Abstract Characterising the unsaturated hydraulic conductivity of a green roof substrate is essential for accurately modelling runoff detention in response to rainfall events. In this paper, the unsaturated hydraulic conductivities for four representative green roof substrates were determined in an infiltration column using steady state and transient techniques. The conventional Durner-Mualem Hydraulic Conductivity Function (HCF) model, for which parameters were calibrated based on the measured Soil Water Release Curve (SWRC) data, was shown to provide a poor fit to the experimental data. A new three-segment HCF was, therefore, proposed to fit measured unsaturated hydraulic conductivity data. Detention tests were carried out on 100 mm and 200 mm deep substrates using four simulated storm events. The runoff and moisture content data collected during the detention tests was used to validate the HCFs using the Richards Equation. The new three-segment HCF resulted in simulated runoff and moisture content profiles that closely matched the measured data (with mean Rt2 = 0.754 for modelled runoff), in contrast to predictions made using the conventional Durner-Mualem model (with mean Rt2 = 0.409 for modelled runoff). It was also demonstrated that further simplification of the HCF to a function defined by moisture content at just two points – the saturated hydraulic conductivity and at an unsaturated hydraulic conductivity of 0.1 cm/min – provides a model that is fit-for-purpose for green roof runoff estimation (with mean Rt2 = 0.629 for modelled runoff).

中文翻译：

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不饱和水力传导率测量对绿色屋顶滞留建模的重要性

摘要 表征绿色屋顶基质的非饱和导水率对于准确模拟降雨事件造成的径流滞留至关重要。在本文中，使用稳态和瞬态技术在渗透柱中确定了四种代表性绿色屋顶基材的不饱和水力传导率。传统的 Durner-Mualem 水力传导函数 (HCF) 模型的参数是根据测量的土壤水分释放曲线 (SWRC) 数据校准的，结果表明与实验数据的拟合不佳。因此，提出了一种新的三段 HCF 来拟合测量的非饱和水力传导率数据。使用四个模拟风暴事件在 100 毫米和 200 毫米深的基材上进行了滞留测试。在滞留试验期间收集的径流和水分含量数据用于使用理查兹方程验证 HCF。与使用传统 Durner-Mualem 模型（平均 Rt2 = 0.409，对于模拟径流的平均 Rt2 = 0.754）相比，新的三段 HCF 产生了与测量数据密切匹配的模拟径流和水分含量剖面（平均 Rt2 = 0.409）。模拟径流）。还表明，将 HCF 进一步简化为仅由两个点的水分含量定义的函数——饱和导水率和 0.1 cm/min 的不饱和导水率——提供了一个适合绿色环保的模型屋顶径流估计（模拟径流的平均 Rt2 = 0.629）。与使用传统 Durner-Mualem 模型（平均 Rt2 = 0.409，对于模拟径流的平均 Rt2 = 0.754）相比，新的三段 HCF 产生了与测量数据密切匹配的模拟径流和水分含量剖面（平均 Rt2 = 0.409）。模拟径流）。还表明，将 HCF 进一步简化为仅由两个点的水分含量定义的函数——饱和导水率和 0.1 cm/min 的不饱和导水率——提供了一个适合绿色环保的模型屋顶径流估计（模拟径流的平均 Rt2 = 0.629）。与使用传统 Durner-Mualem 模型（平均 Rt2 = 0.409，对于模拟径流的平均 Rt2 = 0.754）相比，新的三段 HCF 产生了与测量数据密切匹配的模拟径流和水分含量剖面（平均 Rt2 = 0.409）。模拟径流）。还表明，将 HCF 进一步简化为仅由两个点的水分含量定义的函数——饱和导水率和 0.1 cm/min 的不饱和导水率——提供了一个适合绿色环保的模型屋顶径流估计（模拟径流的平均 Rt2 = 0.629）。与使用传统 Durner-Mualem 模型所做的预测相反（模拟径流的平均 Rt2 = 0.409）。还表明，将 HCF 进一步简化为仅由两个点的水分含量定义的函数——饱和导水率和 0.1 cm/min 的不饱和导水率——提供了一个适合绿色环保的模型屋顶径流估计（模拟径流的平均 Rt2 = 0.629）。与使用传统 Durner-Mualem 模型所做的预测相反（模拟径流的平均 Rt2 = 0.409）。还表明，将 HCF 进一步简化为仅由两个点的水分含量定义的函数——饱和导水率和 0.1 cm/min 的不饱和导水率——提供了一个适合绿色环保的模型屋顶径流估计（模拟径流的平均 Rt2 = 0.629）。