绿色屋面径流量控制效果评估方法研究

Study on Evaluating Runoff Volume Capture Performance of Green Roof

由于降雨的随机性,次降雨的绿色屋面径流量控制率存在较大差异,若干场次降雨的径流削减实测无法反映绿色屋面长期的径流削减效果。为客观评估绿色屋面径流量控制能力,基于绿色屋面装置实验,提出了根据蒸发蒸腾特征分段的绿色屋面水量平衡模型。在此基础上,根据15年的降雨资料,建立降雨特征参数概率分布模型,通过蒙特卡洛随机抽样方法进行不同降雨下绿色屋面径流量控制率计算,从而建立了绿色屋面径流量长期控制效果与能力的评估方法。通过对杭州市绿色屋面的评估表明:杭州市绿色屋面在10~3月和4~9月的径流量控制率分别为50.9%、69.2%。该评估方法能有效避免随机降雨与季节对绿色屋面性能的影响,评价结果具有全面性和科学性。

Because of the randomness of rainfall characteristics, the volume capture ratio of runoff for green roof vary largely in different precipitation events. It is not justifiable to evaluate the long-term average retention of green roofs with limited precipitation events. Water balance model was established to evaluate the volume capture ratio of runoff for green roofs, and the period was divided into stages according to the evapotranspiration characteristics of green roof setups. Based on the 15 years’ historical rainfall data, the probabilistic model of local rainfall characteristics was introduced. The volume capture ratio of runoff for individual precipitation events were calculated based on Monte-Carlo method, and then the long-term average hydrologic performance of green roof was determined. The results show that green roof’s volume capture ratio of runoff is 50.9% from Oct. to Mar. and 69.2% from Apr. to Sep. in Hangzhou. This method excludes the effect of randomness which are associated with precipitation events and seasons, and the result is comprehensive and scientific.