Study On Rainwater Infiltration Efficiency And Swmm Model Simulation Of Sunken Green Space And Permeable Pavement

With the acceleration of urbanization,the climate and underlying surface conditions in Xi’an have changed significantly that leading to deteriorating of water environment,increasing risk of water-logging,losing of rainwater resources and other problems in urban ecological environment,the traditional rainwater discharge model can no longer to meet the needs of sustainable urban development,but low impact development(LID)rainwater system research and application measures are showing advantages.According to the concept of LID rainwater source reduction and combined with the characteristics of rainfall in Xi’an,it is of great significance through the adoption of certain engineering or non-engineering measures to collect natural rainwater that full and reasonable use in improving water resource utilization,reducing the risk of urban water-logging and achieving rainwater resources recycle and utilization.However,there are few examples of rainwater infiltration efficiency in urban green infrastructures in Xi’an at present.In order to achieve the goal of water resources utilization efficiently,this paper chooses the Chang an campus of Northwest University as the study area,using the combined methods that site test and the SWMM model during the whole research,the rainfall infiltration efficiency and surface runoff characteristics of sunken green space and permeable pavement are mainly observed for obtaining the measured permeability of the numerical sequence.Furthermore,SWMM model was used to simulate the runoff hydrology process of the underlying surface,which assumed that sunken green space replaces the traditional green land and the permeable pavement replaces the current hardened road,and also through the comparison of the different underlying surface combination situation,the hydrology,social and economic benefits arising from the sunken green space and the permeable pavement are estimated.The results showed that when the parameters of the sunken green spaces are the depth of 10cm and the green rate is 40%,and the parameters of the permeable pavement are the thickness of 7.5cm and the porosity is 0.28,which could reduce the total surface runoff 88.54m3,and under the condition of average rain intensity of 9.69 mm/h and rainfall of 27.5mm,which could reduce the peak flow rate to 10.17%and the time of occurrence of delayed peak was 0.16 h in the selected study area with an area of 4.7 ha that also provide a useful reference for the construction of engineering measures in the same area in Xi’an.