AFRI in ACTION: Recharging California’s Depleted Groundwater

Recharging California's Depleted Groundwater1California produces more than one half of our nation’s fruits and vegetables. The state’s epic drought is not just devastating for its farmers, it is hurting American consumers. Even with the return of rainy weather this winter, it will take more to recover their dwindling groundwater supply.

The San Joaquin Valley may be ground zero of this drought. It contains some of the most productive farmland in the US, growing more than 250 annual and perennial crops and generating over 7 percent of the nation’s total agricultural output.

Over the years, however, market trends have moved many farms from growing row crops, like cotton and vegetables, to perennials, such as grapes and almonds. Because perennials need more water throughout the year, farmers have increasingly had to tap into groundwater for irrigation. As a result, reserves are depleting.

Researchers at the University of California, Davis, working with an AFRI grant, are diving into the problem of recharging groundwater aquifers. They are analyzing periodic floods of perennials, which can help replenish underground aquifers. Flooding fields had previously been thought to negatively impact the perennial plants, but some have proven surprisingly resilient.

The researchers are measuring whether there is an actual decrease in crop productivity and assessing where the trade-offs in productivity outweigh the benefits in recharging groundwater. With most groundwater supplies emptied for at least the near future, this research will help farmers adapt to the new seasonal variations in which surface water ebbs and flows.