Construction Of Water Quality Assessment System Based On Pollution Traceability And AHP Method

With the rapid development of our social economy,the water environment problem appears day by day,more and more attention by everyone.In 2015,The State Council publicly released the Action Plan for Water Pollution Prevention and Control,proposing to carry out scientific treatment as a whole and strengthen water environment management in river basins to guide the prevention and control of water pollution in all regions of the country.The Opinions on Comprehensively Implementing the River Chief System,issued in 2016,requires all regions and departments to establish and improve the organizational system of the river chief system and clarify the implementation of responsibilities,which has achieved good results in recent years.Known as "Chengdu Backyard Garden" and "Jin Wenjiang",Wenjiang District has been actively responding to the national call,continuously paying attention to the control and management of water environment quality,and striving to build a "water-friendly city".In recent years,Wenjiang District has issued a number of documents,which further strengthens its determination to win the battle of water pollution prevention and control.It proposes to strengthen the construction of ecological civilization,establish and improve management mechanisms such as the river and lake chief system,innovate performance assessment and evaluation methods,and explore the construction of town(street)water environment quality assessment system.This article takes Wenjiang District,Chengdu City as the research object.Through the collection and organization of basic data,relevant information such as hydrology,administrative division,water environment quality,and management status in the region is understood.Six street offices and three townships are selected as the assessment objects.Considering that there are currently 8 water quality monitoring sections in Wenjiang District,with a relatively small number,and the water quality assessment is difficult to trace the source of pollution at the administrative boundary section of the river,and the responsible party is not clear,a pollution source investigation is conducted on the regional water environment quality,and the results are used as indicators for the Analytic Hierarchy Process to construct an evaluation index system.The main conclusions include the following:(1)Conduct investigation and evaluation of pollution sources,using inventory based(output coefficient method)and receptor based model(APCS-MLR)methods to analyze and evaluate regional pollution sources.Finally,the system is applied to the evaluation.According to the assessment results,combined with the idea of performance assessment,suggestions and measures can be put forward for pollution control,supervision and management of each responsible unit,so as to stimulate the enthusiasm of each department for water control and realize the long-term management of water control work.In the actual operation,we should always summarize the specific problems,solutions and experiences encountered in the process of system application,adjust flexibly,and study and establish a long-term working mechanism.The results of the inventory method(output coefficient method)indicate that:(1)COD is the main pollutant in the basin,accounting for 80%,followed by TN.(2)The main source of pollution in the basin is the discharge of domestic sewage.Except for TP,the amount of pollutants discharged from domestic sources is higher than that from industrial and agricultural sources From the perspective of administrative units,the pollution emissions of Liucheng Street are relatively high,and the area is located in the main urban area of Wenjiang,with a relatively dense population.The results of the receptor model(APCS-MLR)indicate that:(1)three principal components were extracted,the first being total nitrogen and dissolved oxygen,which indirectly reflects a certain degree of eutrophication in the watershed;The second principal component,chemical oxygen demand,indicates that the water body in the basin has been polluted to a certain extent;The load variable of the third principal component is p H,and the main source may be non-point source pollution in Wenjiang District Through APCS/MLR analysis,it is known that the contribution rates of the first principal component to total nitrogen and dissolved oxygen pollution indicators are 45.11% and 9.17%,respectively;The contribution rate of the second principal component to the chemical oxygen demand index was 91.93%;The pollution contribution rate of the third principal component to the p H index is 20.81% After analyzing the water quality of the sections,it can be seen that the top three sections with comprehensive scores are Tuqiao,Chengnan Transit Road Bridge,and Liujiahao sections,indicating that these sections have serious pollution and should be strengthened in management.Based on the above two methods,it can be concluded that the main pollutants in Wenjiang District are COD and TN,and the main source of pollution is domestic sources.There is widespread non-point source pollution in Wenjiang District,so it is necessary to pay attention to controlling its emissions and governance.(2)Construct a water environment quality assessment and evaluation system in Wenjiang District through the Analytic Hierarchy Process.Referring to the existing environmental evaluation indicator system,this study has established five primary indicators,namely "water environment quality","water environment management","environmental construction","public participation",and "financial indicators",as well as 15 secondary indicators,including "water quality indicators meeting standards" and "water sensory indicators meeting standards".The index weight is combined with the Delphi method method,and the hundred point system scoring standard is used to assign values to each index.From the ranking results of the criteria layer,it can be seen that water environment quality and water environment management are relatively more important,with weights of0.4087 and 0.2643,respectively;From the overall ranking results of the indicator layer,the first priority is the water quality indicator that meets the standard,with a weight of 0.227.The second priority is the water sensory indicator that meets the standard and the public satisfaction indicator,with weights of 0.136 and 0.121,respectively.This proves that for the assessment of towns(streets),the quality of water quality and public response are given priority.After establishing the evaluation index system,taking A Town as an example,the system was tested,and the final performance evaluation score of A Town was 92.91 points.Taking this as an example,calculate the scores of other towns(streets)and list their rankings,and based on the assessment results,implement water environment ecological compensation for the towns(streets)and the main party and government leaders.Through economic means,strengthen the ecological environmental protection responsibility of towns(streets),stimulate the enthusiasm of various departments in water control,and promote comprehensive treatment of water environment pollution.Through the analysis of environmental pollution sources,suggestions and measures can be proposed for the pollution control,supervision and management of each responsible unit,and a water environment quality assessment system for towns(streets)can be further constructed.Based on the assessment results and combined with the concept of performance assessment,long-term management of water control work can be achieved.In practical operation,it is also necessary to constantly summarize the specific problems,solutions,and experiences encountered in the application process of the system,adjust flexibly,and study and establish a long-term working mechanism.