The Non-point Source Pollution Simulation in the Xiangxi River Watershed of Three Gorges Reservoir Area in China Based on SWAT Model

A good numerical non-point source pollution model is an efficient tool for non-point source pollution management, which can be used to analyze the temporal and spatial rules of pollutant discharge. In this paper, SWAT model is adopted to estimate the contribution of non-point source pollution in the Xiangxi River watershed of Three Gorges Reservoir Area in China in 2002-2007a. With the predicted values generally matched well with the observed values during calibration and validation (R2¿ 0.7 and Nash-Suttcliffe ¿ 0.5), This study shows that SWAT is able to predict streamflow and nutrients with satisfactory results. The results indicated that the NPS load of the Xiangxi river watershed basicly increased year by year. It increased from 8764 t in 2002a to 18838 t in 2007a and the NPS pollution were closely correlated with the temporal distribution of rainfall-runoff. Also the pollutant yields were mainly affected by the spatial distribution of slope, soil type, and land-use conditions. The subbasins with high proportion of cropland will geneate the more NPS polltion load. These understanding and analyses about characteristics of non-point source pollution are foundations of water quality management. To prevent water body from soil erosion and non-point source pollution, effective and powerful measures should be carried out in crucial period and area.