The Ogallala, or High Plains Aquifer, which covers about 30 percent of the United States' irrigation needs, could be mostly depleted within the next 50 years if current water-usage trends continue.
According to a study conducted by agronomy and engineering professors at Kansas State University, the aquifer will be 60 percent depleted by 2060 unless water use is immediately reduced, in which case, the aquifer's lifetime could be extended to 2110.
"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," David Steward, Civil Engineering professor, 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."
The project, which was funded by the USA, the National Science Foundation and K-State's rural Transportation Institute, used past and present measurements of groundwater levels in Ogallala to predict the effect that the ongoing water decline would have on cattle and crop production in the U.S.
The findings showed that by 2010, 30 percent of the aquifer's water had been used. If current usage continues, an additional 39 percent of water is expected to be tapped by 2060 resulting in the loss of 69 percent of the aquifer's total groundwater.
According to Steward, who led the project, it would take from 500 to 1,300 years for the aquifer to refill given the current recharge rates. However, because water efficiencies are improving, the depleting could be avoided -- and production increased -- if the aquifer is used more judiciously.
"Water use efficiencies have increased by about 2% a year in Kansas, which means that every year we're growing about 2% more crop for each unit of water. That's happening because of increased irrigation technology, crop genetics and water management strategies," Steward explained.
Researchers constructed several possible scenarios that reduced the current pumping rate by 20, 40, 60 and 80 percent. According to Steward, the 80 percent predictions were made based on the aquifer's natural groundwater recharge rate of about 15 percent of current pumping.
"As a society, we have an opportunity to make some important decisions that will have consequences for future generations, who may or may not be limited by those decisions," he said.