基于SWAT模型的古蔺河流域面源污染模拟研究

Research on Non-point Source Pollution Simulation in Gulin River Based on SWAT Model

近年来古蔺河水质日益变差,为了解古蔺河流域面源污染的时空分布特征与关键污染源区(CSAs),首先运用分形理论确定流域最佳集水面积阈值,然后基于SWAT模型进行子流域划分,在此基础上研究古蔺河流域农村面源污染的迁移转化及污染负荷,结果表明:流域最佳集水面积阈值为1 500 hm^2,此时子流域划分为37个;模型月平均径流与氮、磷负荷模拟评价指标Nash系数大于0.5,决定系数R2大于0.6,SWAT模型在研究区有较好的可适用性;古蔺河流域2013年TN输出量为2 761.72 t,TP输出量为338.27 t,古蔺镇、德跃镇、石屏乡污染负荷占比较大,各子流域污染源贡献率排序均为化肥>畜禽养殖>居民生活,因此农业化肥和古蔺镇、德跃镇、石屏乡是流域面源污染防治的重点。

In recent years,Gulin River water quality is becoming worse. In order to know the spatial and temporal distribution characteristics of non-point source pollution and critical source areas（ CSAs） in Gulin River Basin. Firstly,the fractal theory is used to determine the most suitable threshold of drainage area（ TDA）. On this basis,this paper studies the migration and pollution load of non-point source pollution in the rural area of the Gulin River Basin based on SWAT model,the results show that： the most suitable threshold of drainage area is 1 500 hm^2 and the basin is divided into 37 sub-watersheds; the monthly average runoff and nitrogen and phosphorus load of the model simulation evaluation index Nash coefficient is more than 0. 5,and the decision coefficient R2 was more than 0. 6,so the SWAT model has good applicability in the research area. In 2013,the output of TN in Gulin River Basin is 2 761. 72 t,and the output of TP is 338. 27 t. The pollution load of Gulin Town,Deyue Town,Xiang Shiping accounted for a larger proportion and the ranking of the contribution rate of the pollution sources in each sub-basin are all chemical fertilizer livestock breeding domestic pollution.Therefore,the agricultural chemical fertilizer,Gulin Town,Deyue Town,Xiang Shiping are the key point for the prevention and control of the non-point source pollution in the basin.