Study On Rainwater Control In Existing District Of Wuhan Based On Sponge City Concept

With the accelerating development of urbanization,the problems of flood disasters and water pollution in Wuhan have become increasingly prominent in recent years.The traditional concept of rapid drainage and rapid drainage can not meet the needs of urban development.Therefore,the construction of sponge city has been put on the agenda.The plot land occupies an important position in urban construction,and the annual average yield accounts for 50% of the total urban runoff.New residential districts must strictly follow the current norms and adopt the sponge concept to control rainwater.However,many existing residential districts are prone to waterlogging because of their traditional rainwater control mode.In addition,the site layout,pipe network layout and hardened area of underlying surface of existing residential areas have been basically fixed.Combining sponge technology with traditional "grey" rainwater system of existing residential areas will be constrained by the current site conditions,and it will be difficult to implement.At present,there are few literatures on rainwater control in existing residential areas in Wuhan.Therefore,this paper chooses the existing residential area as a foothold,guided by the concept of sponge city construction,and studies the rainwater control in the existing residential area.According to the distribution map of waterlogging in Wuhan,16 existing districts around Zhongnan Road and Youth Road in the heavily waterlogged area were selected for investigation.The distribution regularity of water accumulation points on each underlying surface was analyzed.Water accumulation points were mainly distributed at intersections and sides of roads,under paved square corners and rain falls pipes.Then,according to the rainwater path,from the three processes of runoff generation,confluence and discharge,the causes of rainwater problems in residential areas under the traditional rainwater control mode and the advantages and necessity of implementing rainwater control in existing residential areas based on the concept of sponge city are analyzed.In this paper,the strategies of rainwater control in existing residential areas are analyzed from three aspects: the selection and layout of sponge measures,the optimization of underlying surface and the utilization of surrounding open space.The selection of sponge measures should be based on the vertical,gradient and spatial conditions of the site,and be compared with the ecological,economic and social benefits.The optimization of underlying surface should focus on solving the problem of stagnant water and optimizing the form of rainwater management according to the distribution law of accumulated water points.The use of surrounding open space belongs to the control of rainwater from the end of the drainage process with the help of the outdoor site.It is necessary to take into account the distribution of rainwater pipes,canals,vertical and outdoor land in the site as a whole.Finally,this paper takes Jinneng District as the research object,adds sponge measures,optimizes underlying surface,and implements sponge transformation.Because of the insufficient space for the renovation of the residential area,it is the first time to try to discharge the runoff from the residential area to the water body of the nearby park,and to assist in rainwater regulation and storage with the help of the outdoor field.The SWMM model is used to simulate the effect of rainwater control before and after the renovation of the residential quarter,and the results show that the increase of sponge measures and the optimization of underlying surface can effectively reduce surface runoff and pipeline catchment flow,and that the total amount of rainwater discharge can be effectively reduced and the total runoff control rate can be improved by using the rainwater storage from the end of the outfield,which can effectively solve the problem of insufficient space for adding sponge measures in the site.Reduce the pollutants in runoff and improve the quality of rainwater.