Study On The Comprehensive Management Of Water Environment In The "Xuancheng Section" Of The Shui Yangjiang River's Mainstream

With the population increase and fast-developing national economy,issues related to the water environment are increasingly serious in recent years.The serious waste of water resources,the frequent occurrence of water pollution incidents,and the contradiction between the supply and demand of water resources have reached a stage of intense development.In order to curb the deteriorating situation in the water environment,the government has attached the great importance to and introduced a series of policies and regulations,and also put forward the requirements for the full implementation of the RiverChief Mechanism by the end of 2018.As the primary tributary of the Yangtze River,Shuiyangjiang River,the largest river system in Xuancheng City,Anhui Province,studies the water environment quality,water environment capacity,and water environmental remediation measures in the Xuancheng section of the Shuiyangjiang River's mainstream,which helps to understand the specific conditions of the river.Targeted suggestions for the management of the river may be helpful for learning and learning from other regions,and promoting the full implementation of the “River-Chief System” and “Each policy for Each River”.The main work of this paper is as follows:(1)The pollution sources of industry,life,agriculture,livestock and poultry husbandry in the Xuancheng section of the Shuiyangjiang River's mainstream,and pollution sources were evaluated using the equivalent pollution load method.The results showed that the source of river pollution was mainly domestic sources of pollution.The ratio of equal pollution load was as high as 75.81%,followed by agricultural pollution sources,livestock and poultry farming pollution sources and industrial pollution sources;total nitrogen was the most important pollutant,followed by total phosphorus,the sum of the equivalent pollution load ratio between them is 83.54%,which may be related to the unreasonable use of nitrogen fertilizer and phosphate fertilizer,and low treatment rate of the domestic sewage.(2)The single-factor assessment method,Nemerow pollution index method,fuzzy comprehensive evaluation method and grey correlation analysis method were used to evaluate the water quality in the study area,and improvements were made in the steps of fuzzy comprehensive evaluation method and grey correlation analysis of legal weights.The AHP reduces the impact of subjective factors on water quality assessment and enhances objectivity.The results showed that total nitrogen was the main reason for the excessive water quality.The average annual water quality of each section and the entire river section was Class III water,and the quality of drinking water sources did not meet the requirements.Compared with the four evaluation methods,the improved AHP-GCA method has a better applicability.(3)Calculate the water environmental capacity of the Xuancheng section in the Shuiyangjiang River's mainstream based on the one-dimensional water quality model,and calculate the reduction of the pollution source based on the pollution source emission status.At present,the total amount of pollutants in water has far exceeded the water environment capacity of the reach.Among them,Shuiyangjiang Xuancheng Reserve and Shuiyangjiang Xuancheng Development and Utilization District — Shuiyangjiang River Xuanzhou Agricultural Water Use Area is the most serious and needs to be reduced.The water environment capacity COD is 9184.09 t/a,the total nitrogen is 2251 t/a,and the total phosphorus is 140.09 t/a.By controlling the largest source of pollution pollution in the river basin,the COD reduction rate can be reduced to 2.53%,and the total nitrogen reduction rate can be reduced to 62.33% and the total phosphorus reduction rate was reduced to 8.57%.(4)Combining the above research results,in order to improve the water environment and water ecological situation,put forward water resources protection measures,point source and non-point source pollution control programs,river ecological restoration projects,and strengthening water environmental law enforcement supervision and other capacity management programs.According to the problems in the management of water environment in the river basin,a long-term management mechanism with the " River-Chief System" policy background has been put forward,with a view to establishing a relatively complete management system to promote the harmonious development of the water environment and the regional economy.