Green roofs (GRs) are well known for source control of runoff quantity in sustainable urban stormwater management. By considering the inherent randomness of rainfall characteristics, this study derives the probability distribution of rainfall retention ratio and its statistical moments. The distribution function of can be used to establish a unique relationship between target retention ratio ⁠, achievable reliability AR, and substrate depth h for the aleatory-based probabilistic (AP) GR design. However, uncertainties of epistemic nature also exist in the AP GR model that makes AR uncertain. In the paper, the treatment of epistemic uncertainty in the AP GR model is presented and implemented for the uncertainty quantification of AR. It is shown that design without considering epistemic uncertainties by the AP GR model yields about 50% confidence of meeting ⁠. A procedure is presented to determine the design substrate depth having the stipulated confidence to satisfy and target achievable reliability ⁠.

绿化屋顶（GRs）以可持续的城市雨水管理中径流量的源头控制而闻名。通过考虑降雨特征固有的随机性，本研究推导了降雨保持率及其统计矩的概率分布。的分布函数可用于在基于偶然性的概率（AP）GR设计中，目标保留率⁠，可实现的可靠性AR和衬底深度h之间建立唯一的关系。但是，AP GR模型中存在认知性质的不确定性，使得AR不确定。在本文中，提出了针对AP GR模型的认知不确定性的处理方法，并将其用于AR的不确定性量化。结果表明，不考虑AP GR模型的认识论不确定性的设计产生的满足⁠的信度约为50％。提出了确定具有规定置信度的设计基板深度的程序，该置信度满足并以可达到的可靠性为目标。