Report: Simulating the sensitivity of evapotranspiration and streamflow to large-scale groundwater depletion

Click here to read the report. Here’s the abstract:

Groundwater pumping has caused marked aquifer storage declines over the past century. In addition to threatening the viability of groundwater-dependent economic activities, storage losses reshape the hydrologic landscape, shifting groundwater surface water exchanges and surface water availability. A more comprehensive understanding of modern groundwater-depleted systems is needed as we strive for improved simulations and more efficient water resources management. Here, we begin to address this gap by evaluating the impact of 100 years of groundwater declines across the continental United States on simulated watershed behavior. Subsurface storage losses reverberate throughout hydrologic systems, decreasing streamflow and evapotranspiration. Evapotranspiration declines are focused in water-limited periods and shallow groundwater regions. Streamflow losses are widespread and intensify along drainage networks, often occurring far from the point of groundwater abstraction. Our integrated approach illustrates the sensitivity of land surface simulations to groundwater storage levels and a path toward evaluating these connections in large-scale models.

Groundwater movement via the USGS

Typical water well

Artesian well Dutton Ranch, Alamosa 1909 via the Crestone Eagle

The plains around DIA were parched by the scorching 2012 drought, although groundwater pumping along the South Platte River enabled some farms to continue irrigating — photo by Bob Berwyn

The High Plains Aquifer provides 30 percent of the water used in the nation’s irrigated agriculture. The aquifer runs under South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, New Mexico and Texas.

From KUNC (Luke Runyon):

Groundwater pumping is causing rivers and small streams throughout the country to decline, according to a new study from researchers at the Colorado School of Mines and the University of Arizona.

“If you pump near a stream you’re going to change the amount of water that flows through the stream, because some of that stream water is going to basically get pulled to the well instead of flowing down the stream,” said Reed Maxwell, hydrologist at Colorado School of Mines and the study’s co-author.

Maxwell says his new study with hydrologist Laura Condon at the University of Arizona goes broad, quantifying the effect of pumping across the country.

“What we found is that we have actually depleted streams quite a bit,” Maxwell said.

The study finds that since the 1950s groundwater pumping has caused some stream flows to decline upwards of 50 percent. Some streams have disappeared from the surface altogether, seeping underground to refill pumped groundwater, the study finds.

Declines are particularly stark in portions of the Colorado River basin and on the Great Plains, Maxwell said.

Using a computer model, researchers were able to envision what rivers across the U.S. would’ve looked like without widespread groundwater pumping, which took hold in the 1950s.