Harnessing the power of geophysical imaging to Recharge California's Groundwater

Team: Rosemary Knight, Paul Gosselin, Mike Lepech
Large scale (Scaling)

Field crew for the first tTEM survey in California, standing beside an early version of the tTEM system at a recharge pone in Tulare Irrigation District. From Left to right: Esban Auken, Rosemary Knight, Ahmad Behroozmand, Meredith Goebel. Credit: *Aaron Fakuda*.

Many groundwater systems around the world are out of balance, with demand for water far exceeding the supply. These systems are naturally recharged when rainfall and snowmelt seep into the ground, often via reservoirs, lakes, and rivers, to replenish the aquifers, but this natural recharge cannot keep up with the extraction rates. To restore balance to these systems, state and local water agencies are implementing methods to complement the natural recharge through managed recharge, by spreading water on the ground surface for it to move downward into the aquifers. The challenge is identifying locations where there are “fast paths” of coarse-grained sand and gravel that can efficiently move the water from the ground surface to the aquifers.

This team set out to discover fast-paths for groundwater recharge. We relied on geophysical data, driller’s logs, and other existing datasets. We have developed a web-based application – fastpath – that allows users to derive actionable data from complex geophysical data, providing maps evaluating the suitability of areas for recharge to enable end-user decision making. We have also developed an online course that educates users on the key steps in the workflow, which range from understanding and entering the geophysical data to evaluating potential sites for fast-paths.

We have begun to deploy this application, starting in California, by providing actionable data to end-users who are trying to correct the imbalance in the groundwater systems. This helps address the need for a sustainable supply of groundwater for agriculture, urban and rural communities, and ecosystems.

Steve Purves and Rowan Cockett from Curvenote implemented the fastpath web-based application (https://fastpath.stanford.edu/). In addition we worked closely throughout the project with the following partners: Paul Baumann (Principal Geophysicist, BGC Engineering), Christina Buck (Assistant Director, Butte County Water and Resource Conservation Department), Kassy Chauhan (Executive Director, North Kings GSA), Aaron Fukuda (Manager, Tulare Irrigation District), Charlotte Gallock (Director of Water Resources/Chief Engineer, Kings River Conservation District), Tim Godwin (Supervising Engineering Geologist, California Department of Water Resources), Jenny Marr (Division of Planning, California Department of Water Resources), Julie Rentner (President, River Partners), Jesse Roseman (Principal Analyst, Environmental and Regulatory Affairs, Almond Board of California), Derrik Williams (Principal Hydrologist, Montgomery and Associates), and Matt Zidar (Water Resources Manager, San Joaquin Department of Public Works).

This project also contributes toward the Freshwater flagship destination.