Inconsistencies emerge between regional and local-scale water security metrics at military installations

Abstract Recent United States federal policy for military installations has emphasized the importance of developing a standardized approach for water security assessment to monitor changes in water resources and the ability for an installation to meet both its civilian and mission needs. For military installations in the United States, these assessments must consider demands both inside and outside the installation’s fence line, as regional resources are required to meet mission readiness. Focusing on physical water scarcity, this study compares four water security metrics with unique formulations and spatial resolutions, including an installation-scale metric and multiple regional metrics defined for either baseline conditions or the future. We evaluate these metrics across thirty United States Air Force installations and find little congruency. Notably, the two future metrics we consider both include indicators for seasonal variability and interannual variability, however there is no correlation in these indicators between the two metrics. Using three Air Force installations as case studies, we evaluate how variability across water security metrics can lead to inconsistent representations of water security, causing ambiguity for decision-makers who rely on these assessments. We emphasize the importance of incorporating both site-specific and regional indicators of water security rather than relying upon a single, aggregate metric of water security.