Characteristics and control of urban rainfall-runoff in mountainous city
山地城市暴雨径流污染特性及控制对策

In order to understand pollutant characteristics of urban storm runoff in mountainous city,and enrich basic data which was still weak in our country,four storm events were investigated and samples from four kinds of land surfaces were analyzed.The concentrations of TSS,COD,TP,TN and NH3-N were monitored.The results showed that the early 2～3 mm and 1.8 mm runoff should be controlled for traffic road with slope 2.5% and campus sidewalk with slope 30% correspondingly from the point of view of pollutant concentrations reduction.Concentrations of pollutants from road and campus sidewalk reduced quickly with the prolongation of rainfall time.The steeper the slope was,the faster the pollutant concentration reduced.With regard to the average concentration,all pollutants from campus roof and lawn met class V surface water standard except TN and NH3-N,which was the same with TP concentration from traffic road and campus pavement.However,concentrations of COD,TN and NH3-N from traffic road and campus pavement were 2～8,1.9～3.1 and 1.9～4.3 times higher than class V surface water standard respectively.As regard to runoff from traffic road,the ratio of average concentration to initial consistence of TN,TP and NH3-N and the reduction rate of pollutant concentrations after runoff occurred 20 minutes during a single rainfall event were similar to each other(i.e.,0.5～0.53 and 50%～55%),while the same property for COD and TSS were 0.35～0.37 and 78%～84%,respectively.The rate of concentration decrease for every pollutant monitored when the runoff from campus sidewalk had started for 20 minutes could all exceed 90%(i.e.,90%～96%) and the ratio of average concentration to initial consistence of all pollutants investigated was close to each other(i.e.,0.3～0.4).A reference of runoff pollution control in mountainous city was given in this study.