The inequitable exposure of socially vulnerable groups to water shortages across the United States

Socially vulnerable populations in the United States are bearing the highest costs of water scarcity, which is likely to worsen with climate change, population growth, and growing disparities between areas with high water demand and the location of available supplies. Prior research showing that socially vulnerable groups are inequitably exposed to water shortages has focused on singular dimensions of social vulnerability, typically in relatively localized geographies, leaving us with an incomplete understanding of the national scope of the shortage risks. This study combines data on surface water shortages with the U.S. Center for Disease Control's Social Vulnerability Index (SVI) to spatially identify clusters of high-shortage, high-vulnerability hotspots from 71 195 census tracts across the conterminous United States. We estimate that 5 percent of the population of the lower 48 states-nearly 15 million people-lives in high-SVI, high-shortage hotspot areas. We examine the relationship between exposure to water shortage and (a) SVI, (b) SVI themes, and (c) 15 indicators used to construct SVI across the U.S. and within hotspots. We find evidence that water shortages constitute an environmental injustice, as multiple dimensions of social vulnerability are disproportionately exposed to water shortages. However, the distinct dimensions of vulnerability that are correlated with a higher probability of exposure to water shortage vary across regions and within hotspots, indicating that adaptation strategies will have to be tailored to their specific contexts. This statement is to certify that all Authors have seen and approved the manuscript being submitted. We confirm that the article is the Authors' original work and that we have no conflicts of interest.

Automated summary

Socially vulnerable populations in the United States bear the highest costs of water scarcity, but prior research has only focused on singular dimensions of vulnerability, leaving an incomplete understanding of the national scope of shortage risks. This study combines data on water shortages with the Social Vulnerability Index (SVI) to identify hotspots of high shortage and vulnerability across the country. The study found that approximately 15 million people in the lower 48 states live in high-SVI, high-shortage areas. Water shortages disproportionately affect socially vulnerable groups, but the specific dimensions of vulnerability vary across regions and hotspots, requiring tailored adaptation strategies.