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Water environment has become one of our major environmental problems to be solved, and non-point source pollution is one of the main important watershed and water quality deterioration. Tiaoxi as one of the main river into the lake of Taihu Lake Basin, the water quality is good or bad is directly related to the water quality of Taihu Lake. With the strengthening of the point source pollution control, the proportion of non-point source pollution in Tiaoxi Valley is gradually increasing. However, little is known about migration and transformation law Tiaoxi watershed non-point source pollution, and therefore, it is difficult to come up with effective measures to fundamentally solve basin water pollution problems. In view of this, this study uses mathematical statistical analysis method, geographic information technology (Geographical Information System, GIS) and model simulation and other methods source apportionment and control research Dongtiao Creek upstream typical small watershed agricultural non-point source pollution, in-depth understanding of an agricultural watershed sources of non-point source pollutants, contribution, migration and transformation law, identified from the macro-scale soil erosion in the basin-wide, the loss of non-point source load and its critical source areas, and agricultural non-point source watershed management control measures (Best Management Practices, BMPs) study, provide the basis for the formulation of non-point source pollution control strategy for the entire watershed. The main contents and results are as follows: (1) to establish suitable for typical small watershed of East Tiaoxi River Basin agricultural non-point source pollution model - soil water body evaluation model (SWAT runoff, sediment, the rate of the nutrient load carried and verification ). The rate of runoff and water quality monitoring data for 1999-2008 in accordance with the the Pingyao Bridge station. The model calibration runoff, sediment, ammonia nitrogen and total phosphorus correlation coefficient R2 were 0.90,0.96,0.89,0.72 validation period runoff, sediment, ammonia nitrogen and total phosphorus correlation coefficient R2 were 0.83,0.80,0.81,0.74 showed good agreement. (2) based GIS information platform, soil erosion assessment model (USLE) East Tiaoxi typical small watershed soil erosion intensity estimate evaluation, identify soil erosion critical source areas. The results show that the East Tiaoxi typical small watershed soil erosion ways hydraulic erosion, 2347 t/km2 average soil erosion modulus; soil erosion intensity with mild erosion, showing high northern and southern ends of the central region of low trend; different land types of soil erosion intensity difference was significant, the average annual erosion modulus of urban land use gt; rural living land gt; farmland gt; woodland gt; garden; moderate intensity erosion zone occurs mainly in actic and slope 7 ° -12 ° The farmland, pole strength and severe erosion District mainly in arable land, urban land and rural land slope is greater than 12 °. (3) the establishment of a survey of pollution sources, the assessment of soil erosion, non-point source pollution simulation based on the loss of non-point source pollution risk evaluation index system and evaluation methods to determine the risk of the loss of non-point source watershed area. The results show that, the Upper East Tiaoxi typical basin is extremely sensitive areas, highly sensitive area, moderately sensitive, mildly sensitive areas and slight sensitive zone area, respectively, accounting for 24.3% of the total watershed area, 38.4%, 11.4%, 16.8 % and 9.1%, respectively; soil erosion is caused by the loss of nitrogen and phosphorus in the soil, the extent of rainfall intensity, topography, land use patterns and vegetation cover factors; nitrogen, phosphorus forms are important factors that affect its loss. The typical locale (4) on the basis of the risk assessment of non-point source, it is able to represent the overall outlook of watershed BMP implementation of regional application SWAT model from nutrient management (fertilizer 10% reduction, 20% reduction in fertilizer) tillage management (high line strip planting along the contour trenching), landscape management (5% of returning farmland to forests, 10% of returning farmland to forest) three the BMP control area set 2000 to 2008, non-point source load scenario simulation Basin control effect and river water quality response. The results show that, perform contour strip cropping measures to cut pollutants overall significant effect, and water quality improvement, including sediment, organic nitrogen, organic phosphorus reductions were 52.48%, 31.2% and 31.09%, river sediment , ammonia nitrogen, total phosphorus concentration decreased by 9.3%, 27.2% and 25.3%, respectively; returning farmland certain measures of sediment and pollution load reduction and water quality improvement, and fertilizer non-point cut is not a typical watershed of the Upper East Tiaoxi source reduction measures.
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