The Research Of Surface Runoff And Non-point Source Pollution Of Zhouhe River With SWMM Model

China is one of the countries with scarce water resources in the world,and its per capita water resources are only a quarter of the world average.After the founding of New China,the country vigorously developed industry but lacked protection for the ecological environment,resulting in serious pollution of most of the water bodies in China.After the reform and opening up,the country began to pay attention to environmental pollution.Since the 18 th National Congress,China has established five The integrated development pattern takes ecological civilization construction as a basic national policy of China and strives to restore ecological balance.The state has issued a series of documents for the construction of ecological civilization,and governments at all levels have also actively advanced the construction of ecological civilization in response to the national call.In the construction of ecological civilization,the control and prevention of water pollution is an important part.At present,many experts and scholars in China have conducted research on non-point source pollution in watersheds and have achieved certain results.At the same time,the application of the model has played an important role in the study of the water environment.Many experts and scholars in China have tried to use the model to simulate the water environment so that the pollution of the water environment can be more intuitively presented to us.In this paper,the SWMM model was used to simulate the Zhouhe River basin in Zhidan County,Yanan City,and the changes of hydraulic and water quality in the basin were observed.The primary rules I were found are as follows:1.Combine the relevant data of Zhidan County,the location of the Beiluo River Basin,according to the relevant parameters of the local torrential rain intensity formula,and combine the Chicago Rain Pattern Generator developed by the Water Supply and Drainage Research Laboratory of Beijing Polytechnic University to simulate and generate 0.5 of the Zhouhe River Basin.a,1a,2a,3a,5a,10 a,20a,50 a,a total of eight rainfall intensity during the return period,statistics of the relationship between rainfall intensity and time according to simulation results,and plotting curves;comprehensive research results of other scholars have been determined Permeability coefficient,impervious rate and other parameters of the underlying surface in the Zhouhe River Basin;other characteristics of the Zhouhe River were determined based on Zhouhe River's geographical location and weather data.2.Based on the establishment of national-level ecological county chemical fertilizer application intensity indicators,the non-point source pollution of each underlying surface in the Zhouhe River Basin was simulated.By analyzing and simulating the results,we found the pollutants in the surface runoff of each underlying surface.The concentration decreases with the increase of rainfall intensity,but the concentration of pollutants in rivers increases with the increase of rainfall intensity.In view of this phenomenon,we can conclude that the greater the rainfall intensity,the greater the amount of pollutants carried away by the formation of surface runoff erosion;but the increase in precipitation is greater than the increase in the amount of pollutants,so there will be pollution in the surface runoff The decrease in theconcentration of matter;for rivers,the amount of water is much greater than the amount of water produced by rainfall,so the total amount of pollutants has a greater impact on the overall river water quality.3.According to the data in the “National Handbook of Pollutant Loss Factors for Agricultural Pollution Sources for the First National Survey of Pollution Sources,” the intensity of chemical fertilizer application in Zhouhe River Basin was 502 kg/ha for nitrogen fertilizer and 58.35 kg/ha for phosphate fertilizer.This data was input into the model for simulation,and compared with national indicators,it was found that the total amount of nitrogen has increased significantly.In the Zhou River basin,only 13% of cultivated land will be cultivated.If this happens in areas with more arable land,nitrogen pollution will become more serious.4.Based on the simulation results,we analyzed the pollutants in the estuaries of the Zhou River and found that the concentrations of ammonia nitrogen and TP basically meet the water level III indicators of surface water,and the ammonia concentration exceeds the standard only in the event of a torrential rainfall intensity in 50 years.Therefore,the national proposal can be considered as The fertilizer application intensity is suitable for the Zhou River Basin.However,in the plains and more cultivated areas,its reasonable chemical fertilizer use intensity is 210kg/ha~220kg/ha.5.By analyzing the simulation results,we found that the contribution of nitrogen to the countryside is the highest,and the contribution of farmland to phosphorus is the highest.Therefore,agricultural non-point source pollution can be considered as the main component of non-point source pollution.According to this conclusion,we can control non-point source pollution by controlling the amount of chemical fertilizers,promoting scientific breeding,and increasing the proportion of organic fertilizers.