| Taihu Lake is the third largest freshwater lake in China, its main environmental problem at present is eutrophication of water body. Nitrogen and phosphorus are the restricting factors. Point source pollution generated by industry is fewer and fewer in recent years, but the eutrophic degree of Taihu water body has not been improved, the deterioration of its water quality is still serious. So it means that nonpoint source pollution has been primary to water environment. And among all sorts of nonpoint source pollutions, agricultural nonpoint source pollution is the biggest one.Based on reading lots of relevant references, this paper summarizes present research of agricultural nonpoint source pollution, and then select a typical small agricultural watershed around Taihu area, in which the experiment in situ was conducted between May and September, 2007. Runoff, sediment and water quality at the outlet and the runoff plots under different land use type in the basin were all monitored. Whereafter, this paper generally posts the characteristics of rainfall, runoff and sediment yield, and builds the models of runoff and sediment on slope. Then, the transfer laws of nitrogen and phosphorus from soil in the storm runoff are analyzed, and the nonpoint source transfer models of nitrogen and phosphorus on slope are set up. Furthermore, SCS Curve Number Method, Modified Universal Soil Loss Equation and transfer models of nitrogen and phosphorus in SWAT model are all validated, each of them is fit for this basin. So it's expected that the research findings based on the spot can be used to other area of Taihu watershed, and provide scientific basis for controlling agricultural nonpoint source pollution and simply solving the problem of eutrophication in Taihu Lake, eventually play an impelling action in comprehensive treatment to water pollution in Taihu watershed.In addition, this paper makes use of SWAT model to compute surface source pollution load. The precision of SWAT model is fairly good.
|
PDF Full Text Request