Spring 2023 GES Seminar with Dr. Rosemary Knight

Harnessing the Power of Geophysical Imaging to Recharge California’s Groundwater

Dr. Rosemary Knight, Professor of Geophysics of Earth System Science and
Senior Fellow at the Woods Institute for the Environment, Stanford University

Abstract: California’s past has involved cycles of floods and droughts, and this is predicted to continue, with more extreme floods and more extreme droughts due to climate change. There is great interest now in flood-MAR – managed aquifer recharge – where flood water is captured and used for recharge to recover from the last drought and prepare for the next. Identifying the optimal site for groundwater recharge requires considering many factors, one of which is the subsurface geology. If the recharge operation involves spreading of water on the surface, and the objective is to maximize the volume and rate of recharge, an ideal site will have “fast paths” of coarse-grained materials from the surface to the water table. Geophysical imaging is an efficient way of searching for these fast paths. We are working with data (25,000 km) acquired using the airborne electromagnetic (AEM) method and data acquired using a ground-based towed EM method, mapping out fast paths in California’s Central Valley.