From the California Farm Bureau Federation:
Using farmland for wintertime aquifer recharge could help nearby communities replenish their groundwater supplies, according to University of California research showing that nearly 300 rural communities could benefit.
The research is part of ongoing work to determine how flooding farmland in the winter could refill underground water supplies.
Helen Dahlke, a professor at UC Davis, has been evaluating ways to flood agricultural land when excess water is available during the winter, in order to recharge groundwater.
If relatively clean mountain runoff is used, Dahlke said, the water filtering down to the aquifer could also clean groundwater that has been affected by nitrogen or pesticide.
A map developed in 2016 by UC Cooperative Extension specialist Toby O’Geen identified 3.6 million acres of farmland with the best potential for managed aquifer recharge, based on soil type, land use, topography and other factors. Now, Dahlke and colleagues have analyzed the map, finding nearly 3,000 locations where flooding suitable farmland would recharge water for 288 rural communities.
“If we have the choice to pick a location where recharge could happen, choose those upstream from these communities,” Dahlke said.
She said she believes wintertime flooding for groundwater recharge can help water districts comply with the state’s Sustainable Groundwater Management Act.
“We have to do anything we can to store any surplus water that becomes available to save it for drier times, and our aquifers provide a huge storage for that,” she said.
Dahlke’s lab collaborates with UC farm advisors and specialists and with scientists at other UC campuses to learn about the agronomic impacts of flooding a variety of crops, including almonds, alfalfa and grapes.
UC said the lab’s groundwater banking project plans more studies in groundwater basins across the state, to learn more about suitable locations, technical implementation and long-term operation. The scientists also plan to address operational, economic and legal feasibility of groundwater banking on agricultural land.
