| With the gradual completion of the first and second batch of sponge city construction pilot projects in China,the sponge transformation projects of built-up areas are in full swing throughout the country.However,in the design of sponge transformation scheme,due to the existence of existing buildings,the sponge transformation is limited,resulting in the transformation effect is difficult to achieve the expected goal.Taking a typical sponge transformation project in a compound area of Wuhan City as an example,starting from the existing problems,this paper puts forward the sponge transformation design scheme guided by the goal,compares and selects the schemes,and recommends the better design scheme.By using the infoworks ICM model and mathematical model calculation method,this paper analyzes the four specific indicators corresponding to water safety,water ecology and water environment: pipeline overload capacity,water quality and water quality The accessibility of the design index of the recommended scheme was evaluated,and the effect of the sponge transformation of the recommended scheme was evaluated by comparing the pipeline network,waterlogging,runoff control and non-point source pollution before and after the transformation.The main research contents and conclusions are as follows(1)Problem analysis and status simulation of the study area.According to the investigation results,the existing problems in the study area are analyzed,including waterlogging and runoff control,inspection well overflow and non-point source pollution.In this paper,infoworks ICM software is used to build the current situation model and verify it.The overload capacity of the current pipeline,the prevention and control capacity of waterlogging and the current annual runoff control rate are simulated and calculated respectively.The surface pollution load modulus model is used to calculate the non-point source pollution in the study area and quantify the current situation.(2)The sponge transformation scheme is put forward.The sponge transformation scheme is divided into three parts: road transformation,pipe network transformation and underlying surface transformation.In order to find a better sponge transformation scheme,this paper puts forward four transformation schemes,and makes comprehensive comparison and selection from three aspects of economy,function and feasibility,and recommends the optimal sponge transformation scheme.(3)Evaluation of the effect of the recommended scheme.(1)Accessibility evaluation of design index.The infoworks ICM model is constructed to simulate the water safety and water ecology indexes of the design scheme,and the model algorithm recommended by the guide is used to calculate the water environment indexes.According to the simulation results and combined with the sponge transformation design index system,the specific indexes of water safety,water ecology and water environment meet the design index accessibility.(2)Comparative analysis before and after the transformation.The pipeline overload capacity is reflected by the number of overflow nodes and the proportion of pipeline overload,while the prevention and control capacity of waterlogging is reflected by the maximum waterlogging depth.By comparing the current situation with the simulation results after transformation,it can be seen that the improvement proportion of overflow nodes is 100%,100%,84.61% and 72.70% respectively in the return period of 1a,3a,5A and 10A;The improvement rates of pipeline overload were 100%,100%,14.27%and 1.37% respectively;The improvement proportion of maximum waterlogging depth was 86.45%,64.62%,59.96% and 29.56% respectively.By comparing the simulation results of annual runoff,the total runoff is reduced by 39.15% and the control rate of annual runoff is increased by 16.78%.According to the non-point source pollution situation and the calculation results of the design scheme,it can be known that the purification capacity of the source pollution after the transformation is 0.95t/a.The sponge transformation design scheme can significantly improve the existing pipe network,waterlogging,total runoff and non-point source pollution.The improvement effect of the design scheme on the existing pipe network and waterlogging will weaken with the increase of return period. |
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