Effect of human activities on sediment reduction in Miyun Reservoir watershed

Based on rainfall and hydrological data of the Miyun reservoir, effect of human activities on sediment reduction in Miyun Reservoir has been evaluated by using runoff coefficient method, double accumulative curve method and separation evaluation method.The results showed that: the relativity between the cumulative sediment discharge and the cumulative rainfall erosion force is the largest; compared with the baseline period 1956-1973, during 1974 to 1997, human activities reduce sediment discharge 44.328 million tons, 1.847 million tons per year, sediment reduction effect was 51.6%, and during 1998 to 2007, it reached 82.5%. In these two phases, human activities´ contribution rates of changes in sediment discharge were 78.5% and 71.9%.