Research On Pollution Reduction And Closure Effect Of Urban Underlying Surface In View Of Sponge City Theory

With the acceleration of urbanization and the aggravation of the extreme climate,the area of impermeable underlying surface is increasing.Urban waterlogging,urban water pollution and many other relative issues are appeared in a large number of cities in recent years.It has caused serious economic losses to the nation and resulted in serious negative effect to the society.Sponge city refers to the city which has the function of water absorption,water filter and good resilience in response to climate change and natural disasters.It plays a part in water storage,water seepage and water purification in the rainning days.Meanwhile,it can release and take advantage of the storage rain during the drought.In other words,sponge city,which is similar to the low impact development,water sensitive urban design and green infrastructure,is a concept of rainwater management and utilization.This paper is on the basis of analysis and research of low impact development,water sensitive urban design,green infrastructure and sponge city concept,regards the urban underlying surface as the important research subject,simulated urban underlying surface made by mixed clay and sand with different proportions,through the hour maximum rainfall of central urban district in Ganzhou to study the pollution reduction and closure effect of the underlying surface with different permeability.The results shows that the storage and infiltration rate is about 40.22% when the ratio of permeable and impermeable underlying surface is 3:1,When the ratio is 4:1,the rate is above 50%.In general,the underlying surface removal rate of pollutants is positively correlated with its storage and infiltration rate.The SS removal effect of permeable underlying surface is obvious,for COD,NH₄-N,Pb and TP have some certain removal effect.In the end,taking a residential area in Ganzhou to put forward the planning and design strategy of urban underlying surface in three aspects: control and transform impervious underlying surface area,increase the permeable underlying surface proportion and optimize permeable underlying surface.