In the face of a changing climate, arid-climate states like California have responded by  developing strict water legislation to help ensure future water supply. Sufficient water resources are vital to helping California maintain its agricultural economy, provide drinking water for a burgeoning population, and honor existing water rights. The Sustainable Groundwater Management Act (SGMA) of 2014 requires California water managers to develop sustainable management approaches that halt overdraft and bring groundwater basins into balanced levels of pumping and recharge by 2040. 

Our group’s geophysical research is driven by an interest in the potential of one promising sustainable groundwater management strategy to help California meet its water resource management needs. Using Flood-MAR (Managed Aquifer Recharge), river water is diverted when water flow is high during winter onto fallow–dormant agricultural fields to recharge shallow aquifers.In order to develop this strategy at a scale capable of meeting the needs of California, several questions must be answered, such as: Where does the water go and does it make it to the aquifer? What is the rate of recharge and how much is infiltrated to the aquifer? What is the quality of the infiltrated water and is that quality maintained in the subsurface? What is the structure of the subsurface geology and does it improve or hinder desired recharge rates?

The Berkeley Lab Environmental Geophysics group is combining traditional geophysical methods with novel sensors and modeling codes to help answer these questions across scales. Example of our efforts include using time-lapse geophysical methods to:

• Accurately monitor water infiltration through the subsurface to the unconfined aquifer to quantify flowpaths and recharge volume during flooding, and to develop strategies to optimize recharge
• Understand the controls on riverbed clogging to ensure peak performance at a riverbank filtration facility
• Understand post-fire effects on surface and groundwater quality at watershed scale
• Quantify the link between a shallow aquifer and groundwater-dependent ecosystems