Study On Waterlogging Prevention And Control Strategy Based On Sponge City Concept In Southern Water-rich Cities

Sponge city is the goal of eco-city construction of new urbanization in China.In the "no water accumulation in light rain","green mountains and green water" and other aspects of urban planning and construction has achieved obvious results.However,the analysis of basic conditions such as urban water accumulation and spatial environment in urban waterlogging prevention and control is still inadequate,which leads to the problems of low project site selection and timing benefits in the planning and construction of sponge city.By investigating the research status of waterlogging prevention and control at home and abroad,this paper starts from the theoretical research and practice related to sponge city construction and waterlogging disaster prevention and control,and takes the waterrich cities in southern China as examples to analyze the spatio-temporal characteristics of water resources,rainfall and rainstorm flood disasters.The causes of waterlogging disasters are analyzed from the natural conditions and urban planning and construction,and the mechanism of waterlogging disasters is analyzed from the perspective of natural disaster risk system theory.Based on the concept of sponge city,the waterlogging prevention and control factors and the risk of waterlogging are identified from the urban water circulation system.A comprehensive analysis method of waterlogging prevention and control factors and waterlogging risk was proposed through the suitability evaluation of sponge city construction and scenario simulation.According to the suitability degree of sponge city construction and waterlogging risk degree,combined with the present situation of drainage system,Waterlogging prevention and control measures are explored from three aspects: sponge system planning,"grey-green" drainage waterlogging prevention project and low-impact development(LID)non-engineering measures.Based on the characteristics of water-rich cities in southern China,this paper selects nine indicators,including elevation,slope,vegetation,water system,building density,Network density,distance to road,population density and land use function,from three aspects of physical geography,urban construction and population economy by AHP-entropy weight method assisted by GIS,to construct a suitability evaluation system for sponge city construction.According to the suitability degree of sponge city construction,the evaluation results were divided into five grades:extremely unsuitable area,relatively unsuitable area,general suitable area,relatively suitable area and extremely suitable area.Through the scenario simulation method assisted by MIKE,the drainage capacity of the pipeline and the degree of waterlogging risk were evaluated.The drainage capacity of the pipeline was evaluated by the filling degree of the pipeline under different rainfall scenarios.According to the time and depth of surface water accumulation,the evaluation results of waterlogging risk were divided into four grades: no risk,low risk,medium risk and high risk.Based on the concept of sponge city,through the superposition analysis of the evaluation results of sponge city construction suitability and waterlogging risk,and combined with the current drainage system,the site selection,construction sequence and drainage and waterlogging prevention scheme of sponge facilities were rationally arranged.The rainwater ecological security pattern,the three-level sponge drainage waterlogging prevention system and the waterlogging emergency management platform will be further constructed.And taking the west area of a town in Dongguan City as an example,the practice analysis and scheme design are carried out to build a sponge city with "no water accumulation in light rain and no waterlogging in heavy rain".