Dipartimento di Ingegneria civile, ambientale e architettura-Sezione Idraulica, Facoltà di Ingegneria Università degli Studi di Cagliari, Cagliari (CA), Italy.
PLoS One. 2021 Jan 29;16(1):e0246429. doi: 10.1371/journal.pone.0246429. eCollection 2021.
Flooding risk in cities has been recently exacerbated by increased urbanization and climate change, often with catastrophic consequences in terms of casualties and economic losses. Rainwater harvesting systems and green roofs are recognized as being among the most effective blue-green mitigation measures. However, performances of these systems have currently been investigated only at laboratory or very-small local scales. In this work, we assess the potential benefit of the extensive installation of these solutions on all the rooftops of 9 cities, with different climatological and geographical characteristics. Both surface discharge reduction and delay between rainfall and runoff peak generation have been investigated. Green roofs ensure a larger average lag time between rainfall and runoff peaks than rainwater harvesting systems, without significant differences between intensive and extensive structures. On the other hand, the cost-efficiency analysis, considering the entire urban area, shows a higher retention capacity with a lower financial investment for rainwater harvesting rather than for green roofs in most cases. For extreme rainfall events, large-scale installation of rainwater harvesting systems coupled with intensive green roofs over the entire city have shown to be the most efficient solution, with a total discharge reduction that can vary from 5% to 15%, depending on the city characteristics and local climate.
城市内涝风险最近因城市化和气候变化而加剧，这通常会导致人员伤亡和经济损失等灾难性后果。雨水收集系统和绿色屋顶被认为是最有效的蓝绿缓解措施之一。然而，这些系统的性能目前仅在实验室或非常小的局部尺度进行了研究。在这项工作中，我们评估了在具有不同气候和地理特征的 9 个城市的所有屋顶上广泛安装这些解决方案的潜在好处。研究了表面排放减少和降雨与径流峰值产生之间的延迟。与雨水收集系统相比，绿色屋顶确保了更大的平均滞后时间，降雨和径流峰值之间的差异不明显，无论是密集型还是扩展型结构。另一方面，考虑整个城市区域的成本效益分析表明，在大多数情况下，雨水收集系统的储水能力更高，投资成本更低。对于极端降雨事件，在整个城市范围内大规模安装雨水收集系统并辅以密集型绿色屋顶被证明是最有效的解决方案，总排放量减少幅度可在 5%至 15%之间变化，具体取决于城市特征和当地气候。
