Research Of Urban Low Impact Development Drainage System Design Based On Sponge City Concept

In recent years,with the acceleration of urbanization and the impact of global warming,the urban rain island effect has been increasing,the frequency of extreme precipitation events has increased,and water ecological environment problems such as urban waterlogging,environmental pollution,ecological damage,water shortage have become increasingly prominent.The traditional way of urban construction has been unable to meet the requirements of today's urban construction and development.In order to coordinate the development of the city with the environment,the concept of sponge city construction has been put forward in China.At present,the construction of sponge city in our country is in full swing,but in many aspects,the technology is still immature.It still needs a long process of exploration and practice to truly realize the construction of sponge city in an all-round way.Firstly,this paper analyses the research and application progress of sponge city concept at home and abroad,and points out the deficiencies of current research.Subsequently,the objectives,principles,ideas,relevant parameters,applicability and performance benefits of typical sponge city measures are studied and summarized,and the specific quantitative decomposition technical route of annual total runoff control objectives is put forward.Secondly,taking Jianli County West Living Area(which belongs to the built urban area)as an example,through the process of collecting and sorting out basic data,designing rainfall scenarios,selecting model calculating methods,calibrating and validating model parameters,the SWMM model suitable for the study area is constructed.Through model simulation,the characteristics of runoff,drainage capacity of pipeline network,waterlogging factors and non-point source pollutants are studied and analyzed.Finally,through the quantitative decomposition method of annual total runoff control objectives,the rainwater control objectives of each sub-catchment area in the study area are determined step by step.Combined with the actual situation of the study area and the applicability analysis of LID,three sets of LID combination schemes are put forward,and the LID scale of each scheme is determined by quantitative calculation and model checking,so as to meet the control objectives.The simulation results show that the peak runoff and pollutant load of surface runoff and runoff are significantly reduced after the LID measures are added to the drainage system,which proves the validity of LID design.The hydrological,hydraulic and water quality simulation results of three LID schemes are analyzed,and the control effects of each scheme are compared.The recommended scheme is selected through economic benefit analysis.This study can provide theoretical reference for the LID reconstruction design of the actual sponge city drainage system,and also provide some technical support for the sponge city construction in the selected research area.