Colorado River drought drives unprecedented pattern of groundwater loss

Using satellite technology, Virginia Tech geoscientists estimated groundwater depletion across the Colorado River Basin, finding recent losses greater in the historically resilient Upper Basin.

Declining Colorado River flows and falling water levels at Lake Powell and Lake Mead are highly visible signs of the Southwestern megadrought.

Unseen below ground, groundwater reserves in the Colorado River Basin are disappearing just as fast — and in an unexpected new pattern, according to research from Virginia Tech.

Historically, groundwater has declined more in the Lower Basin.

But the system has hit a turning point: The Upper Basin is now experiencing rapid groundwater losses, with surface-water shortages increasingly affecting groundwater as well.

To isolate changes in groundwater stocks across both basins, Virginia Tech’s Susanna Werth and a team of geoscientists combined measurements from NASA’s Gravity Recovery and Climate Experiment satellite mission with estimates of surface water, soil moisture, and snow-water storage from 2004 to 2023.

Their findings were published in Water Resources Research.

Results

point to an acceleration in groundwater depletion after 2019.

During the severe drought from 2020 to 2022, the Upper Basin lost about 4.6 trillion gallons of groundwater.

This was nearly double the loss in the Lower Basin, which was estimated at 2.5 trillion gallons.

"We generally think of the Upper Basin as more resilient because of its snowmelt-driven recharge,” said lead author Esther Oyedele, a geosciences graduate student at Virginia Tech.

The report adds to ongoing university-led research relevant to veterinary medicine, animal health, and clinical decision-making.

university website: Virginia-Maryland College of Veterinary Medicine