Non-point source modeling system of the Miyun Reservoir watershed

A soil water and assessment tools(SWAT) based non-point source(NPS) modeling system of the Miyun Reservoir watershed was established based on investigation of point and NPS pollution and digital elevation model,land-use,soil,weather, hydrological and water quality data,and agricultural management practices.Measured time-series stream flow and water quality data were used to calibrate and verify the modeling system.The hydrological and sediment simulations agree well with observations in both the Chao River and Bai River sub-watersheds,with coefficients of determination and Nash-Suttcliffe coefficients larger than 0.77.The simulation results for the total nitrogen and total phosphorus in the Chao River sub-watershed are better than those in the Bai River sub-watershed.The results show that the NPS modeling system can also be applied to simulate and predict NPS loadings in the Miyun Reservoir.