Writing in the journal Nature Sustainability
, an interdisciplinary team that includes Julie Zimmerman
, professor of green engineering at the Yale School of Forestry & Environmental Studies (F&ES), analyzed trends in global water usage from 1980 to 2016. They focused particularly on so-called inflexible consumption, the curtailment of which would cause significant financial and societal hardship. Those uses include irrigating perennial crops, cooling thermal power plants, storing water in reservoirs, and quenching the thirst of livestock and humans.
For the study, the team of scientists, led by Yue Qin
of the University of California, Irvine (UCI), constructed a water stress index that takes into account the scarcity, flexibility and variability (a comparison of annual runoff to storage capacity) of global supplies.
Evaluating watersheds on six continents, they found numerous hot spots — places where a drought or heat wave could put a strain on reserves — as well as numerous chances to conserve resources through new technologies and better management practices.
According to the study, the top 10 percent of the most stressed river basins support about 19 percent of the world’s population, 19 percent of thermal electricity generation and one-third of irrigated agricultural production. In addition, the researchers discovered a significant increase in water stress for the worst-impacted regions over the 37-year study period.
“Many studies evaluating water scarcity have mainly centered on the share of the available supply being consumed by humans, but this ignores the fact that some uses are more flexible or productive than others,” said Qin, a postdoctoral scholar in Earth system science at UCI. “By looking at how water is actually used, we can begin to see what water is really difficult to do without and if there are any opportunities for savings in other areas.”