Research On Agriculture Non-point Source Of Nitrogen And Phosphorus Load About Shuangxi Reservoir Watershed

Water pollution problem has become one problem of the world’s attention, and agricultural non-point source pollution is the major factor of water pollution.In this paper,we use the AnnAGNPS model to quantify the agricultural non-point source pollution in Shuangxi reservoir watershed. The main contents and conclusions of the study are the following:(1) According to the data of soil type, land use type, fertilizer and pesticide application, weather, crop management data, I set up the basin database.This paper uses the total nitrogen, total phosphorus pollution load in2011to verify the applicability of AnnAGNPS model in the basin. Total nitrogen load for simulation capability is strong, but the ability to simulate the total phosphorus load is general. Overall, the AnnAGNPS model of nitrogen and phosphorus pollution load applied in the reservoir basin is feasible.(2) This paper uses AnnAGNPS model to simulate Shuangxi reservoir watershed, total nitrogen、particulate nitrogen dissolved nitrogen pollution load was224.7t、92.2t、132.5t in2013, total phosphorus、particulate phosphorus、dissolved phosphorus pollution load was45.2t、36.3t、8.9t in2013.(3) The monthly total nitrogen、monthly total phosphorus、monthly rainfall of Shuangxi reservoir watershed has a small peak in July2013. Runoff、 total phosphorus and total nitrogen pollution load curve trend is consistent with the rainfall. Within the basin, rainfall mainly is concentrated in6-8months, runoff、total nitrogen and total phosphorus load is relatively large in these months, the results showe the time characteristics are July output> June> August.(4) Simulation results show that nitrogen and phosphorus pollution load present some similarities on the spatial distribution, nitrogen and phosphorus pollution load concentrate on both sides of the river and sloping land.Non-point source pollution load is very uneven in the spatial distribution, different land use has larger differences in pollution load, nitrogen and phosphorus pollution load per unit area of paddy field and dry land is the largest, total nitrogen pollution load per unit area is21-30kg/ha, total phosphorus pollution load per unit area is4.9-10.8kg/ha, rural residence pollution load per unit area is the second, grassland and woodland pollution load per unit area is minimal.(5) This paper proposes three kinds of management measures:reduction of fertilizer, tillage, returning farmland to forest. Through comparative analysis, the measure of reduction of fertilizer has a significant reduction effect for the total nitrogen and total phosphorus, the reduction rate reaches more than20%; the measure of tillage has a general reduction effect for the total nitrogen and total phosphorus, the reduction rate reaches about4%; the measure of returning farmland to forest has a better reduction effect, the reduction rate reaches about8%. Combined with the actual situation of Shuangxi reservoir watershed, in order to better reduction of non-point source pollution load basin, we can take methods of reduction of fertilizer、tillage and other methods to reduce non-point source pollution from agriculture caused.