The Flux Simulation Of Nitrogen And Phosphorus In Non-point Source Pollution In Tangxun Lake Watershed

Tangxun Lake,as the national key lake and the largest downtown lake,the importance of its water quality is self-evident.With the comprehensive interception of the point source pollution around Tangxun Lake,the impact of non-point source pollution on the water quality of the lake is gradually deepened.In the past,the study of non-point source pollution in the Tangxun Lake watershed is divided into qualitative analysis and conventional water quality monitoring.The study of these two methods can not judge the distribution of non-point source pollution in advance,and then take measures to reduce the impact of non-point source pollution on the lake water quality.By analyzing the non-point source pollution calculation method,it can be seen that the model simulation is more advantageous than the traditional output coefficient method.In addition,the use of SWAT model in complex watershed especially in downtown lake watershed is lacking of appropriate research.Therefore,this study chooses the SWAT model to simulate the non-point source pollution in the Tangxun Lake watershed,and discusses the temporal and spatial distribution of non-point source pollution.After the model simulation,four points of research and analysis conclusions are obtained:(1)The application of the SWAT model in the Tangxun Lake watershed has achieved the expected results.It also shows that the model has high simulation precision for the non-point source pollution in the study area.This is a useful attempt to apply this model to the precise simulation of non-point source pollution in the complex downtown lake watershed.(2)Watershed atmospheric rainfall can directly lead to non-point source pollution.The simulation results of SWAT model show that the flux of non-point source nitrogen is 38.4t/a in Tangxun Lake watershed in 2015,and the flux of non-point source phosphorus in the watershed is 6.1t/a.The maximum monthly flux of nitrogen and phosphorus is in the middle of May,the flux of non-point source nitrogen was 4.49t/mon,flux of phosphorus is 0.98t/mon.(3)Land use types have a direct effect on the loss of nitrogen and phosphorus.The nitrogen and phosphorus loss intensity of the non-point source pollution in agricultural land is significantly higher than that of other land use types in Tangxun Lake watershed in 2015.