If current irrigation trends continue, 69% of the groundwater stored in the High Plains Aquifer of Kansas — also known as the Ogallala Aquifer — will be depleted in 50 years. However, immediately reducing water use could extend the aquifer's lifetime and increase net agricultural production through the year 2110, the university said.
Those findings are part of a recently published study by David Steward, professor of civil engineering, and colleagues at Kansas State University. The study investigates the future availability of groundwater in the aquifer and how reducing use would affect cattle and crops. The aquifer supplies 30% of the nation's irrigated groundwater and serves as the most agriculturally important irrigation in Kansas.
"Tapping Unsustainable Groundwater Stores For Agricultural Production in the High Plains Aquifer of Kansas, Projections to 2110" appears in the scientific journal Proceedings of the National Academy of Sciences of the United States of America. The study took four years to complete and was funded by the National Science Foundation, the U.S. Department of Agriculture and Kansas State University's Rural Transportation Institute.
"I think it's generally understood that the groundwater levels are going down and that at some point in the future groundwater pumping rates are going to have to decrease," Steward said. "However, there are lots of questions about how long the water will last, how long the aquifer will take to refill and what society can do."
Steward conducted the study with Kansas State's Michael Apley, professor of clinical sciences and an expert in cattle production; Stephen Welch, professor of agronomy, who helped with a statistics method called bootstrapping; Scott Staggenborg, adjunct professor in agronomy who studies agricultural production methods; Paul Bruss, a 2011 master's degree graduate in civil engineering, and Xiaoying Yang, a former postdoctoral research assistant who is now at Fudan University in China.
Using measurements of groundwater levels in the past and present day in those regions, Steward and colleagues developed a statistical model that projected groundwater declines in western Kansas for the next 100 years and the effect it will have to cattle and crops.
According to their model, researchers estimated that 3% of the aquifer's water had been used by 1960. By 2010, 30% of the aquifer's water had been tapped. An additional 39% of the aquifer's reserve is projected to be used by 2060 — resulting in the loss of 69% of the aquifer's groundwater given current use. Once depleted, the aquifer could take an average of 500-1,300 years to completely refill given current recharge rates, Steward said.
Although the High Plains Aquifer will continue declining, researchers anticipate even greater efficiencies in water use during the next 15-20 years.