雨水花园对实际降雨径流的调控效果研究

基于海绵城市倡导的雨水自然积存、自然渗透、自然净化理念,根据西安地区降雨特征,设计建造了入渗型和防渗型两套雨水花园。2015~2017年对33场次降雨事件径流调控效果进行了监测分析。结果表明:(1)以原状土为填料的防渗型雨水花园设施水量削减率为11.2%~100%(中位数=69.14%);(2)污染物浓度超越概率分析结果显示,径流雨水经过雨水花园系统后,总氮、氨氮、总磷和化学需氧量出流浓度超过地表水环境质量标准Ⅳ类限制的概率,与入流浓度超过地表Ⅳ限制的概率相比,分别降低了58.57%,2.71%,20.57%和29.71%;(3)雨水花园设施场次径流水量削减率与污染物负荷削减率的相关关系在0.857以上;(4)通过监测的场次降雨量及系统进水和出水水质水量,估算的雨水花园系统年径流污染物浓度去除率为11.93%~60.97%,径流污染物年负荷削减率基本在70%以上。

Regulating Effect of Rain Garden on Actual Rainfall Runoff

Based on the concept of natural storage, natural infiltration, natural purification for rainwater advocated the sponge city, infiltration and seepage-proof rainwater gardens were designed and built according to the rainfall characteristics in Xi''an. We monitored the runoff regulating effects in 33 rainfall events from 2015 to 2017. The results showed that:(1) Seepage-proof rain garden filled with undisturbed soil reduced runoff volumes by 11.2%~100% (medium=69.14%). (2) The results of pollutant concentration exceedance probability analysis showed that the probabilities of concentrations of total nitrogen, ammonia nitrogen, total phosphorus and chemical oxygen demand exceed the limit standard IV of the surface water quality decreased by 58.57%, 2.71%, 20.57% and 29.71%, respectively, in the rainwater flows through the garden system, compared with the exceedance probabilities of inflow concentration. (3) The correlation coefficient between the runoff reduction rate and the pollutant load reduction rate was more than 0.857 for 33 rainfall events. (4) Through monitoring the precipitation, water qualities of inflow and outflow, we estimated that the annual pollutant concentration removal was 11.93%~60.97%, and the annual load of pollutants reduced more than 70% in the rainwater garden.