Research On Utilizing Soil Depurating Urban Rainwater To Recharge Groundwater

Water is source of life. With the development of economy and increase of population, shortage of water resource increasingly becomes a kind of austere question faced by human being. China possesses of 22 percent of world population, but it only enjoys 6 percent of world water resource. There are above 400 cities shorting water in 668 cities of China. In order to satisfy increasing demand to water supply, some city blindly overexploits groundwater, which results in regional water level descending and induces ground sedimentation and crack geologic disaster. At the same time, with the development of urban constructing, area of impenetration is increasing year after year, which makes many seriously short of water city not taking full advantage of rainwater. It not only enormously wastes to precipitation, but also induces flood and waterlogging calamity. Therefore, if urban rainwater can be utilized to recharge groundwater, it not only can supply decreasing groundwater resource and prevent ground sedimentation and elevate groundwater level, but also can reduce expense of function and investment to drainpipe in city and lessen flood and waterlogging disaster at rainstorm.Whereas being influenced by environment factors and influx material characters, urban rainwater is polluted in some degree and its content of Chemical Oxygen Demand (COD) reaching thousands mg/L and containing some poisonous matter such as heavy metal etc. If this polluted rainwater is filled to ground, it must pollute groundwater. Therefore, cortroling contamination in rainwater is a hot potato in technology of manual recharge groundwater. Aiming at this question, the paper put forward utilizing layer of soil to depurating rainwater project. The paper researches the rule of soil depurating rainwater and ascertain measure of cortroling contamination, on the basis of which the paper put forward rainwater depurated by soil to manual recharging groundwater project.The paper's chapter 1 puts forward utilizing rainwater to recharge groundwater is the only way to improving environment of city, holding good water circulation system, balancing ecosystem and ensuring sustainable development. Chapter 2 analyses water quality and its effecting factor in different character influx zone and ascertains categories and changing extension of main contamination in rainwater. Chapter 3 and 4 researches soil depuratingfunction and rule to rainwater by soil columniation penetrating examination on the basis of the two former chapters. And it analyses the influence of soil structure, contamination burthen and penetrating deepness to depurating effect, and discusses contaminate cumulation and renewing ability of soil. Chapter 5 discusses soil depurating mechanism to contamination of rainwater. On the basis of examination chapter 6 puts forward the implementary project of utilizing rainwater to recharge groundwater after soil depurating contamination, which exampled by a living zone in Xi'an, and analyses its economic benefits.The research result of the paper indicates that utilizing manual soil dealing with rainwater can reach better depurating effect by reasonable designing and controling. In practical project, especially in the condition of soil with badly penetrating ability and lower groundwater level ,can adopt about one meter deepness manual soil laying on the greenbelt and can also design special manual soil depurating equipment around building to dealing with rainwater, which not only assures depurating effect but also saves occupying area and improves environment. The research results of the paper provides foundation to people rightly and rationally utilizing rainwater resource and controling pollution of not on the spot, and exploits a new effective way to the zone of lacking other recharging water source.