Scientists have long suspected that the weight of snow and ice in nearby mountains could throw off groundwater assessments tied to elevation changes in California’s Central Valley, but they lacked a way to quantify the effect. A new study demonstrates a solution. (Source: Stanford News)

Stanford and local experts discuss ways to mitigate risk to communities and infrastructure amid dramatic swings between flood and drought.

To help find potential groundwater recharge sites, helicopters deploy spaceship-sized antennas and ping the ground with electromagnetic signals, mapping the geology deep below the surface. The technique was piloted in California by researchers at Stanford, led by Rosemary Knight.

"Much of the modeling that's been done in preparation of groundwater sustainability plans throughout the state assumes that if you stop the water level going down, the subsidence is going to stop. But that's wrong," says Stanford geophysicist Rosemary Knight.

In a new study, Stanford's Rosemary Knight and Matt Lees examined the sinking in one area of the San Joaquin Valley over 65 years and projected that subsidence will likely continue for decades or centuries, even if aquifer levels were to stop declining.

A Stanford University study simulates 65 years of land subsidence, or sinking, caused by groundwater depletion in California’s San Joaquin Valley. The results suggest significant sinking may continue for centuries after water levels stop declining but could slow within a few years if aquifers recover.

The state pumps too much groundwater, especially during droughts. Now it's learning to refill the overdrawn bucket. "It's the simplest math in the world," says Stanford professor Rosemary Knight.

Professor of geophysics Rosemary Knight researches the potential of natural groundwater basins to store and keep water as extended droughts threaten California's water supply.

Stanford water experts discuss lessons learned from previous droughts, imperatives for infrastructure investment and pathways for the state to achieve dramatically better conservation and reuse of its most precious resource.

The award from the Society of Exploration Geophysicists (SEG) is given to a researcher who has made distinguished contributions both to the advancement of the science and to the profession of exploration geophysics.

Rapidly worsening drought and a mandate to bring aquifer withdrawals and deposits into balance by 2040 have ignited interest in replenishing California groundwater through managed aquifer recharge. Stanford scientists demonstrate a new way to assess sites for this type of project using soil measurements and a geophysical system towed by an all-terrain vehicle.

Naming priorities such as better land management, an evolved portfolio of 21st-century solutions and more funding for research and development, Stanford experts highlight areas central to success as the Biden-Harris administration aims its sights on safeguarding U.S. drinking water.

Stanford researchers, in collaboration with groundwater managers, are leading an airborne survey effort to investigate where water from the Sierra Nevada Mountains could recharge groundwater aquifers in California’s Central Valley.

Research led by Rosemary Knight uses a spider web-shaped device hanging from a helicopter to map underground water supplies.

“The images really drew attention to a system that’s out of balance,” says Rosemary Knight, who uses geophysical techniques to find promising areas for groundwater recharge.

The Stanford Natural Gas Initiative hosts the first big data workshop for students and industry leaders on data science techniques for better understanding and managing subsurface resources.

Stanford Earth's David Lobell, Rob Jackson, Erik Sperling, Dustin Schroeder, Sally Benson, Roz Naylor, Michael Machala, Rosemary Knight and Kate Maher have received funding for interdisciplinary research to solve major environmental problems.

With new rules for groundwater management coming into effect, engineers are looking to harness an unconventional and unwieldy source of water: the torrential storms that sometimes soak California.

Stanford Earth geophysicist Rosemary Knight discusses how her recent research integrating two types of remote sensing data could help water managers in California's Central Valley.

New research provides insight on a common cause of drinking water contamination in coastal areas: intrusion of ocean saltwater into freshwater aquifers.

Research by Rosemary Knight shows that unless action is taken, parts of the Central Valley will sink more than 13 feet over the next 20 years. Stopping it will require strategic replenishment of shrinking aquifers.

Overpumping in California has depleted groundwater storage capacity and caused the land to sink. A new model could help water managers zero in on where to replenish aquifers by flooding fields.

Stanford Earth's Rosemary Knight is a panelist for a professional development conference for participants of the Diversifying Academia, Recruiting Excellence Doctoral Fellowship Program (DARE).

New rules and new technology are giving farmers and managers a better look at groundwater supplies.

The Central Valley is one the main food suppliers in the U.S., but it now faces a host of environmental concerns. Research from Stanford Earth shows over-pumping aquifers can release toxic arsenic.

In GEOPHYS 190: Near-Surface Geophysics, Rosemary Knight and Dustin Schroeder help students apply geophysical imaging methods and tools to sustainable water management. 

Research by Stanford Earth’s Ryan Smith, Rosemary Knight and Scott Fendorf shows overpumping groundwater could cause deadly water quality problems.

Pumping an aquifer to the last drop squeezes out more than water. A new study suggests it can also unlock dangerous arsenic from buried clays. Sinking land may provide an early warning and measure of contamination.

Geophysics professor Rosemary Knight comments on a study she co-authored showing that sinking land caused by intensive groundwater pumping in California is releasing trapped arsenic, a known carcinogen.

Ryan Smith, a doctoral candidate in geophysics, explains research he led showing that continued heavy pumping of groundwater in the Central Valley could threaten water supplies with arsenic contamination.

As a geophysics professor at Stanford Earth, Knight has put both graduate and undergraduate education at the forefront of her efforts.

Stanford Earth’s Rosemary Knight recently spearheaded a project to map underground freshwater resources and forecast the intrusion of saltwater into aquifers beneath the California coastal town of Marina.

Over-pumping groundwater has drastically and permanently reduced the water storage capabilities of land in one of California’s most important farming areas.

Scientists use Earth-imaging technologies to study the intrusion of saltwater into freshwater aquifers along the California coast.

Rosemary Knight's team developed a way to measure the amount of groundwater in the Earth from readings taken hundreds of miles above the planet. On KPIX