| Analysis and research on 11 sessions of rainfall runoff process of urban rainfall experiment in Xi`an and artificial rainoff experiment,summarizes the urban rainfall runoff characteristics in xi`an,including the variation of the rainfall runoff pollutant concentration with rainfall,runoff pollutants concentration distribution,pollutants erosion features.And estimated the amount of rainfall runoff pollutant load per year in Xi`an.Also studied the feasibility and value of artificial rainfall experiment in urban runoff pollution research.The results show that:(1) The results of urban rainfall experiment in Xi`an show that,Most sources of runoff pollution is the city dust that below 2mm.Under the heavy rain conditions,traffic main road runoff pollution situation is more seriously than the road in living area,runoff pollution situation of old asphalt roof in living area is more seriously than the the new building cement roof in living area.It indicated fully that violent social activity and the roof of asphalt materials had greater pollution potential,and the most pollutant concentration of the rainfall runoff is exceed the national surface water quality standard(GB3838-2002) in Grade V standard,and the water quality is worse than Grade V.(2) The results of the rainfall runoff pollution characteristics analysis show that under the heavy rain condition,the rainfall runoff scouring the urban under surface heavly,pollutant concentration change quickly;there is on direct relationship between session rainfall runoff pollutant concentration average and rainfall intensity or rainfall prcipitation,and rainfall runoff experiments present first flush phenomenon.(3) According to the test data of urban rainfall experiment in Xi`an,estimated the urban runoff pollution load from august 2013 to august 2014 in Xi`an,and the pollution load of SS、COD、NH3-N、TN、TP、Cu and Zn is 14731.80t、7890.46t、37.76t、910.13t、54.50t、1.04t、5.19 t respectively,so that it explained that the rainfall runoff pollution in Xi ’an is more seriously.(4) The results of the artificial rainfall experiment shows that its representation of eigenvalues are more poor than the urban rainfall experiment,the reason is that the test parameters of artificial rainoff experiment is not accurate enough.But its relationship between session rainfall runoff pollutant concentration avera ge and rainfall intensity or rainfall precipitation is the same to the results of urban rainfall experiment.(5) Through the source control and migration pathways,analyzed the control methods of urban rainfall runoff pollution in Xi`an,and improve the utilization of rainwater resources. |
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