Assessing Population Vulnerability to Water Service Disruptions: A Targeted Index to Inform Infrastructure Planning and Management

Abstract

Water distribution systems are critical to the stability and well-being of communities but remain highly vulnerable to disruptions from natural disasters and aging. These disruptions do not impact all populations equally, making it essential to incorporate differential vulnerability into water infrastructure management and planning. A common method for assessing such disparities is the use of a social vulnerability index (SVI). Although various SVIs have been developed by researchers and government agencies, they are often generic—intended for general disaster preparedness or infrastructure challenges—and may omit key factors relevant to water service disruptions or include irrelevant ones. Consequently, these indices may not adequately identify areas critically vulnerable to water-related disruptions. This study develops a water-specific SVI to classify counties based on their vulnerability to water service interruptions. The index addresses the social vulnerability dimension of water disruption risk, capturing population sensitivity to disruptions and the characteristics that limit communities’ capacity to cope with and recover from them. Twenty-one relevant factors were selected and grouped into three categories: health-related, socioeconomic, and housing-related vulnerabilities. Principal component analysis (PCA) was used to reduce dimensionality, followed by Pareto ranking to construct the index. For comparison, an alternative version of the index was also developed using percentile ranking. The resulting water-specific SVI was compared with FEMA’s existing SVI to highlight the importance of a tailored index. Significant differences were observed. For example, several counties in the western US ranked as low or moderate vulnerability in FEMA’s index but were identified as highly vulnerable in our analysis due to aging infrastructure, high rental occupancy, and inadequate plumbing—factors not captured by FEMA’s SVI. The proposed SVI provides a more targeted tool for policymakers, urban planners, and emergency managers to prioritize investments, allocate resources effectively, and enhance the resilience of water infrastructure systems.