A spatially detailed blue water footprint of the United States economy

This paper quantifies and maps a spatially detailed and economically complete blue water footprint for the United States, utilizing the National Water Economy Database version 1.1 (NWED). NWED utilizes multiple mesoscale (county-level) federal data resources from the United States Geological Survey (USGS), the United States Department of Agriculture (USDA), the US Energy Information Administration (EIA), the US Department of Transportation (USDOT), the US Department of Energy (USDOE), and the US Bureau of Labor Statistics (BLS) to quantify water use, economic trade, and commodity flows to construct this water footprint. Results corroborate previous studies in both the magnitude of the US water footprint (F) and in the observed pattern of virtual water flows. Four virtual water accounting scenarios were developed with minimum (Min), median (Med), and maximum (Max) consumptive use scenarios and a withdrawal-based scenario. The median water footprint (F_CUMed) of the US is 181 966Mm³ (F_Withdrawal: 400 844Mm³; F_CUMax: 222 144Mm³; F_CUMin: 61 117Mm³) and the median per capita water footprint (F′_CUMed) of the US is 589m³ per capita (F′_Withdrawal: 1298m³ per capita; F′_CUMax: 720m³ per capita; F′_CUMin: 198m³ per capita). The US hydroeconomic network is centered on cities. Approximately 58% of US water consumption is for direct and indirect use by cities. Further, the water footprint of agriculture and livestock is 93%of the total US blue water footprint, and is dominated by irrigated agriculture in the western US. The water footprint of the industrial, domestic, and power economic sectors is centered on population centers, while the water footprint of the mining sector is highly dependent on the location of mineral resources. Owing to uncertainty in consumptive use coefficients alone, the mesoscale blue water footprint uncertainty ranges from 63 to over 99% depending on location. Harmonized region-specific, economic-sectorspecific consumption coefficients are necessary to reduce water footprint uncertainties and to better understand the human economy's water use impact on the hydrosphere.