Agronomy and engineering professors at Kansas State University are keeping a watchful eye on a crucial resource for a significant portion of the nation's breadbasket – the Ogallala, or High Plains Aquifer.
The aquifer, which supplies about 30% of the nation's irrigation needs, could be 69% depleted in the next 50 years if current trends continue. However, if water use is immediately reduced, the aquifer's lifetime could be extended to 2110 – all while increasing agricultural production.
K-State Professor of Civil Engineering David Steward lead the project, which was funded by the USDA, the National Science Foundation and K-State'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, along with research associates in cattle production, agronomy and civil engineering colleagues, used past and present measurements of groundwater levels in key Ogallala regions to predict the affect ongoing water declines in the heart of the U.S. will have on cattle and crop production.
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.
Better tech to come
However, there is a silver lining, researchers note: water efficiencies are improving.
"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.
While peak water use is expected in 2025, cattle and corn production will continue at peak until 2040. Projections past that time frame will depend on decisions made today.
However, the team conducted several scenarios that reduced the current pumping rate by 20%, 40%, 60% and 80%. Steward said the researchers went as high as 80% because that closely aligned with the aquifer's natural groundwater recharge rate of about 15% of current pumping.
Steward said if farmer are able to save water today, there will be a substantial increase in the number of years irrigated agriculture can continue.
"We really wrote the paper for the family farmer who wants to pass his land on to his grandchildren knowing that they will have the same opportunities that farmers do today," Steward said. "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."