The Research About The Rain Flood Safety Of The Urban Rainwater Utilization

In modern society, the development pace of rural to urban is increasingly speeding up,but the water resource shortage, rain flood safety issues (floods, runoff pollution)followed byrapid development of urbanization has become the main factors which restrict thedevelopment of the city. So relieving and solving the problem of urban water resource andnatural water pollution caused by flood and runoff is of great significance, and this alsocauses the extensive concern of the state and society. Traditional utilization way of rainwatercan no longer meet the requirements. Through the rainwater drainage and treatment ofcombined system or separate system, the local rain water agglomeration phenomenon issolved and some pollutants are removed by collecting rain water treatment, but there aremany shortcomings. So how to control source and the economic and environmental runoffreduction system gradually has become the mainstream of rain water utilization in this age.It was analyzed that the urbanization of rainwater brings safety hazards in the paper.Rainfall in Beijing was taken as an example. The characteristics of rainfall runoff in Beijingand pollution condition and so on were studied. Then they were studied that the underlyingsurface system of rainwater runoff and runoff pollutants reduction effect. At the same time,and alleviating security and solutions were simply analyzed and expounds.According to the research, rainwater in Beijing is mainly concentrated in the summer.Under the rainfall returning period of original pipe network, floods occur frequently.Besides，the pollutant concentration of the Initial rainfall runoff is very high and is beyond the qualitystandard of the Ⅴ class surface water.If the pollutants were into natural water bodies, itwould be easy to exceed water self-purification capacity, causing serious pollution. Butthrough the analysis of the characteristics of rainwater runoff, the water quality is graduallygetting better when the rainfall duration is up to10~20min. And it can be recycled aftersimple treatment. If initial rainwater can be processed in situ treatment, the runoff and thepollutants would be reduced.Under laboratory conditions, reduction of the role of rainwater runoff and pollutantsfrom different underlying surfaces system (permeable brick underlying surface, green spaceunderlying surface) was studied in the paper. The results show that the reduction effect ofgreenbelt system for rainwater runoff is better than the glass underlying surface andpermeable brick pavement underlying surface. And the removal effect of runoff pollutantsfrom greenbelt system is also good. The removal rate of COD is from52.9%to74.1%; SSremoval efficiency is from53.9%to66.2%; removal effect on total nitrogen is from46.9%to60.9%; removal rate of TP is from42.5%to60.1%.And it is showed that, removal rate of the Greenbelt soil pollutants gradually increased with increasing soil thickness. The optimumthickness is70~100cm.To the solution to security issues, the rain-engineering and non-engineering combiningtheory was put forward. In order to mitigate and resolve rainwater security issues, it would beused as the principle that national polices and rainwater management techniques rainwateraccumulation. That is to say, the State Legal Policy is guide, combined with the managementpolicy of rainwater runoff, using rainwater accumulating technology, and multi-partycooperation and macro-control.The establishment of social management, eco-green space system and the coexistence ofa variety of regulating way can promote social, economic and ecological development.