Abstract Urbanization modifies the hydrologic cycle, resulting in increased runoff rates, volumes, and peak flows in the drainage network. In this paper, the implementation of green roofs as source control solutions for mitigating the impacts of urbanization is analysed at the urban catchment scale. The hydrologic-hydraulic response of a 2 km2 urban basin is investigated under various implementation scenarios and rainfall characteristics. In particular, a distributed hydrologic model is employed to assess the impact of 4 spatially homogeneous installations of green roofs (25%, 50%, 75%, 100% of roofs area converted) when forced by 6 storms differing in both duration and return period. In addition, a spatially heterogeneous configuration is tested, with green roofs concentrated where the drainage network is more prone to high degrees of filling. Results show that implementing green roofs at the urban watershed scale can be considered a valuable strategy to reduce both flow peak and volume in urban drainage networks, although the approach is more effective for frequent storms of smaller magnitude. In addition, it is found that the urban system may respond non-linearly to the extent of green roofs implementation in terms of peak flow reduction at the network outlet, and that non-linearity is mainly related to the network being close to its flow convey capability. Finally, planning redevelopment efforts on the basis of local insufficiencies in network convey capacity has the potential of increasing the effectiveness of Low Impact Development solutions.

中文翻译：

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评估绿色屋顶在高洪水风险城市集水区缓解雨水径流的性能

摘要 城市化改变了水文循环，导致排水网络中径流速率、流量和峰值流量增加。在本文中，绿色屋顶作为源头控制解决方案以减轻城市化影响的实施在城市集水区进行了分析。在各种实施方案和降雨特征下研究了 2 平方公里城市流域的水文-水文响应。特别是，采用分布式水文模型来评估 4 个空间均匀的绿色屋顶装置（转换屋顶面积的 25%、50%、75%、100%）在受到持续时间和重现期不同的 6 场风暴的影响时的影响. 此外，还测试了空间异质配置，绿色屋顶集中在排水网络更容易出现高度填充的地方。结果表明，在城市流域尺度上实施绿色屋顶可以被认为是减少城市排水网络中流量峰值和流量的一种有价值的策略，尽管这种方法对于强度较小的频繁风暴更有效。此外，发现城市系统在网络出口峰值流量减少方面可能对屋顶绿化实施程度做出非线性响应，非线性主要与网络接近其流量输送有关。能力。最后，根据当地网络传输能力不足来规划重建工作有可能提高低影响开发解决方案的有效性。