently need. This study used RUSLE and GIS to assess soil loss in the Yanhe watershed. All factors used in the RUSLE were calculated for the watershed using local data. RUSLE-factor maps were made. The mean values of the R-factor, K-factor, LS-factor, C-factor and P-factor were 970 209 MJ km(-2) h(-1) a(-1), 0.0195 Mg h MJ(-1) mm(-1), 10.27, 0.33359 and 0.2135 respectively. The mean value of the annual average soil loss was found to be 14 458 Mg km(-2) per year, and the soil loss rate in most areas was between 5000 and 20 000 Mg km(-2) per year. There is more erosion in the centre and southeast than in the northwest of Yanhe watershed. Because of the limitations of the RUSLE and spatial heterogeneity, more work should be done on the RUSLE-factor accuracy, scale effects, etc. Furthermore, it is necessary to apply some physical models in the future, to identify the transport and deposition processes of sediment at a large scale. Copyright (c) 2005 John Wiley & Sons, Ltd.