Study On Quantity And Quality Problem Of Stormwater Utilization Of Lawn

With the expanding of the city zone, the impervious ground areaincreases consequently. As a result, a large amount of rainfall runs out withoutfull utilization, the peak value of rainfall runoff is raised significantly and thesink flow time is shortened. To make use of rainwater in flood seasons is oneof the important measures for urban rainwater utilization, alleviation of urbanwater resources shortage and also an improvement of ecological environment.For example, retaining storm water runoff from imperious areas such as roofsand roads surface into leaching wells or lawns is good way for recharginggroundwater and adjusting runoff so that flood peak of river can be reducedand flood risks can be mitigated. In order to gather the rainfall to the largest extent, and convert the limited rainfallflood into useful water resources, the collection of the rainfall should be adapted tolocal conditions. When retaining storm water runoff to recharge groundwater,the impact of pollutants in rainwater on groundwater environment should befully examined in order to prevent ground water from pollution. In this thesis, through the research on the infiltration characteristic of soilunder different rainfall conditions and the relationship between rainfall andrunoff in residential quarter under the condition of designed rainstorm, therelationship between rainfall and runoff with different ratio of area to lawn andthe potential utilization in sunken-lawn with different lawn area under differenttypical year are studied. By comparing the simulation of the process of rainfalland runoff through using Hydrus model and F~f conceptual model, therainwater utilization modes and potential in residential quarter are discussed.Furthermore, based on the soil column experiments, the impact of storm wateraccumulation on the soil infiltration characteristics and the correspondingengineering measures are discussed. Based on the site data, the fluctuation of the pollutants concentration andwater quality of the road surface and roof surface runoff of Beijing City are IIanalyzed, and main influential factors are probed accordingly. Through theexperiments and study of the adsorption effect of soil particle on rainwaterpollutant, the saturated-unsaturated soil water movement model and pollutanttransportation model are established, and the purification ability of soil aquiferwith some thickness to the infiltration rainwater is estimated by applyingmathematic equation of solute movement and transportation in soil.Consequenlty, the soil relative safe use time of aquifer with various depthpolluted by heavy metals such as Hg, Cr, Cd, Pb and degradative pollutantssuch as NH4-N, COD is calculated. The results of soil column experiments areused to calibrate the pollutant adsorption and transfer parameters. By makinguse of the numerical simulation, the pollutant transformation situation and thepollution to the soil cross section under different pollutant load in storm wateraccumulation are analyzed. The results of this dissertation lay scientificfoundation for environmental impact assessment and the planning of rainfallutilization.