Research On Sponge City Idea And Its Application In Urban Waterlogging Planning

With the acceleration of Urbanization,the impermeable coverage increasing and runoff condition changing of the underlying surface generally causes significant reduction of storage and infiltration while causes the faster slope and pipeline concentration and the increase of runoff at the urban area.Urban heat island effect results in short-period precipitation increase frequent occurrence of urban waterlogging.The statistics of Ministry of Housing and Urban-Rural Development in 2010 indicated that 62%of the 351 cities have suffered from various degrees of waterlogging among of which 137 cities suffered from more than 3 times waterlogging disasters from 2008 to 2010;and the situation has become more serious since 2011 and waterlogging pursuantly has become one of the main environmental problems caused by urbanization.As urban waterlogging cannot be drastically solved by traditional engineering facilities it is imperative to find a new way to solve this problem.In the current study,on the basis of the idea of sponge city,to realize the runoff restore its state as far as possible of that before the development of the city via low impact development(LID)facilities by changing the impermeable conditions of the underlying surface,and to realize the rainwater resources utilization.Application of the low impact development measures to the urban waterlogging planning control the drainage from the source and waterlogging stress thereby is to be reduced.The results of this paper are expected to provide method references for urban waterlogging planning under the background of rapid urbanization.In this paper,the connotation of sponge city was introduced,and the current research situation of sponge city at home and abroad as well as the construction measures corresponding to the principle of "infiltration,stagnation,storage,purification,usage and drainage " was summarized.The LID,which is an effective way for sponge city to reduce the stress of drainage pipeline networks via decreasing rainwater drainage,was clearly pointed out.Comparison of traditional rainwater technologies and the LID was carried out via review and analysis of technical framework of the sponge city construction and the LID,and applicable method of sponge city idea to regional flood control planning has been clarified to some extent.In this paper,the basic principle and structure of SWMM model was introduced.Because SWMM has powerful simulation function for the urban drainage system and has a built-in LID module;it was adopted to develop rainfall-runoff model for plain river network.Model calculation for the LID facility scale has been performed and based on the calculated results,analysis of effects of different planning methods of urban waterlogging has been conducted.Area of Jichanghe of Economic development done of Changzhou City was chosen as the study location.It is essential to increase the size of the drainage of 6m3/s,to build 5 sluices and 1 drainage pumping stations according to the traditional engineering planning scheme.Whereas,based on sponge city idea via the construction of LID facilities,the essential facilities are to set the rain barrel,the rain garden,the permeable pavement,Vegetative swale,urban green land and artificial water of 10.591,57.88,49.75,75.853,123.3 and 26.52hm2,respectively.Compared with the traditional drainage planning,waterlogging could be better controlled in the case of the LID as runoff coefficient has been reduced by 33.8%,the peak has been delayed in time for 15 minutes and has been reduced in scale by 25.8%,water retention nodes and pipe section have been reduced to 10 and 4,and the average water retention time(or waterlogging time)has been reduced by 0.42hours.