Water Supply Risk in the United States 2015–2050 Considering Projected Changes in Population and Thermoelectric Power Demand

Examination of water supply risk is important to identify
areas
of potential insecurity and prioritize allocation of resources. This
work builds on and advances a previous U.S. water supply risk analysis
developed at county-scale resolution, which did not account for water
flow between counties and identified some counties on major rivers
as being at high risk. This limitation is addressed in the present
study. The analysis utilized data from U.S. Geological Survey water
use reports to assess current water supply risk and also projected
water supply risk in 2050. Flow volumes were calculated using the
Water Supply Sustainability Index (WaSSI) tool developed by the USDA
Forest Service, enabling the analysis to account for changes in climate
and hydrology and changes in water demand. A modified Water Risk Index
(WRI) was formulated, including five factors to which scaled values
were assigned. Results indicate that accounting for natural transfers
of water in counties in addition to local precipitation reduced the
risk profile of many counties, with a maximum of 36 classified as
high or very high risk, compared to over 400 identified in the highest
risk category in the previous analysis.