Risk Assessment Of Agricultural Non-Point Source Pollution In Wuhan Based On ArcGIS

As the point source pollution has been more effectively controlled,agricultural non-point source pollution becomes the main source of environmental pollution.Therefore,estimating the agricultural non-point source pollution and analyzing the distribution of risk are very important for prevention and control of the agricultural non-point source pollution.The main research contents and conclusions are as follows:(1)Total nitrogen and total phosphorus equal standard pollution which caused by the agricultural non-point source pollution were the use of fertilizers(56.02%),livestock farming pollution(25.86%),rural domestic sewage and waste(14.03%),aquaculture(4.08%).(2)Based on multi-factor comprehensive evaluation method,combined with the grey clustering method and ArcGIS,five factors including rainfall erosion,soil erodibility,slope and length,river network distribution,land use were selected to evaluate the risk of agricultural non-point source pollution in Wuhan.The results showed that extremely high risk and high risk areas caused by agricultural non-point source pollution were less than 0.1%,distributed in Caidian district,Hongshan district,Huangpi district,Qingshan district,Xinzhou district,and Jiangxia district.These areas which were tiny and dangerous can be prevented and controlled as key points.The proportion of moderate risk area caused by agricultural non-point source pollution was 31.51%in Wuhan.In Qiaokou district,Jianghan district,and Wuchang district,the proportions of moderate risk area were highest,58.16%,76.11%and 54.10%respectively.But the three districts are in the center of Wuhan which have very few agricultural activities.So the government need to strengthen supervision,intensify the building of local rain sewage pipe network.In Caidian district,Dongxihu district,Hannan district and Xinzhou district,the proportions of moderate risk area were 33.66%,39.24%,40.20%and 32.13%.Because of the frequent agricultural activities,the four districts had the maximum likelihood of agricultural non-point source pollution,so they were the key districts to the prevention and control of agricultural non-point source pollution in Wuhan.(3)Through analyzing risk factors in Caidian district,Dongxihu district,Hannan district and Xinzhou district,the results showed that rainfall erosion factor,soil erodibility factor and land use factor had a greater role in promoting the risk of agricultural non-point source pollution.