Resilience framework for urban water supply systems planning

As the concept of resilience is becoming a criterion in planning, water utilities are seeking support and practical guidance to enhance their conventional risk-based planning processes. This paper presents a resilience framework for urban water supply systems planning during the transition towards integrated water resources management. Based on a synthesis of literature across engineering, ecological and social sciences, resilient system performance is defined using crossings of fail-safe and safe-fail thresholds as key indicators. System performance curves conceptually illustrate the capabilities withstanding, absorptive, restorative, adaptive, transformative, and anticipative (WARATA), during sudden and gradual disruptions. Sustainability goals are explicitly considered in the resilience framework, and the role of transformative and anticipative capabilities to facilitate transitions is discussed. Specifically, the desirability of physical design and predicted community consequences from performance impact and collapse can be used in resilience management to prioritize between fail-safe and safe-fail system capacities. Finally, key considerations for operationalizing the framework are summarized, including how issues related to social justice can be addressed when simulating performance and deriving metrics. While this paper focuses on urban water supply, the framework could be applied to other service-providing infrastructure where resilience-based planning supported by quantitative evidence is required to inform investments.