WaterTalk: Water Resources and Food Supply Chains

Megan will discuss two recent papers related to her work assessing water resources and food supply chains

Part #1. Groundwater depletion embedded in domestic transfers and international exports of the United States

The United States plays a key role in global food security by producing and exporting agricultural products. Groundwater irrigation is increasingly important in agricultural production, nearly tripling since records began in 1950. Increased reliance on groundwater and prolonged unsustainable pumping of aquifers has led to groundwater depletion in many areas. In this study, we ask: How much groundwater depletion is embedded in the domestic transfers and international agricultural exports of the United States? How much do domestic and international agricultural commodity fluxes rely on unsustainable groundwater use? To address these questions we quantify the amount of nonrenewable groundwater that is incorporated into agricultural commodities produced in the U.S. and transferred both within the country and exported internationally. We find that the mass transfer of agricultural goods reliant on unsustainable groundwater decreased from 2002 to 2012, but their value in national and international supply chains increased by 54% and 31%, respectively. Our results underscore the importance of considering the long-term risks posed to global agricultural supply chains from  unsustainable groundwater use. 

Part #2. Food flows between counties in the United States

Food consumption and production are separated in space through flows of food along complex supply chains. These food supply chains are critical to our food security, making it important to evaluate them. However, detailed spatial information on food flows within countries is rare. The goal of this paper is to estimate food flows between all county pairs within the United States. To do this, we develop the Food Flow Model, a data-driven methodology to estimate spatially explicit food flows. The Food Flow Model integrates machine learning, network properties, production and consumption statistics, mass balance constraints, and linear programming. Specifically, we downscale empirical information on food flows between 132 Freight Analysis Framework locations (17,292 potential links) to the 3,142 counties and county-equivalents of the United States (9,869,022 potential links for each commodity). Subnational food flow estimates can be used in future work to improve our understanding of vulnerabilities within a national food supply chain, determine critical infrastructures, and enable spatially detailed footprint assessments.