| To collect and utilize rainwater resources in units of urban residential area, is an effective way to alleviate the shortage of urban water resources, reduce city floods and improve urban water environment.It is of great significance to evaluate available volume of stormwater resources in urban residential area.As a precondition,Laws of runoff producing and variation of runoff water quality on different underlying surface in urban residential area should be studied.In this research,experiments of rainfall-runoff process and changing process of runoff water quality on different underlying surface are carried out in an urban representitive residential area. The hydrological coefficients of underlying surface such as runoff coefficient and the discharge quantity of initial rainwater of each type of underlying surface are obtained. The evaluating method and modle of available volume of stormwater resources in urban residential area are proposed. The available volume of stormwater resources of normal flow year in urban residential area is evaluated.The main contents and achievements are as follows:1. Based on the study of domestic and foreign literature,the differences and connections among rainfall,rainfall runoff and the amount of stormwater resources are discussed.The concept and meaning of available volume of stormwater resources in urban residential area is defined. The evaluation method and modle of available volume of stormwater resources in urban residential area is proposed.2. By carrying out natural rainfall runoff producing and artificial rainfall runoff producing experiment in urban residental area,the process of rainfall and runoff producing on different underlying surface is studied,and runoff producing laws of various underlying surface under different condition of precipitation and rainfall indensity have been obtained.In the process of precipitation and runoff,there exist a trend of linear increase between precipitation and runoff, and a trend of logarithmic increase between the runoff coefficient and precipitation on different types of underlying surface.Runoff intensity and rainfall intensity demonstrate a consistency trend,and runoff intensity presents a hysteretic nature. The average of first loss and runoff coefficients of different types of underlying surface under the condition of different levels of rainfall are obtained.3. By carrying out runoff water quality experiment,the changing process of runoff water quality is studied and the changing laws of runoff water quality on different underlying surface are obtained.The rules of variation of runoff water quality is found that the air pollutants and contaminants on the underlying surface decrease in the process of rainfall and runoff.Rainfall pollutant concentration declines during rainfall process while runoff pollutant concentration on various types of underlying surface decreases during runoff process. According to changing laws of runoff water quality with runoff amount, the discharge quantity of initial rainwater at each type of underlying surface is ascertained.4. Based on acquired laws of runoff producing and variation of runoff water quality on underlying surface of residental area under different condition of rainfall process,daily precipitation files of normal flow year of the study area, hydrological parameters like first loss,runoff coefficient under different level of precipitation and discharge quantity of initial rainwater,as well as caculating modle,the stormwater resources of different underlying surface in the study area are evaluated. Result shows that in normal flow year,the amount of stormwater resources in the study area reaches 86750m3. |
