Depleted groundwater poses risks to communities, agriculture, and ecosystems in California’s Central Valley. Researchers from Stanford University have found that land historically used for agriculture could also serve as a key area for aquifer recharge. According to a study published in Earth and Space Science, scientists assessed the Central Valley to find areas where surface water could rapidly penetrate and replenish underground aquifers.
Lead study author Seogi Kang noted, “We were hoping to see a relatively big portion of agricultural land that’s suitable for recharge, and that’s what we’re seeing.” Groundwater in the Central Valley is crucial for drinking, irrigation, and ecosystem support, especially during dry spells. Unfortunately, current usage is outpacing natural replenishment, leading to various consequences, including land subsidence.
Water agencies are now seeking methods to utilize excess surface water during wet years to recharge groundwater. However, the effectiveness depends on the land’s properties. Sandy and gravelly areas offer better infiltration, while clay-heavy sections can hinder water from reaching aquifers. Rosemary Knight, senior author of the study, emphasized the importance of strategic placement, stating, “Surface water is very valuable. You don’t want to put it somewhere where it’s not going to provide a benefit in terms of recharge.”
The research team employed electromagnetic data collected by helicopter surveys, covering 20,000 kilometers of the Central Valley. This data was compared to well logs, identifying areas with favorable conditions for water absorption. They developed a web application called “fastpath,” aiding stakeholders in determining effective water pathways.
The mapping efforts revealed up to 13 million acres could be suitable for groundwater recharge, notably in areas where crops like orchards and vineyards are grown. The team’s findings are publicly available, providing various metrics for evaluating recharge potential. Knight plans further exploration of electromagnetic data to address other groundwater issues, saying, “How do we take advantage of all these data that are now available, to go from sensors to solutions? That’s what I’m all about.”
The research was supported by the Stanford Doerr School of Sustainability, the Gordon and Betty Moore Foundation, and the United States Department of Agriculture. Co-author Meredith Goebel also contributed significantly to the study.
The original report was published by the Stanford Doerr School of Sustainability.
