Study Of Agricultural Non-point Source Pollution In Mountainous Regions On Taihu Basin

For the moment, most studies of non-point source pollution are concentrated on the river network in Taihu Lake basin. But there has been less concern regarding to the agricultural non-point source pollution in mountainous regions on the basin. In this paper, from the actual situation, in order to meet the National Natural Science Fund projects "Taihu Basin eutrophication control mechanism study", Large soil artificial groove laboratory tests and Yixin situ field tests are made to gain the rules of non-point source pollution in slope and the key factors affecting the rules, and a non-point source pollution load models on slope and a mountainous regions small watershed non-point source pollution model are established to account the agricultural non-point source pollution of mountainous regions in basin, which can be used to estimate the extent of pollution as a beneficial scientific basis.The main conclusions are as follows :(1)The major factors which impact non-point source pollution on slope are: runoff, slope, vegetation cover and soil surface concentration of pollutants. Vegetation cover and runoff are more sensitive, which have a greater impact to the non-point source pollution on slope.(2) Te quantitative correlativity among the runoff water contaminant transport flux and the concentration of pollutants on soil surface, runoff track circulation, Factor slope and vegetation cover are established. Coupled with soil Non-point source pollutants nitrogen and phosphorus models, non-point source pollution of nitrogen and phosphorus load model of slope were established, which can be well used to simulate non-point source pollutants loss and transformation on soil surface in once rainfall incident, and the simulation error is within 20%.(3) The hydrological model and sediment erosion model were established by indoor soil groove test after parameters validation, and have been validated in the field experiments at Yixing. The precision of hydrology and sediment erosion model is high, because it has a physical basis and can be more suitable for the small watershed lacking long-term observation data.(4) By the analysis of the output process of non-point source pollution on small slope, a small basin non-point source pollution model is established. The model is capable of simulating the outflow and non-point source pollutant concentration process of the Small Watershed, which provide a good working tool to forecast non-point source pollution output process and outflow in once rainfall incident.(5) The agricultural non-point source pollution should be controlled from the source, including measures as follows :Firstly, improve fertilizers and pesticides, promote the use of film with a new release fertilizers and pesticides; secondly, promote agricultural production in the best management model after learning advanced foreign management experience in agricultural production; make full use of advantages of the terrain and the field, with the local dominant plant and aquatic crops, establish a buffer zone to degrade agricultural non-point source pollution.