Department of Civil and Environmental Engineering, Shiraz University, Shiraz, Iran.
Department of Civil and Architectural Engineering, Sultan Qaboos University, Muscat, Oman.
J Environ Manage. 2023 May 15;334:117463. doi: 10.1016/j.jenvman.2023.117463. Epub 2023 Feb 18.
As a critical element in preserving the health of urban populations, water distribution systems (WDSs) must be ready to implement emergency plans when catastrophic events such as contamination events occur. A risk-based simulation-optimization framework (EPANET-NSGA-III) combined with a decision support model (GMCR) is proposed in this study to determine optimal locations for contaminant flushing hydrants under an array of potentially hazardous scenarios. Risk-based analysis using Conditional Value-at-Risk (CVaR)-based objectives can address uncertainties regarding the mode of WDS contamination, thereby providing a robust plan to minimize the associated risks at a 95% confidence level. Conflict modeling by GMCR achieved an optimal compromise solution within the Pareto front by identifying a final stable consensus among the decision-makers involved. A novel hybrid contamination event grouping-parallel water quality simulation technique was incorporated into the integrated model to reduce model runtime, the main deterrent in optimization-based methods. The nearly 80% reduction in model runtime made the proposed model a viable solution for online simulation-optimization problems. The framework's capacity to address real-world problems was evaluated for the WDS operating in Lamerd, a city in Fars Province, Iran. Results showed that the proposed framework was capable of highlighting a single flushing strategy, which not only optimally reduced risks associated with contamination events, but provided acceptable coverage against such threats, flushing 35-61.3% of input contamination mass on average, and reducing average time-to-return to normal conditions by 14.4-60.2%, while employing less than half of the initial potential hydrants.
作为保护城市人口健康的关键因素，供水管网系统（WDS）必须准备好在发生污染等灾难性事件时实施应急预案。本研究提出了一种基于风险的仿真优化框架（EPANET-NSGA-III）与决策支持模型（GMCR）相结合的方法，以在一系列潜在危险的情况下确定污染物冲洗消防栓的最佳位置。基于条件风险价值（CVaR）的风险分析可以解决关于 WDS 污染模式的不确定性问题，从而提供一个稳健的计划，以在 95%置信水平下最小化相关风险。通过 GMCR 的冲突建模，通过确定相关决策者之间的最终稳定共识，在 Pareto 前沿内实现了最优折衷解决方案。一种新的混合污染事件分组-并行水质模拟技术被纳入综合模型中，以减少模型运行时间，这是优化方法的主要障碍。模型运行时间几乎减少了 80%，使得所提出的模型成为在线仿真优化问题的可行解决方案。该框架解决实际问题的能力在伊朗法尔斯省拉默德市的 WDS 中进行了评估。结果表明，所提出的框架能够突出显示单个冲洗策略，该策略不仅可以优化降低与污染事件相关的风险，而且可以提供对这些威胁的可接受的覆盖范围，平均冲洗输入污染质量的 35-61.3%，同时将平均恢复正常条件的时间减少 14.4-60.2%，而使用的初始潜在消防栓数量不到一半。
