Rodriguez Mayra, Cavadini Giovan Battista, Cook Lauren M
Department of Urban Water Management, Swiss Federal Institute for Aquatic Research, Dübendorf, Switzerland.
Department of Urban Water Management, Swiss Federal Institute for Aquatic Research, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Switzerland.
Water Res. 2024 Apr 1;253:121284. doi: 10.1016/j.watres.2024.121284. Epub 2024 Feb 6.
Green stormwater infrastructure (GSI) is growing in popularity to reduce combined sewer overflows (CSOs) and hydrologic simulation models are a tool to assess their reduction potential. Given the numerous and interacting water flows that contribute to CSOs, such as evapotranspiration (ET) and groundwater (GW), these models should ideally account for them. However, due to the complexity, simplified models are often used, and it is currently unknown how these assumptions affect estimates of CSOs, GSI effectiveness, and ultimately planning guidance. This study evaluates the effect on estimates of CSOs and GSI effectiveness when different flows and hydrologic processes are neglected. We modified an existing EPA SWMM model of a combined sewer system in Switzerland to include ET, GW, and upstream inflows. Historical rainfall data over 30 years are used to assess volume and duration of CSOs with and without three types of GSI (bioretention basins, permeable pavements and green roofs). Results demonstrate that neglect of certain flows in modelling can alter CSO volumes from -15 % to 40 %. GSI effectiveness also varies considerably, resulting in differences in simulated percent of CSO volume reduced from 8 % to 35 %, depending on the GSI type and modeled flow or process. Representation of GW within models is particularly crucial when infiltrating GSI are present, as CSOs could increase in certain subcatchments due to higher GW levels from increased infiltration. When basing GSI planning decisions on modeled estimates of CSOs, all relevant hydrologic processes should be included to the extent possible, and uncertainty and assumptions should always be considered.
绿色雨水基础设施（GSI）在减少合流制污水溢流（CSO）方面越来越受欢迎，水文模拟模型是评估其减排潜力的一种工具。鉴于导致合流制污水溢流的水流众多且相互作用，如蒸发散（ET）和地下水（GW），理想情况下这些模型应将它们考虑在内。然而，由于其复杂性，通常使用简化模型，目前尚不清楚这些假设如何影响合流制污水溢流的估计、绿色雨水基础设施的有效性以及最终的规划指导。本研究评估了忽略不同水流和水文过程时对合流制污水溢流估计和绿色雨水基础设施有效性的影响。我们修改了瑞士一个合流制排水系统现有的美国环境保护局暴雨管理模型（SWMM），以纳入蒸发散、地下水和上游入流。利用30年的历史降雨数据评估有无三种类型绿色雨水基础设施（生物滞留池、透水路面和绿色屋顶）时合流制污水溢流的水量和持续时间。结果表明，建模时忽略某些水流会使合流制污水溢流的水量变化-15%至40%。绿色雨水基础设施的有效性也有很大差异，根据绿色雨水基础设施的类型以及建模的水流或过程，模拟的合流制污水溢流减少百分比差异在8%至35%之间。当存在渗透型绿色雨水基础设施时，模型中对地下水的表示尤为关键，因为由于渗透增加导致地下水位升高，某些子汇水区的合流制污水溢流可能会增加。在基于合流制污水溢流的模型估计做出绿色雨水基础设施规划决策时，应尽可能纳入所有相关的水文过程，并且始终要考虑不确定性和假设。
