Nutrient Management Research Database

Groundwater pumping chronically exceeds natural recharge in many agricultural regions in California. A common method of recharging groundwater — when surface water is available — is to deliberately flood an open area, allowing water to percolate into an aquifer. However, open land suitable for this type of recharge is scarce. Flooding agricultural land during fallow or dormant periods has the potential to increase groundwater recharge substantially, but this approach has not been well studied. Using data on soils, topography and crop type, we developed a spatially explicit index of the suitability for groundwater recharge of land in all agricultural regions in California. We identified 3.6 million acres of agricultural land statewide as having Excellent or Good potential for groundwater recharge. The index provides preliminary guidance about the locations where groundwater recharge on agricultural land is likely to be feasible. A variety of institutional, infrastructure and other issues must also be addressed before this practice can be implemented widely.

• Groundwater pumping often occurs at rates that exceeds the rate of recharge, threatening the future supply of groundwater.
• Intentional flooding open fields a practice that allow for “banking” of groundwater for time when water availability is limited.
• This study developed an index to identify areas that have promising potential for groundwater banking.

• 3.6 million acres of California agricultural land were identified as having excellent or good suitability for groundwater recharge.
• This index is the first step in constructing a comprehensive framework for growers to widely implement groundwater recharge practices.
• The ability of a soil to allow for deep water percolation, the presence of flat topography, and a lack of soil salinity are a few of the characteristics that make soil appropriate for groundwater recharge.