Water resource managers in the West have long been comforted that groundwater stores can augment traditional snow-fed sources like rivers and reservoirs during shortages.
As that contingency becomes more likely as traditional water sources struggle to quench a thirsty public’s demand, new research shows that western groundwater stores are more dependent on mountain snowpack than previously thought . That’s bad news considering that there is a well-documented trend of declining snowfall rates in western mountain ranges attributed to climate change.
Mike Dettinger, a U.S. Geological Survey (USGS) hydrologist who works in the Climate, Atmospheric Science and Physical Oceanography division at Scripps Institution of Oceanography, San Diego, worries that conventional assumptions about groundwater plentitude could be creating a false sense of security among water agencies that believe digging more wells would offset the consequences of climate change. Dettinger is among a small group of researchers leading efforts to create a monitoring network that can detect changes in groundwater supply in the West, a region that pumps from the ground about 40 percent of its total water supply.
“There is a growing concern about the future of the region’s groundwater,” said Dettinger. “At present we have no way of knowing whether changes are occurring. Some form of monitoring that would allow us to recognize changes in recharge if they occur is needed.”
USGS and State of California officials agree and they are soliciting proposals to create experimental monitoring programs to measure rates of replenishment, or recharge, into aquifers. Guido Franco, the technical lead for Climate Change Research in the California Energy Commission’s Public Interest Energy Research (PIER) program, said that his agency hopes to eventually create a long-term monitoring network to track potential shifts in groundwater recharge.
Independent of each other, hydrologists, geochemists, and researchers from related fields have developed innovative ways of measuring the complicated process that brings water from mountainsides to water wells. Dettinger said these new developments, if combined correctly, could allow researchers to measure year-to-year recharge rate changes that were impossible to measure 20 years ago. With climate change likely to change how the West gets its water, the breakthrough comes none too soon.
— Robert Monroe