Exposure of urban food-energy-water (FEW) systems to water scarcity

Income and population growth increase demands for commodities such as food, energy, and water in cities. Water resources are used outside of cities to produce the food and energy goods that are eventually consumed in cities. In this way, urban water scarcity is impacted directly by local water shortages and indirectly by water scarcity in locations along the supply chain. Both direct and indirect water scarcity risks have important implications for urban water, food, and energy security. In this study, we develop a novel metric of the urban food-energy-water (FEW) nexus that quantifies both direct and indirect water scarcity exposure to urban areas. We quantify and visualize direct and indirect FEW water scarcity for 69 metropolitan statistical areas within the continental United States. We show that cities typically import commodities from nearby locations with similar water resource constraints, and generally have similar local and indirect water scarcity. In particular, cities in the western United States have scarce local water resources and also import commodities from other water-scarce western locations. This study improves our understanding of water scarcity exposure of critical food and energy resources in U.S. urban areas, enabling policy makers to improve the reliability of urban food and energy receipts.