Improving groundwater sustainability in California

Groundwater is a critical source of water for both California farms and communities, so the State of California enacted the Sustainable Groundwater Management Act which requires local agencies in high- and medium-priority groundwater basins to develop and implement groundwater sustainability plans.

To assist local agencies as they develop these plans, the California Department of Water Resources (DWR) will conduct airborne electromagnetic (AEM) surveys in California’s high- and medium-priority groundwater basins. The project will generate coarse-grid subsurface maps that provide framework information about large-scale aquifer structure. The AEM data supports the development or refinement of hydrogeologic conceptual models as well as helps to identify possible areas for recharging groundwater.

“Statewide AEM surveys will further DWR’s technical assistance services supporting local communities as they work to manage their groundwater supply to ensure its reliability,” said Steven Springhorn, acting DWR deputy director of statewide groundwater management.

“AEM data will give locals a better understanding of their groundwater basins and will provide a dataset that supports the overall implementation of SGMA and groundwater sustainability agencies’ development of groundwater sustainability plans.”

Taking an MRI of the ground’s subsurface

During an AEM survey, a helicopter tows electronic equipment that transmits radio waves to the ground and measures the response that returns. The process has been compared to taking an MRI of the ground’s subsurface, and the data collected is used to create continuous images that are interpreted for underground geology to a depth of about 1,000 feet.

The surveys are funded by voter-approved Proposition 68, Senate Bill 5, and the General Fund. The AEM project is expected to start this summer and DWR will hold a public webinar in advance to launch the project.

Local team with global knowledge

DWR has selected Ramboll, a consulting engineering group, to lead the team conducting the surveys and interpretating the data. Along with Ramboll, the team consists of GEI, a consulting engineering and environmental firm with five locations in California, and SkyTEM which will provide the AEM field survey. “We are proud to support the implementation of the Sustainable Groundwater Management Act by providing high-quality data. With proven technology and solid experience from similar projects, we look forward to the exciting collaboration with DWR, the groundwater sustainability agencies as well as the people in California,” says Jeff Rogers, Director, Ramboll Water in the US. The helicopter services needed for the AEM Survey are provided by Sinton Helicopters, located in in Paso Robles, California, and Aarhus University from Denmark will provide specialized academic expertise.

Ramboll and SkyTEM have previously conducted similar surveys in California as well as in other countries including Denmark, where the technology has been used to create detailed mapping of the country’s groundwater resources.

Rewarding collaboration

Denmark and California are sharing knowledge through the Danish Water Technology Alliance (WTA) where Ramboll and SkyTEM are participating. The 9th of March, Denmark and California took the next joint step on the way toward a more resilient, sustainable, and efficient water sector by signing a new Memorandum of Understanding. “It is a great pleasure to hear that Danish expertise and technology will be a part of the Californian efforts related to sustainable groundwater management. In times of transition, international partnerships and knowledge sharing are essential. Therefore, we are very excited to be strengthening our collaboration with California and taking a joint step towards a climate-friendly water sector through the MoU we recently signed,” says Lone Dencker Wisborg, Ambassador of Denmark to the US. For more information, visit DWR’s statewide AEM surveys project webpage.