Pollution And Management Researches On Urban Rainfall Runoff From Impervious Surfaces In Suzhou New District

With the rapid development of economic and the improvement in the urbanizationlevel,the area of impervious surfaces increases continuously, which brings about even moreserious urban stormwater problems.The urban runoff from impervious surfaces, especiallyat the initial stage of rain, carries volume of pollutants drain to the urban rivers and effectssuch as ecological damage, environmental pollution.At present, most of cities face theproblem of pollution-induced water shortage or water resources shortage, but the rainwaterutilization has not even begun in some areas.The region of research in the paper is Suzhou New District, and the analysis wasgiven to the quality of rainfall and runoff at different underlying surfaces, in order tomaster the characteristics of rainfall runoff pollutant from impervious surfaces. It issignificant to provide a basis reference for the development of effective control measuresof runoff and rational utilization of rainfall resources to solve the problem of urbanrainfall.According to the main types of imervious surfaces of Suzhou, the paper choses theasphalt pavement and three roofs with different materials (cement,tile,asphalt) as typicalgathering ground of the urban rainfall runoff. Analysis on the quality of rainfall from fourpoints and the main results of this paper are shown as followed:(1) The roof runoff quality is better than the urban road runoff quality,the roof runoffis made up of oxygen consuming matter and solid particulate matter. And thecontamination degree of roof runoff differs greatly with its materials. Comparativelyspeaking, water quality of road runoff is comlex and poor. The road runoff water qualityobjectives such as COD, SS, TN, TP, etc are highest.(2) Although the pollutant concentration of runoff changes along with the course ofrainfall process,the general trend is that the rainfall runoff is more seriously polluted at theinitial stage of rainfall; thepollutant concentration could reach very high level.As rainfalldurationextends, the pollutant concentration dropsstep by step until it is stabilefinally.(3)The influence factors of runoff quality is complex,such as rainfall intensity, dryperiods, properties of runoff surface, druation and volume of rainfall,temperature,season,ect conditions have observably influence on the quality of runoff, especially at the initialrainfall.(4) Normally, there is a fine linear correlation relation between the SS value and theCOD value, when it is not the same time of rainfall event and sampling point, the level of relevance is different. The correlations among different pollutants are significant. So thereduction of SS source can decrease the other pollutant loads.(5) The important influence factors of the first flush effect are rainfall intensity andamount of precipitation. Different intensitys of rainfall affect the first flush to a differentdegree. The greater intensity of rainfall affects the first flush more heavily.Thecontaminants have the different degree of first flush,and the first flush of SS, CODCrismost evident in general.(6)Finally, the article puts forward some measures to do well in the managementpractice of urban runoff pollution and the rainwater utilization in Suzhou New Districtwhich base on the characteristic of Suzhou and experimental results.