Climatic and Anthropogenic Influences on Freshwater Availability in the Eastern United States

The objective of this research is to assess the sensitivities of freshwater availability in the eastern U.S. to the three main influences: changes in climate, land use, and water withdrawals. These sensitivities are quantified in terms of the dimensionless measures known as elasticities, such as climate, land-use, and water-withdrawal elasticities of streamflow. The climate elasticities are represented by precipitation and temperature elasticities; the land-use elasticities are represented by agriculture-land, grass-land, forested-land, and urban-land elasticities; and water-withdrawal elasticity is represented by freshwater-withdrawal elasticity. We document that a multivariate approach to estimation of such elasticities is necessary, with very different results obtained when one does not consider multivariate interactions among climate, land-use and water-use. For example, our results indicate that across the entire eastern U.S. (water resource regions 01, 02, and 03) and in each region alone, both annual mean and annual minimum flows appear to be quite sensitive to changes in both climate and land-use and those elasticities are markedly different when each are estimated independently, as if climate and land-use were truly independent variables.