U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Water Systems Division, Water Resources Recovery Branch, Cincinnati, OH, USA.
School of Planning, University of Cincinnati, Cincinnati, OH, USA.
J Environ Manage. 2019 Apr 15;236:571-580. doi: 10.1016/j.jenvman.2018.12.089. Epub 2019 Feb 14.
Using combined sewer systems to handle excess stormwater runoff is common in older urban areas. Combined sewer overflow (CSO) events occur when hydraulic capacity is exceeded, and untreated wastewater discharges to surface waters. As urban population density increases, and more demand is placed on infrastructure, CSO events happen more often and cause serious environmental problems and public-health risks. Recently, green infrastructure (GI) has been integrated with existing gray infrastructure (GrayI) to reduce CSO events. However, there lacks a goal-oriented planning framework for eliminating CSOs at a watershed/sewershed scale. Moreover, existing stormwater simulations based on catchments or other geographic units, do not consider spatial variation within the unit, such as distribution, attribution, ownership, and management of GI. We propose a scenario-based Stormwater Management Planning Support System for CSOs (SMPSS-CSO) to provide a platform for reducing CSO events by coordinating parcel-based installations of GI. We applied the SMPSS-CSO to a sewershed with a single CSO location in Cincinnati, Ohio and developed four scenarios representing increased use of GI (rain barrels, green roofs, porous pavements, and detention basin) based on its cost, difficulty of installation, and property ownership. Runoff quantity, time of concentration, and peak flow rate were simulated using the curve number method. Our analysis shows a 41% reduction in stormwater runoff is necessary to eliminate CSO events for a two-year rainfall, required 97.25% of private and 27.59% of public parcels to install GI. GI alone cannot eliminate CSO events in this sewershed and must be incorporated with additional GrayI (e.g., storage tanks, pipes). The SMPSS-CSO has the potential for including multiple stakeholders' preferences and concerns in the searching for preferable scenarios.
利用合流制下水道系统来处理过多的雨水径流在旧城区很常见。当水力容量超过极限时，就会发生合流制污水溢流（CSO）事件，未经处理的废水排放到地表水中。随着城市人口密度的增加，对基础设施的需求也越来越大，CSO 事件发生的频率更高，造成了严重的环境问题和公共健康风险。最近，绿色基础设施（GI）已与现有的灰色基础设施（GrayI）相结合，以减少 CSO 事件。然而，在流域/下水道流域范围内消除 CSO 事件缺乏一个有针对性的规划框架。此外，现有的基于集水区或其他地理单元的雨水模拟并没有考虑到单元内的空间变化，例如 GI 的分布、归因、所有权和管理。我们提出了一个基于情景的雨水管理规划支持系统来减少 CSO 事件（SMPSS-CSO），该系统提供了一个平台，通过协调基于地块的 GI 安装来减少 CSO 事件。我们将 SMPSS-CSO 应用于俄亥俄州辛辛那提市一个只有一个 CSO 地点的下水道流域，并根据成本、安装难度和财产所有权，开发了四个代表增加 GI 利用的情景（雨水桶、绿色屋顶、多孔路面和调蓄池）。使用雨型法模拟了径流量、集流时间和峰值流量。我们的分析表明，需要减少 41%的雨水径流量才能消除两年降雨量的 CSO 事件，需要安装 GI 的私有地块为 97.25%，公有地块为 27.59%。在这个下水道流域，仅 GI 无法消除 CSO 事件，必须与其他 GrayI（例如，储油罐、管道）结合使用。SMPSS-CSO 有可能在寻找更优方案时纳入多个利益相关者的偏好和关注点。
