Study On Technical Mode For "Sponge City" Construction In Wuhan

In recent years,with the speeding up of urbanization in our country,the impervious area of city underlying surface increased,urbanization has long been recognized as affecting the natural of hydrological characteristics and consequently cause a series of highlight problems,such as Water Environment Deterioration,Waterlogging Risk aggravation,Runoff Pollution seriously,and Rainwater resources running off.The state strongly promoted the construction of sponge city which is a site designed strategy with a goal of maintaining or replicating the predevelopment hydrologic regime through the use of design techniques to create a functionally equivalent hydrologic landscape and finally achieves the goal of protecting or improving eco-environment.At present,30 cities have become the national sponge city pilot,and more than 130 cities have formulated the sponge city construction program.Wuhan was established as the first batch of sponge city pilot zone,which is in the important stage of planning,design and construction.However,the development of sponge city in China is still in the initial stage,and the theoretical system and calculation method are not perfect.It is of great practical value and theoretical significance to study on technical mode of sponge city construction in Wuhan.Taking the sponge city pilot construction project of Qingshan demonstration area in Wuhan as the example,the evaluation system for sponge measures comprehensive benefit is established as the storm water management model(SWMM)and Analytic Hierarchy Process(AHP).Studying the technical mode of sponge city construction in different urban space combined with the natural environment characteristics of Wuhan.The conclusions obtained was as following:(1)Study on SWMM model modeling technology.On the basis of summarizing structure,principle and modeling steps of SWMM model,building SWMM model of research area and operating parameters reliability of model combined with the land used,topography and current situation of pipe network in Qingshan district is tested and verified.(2)Study on comprehensive benefit evaluation system of sponge measures.Summarizing the typical measures of different benefit index,the evaluation system for sponge measures comprehensive benefit containing environmental benefit,economic benefit and social benefit is carried out with AHP.(3)Benefit evaluation of single sponge measures.Sponge measures is determined preliminary combining site conditions and usage characteristics of sponge measures.Comprehensive benefits of single sponge measure with SWMM model and AHP is evaluated.The preferential order for sponge measures comprehensive benefit was as follows: rain barrels > grassed swales > sunken-lawn > permeable pond > permeable brick >green roofs > permeable pavement.(4)Study on the technological mode of sponge city construction in Wuhan.The SWMM model of Wuhan’s residential buildings,municipal roads,urban squares,urban parks and urban waterfront areas are established,and the combination mode of sponge measures is designed to simulate the effect of each mode evaluated by AHP.According to the evaluation results of each mode and the natural environment characteristics of Wuhan,the suitable mode for different land use types of Wuhan is concluded.For residential buildings,it summarizes the construction technology mode of sponge city in low density,medium density,high density,and new building,old building.For municipal roads,it summarizes the construction technology mode of sponge city in single,double,three,four pairs and new road,old road.For the city square,it gives the construction technology mode of sponge city in sinking,platform and square with different usage properties.For urban parks,the appropriate sponge city construction technology mode is proposed according to neighborhood,regional and metropolitan parks.For urban waterfront areas,the sponge city construction technology mode of Wuhan waterfront area is summarized according to riverside,lake and island types.(5)Study on the sponge city construction case.On the basis of the above theoretical study,a caseof a plot of Qingshan sponge demonstration area in Wuhan is studied,and its rainwater runoff is simulated by SWMM.According to the simulation results and the evaluation index of the demonstration project,three optimization schemes are designed by choosing the appropriate technological mode of sponge city construction.By the use ofAHP to evaluating the optimization schemes,the result shows that the comprehensive benefit value of the three optimization schemes is higher than the original scheme,and the effect of rain and flood control is close to the original design scheme,and greatly improves the economy.