The highly productive agricultural regions in the high plains are drawing water from the Ogallala Aquifer at an unsustainable rate, according to a new report. Wikimedia Commons/Dehaan
New research indicates the Ogallala Aquifer will be depleted by nearly 70 percent by 2060, presaging consequences for the rich agricultural area that draws upon it for irrigation.
September 3, 2013—The highly productive agricultural regions in the high plains are drawing water from the Ogallala Aquifer at an unsustainable rate. The aquifer has already been depleted by 30 percent. Continued pumping at current rates will leave the aquifer nearly 70 percent depleted by 2060.
Those are the key conclusions of research published recently by a team led by David A. Steward, Ph.D., PG, A.M.ASCE, a professor of civil engineering at Kansas State University. The report, “Tapping Unsustainable Groundwater Stores for Agricultural Production in the High Plains Aquifer of Kansas, Projections to 2110,” was published online in the Proceedings of the National Academy of Sciences.
The Ogallala Aquifer covers approximately 174,000 sq mi, making it one of the largest in the world. It lies beneath portions of eight states, supplying 30 percent of all water used in irrigation nationwide. It is also the source of drinking water for approximately 1.8 million residents. The Ogallala Aquifer is part of the larger High Plains Aquifer System.
The team examined 46,000 data points from the Kansas groundwater observation well network. Water levels are measured monthly, quarterly, and annually at several thousand wells in the network. The researchers began with a sample of 3,000 wells, some with data extending back to 1960.
“By looking at the change in individual wells we could use geostatistical methods to interpolate the value between the wells,” Steward says. “And then, by looking at the change of that surface over time, we could see the changes in storage.”
That data was then overlaid with data from water use reports that Kansas has required from all water rights holders in the state since 1981. The data indicates that water use has been declining slightly.
“Part of it might be attributed to the advent of meters,” Steward says. “Most of the wells in western Kansas have meters now. Previous studies show that people without meters generally tend to over-report water use.”
Another likely cause is the first appearance of a soon to be growing problem. As water levels drop in wells, it becomes more difficult to extract water from them. “In some places in west-central Kansas, we’ve already seen regional declines in the amount of water we can pump,” Steward says. “Most of western Kansas will see that beginning around 2025.”
Data from the U.S. Geological Society reveal that water levels in
the Ogallala Aquifer declined—shown as yellow, red, and
orange—from 1980 through 1995 in Kansas, Colorado, Oklahoma,
New Mexico, and parts of Nebraska and Texas. Wikimedia
The research notes that the recharge rates of the aquifer currently provide 15 percent of the water pumped per year, leaving 85 percent to come from aquifer reserves. The researchers note it would take between 500 and 1,300 years to fully recharge the aquifer, once depleted.
“I think it’s generally understood that there must be reductions in pumping at some point in the future,” Steward says. “People realize that the groundwater levels are going down and they can’t go down forever.”
Indeed, in 2012 Kansas Governor Sam Brownback signed several key pieces of legislation focusing on water resources in the state, including a measure that gives landowners incentives to conserve water. Statewide, approximately 85 percent of water consumed in Kansas is used for irrigation.
The research indicates that water available from the Ogallala Aquifer will begin to decline by 2025. It notes that at current water-usage rates, agriculture production in Kansas will peak in 2040, followed by decades of decline. The gap can be attributed to advances in irrigation technology, crop genetics, and water management practices. Together these contribute to a linear trend in which the state increases agriculture production by 2 percent per unit of water every year.
However, if the state were able to reduce water use by 20 percent, agriculture production would peak in 2070, and the following decline would be less pronounced, Steward says.
“The benefit of saving water now is that efficiency is increasing linearly and looks like it will increase linearly into the future,” Steward says. “By saving water now, we are providing time for the people who look at crop genetics and the people who look at irrigation strategies to be able to devise strategies to use water more efficiently.
“That means not only will the time of peak production move into the future, that decline that you would expect with using less water will be a slower curve,” he adds.
Steward says a multidisciplinary approach is the only way to address the situation in the future, with civil engineers working together with crop experts and researchers in veterinary medicine to understand and mitigate the impact of less available water.
“If we are looking at trying to help society with the planning process—which is a really important thing for civil engineers—we need to be able to work outside our discipline,” Steward says. “To look at something like this—you can’t simply solve it from a perspective of a civil engineer who’s a water resources expert.
“This kind of a study really emphasizes the need for civil engineers to get outside of the disciplinary box and look at civilian infrastructure from brand new perspectives,” Steward adds. “We as civil engineers have the challenge ahead of us to deal with societal problems from a much more holistic standpoint.”