Research On Optimal Design Of Rainwater System Under The Sponge City Strategy

With the continuous development of urbanization,coupled with the impact of climate change,the problem of urban waterlogging is increasingly serious.Therefore,the country put forward the sponge city strategy,and based on this strategy,the planning and construction of urban waterlogging prevention and drainage system is also under way.Under the sponge city strategy,this paper studies the optimization method of urban rainwater system based on multi-objective programming model and storm water management model(SWMM).According to the optimization results,this article also systematically analyzes the problem of urban waterlogging,so as to verify the reliability of the optimization method.This paper first gives a brief overview of the sponge city strategy and briefly introduces several key contents of the current sponge city construction.On the basis of the traditional storm water system design theory,the important parameters such as design recurrence period,runoff coefficient and annual runoff total control rate are introduced to provide guidance for the follow-up research.Secondly,under the guidance of the sponge city strategy,the multi-objective optimization models of low impact development(LID)rainwater system and rainwater pipe network system are established respectively with economic and environmental indicators as objective functions.The multi-objective problem is transformed into a single-objective problem and the genetic algorithm is used to optimize the solution.Combined with examples,the optimization scheme of LID rainwater system and rainwater pipe network system in the region is obtained.At the same time,based on the SWMM,the effects of different combination schemes of LID rainwater system and rainwater pipe network system on rain and flood control are compared,and the roles of the optimized LID rainwater system and rainwater pipe network system in waterlogging prevention and drainage are analyzed,which also verify the effectiveness of the optimized model.Finally,through the SWMM model,the waterlogging model of urban inland river that are part of the excess stormwater runoff discharge system is established.The design water level of the river is optimized through such optimization measures as river emptying,optimization of pump station control rules,setting of storage space and adding LID rainwater system,so that the excess rainwater could be discharged smoothly by urban rainwater pipe network and urban waterlogging prevention engineering facilities.Based on the whole optimization scheme of rainwater system,this paper analyzes the risk of urban waterlogging,which verifies the effect of optimization of urban rainwater system.Also,according to the numerical optimization results of the rainwater system,the way to scientifically construct the urban waterlogging prevention and drainage system is explored preliminarily.