As California’s drought grinds on, the state is in chronic groundwater overdraft: more water is being pumped out of underground sources than filters back in. UC Davis researchers are encouraged by early results from tests to see if deliberately flooding farmland in winter can replenish aquifers without harming crops or affecting drinking water.

“On-farm flooding looks very promising,” said Professor Helen Dahlke, a hydrology expert with the UC Davis Department of Land, Air and Water Resources. "We're pleasantly surprised by how quickly water tables have responded to on-farm flooding without damage to crops."

Not all crops or soils are suitable for deliberate flooding, but alfalfa, pears, wine grapes, and some almonds, peaches and plums might be suitable. The California Soil Resource Lab at UC Davis has developed an interactive map of the state that shows areas best suited for “groundwater banking,” especially if this year’s predicted El Niño brings a wet winter.