Enhancing Resilience of Intermittent Water Supply Systems to Power Outages

Abstract

An estimated 1.3 billion people in South Asia, Latin America, and Africa receive water for domestic purposes through piped networks for limited periods, referred to as intermittent water supply (IWS). Electricity intermittency is one of the main causes of water supply intermittency. In water supply systems, electrical power is used for pumping water from the sources to the treatment plants and then to users via the water distribution systems (WDSs). If the electrical power system fails to supply at WDSs pumping stations, this will lead to failure in water distribution systems. To ensure more sustainable IWS systems, evaluating and enhancing water infrastructure resilience is crucial. Understanding the underlying system’s inherent resilience is a prerequisite for enhancing its resilience. This study presents a novel approach for investigating the performance of an IWS system under power outage (modeled as pump failure) scenarios and identifying potential intervention strategies to enhance network resilience to limited power availability. The proposed methodology employs a two-step strategy: in the first step a global resilience analysis approach is used to investigate the performance of an IWS system under pump failure scenarios to identify and localize its main vulnerabilities. In the second step optimum adaptation intervention strategies are identified by the application of the evolutionary multiobjective optimization method. A nondominated sorting genetic algorithm (NSGA-II) is used for the optimum operation and rehabilitation of IWS systems considering three objectives: the operation and rehabilitation costs, the level of equity, and the proportion of effective supply hours. The results show that while the adaptation strategy of optimal operation intervention improved equity and effective supply hours slightly, the adaptation strategies of optimum operation and rehabilitation intervention significantly increased the system resilience to power outage/pump failure scenarios by improving both equity and effective supply hours.