Simulation and scenario analysis of soil erosion in the Miyun Reservoir watershed

The Soil and Water Assessment Tool (SWAT) was applied to the Miyun Reservoir watershed to simulate soil erosion. Two tributaries within this watershed, the Chao and Bai rivers, were simulated separately and hydrological and soil erosion processes were calibrated and validated using observed data from downstream gauging stations. Data analyses and simulation results indicate that soil erosion in both sub-watersheds predominantly occurs during flood seasons, and soil erosion is closely correlated with the spatial distribution of rainfall. Although the Bai sub-watershed has a larger drainage area than the Chao sub-watershed, the former contributes less sediment to the Miyun Reservoir than the latter because two upstream reservoirs (Yunzhou and Baihepu) intercept upstream sediment. Several rainfall scenarios were set up to simulate the influence of changing rainfall patterns; as a result, key areas of soil erosion were identified.