Application Of Sponge City Construction Mechanism In Plain River Network Area

In 2014,the proposal of sponge City Concepy' marks that Chinese urban stormwater management has entered a new stage.However,due to the lack of rounded technical system and effective assessment methods,the current construction results are mixed.Sponge city construction is not a uniform design pattern or blind accpeting,it must be improved and optimized according to urban characteristics.As a representative of typical plain water network cities in China,Suzhou has its special geomorphology and geological features.This paper takes the Suzhou sponge construction pilot area as an example to carry out the following research:(1)Analyzing the basic materials such as topography,geomorphology,soil geology,flood control and drainage system,water system river network in the pilot area of Suzhou,it is concluded that the sponge city construction in the plain river network area faces the problems of high groundwater level,high soil moisture content,large area of impermeable underlying surface and the low soil permeability.(2)The river network in the pilot area is densely covered,meanwhile the fourth or fifth-level river channels can effectively alleviate the risk of urban flooding.As a result,the focus of sponge city construction in the plain river network area should focus on the reduction of runoff pollution rather thanrunoff control.Based on the existing problems,it is proposed that the selection of low-impact development facilities in plain water network cities should follow the principle of “stagnation,storage and purification” and take into account the concept of “infiltration,use and drainage”.(3)The path of the rainwater pipe network is short,so it is difficult to divide the largescale watershed partition.This study divide the research area from three levels: zoning-flood control and drainage section-plot construction type by using DEM spatial analysis method of GIS and Artificial depicting(4)The actual rainfall monitoring values were used to determine the parameters of Infoworks ICM and PCSWMM,confirming a group of model parameters suitable for the construction evaluation of the pilot area.(5)Using Infoworks ICM model to analysis the status quo of four typical pilots.Proposing the LID layout schemes of reconstruction and new construction areas from different land types.Based on the layot,the potential control of runoff of different land types was analyzed.Accoding to the results,the priority of sponge construction is:residential land>public facilities land>commercial land>road land.(5)Using Infoworks ICM to evaluate the current runoff control volume in the pilot area,the estimated value is 54.54%,and the target of the runoff control rate in the pilot area is determined to be 75% in combination with the requirements of the Guide.(6)In order to analyze the target accessibility of the sponge construction in the pilot area,the LID transformation and new layout plan were added to the four typical construction plots.Evaluating the current situation of the study area and the effect of sponge construction by PCSWMM.the results of simulation show that :through the renovation of the current plots and the sponge construction of new plots,it is possible to achieve 75.27% total runoff control and 47.68% runoff pollution reduction in the pilot area.At the same time,it can effectively reduce the pipe network load and improve the risk response capabilities.