Vulnerability, Risk, and Mitigation Assessment of Water Supply Systems for Insufficient Fire Flows

Water supply systems' vulnerability toward physical, chemical/biological, and cyber threats has drawn significant attention to their potential failure. These systems are critical not only because they must provide sufficient water for "everyday" municipal users but they also must deliver significant flows and volumes of water with high reliability during emergencies such as pipe failures, power outage, and fires. In this study, a methodology is developed to determine the vulnerable components of a water distribution system with respect to a fire event by utilizing a risk based optimization procedure. Using this methodology, vulnerability analysis is performed for a water supply system under three scenarios: (1) accidental failure due to soil-pipe interaction, (2) accidental failure due to a seismic event, and (3) malevolent attack. Several mitigation strategies based on hardening of specific sets of water mains are evaluated through further simulation. Finally, the mitigation strategies are assessed with a benefit-cost analysis to complete the system risk analysis.