Water securityGroundwater deficit growing in important western U.S. aquifers
By 2050, climate change will increase the groundwater deficit even more for four economically important aquifers in the Western United States, a new report says. Groundwater deficits are expected to worsen in four important aquifers, creating a precarious balance between usage and recharge. The new report is the first to integrate scientists’ knowledge about groundwater in the American West with scientific models that show how climate change will affect the region.
By 2050, climate change will increase the groundwater deficit even more for four economically important aquifers in the Western United States, reports a University of Arizona-led team of scientists.
The new report is the first to integrate scientists’ knowledge about groundwater in the American West with scientific models that show how climate change will affect the region.
“We wanted to know, ‘What are the expectations for increases and decreases in groundwater as we go forward in this century?’” said lead author Thomas Meixner, a UA professor and associate department head of hydrology and water resources. “In the West, 40 percent of the water comes directly from groundwater.”
Climate models predict that, in general, wet regions will become wetter and dry regions will become drier. The Southwest is expected to become drier and hotter.
“Aquifers in the southern tier of the West are all expected to see slight-to-significant decreases in recharge as the climate warms,” Meixner said.
UA reports that groundwater already is being withdrawn from the aquifers of California’s Central Valley, the central and southern portions of the High Plains and Arizona’s San Pedro faster than the groundwater is being recharged.
Climate change will make the groundwater deficits worse in those aquifers, the researchers report.
For the Death Valley and Wasatch Front aquifers, the effect of climate change on the balance between usage and recharge is not so predictable.
In contrast, Western aquifers at about the latitude of Boulder, Colorado, and farther north are likely to be recharged faster than people withdraw the water, the team reports. The northern aquifers the researchers studied are the northern High Plains, the Spokane Valley, the Williston Basin and the Columbia Plateau.
“In the long term, pumping has to equal recharge. You can get there through slow social adjustment. You could slowly decrease water withdrawal by conservation and efficiency,” Meixner said. “Or you can hit bottom and have farm abandonment and dry wells.
“It’s a social decision as to who gets the water,” he said. “The southern regions of the Western U.S. must be prepared to adapt to a much drier future.”
The report is an outgrowth of a workshop held at the U.S. Geological Survey’s John Wesley Powell Center for Analysis and Synthesis. The National Science Foundation and USGS funded the workshop.
To synthesize existing knowledge and predict how climate change would affect Western groundwater, Meixner gathered sixteen experts in climate change and in hydrology of the Western U.S.
