Study On Spatial Pattern Optimization Of Sponge City In Dashiqiao Southern New Town Demonstration Area

In the process of urbanization construction in China,there are a series of problems in the city,such as water pollution,frequent floods and threats to the urban ecological environment,which will seriously affect the future urban construction.Sponge city is a new concept of urban construction and development.Under the background of large ecological city and ecological civilization construction in China,sponge city can meet the specific urban development mode through the natural accumulation,natural infiltration and natural purification of rainwater.The introduction of sponge city concept can better solve the problems existing in these urban construction,which is the trend of urban construction and development in the future ? Dashiqiao City is a mineral resource city.The urban pollution caused by long-term mining in the city and the cow water phenomenon caused by terrain sensitivity in some areas are great challenges in sponge construction.Therefore,it is necessary to optimize the spatial pattern of sponge city and solve the problems of rain and flood safety and water environment in the process of spatial pattern optimization.First of all,the basic natural conditions of Dashiqiao City and sponge demonstration area are analyzed,including the current situation of water resources,topography and other natural conditions,runoff coefficient of various types of land in the demonstration area,the planning and construction management and control objectives of sponge city in the demonstration area are determined,and the water quantity and quality are studied to analyze the construction demand of sponge city.Secondly,the existing master plan of the demonstration area is analyzed and determined,the comprehensive influencing factors of sponge city are analyzed,the situation of water system,green space,road and drainage pipe network in the master plan of the demonstration area is analyzed,the problems are put forward and the space optimization solution strategy is given.Based on the extraction and analysis of the master plan data and the SWMM simulation of the rainwater runoff and water quality in the demonstration area in combination with the current urban development factors,the possible flood problems and water environment problems in the future urban construction of the demonstration area are simulated,the flood risk points and risk areas in the demonstration area are determined,and the pollutant load under the return period is determined.The simulation results further indicate that Optimize the spatial pattern of sponge city.Finally,combined with the simulation results and the analysis of the overall planning,aiming at the problems of flood and water environment,the original planning is optimized from four aspects: urban water system space,green space,road space and urban underground drainage network space.Water system space: Based on the division of river basin management and control unit,following the composition of natural rainwater and flood system "source emission reduction-Midway transmission-end regulation and storage",the ecological drainage mode of sponge city is classified,the ecological drainage process of rainwater runoff is optimized,and the overall water system layout is optimized by calculating the water volume of storage and drainage space of water system;green space: according to the green type of sponge City,the green space is completed Improve its quantitative indicators,consider the spatial coupling relationship with the water system to determine the layout,and determine the type of low impact development facilities in the demonstration area according to the "source emission reduction-Midway transmission-end regulation and storage";road and drainage pipe network space: combine the low impact development facilities to design the road and optimize the layout of the pipe network.The SWMM model is used again to simulate and evaluate the optimization effect of sponge city in the demonstration area.It is concluded that both the rainwater runoff and the four kinds of pollutants have been reduced.Through the optimization of the spatial pattern of sponge City,a model area of sponge city with landscape charm and livable and suitable for business can be built.