Practice Research On The Control And Storage Of Initial Rainwater Pollution In Hefei Ershibu River

With the development of sponge city construction,rainwater management has been paid more attention.The runoff generated by rainfall washes and scours the impermeable areas of the city,and carries pollutants directly into the municipal rainwater pipe network,and finally enters the river through the outlet,resulting in the deterioration of the water quality of the river.This paper takes the Shierbu River in Hefei City as the research object.Through the investigation and analysis of pollution sources,use the Storm Water Management Model（SWMM）^[1]model to evaluate the initial rainwater retention at the river outlet,and to further optimize the volume of the initial rainwater storage tank.The research content of the article is as follows:The first is to analyze and investigate the geographical location of the research water body,climate and meteorology,river water system,etc.,combined with the urban flood control plan of Hefei City,the comprehensive urban drainage（rainwater）waterlogging prevention plan,the initial rainwater pollution control plan in the central city,the special plan for the sponge city,Comprehensive analysis of water body zoning land property planning and other control planning.The second is to investigate and analyze water pollution sources from two aspects:point source and non-point source.Among them,in terms of point source pollution,the pollution situation is mainly determined by investigating the number of outfalls with sewage in the dry season and the water quality detection data of the outfalls,combined with the traceability and investigation of the municipal pipe network upstream of the outfalls.In terms of non-point source pollution,the river catchment area is divided into residential areas,commercial areas,industrial areas,demolition areas,green areas,and traffic road areas,and the industries that may discharge pollutants and the corresponding enterprise and institution areas are focused on the investigation,combined with rainfall.During the incident,the water quality changes at each monitoring section of the river channel were comprehensively analyzed,and the main pollution sources of the water body were clearly studied through the calculation of the pollution load.Thirdly,on the basis of investigating water pollution sources and collecting data,coupled with river hydrological conditions and control unit（or sub-basin）divisions,comprehensively judge existing problems in water bodies;combined with historical sample data,make preliminary estimates of pollutant reduction,Calculation and distribution of the total amount of pollutant reduction through the hydrodynamic water quality model,and simulate long-term pollution load changes;optimize the control plan based on the simulation results,and establish the pollution source control path for initial rainwater runoff pollution;and then use model verification by optimizing engineering measures accessibility.Finally,according to the simulation analysis of different interception scales（4-8mm）of the rainwater pipe network system in the target water body basin,the results show that:when the interception scale exceeds 5.3mm,the growth rate of each pollutant reduction rate slows down significantly,and the"investment benefit ratio"decreases.Small,and the best cut-off range is 4.5-5.3mm.The scale of rainwater interception in this study is 5mm.According to the data calculated by the formula method and mathematical model method,combined with the site selection planning,the two initial rainwater regulation and storage schemes of Ershibu River are as follows:Construction scale of Linquan Road storage tank is 42,000 m³,including17,000 m³pipeline storage volume and 25,000 m³effective volume of storage tank;the construction scale of Yuxi Road storage tank is 35,000 m³,of which pipeline storage volume is 10,000 m³,and the effective volume of storage tank is 25,000 m³.25,000m³.Figure[41]table[12]reference[63]...