Rosemary Knight, a senior fellow at Stanford Woods Institute and Stanford geophysics professor, recently testified before the California State Assembly’s Select Committee on Sea Level Rise and the California Economy on the potential use of geophysical methods to help manage groundwater. The hearing, held July 17 in Half Moon Bay, was chaired by Assemblymember Rich Gordon.

Knight spoke about the impact of sea level rise on coastal agriculture along with Mary Scruggs, supervising engineering geologist, California Department of Water Resources, and Norm Groot, executive director, Monterey County Farm Bureau.

She explained how geophysical technology can map complex spatial distribution of saltwater and freshwater along the California coast and provide ongoing monitoring of saltwater intrusion to allow for adaptive groundwater management.

Knight’s presentation highlighted a dataset acquired in the fall of 2012 as an example of how electrical conductivity measurements can provide a two-dimensional image showing saltwater and freshwater to a depth of 150 kilometers along a seven-kilometer stretch of Monterey Bay. This fall the research will expand to include data that can be imaged to a depth of 300 kilometers along a 40-kilometer stretch. Her research is being done in collaboration with Adam Pidlisecky of the University of Calgary and Tara Moran, a research associate with Stanford Woods Institute.

Throughout her testimony Knight emphasized the need for a large-scale perspective on the problem and noted that neither groundwater nor seawater stop at jurisdictional boundaries. She concluded, “There need to be drivers at the state level for a proactive program of consistent and reliable measurement and monitoring before a crisis strikes and it’s too late to respond. Geophysical methods are fantastic tools that can provide the basis for a data-driven, science-driven approach to groundwater management.”

The hearing was the second of four statewide hearings on how sea level rise affects the California economy.