Research On Site Selection And Design Strategy Of LID Measures Based On Rural Non-point Source Pollution Prevention And Control In Shouan Town,Chengdu City

In recent years,the problem of rural non-point source pollution is becoming more and more serious,which has gradually become the bottleneck of rural water environment management.With the acceptance and application of LID in more and more areas,domestic scholars have begun to apply LID in the control of non-point source pollution in rural areas,but a mature theory and technology application system has not yet been formed,and researches on LID site selection are more scarce and need to be further improved and supplemented.Therefore,this study to rural non-point source pollution control as the breakthrough point,the low impact development concepts into rural non-point source pollution control,combining with the characteristics of chengdu plain region rural river basin,with typical characteristics of chengdu plain rural river Shou An town salween district of chengdu as an example,to carry out the LID is applied to the further research of rural watershed non-point source pollution control.Through literature review,hydrological simulation,field investigation and other methods,using Arc GIS,SWAT and other software,starting from hydrological sensitivity,risk of non-point source pollution and functionality of production-production space in a multi-layer screening method,Based on expert experience and identification of key source areas,a scientific,systematic and efficient LID method for site selection is established through quantitative means.Focusing on the key source areas that contribute a great deal to non-point source pollution,and by analyzing the spatial composition of these areas,the accumulation process of pollutants and other characteristics,the corresponding LID design strategies and design priorities are put forward to guide the future non-point source pollution prevention and ecological development of Shouan Town in Wenjiang District.It is expected to enrich theoretical research on the application of China’s low-impact development concept in rural areas,and provide reference for LID application in other similar areas of Chengdu Plain rural watershed in China.The research is mainly divided into the following aspects:1.The topographic index,the core content of the Top Mode model,is selected as the index to analyze the hydrological sensitivity of Shouan Town in the research area,so as to realize the visualization and indexation expression of the hydrological sensitive area in the research area,and then delimit the hydrological sensitive area.The results show that the hydrological sensitive area of Shouan Town accounts for about 6% of the study area,and the distribution of the body is relatively dispersed,and there is no obvious aggregation feature.Because these hydrologically sensitive areas represent the areas that are most prone to runoff and pollution in Shouan Town of the research area,these hydrologically sensitive areas need LID construction especially compared with the low-sensitive areas of hydrology.2.Both at home and abroad at present,and high pollution of non-point source pollution load identification method of application fields,advantages and disadvantages,characteristics such as comparison,finally chooses the SWAT model for river basin of non-point source pollution in the study area of hydrological simulation,simulate the study area is located in the basin in different sub basin pollutant loss situation,and then use Arc GIS10.6platform,Phosphorus loss intensity index method was used to identify the area with high nonpoint source pollution in Shouan Town in the research area,and the catchment area with high non-point source pollution load was designated as the area with high non-point source pollution in the research area.Finally,it is concluded that the highly polluted area of non-point source pollution in Shouan Town consists of four sub-basins with high loss intensity,1,5,7and 13,which account for 23.41% of the total area of Shouan Town in the study area,while the total phosphorus load produced accounts for 52% of the total phosphorus load output in the study area,accounting for more than half.3.This study refers to the relevant theories for determining key pollution source areas proposed by foreign scholars such as Zeyuan Qiu,and attempts to determine key pollution source areas from the perspective of hydrological sensitivity and non-point source pollution risk.Such key pollution sources are not only the areas that are easy to produce runoff,but also the areas with high non-point source pollution load.According to statistics,the total area of key pollution source areas in the research area is about 75 ha,accounting for 2% of the total area of the research area,and such areas are defined as the priority site selection areas for LID measures.By giving priority to setting LID measures in such areas for design renovation,the purpose of achieving higher non-point source pollution removal benefits through lower LID cost input can be regarded as an efficient and reasonable site selection method of LID measures.4.Combined with the characteristics of rural areas in China,based on the concept of production-production,based on the summary of relevant domestic research results on production-production space,combined with the characteristics of this study region,the division of single appropriate space is adopted to clarify the functional connotation of production-production space,and to construct a classification system of productionproduction space at the micro township scale.According to the classification system constructed,with the help of Arc GIS platform,satellite images and field research in the research area were used to demarcate and identify the ecological and biological space in the priority site selection area of LID measures in the research area through manual visual interpretation.According to statistics,the total area of production-production space in the selected area of Shouan Town in the research area is about 75 ha,which is mainly dominated by production space,accounting for about 45 ha in total,accounting for 60%.Ecological space is the second,accounting for 26.3% of the total 19.7ha.The living space is the least,about10.3ha,accounting for 13.7%.After through the analysis of the space of location area grow space composition,contaminant cumulative process characteristics,and combining with the types and characteristics of the LID measures at home and abroad and site requirements,design,etc.,and targeted puts forward all kinds of good space corresponding to the LID design strategy,including the overall design principle,suitable LID measures than choice,design,design process,etc.And further analysis combined with the actual situation of Shouan Town in the research area,pointed out the design focus of the site selection area of LID measures in the catchment area of the internal high pollution sub-watershed,in order to provide more targeted guidance for the future non-point source pollution prevention and ecological development of Shouan Town.