From Phys.org (Rob Jordan):
Superman isn’t the only one who can see through solid surfaces. In a development that could revolutionize the management of precious groundwater around the world, Stanford researchers have pioneered the use of satellites to accurately measure levels of water stored hundreds of feet below ground. Their findings were published recently in Water Resources Research…
Study co-author Rosemary Knight, a professor of geophysics and senior fellow, by courtesy, at the Stanford Woods Institute for the Environment, compared groundwater use to a mismanaged bank account: “It’s like me saying I’m going to retire and live off my savings without knowing how much is in the account.”
Lead author Jessica Reeves, a postdoctoral scholar in geophysics, extended Knight’s analogy to the connection among farmers who depend on the same groundwater source. “Imagine your account was connected to someone else’s account, and they were withdrawing from it without your knowing.”
Until now, the only way a water manager could gather data about the state of water tables in a watershed was to drill monitoring wells. The process is time and resource intensive, especially for confined aquifers, which are deep reservoirs separated from the ground surface by multiple layers of impermeable clay. Even with monitoring wells, good data is not guaranteed. Much of the data available from monitoring wells across the American West is old and of varying quality and scientific usefulness. Compounding the problem, not all well data is openly shared.
To solve these challenges, Reeves, Knight, Stanford Woods Institute-affiliated geophysics and electrical engineering Professor Howard Zebker, Stanford civil and environmental engineering Professor Peter Kitanidis and Willem Schreüder of Principia Mathematica Inc. looked to the sky.
The basic concept: Satellites that use electromagnetic waves to monitor changes in the elevation of Earth’s surface to within a millimeter could be mined for clues about groundwater. The technology, Interferometric Synthetic Aperture Radar (InSAR), had previously been used primarily to collect data on volcanoes, earthquakes and landslides.
More groundwater coverage here.