Practical Study On Urban Rainfall Runoff LID-BMPs

With the acceleration of urbanization, a large number of original natural permeablesurface is replaced by impermeable surface such as buildings, plazas, parking lots and soon. A dramatic change has taken place in original rainfall-runoff-converge-outflow process,a lot of rain can not permeate into the ground so that the flow rate of surface runoffincreases. With the expansion of the city day by day, the increase of the population densityleads to more accumulation of pollutants, these pollutants are washed into the river nearbyby the rain, which causes serious pollution of river water quality. In order to reduce andalleviate the problems of urban waterlogging, non-point source pollution and urban watershortages caused by rainfall runoff, people begin to change the traditional developmentmodel and use the development model which is closer to the nature, so LID-BMPs (LowImpact Development Best Management Practices) becomes a research hotspot.With further research and the development of computer technology, research of urbanrainfall runoff and the modeling software combine with each other more and more tightly.However, as China is still in its infancy in this regard, there are few cases of simulatingLID-BMPs measures by using the modeling software in practical engineering and there aremany researches of control effect of the water quantity but few researches of control effectof water quality. Therefore, in order to enrich the LID-BMPs measures’ practicalapplications combined with modeling software, this research has been carried out.In this research, the central part of Tongli Town is chosen to be the research object,simulation principles of SWMM modeling is studied deep. Based on the analysis ofpollutant sources and characteristics in the research area, the pre-development land uselayout scenario, LID-BMPs1land use layout scenario, LID-BMPs2land use layoutscenario, LID-BMPs3land use layout scenario and LID-BMPs4land use layout scenariohave been designed for the research area. Corresponding SWMM model has beenestablished including the runoff system model, accumulation and erosion of pollutantsmodel, delivery system model and LID modules model. The accuracy of the builded modelhas been verified by detecting the concentration of runoff pollutants during a typicalrainfall.The rainfall runoff control effect of LID-BMPs measures has been simulated by usingthe established model in different rainfall intensities, different rainfall types of peakposition and different LID-BMPs land use layout scenarios. It is proved that, LID-BMPs measures have effect on controlling the quantity andquality of rainfall runoff in different rainfall intensities, different rainfall types of peakposition and different LID-BMPs land use layout scenarios. Meanwhile, it also shows thatLID-BMPs measures have a certain range; rain peak position does not influenceLID-BMPs measures’ effect on controlling the quantity and quality of rainfall runoff; indifferent LID-BMPs land use layout scenarios, the LID-BMPs measure has the best effecton controlling the quantity and quality of rainfall runoff combined with Rain Garden,Grass Swale, Porous Pavement and Green Roof, and it is close to the level of thepre-development land use layout scenario.