Estimating HUC 2-digit sustainable water use over the continental United States using GRACE

Abstract:

Managing water resources so that supplies meet demands over the long-term is of increasing importance due to greater demands from a growing population and shifts in supplies due to climate change. Although the technology and infrastructure to determine spatially-distributed total surface water and groundwater supplies does not currently exist, satellite measurements of water resources have been useful for providing regional or global assessments of sustainable surface water or groundwater use. Here, we apply an innovative technique using GRACE to evaluate the sustainable use of both surface water and groundwater for the continental United States. Annual total water availability was estimated from the difference between the annual maximum and minimum change in total water storage as determined from GRACE. The available portion partitioned to humans was compared to the amount of water being used based on county-level USGS water use estimates to assess total water use sustainability at the HUC 2-digit spatial scale. This evaluation was conducted for a given wet, normal, and dry year according to GRACE records. Projected estimates of precipitation due to climate change across these regions were then used to compare present and future total water use sustainability. Such information is critical to better manage these resources so respective allocations to humans and the environment are more in line with the given quantities available at different spatial scales.