Optimization Of Stormwater Drainage System Planning And Design Based On Sponge City Theory

With accelerative urbanization,hydrological condition of urban is changed.Underlying surface of urban is being changed into hardened ground,whose natural capability of rainwater infiltration and detention is reducing.Additionally,with the change of global climate,waterlogging happenes frequently in urban,which impacts people’s normal life.To solve the above problem,optimization of stormwater drainage system planning and design based on sponge city theory is discussed in this paper.The purpose of this research is to coordinate stormwater network system with LID(Low Impact Development)system;to avoid investing repeatedly;and to acquire integrated benefit of society,environment and economy.First of all,sponge city planning system is proposed based on urban planning system,which includes: the content of sponge city plan in master plan;the objective,principle,train of thought and content of sponge city sector plan;the content of sponge city plan in other sector plans;the content of sponge city plan and method of index system decomposing in regulatory plan;the content and mathod of sponge city paln in site plan.Secondly,the reason of urban waterlogging and runoff pollution is analysed.The spatial and temporal distribution of rainfall and the water quality of runoff of different kinds of underlying surface in Tianjin are introduced.Laboratory study of green roof,depressed green and permeable pavements is made to research the low of runoff control in both quantity and quality under different rainfall conditions and the impact of the structure of LID facilities,such as the thickness and material of substrate layer.Thirdly,the steps of SWMM(Storm Water Management Model)model constucting is proposed,which include subcatchment generalizing,stormwater network generalizing and parameters setting.The mathod of sensitivity and uncertainty analysis for LID parameters is proposed to study the influence of parameters on simulating result.A green roof model established on SWMM is analysed,for example.Finally,an approach of optimization of stormwater drainage system planning and design based on sponge city theory is proposed,which.includes: optimization of stormwater network layout based on graph theory;applicability analysis of LID facilities for different classifications of land;a multi-objective optimization model of stormwater drainage system based on sponge city theory and the method of model solving by using NSGA-Ⅱ(Nondominated Sorting Genetic Algorithm Ⅱ)algorithm and SWMM simulation;evaluation of stormwater drainage system planning based on analytic hierarchy process.A new school A in Tianjin is studied as an example,whose stormwater drainage system planning is optimized by using the approach above.