High Plains aquifer use is expected to decrease by about 50% over the next 100 years, and it is already on the decline – its over-tapping beyond its recharge rate peaked over 10 years ago in some states, Kansas State research suggests.
David Steward, professor of civil engineering, and Andrew Allen, civil engineering doctoral student, recently published the findings in the first paper to look at and quantify peak aquifer depletion.
The High Plains aquifer is used by eight states – South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, New Mexico and Texas – providing 30% of the irrigated water for agriculture production.
The High Plains study builds on a previous study which forecasted the future of the aquifer in Kansas. The new study expanded that research to include the data from a total of 3,200 Kansas wells and 11,000 wells from the other seven states.
To complete the analysis, researchers developed a logistics equation to apply more than 300,000 well measurements to create a historical record of its water level and also its projected water level through 2110.
"When we did the Kansas study, it really focused on those wells in Kansas that were depleting," Steward said. "We came up with a set of projections that looked at how long the water would last and how the depletion process would play out over time. With this study, we wanted to learn how the depletion in various locations plays into a larger picture of the aquifer."
Some states already hit peak draws >>
Some states have hit peak draws
Steward and Allen found that the High Plains Aquifer's depletion followed a south to north progression, with its depletion peaking in 2006 for the entire High Plains Aquifer. Overall, researchers saw that some portions of the aquifer are depleting while others are not. Texas peaked in 1999, New Mexico in 2002, Kansas in 2010, Oklahoma in 2012 and Colorado is projected to peak in 2023. Nebraska, South Dakota and Wyoming are not projected to reach peaks before 2110.
"We are on a declining trend right now for water use in irrigated agriculture," Steward said. "As we project what happens in the future following the existing water use patterns, the amount of depletion and the amount of water that comes out of the aquifer will decrease by about half over the next 100 years."
Additionally, researchers saw that the water depletion rates for each state in the High Plains Aquifer follow a similar bell-shaped curve pattern as the one for oil depletion in the U.S. modeled by the Hubbert peak theory.
While water is a finite resource, Steward said the intent behind the study is not raise alarm, but rather encourage proactivity to manage and preserve this resource.
"This study helps add to the dialogue of how is it that we manage water and the effects of the choices that we make today," Steward said. "It has the same kind of message of our previous paper, which is that our future is not set; it's not cast. The projections we show are projections based on the data we have available that show the trends based on how we used water. People have the opportunities to make choices about the way that things are done, and the findings from this study help add to the dialogue."
The National Science Foundation and the U.S. Department of Agriculture funded the study. The U.S. Geological Survey and the Kansas Geological Survey contributed decades of information about the High Plains Aquifer and the Ogallala Aquifer for analysis.
Find the complete study, " Peak groundwater depletion in the High Plains Aquifer, projections from 1930 to 2110," online.