Study On Sponge Effect Of Urban Greenland

The instantaneous flood is a common phenomenon in the rainy season which seriously affects people's normal travel and environmental safety.At the same time,how to dig the sponge effect of urban greenland,and adjust the capacity of urban greenland is the important aspect to achieve the built of the sponge City and to solve the problem of waterlogging and it is also an important vehicle to promote the construction of the sponge City.This paper takes Nanjing city as an example,explores the influence factors of the sponge effect of city greenland,put forward the optimization of green sponge effect strategy,and takies Tianbao Street ecological project in Nanjing Hexi Area as an example.The paper discusses the factors that affect the sponge effect of urban Greenland and study on the urban greenland and its sponge effect.And discuss the relationship between the sponge effect of the greenland and the landscape structure,forest canopy and litter layer,soil type,topography,elevation and greenland and groundwater level,land use types and drainage methods.The paper do a case study of Nanjing urban greenland.According to the different functions,the urban greenland in Nanjing is divided into five categories,park greenland,square greenland,subsidiary greenland,residential greenland and traffic greenland.According to different vegetation structure,each sampling area divided into four types,called shrub grass combination,shrub grass,grass,flowers and a combination.In the experiment using the ring method for the sampling points and sampling,detection of soil infiltration rate by double ring method.Through the analysis of the experiment,from the view of the vegetation structure,the complex structure of the tree and shrub grass is better.From the view of the green type,the five types of the Nanjing downtown greenland,the sponge effect of the subsidiary greenbelt and park greenland is higher,because their abundant structure are richer,their green conservation management are more in place,human disturbance is relatively small,so the effect of sponge are better.According to the characteristics of soil,the soil bulk density,porosity and water content can affect the soil infiltration and water storage capacity and finally affect the sponge effect of urban greenland.City greenland the smaller soil bulk density,total porosity is greater,the higher water content,permeability of the soil water holding capacity is stronger,the maximum water storage and water storage of soil is greater,the stable infiltration rate is higher,the better the sponge effect of city greenland.At the same time,it is found that the infiltration capacity of urban green land and the capacity of rainwater accumulation are limited.In addition to enriching the vegetation structure and optimizing the soil function can improve the sponge effect of urban greenland.If the drainage of greenland itself is limited,it can also involve in artificial sponge facilities in order to improve the soil infiltration performance and reduce the waterlogging disaster,improve the efficiency of urban rainwater management purposes.Because of the low-lying terrain,Nanjing Hexi Area is the hardest hit of urban waterlogging in recent years.Therefore,-the west of Hexi plate is chosen as the case study object.This paper explores the sponge effect of the greenland of the Tianbao street,and compares the sponge effect before and after the implantation of the artificial sponge.The study found that the vegetation can enrich the planting and application of road rainwater collecting and drainage technology,distribution and penetration technology to significantly improve infiltration and water holding capacity of greenland,so as to improve the effect of green sponge,self filling and reduce the irrigation water.Urban greenland is an important part of urban ecosystem.It is the key link in the management of rainwater storage,and the ability of water seepage and water purification and it is also the main content of the Sponge city building.Better use of the sponge effect of urban greenland can effectively alleviate urban waterlogging and improve urban soil environment and it also has positive significance on promoting the construction of sponge city.