Study On Agricultural Non-point Source Pollution Of Shitoukoumen Reservoir Catchment

China's water environmental problems become increasingly serious,of which agricultural non-point source pollution has become the main source of pollution,and other sources of pollution compared to agricultural non-point source water pollution control,monitoring difficulties,widely distributed,is the current sewage treatment in a major problem.The stone mouth gate reservoir is an important drinking water source in Changchun City.Due to the influence of natural factors and human activities,the water quality in the catchment area is deteriorating,especially the agricultural non-point source pollution is serious,which seriously threatens the safety of drinking water in Changchun city residents,This paper is of great significance to study the agricultural non-point source water pollution in Shitoukoumen reservoir.In this paper,the AnnAGNPS model is used to simulate the agricultural non-point source pollution in the stone mouth gate reservoir by means of field investigation,test analysis and model simulation.The conclusions are as follows:1.The single factor index method was used to evaluate the surface water quality of the catchment basin in 2015.The pollution level and environmental quality of the surface water environment in the study area were determined,and the main pollutants in the surface water environment were analyzed.The results show that the total nitrogen and total phosphorus in the water source of Shitoukoumen Reservoir are serious.The total nitrogen concentration is 1.08-4.72 times of the standard of water environmental functional division(class III,1.0mg / L),and the total phosphorus concentration is 0.6-1.4 times of that of water environmental functional zoning standard(class III,0.05 mg/L).The evaluation results of the monitoring sections of the reservoirs show that the cross section of the Yinma River and the Chaluhe River can meet the water function standard,but the total nitrogen is excessive,which is the water environmental functional zoning standard(class III,1.0 mg/L)of 3.14 times,2.78 times,while the Shuangyang River brick bridge section of 2015 exceeded the standard pollutants for the permanganate index,biochemical oxygen demand,chemical oxygen demand,total nitrogen and total phosphorus,including total nitrogen,total phosphorus The total nitrogen concentration was 5.76 times of that of the water environmental functional zoning standard(class III,1.0 mg/ L),and the total nitrogen concentration was 5.76 times that of the water environmental functional zoning standard(class III,1.0 mg/L)The concentration is 1.85 times of the standard of water environmental functional zoning(class III,0.2 mg/L),which indicates that the watershed is polluted by many sources of urban living and agricultural non-point source pollution,among which agricultural non-point source pollution is heavy.2.Select the 2007-2012 measured monthly average flow,sediment and water quality data on the model parameters,from 2011 to 2012 the measured data to verify the model.The results show that the simulation results are of high accuracy and are suitable for the evaluation of nonpoint source pollution load in the catchment basin of Shitoukoumen reservoir.3.Based on the AnnAGNPS model,the output of total nitrogen,total phosphorus and sediment in the catchment of Shitoukoumen Reservoir in 2015 was quantitatively calculated.The results show that the surface runoff is 54.63 mm,the sediment output is 12.03 million tons,the total nitrogen is 21775 tons,the total phosphorus is 1878 tons.4.The distribution characteristics of nitrogen and phosphorus load in the non-point source of agricultural non-point source were analyzed.The results showed that the change trend of total nitrogen and total phosphorus was basically the same,which had a great correlation with the rainfall in the study area.The total phosphorus emissions were mainly concentrated in the abundant rainfall period(June to September),accounting for 55% and 53% of the annual emissions respectively.In the dry season with low rainfall(November,December,January and February)total nitrogen and total phosphorus emissions accounted for 21% of annual emissions,22%.5.Rainfall and fertilization period is the dominant factor of seasonal variation of agricultural non-point source pollutant output load in the study area.The output of total nitrogen and total phosphorus is mainly distributed in the distribution of rainfall in July and August,and the loss of nitrogen and phosphorus caused by rainfall during fertilization.6.Based on the above analysis of the water quality of the catchment basin and the study of agricultural non-point source pollution,the pollution control source and the control and management measures of the pollutant migration and transformation route of agricultural nonpoint source pollution are combined with the actual situation of the river basin.