Study On Identification Of High Risk Areas Of Non-point Source Pollution In Urban Non Industrial Areas And Design Strategy Of Stormwater Management Measures

In recent years,the environmental problems of urban surface water have become increasingly prominent.Among them,the problem of urban point source pollution has been improved with the improvement of urban sewage treatment system,but urban non-point source pollution is still a thorny problem because of its dispersion and difficult to identify the source.At present,a large number of rainwater sampling workload is excessive,and the high-risk point of urban non-point source pollution is difficult to identify,which has become a hot issue of urban surface water environment.Therefore,based on the reality of China’s cities,this paper explores the identification of high-risk areas of urban non-point source pollution without large-scale measured data,and puts forward the corresponding prevention and control methods and strategies.Based on literature review and existing research,this paper takes Qingyang District(within the Third Ring Road)of Chengdu City as the research object,and constructs the improved multi factor comprehensive evaluation and identification method of urban non-point source pollution risk.The method includes four steps: establishing the index system related to urban non-point source pollution,screening based on the correlation between the measured pollution data and spatial indicators,establishing the index system related to urban non-point source pollution,and establishing the index system Integrate the selected indicators for visualization mapping,and analyze the identified high-risk areas of non-point source pollution.After identifying the high-risk areas,the corresponding optimization strategies are proposed according to the spatial characteristics,hydrological characteristics and layout mode of the corresponding spatial units.Through the above identification method and optimization strategy,the following research results are obtainedFirstly,through the literature review of the basic principles of urban non-point source pollution,non-point source pollution risk assessment,non-point source pollution model principles and parameters,this paper constructs the risk identification index set of urban non-point source pollution;Based on the principles of frequency statistics,operability and spatial correlation,the index set of urban non-point source pollution related to spatial information is formed;Secondly,taking Qingyang District(within the Third Ring Road)of Chengdu as an example,the high-precision urban catchment area was divided,and the measured pollution data and the spatial index eigenvalues of the typical catchment area were obtained;Based on SPSS statistical software,a multiple linear regression model was built to explore the correlation between different spatial indicators and pollutants in catchment area,and six spatial pattern indicators significantly related to pollutant load were screened,including population density,traffic intensity,etc.Finally,the map of high-risk area of spatial non-point source pollution in Qingyang District(within the Third Ring Road)of Chengdu City was obtained by weighted superposition;Thirdly,by combing the catchment characteristics of the site topography,the urban waterlogging risk area map is identified and superimposed with the high-risk area map of spatial non-point source pollution to generate the high-risk area map of topography;Based on the superposition of the two maps,three types of high-risk pollution areas in the process of urban source migration sink are summarized: high-risk pollution area in space(source pollution area),high-risk pollution area in terrain(confluence pollution area),and high-risk pollution area in space terrain complex;Fourth,the research focuses on the high-risk areas of urban non-point source pollution.Through field research and Baidu street view,the paper makes quantitative statistics on the corresponding urban physical space units of relevant high-risk areas,and summarizes the three typical high-risk space units of non-point source pollution: lane space unit,old residential area unit(non Lane space),"street space unit" Based on the characteristics of spatial layout and the factors that can be optimized,the corresponding design strategies of stormwater management measures for high-risk areas of urban non-point source pollution are proposed.