Research Of Regional Low Impact Development Facilities Layout Based On SWMM

In recent years,waterlogging has been widespread in many cities in China,and social and economic activities have suffered losses.In view of the serious consequences of urban waterlogging and the urgency to reform the drainage system,the pilot and promotion stages of sponge city construction in China are advancing rapidly in the overlapping process.However,the research of designing suitable and social LID facilities need to be strengthened urgently.This paper chooses the new urban district of Fuyang City,a plain city in the climate transition area,as the research area,and carries out the application research of low-impact development measures layout by using SWMM model.The purpose is to explore the design method of LID measures in the sponge system of urban drainage system,and to provide reference for the design and layout of low-impact development measures in similar areas with natural conditions and development conditions.Firstly,taking the outstanding problems of waterlogging and water pollution as the breakthrough point,the current situation of drainage and waterlogging prevention system in Fuyang City is analyzed.Based on the current contradiction of water problems,the demand of LID facilities construction is analyzed from the perspective of economic and social development,people's needs and urban development.In addition,the theory and method of constructing SWMM model in new urban construction area are sorted out.In this process,according to the characteristics of DEM data in plain city,the method of dividing sub-catchment area based on Arc Hydro Tools is proposed,and a reasonable dividing result is obtained.The planning model of rainwater pipeline network in the study area is constructed,including 414 circular rainwater pipelines,404 common well points,58 drainage outlets and 404 sub-catchments.Then,the simulation results of SWMM model under different rainfall scenarios in different recurrence periods are applied.The influencing factors of waterlogging are analyzed and the drainage capacity of rainwater pipeline network is evaluated.Subsequently,the location distribution of waterlogging-prone points in the study area is identified.The rainwater pipe network system in the study area can meet the drainage requirement under 2-year recurrence rainfall;under 3-year recurrence rainfall,the local drainage capacity of the rainwater pipe network system is insufficient and the risk of waterlogging exists;under 5-year recurrence rainfall,the surface of the study area will have a certain extent of waterlogging.Finally,on the premise of suitable area analysis and preliminary comparison of LID facilities,with the control objective of no surface waterlogging and no more than 0.5 comprehensive runoff coefficient when the maximum 24-hour rainstorm occurs in 30-year recurrence period,four measures of green roofs,porous pavement,rain garden and sunken greenbelt are selected for localization design.By comparing the runoff control ability,landscape effect,utilization effect of rainwater resources and comprehensive cost of the four measures,the SWMM model is used to obtain four scenarios of layout and combination schemes,which are basic,economic,demonstration and comprehensive consideration schemes,and combined with the characteristics of each combination scheme,the application strategies in the study area are put forward.