山地城市典型硬化下垫面暴雨径流初期冲刷研究

为了解山地城市典型硬化下垫面暴雨径流初期冲刷效应,对山城重庆的8场暴雨进行了径流全过程监测,并与平原城市作了对比分析.结果表明:TSS(总悬浮物)、COD和TP来自城市交通干道的贡献较混凝土屋面大,而TN、NH3-N两者相当;对于重金属,除Cd外,城市交通干道重金属的EMC(Event Mean Concentration)值均高于混凝土屋面.城市交通干道,初期40%的暴雨径流携带了53%±16%TSS,66%±10%COD,59%±2%TN,58%±2%NH3-N,51%±5%TP;而混凝土屋面,初期40%的暴雨径流携带了64%±20%TSS,66%±17%COD,55%±14%TN,52%±14%NH3-N,56%±3%TP,建议两类硬化下垫面至少以初期40%的暴雨径流作为控制量.与平原城市相比,山地城市交通干道初期40%的暴雨径流携带污染负荷TSS与COD的比例比平原城市分别高出16%和22%,初期冲刷效应更加明显.

Study on the first flush effect of impervious underlying surface in a mountainous city

In order to reveal the first flush effect of mountainous cities, eight rainfall events were selected to monitor the quality of the stormwater runoff in Chongqing city,which is regard as a typical mountainous city. The results, which were analyzed by comparing the data in plain cities, showed that the traffic road posed much higher contribution in TSS, COD and TP, though the traffic road and the concrete roof posed the same contribution in TN and NH₃-N; the EMC values of heavy metals from the traffic road were higher than that from the concrete roof except Cd. For the traffic road, 53%±16% TSS, 66%±10% COD, 59%±2% TN, 58%±2% NH₃-N, 51%±5% TP were found in the initial 40% of the stormwater runoff; while 64%±20% TSS, 66%±17% COD, 55%±14% TN, 52%±14% NH₃-N, 56%±3% TP from the concrete roof; therefore, it should be an effective way in controlling the stormwater runoff pollution by collecting and treating the initial 40% runoff. The pollution of TSS and COD in the initial 40% of the stormwater runoff, were 16% and 22% higher than the plain cities, indicating the first flush effect is more obviously.