Prediction of sediment yield on a large watershed in North Central China

Sediment responses for a large agricultural watershed in Shanxi Province, China, were estimated by applying a modified version of the RUNOFF simulation model. The watershed selected for the study consists of steep slopes on highly erodible loessal soils, and experiences severe erosion from interrill, rill, gravitational, and gully sources. The model was used to predict sediment yields from single event summer rainstorms, relfecting a range in hydrologic and vegetative cover conditions. Test results show that the RUNOFF model predicted sediment responses on the watershed with reasonable accuracy. RUNOFF estimated sediment yields to within +/-30% of the measured values for 20 of the 24 selected events used in the study. Simulation results indicate that sediment yeild estimated by the model is primarily governed by the sediment transport capacity of runoff from storm events. Results of the study suggest that RUNOFF may be applicable as a tool to estimate sediment yields for agricultural watersheds in the loessal region of North Central China