Cavadini Giovan Battista, Rodriguez Mayra, Cook Lauren M
Department of Urban Water Management, Swiss Federal Institute for Aquatic Research (Eawag), Überlandstrasse 133, 8600, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, John-von-Neumann-Weg 9, 8049, Zürich, Switzerland.
Department of Urban Water Management, Swiss Federal Institute for Aquatic Research (Eawag), Überlandstrasse 133, 8600, Dübendorf, Switzerland.
J Environ Manage. 2024 Aug;365:121465. doi: 10.1016/j.jenvman.2024.121465. Epub 2024 Jun 19.
By infiltrating and retaining stormwater, Blue-Green Infrastructure (BGI) can help to reduce Combined Sewer Overflows (CSOs), one of the main causes of urban water pollution. Several studies have evaluated the ability of individual BGI types to reduce CSOs; however, the effect of combining these elements, likely to occur in reality, has not yet been thoroughly evaluated. Moreover, the CSO volume reduction potential of relevant components of the urban drainage system, such as detention ponds, has not been quantified using hydrological models. This study presents a systematic way to assess the potential of BGI combinations to mitigate CSO discharge in a catchment near Zurich (Switzerland). Sixty BGI combinations, including four BGI elements (bioretention cells, permeable pavement, green roofs, and detention ponds) and four different implementation rates (25%, 50%, 75%, and 100% of the available sewer catchment area) are evaluated for four runoff routing schemes. Results reveal that BGI combinations can provide substantial CSO volume reductions; however, combinations including detention ponds can potentially increase CSO frequency, due to runoff prolongation. When runoff from upstream areas is routed to the BGI, the CSO discharge reductions from combinations of BGI elements differ from the cumulative CSO discharge reductions achieved by individual BGI types, indicating that the sum of effects from individual BGI types cannot accurately predict CSO discharge in combined BGI scenarios. Moreover, larger BGI implementation areas are not consistently more cost-effective than small implementation areas, since the additional CSO volume reduction does not outweigh the additional costs. The best-performing BGI combination depends on the desired objective, being CSO volume reduction, CSO frequency reduction or cost-effectiveness. This study emphasizes the importance of BGI combinations and detention ponds in CSO mitigation plans, highlighting their critical factors-BGI types, implementation area, and runoff routing- and offering a novel and systematic approach to develop tailored BGI strategies for urban catchments facing CSO challenges.
通过渗透和截留雨水，蓝绿基础设施（BGI）有助于减少合流制溢流（CSO），而合流制溢流是城市水污染的主要原因之一。多项研究评估了单一类型的蓝绿基础设施减少合流制溢流的能力；然而，这些要素组合在实际中可能产生的效果尚未得到充分评估。此外，城市排水系统的相关组件（如滞洪池）减少合流制溢流的潜力尚未通过水文模型进行量化。本研究提出了一种系统方法，用于评估瑞士苏黎世附近一个集水区内蓝绿基础设施组合减轻合流制溢流排放的潜力。针对四种径流路径方案，评估了60种蓝绿基础设施组合，其中包括四种蓝绿基础设施要素（生物滞留池、透水路面、绿色屋顶和滞洪池）以及四种不同的实施率（占可用下水道集水区面积的25%、50%、75%和100%）。结果表明，蓝绿基础设施组合能够大幅减少合流制溢流的水量；然而，由于径流延长，包括滞洪池的组合可能会增加合流制溢流的频率。当上游区域的径流流入蓝绿基础设施时，蓝绿基础设施要素组合减少的合流制溢流排放量与单一类型蓝绿基础设施实现的累积合流制溢流排放量减少量不同，这表明单一类型蓝绿基础设施的效果总和无法准确预测蓝绿基础设施组合场景下的合流制溢流排放量。此外，较大的蓝绿基础设施实施面积并不一定比较小的实施面积更具成本效益，因为额外减少的合流制溢流水量并不足以抵消额外成本。表现最佳的蓝绿基础设施组合取决于预期目标，即减少合流制溢流水量、降低合流制溢流频率或提高成本效益。本研究强调了蓝绿基础设施组合和滞洪池在合流制溢流缓解计划中的重要性，突出了其关键因素——蓝绿基础设施类型、实施面积和径流路径，并提供了一种新颖且系统的方法，为面临合流制溢流挑战的城市集水区制定量身定制的蓝绿基础设施策略。
