Stanford Doerr School of Sustainability researchers use airborne technology to spot groundwater recharge sites

PALO ALTO, Calif. (KGO) — Recently, Stanford researchers soared above the California skies on a kind of aerial scavenger hunt. Probing hundreds of feet into the ground with electromagnetic signals, they were looking for liquid gold – water, or more specifically a place to capture and store it.

“When we look at what the future of fresh water in California is likely to be, the total amount of precipitation will not necessarily be less, but there will be more intense storms, more intense droughts. So the idea is that when we have intense storms, capture the flood waters, divert them to places like this, put them in the ground to recover from the previous drought or prepare for the next one,” says Rosemary Knight, Ph.D. ., a research fellow at the Stanford Doerr School of Sustainability.

She has just published a new study, confirming the ability of airborne technology to locate what are now called “paleo valleys”. These are long, buried riverbed paths created thousands of years ago by the movement of glaciers that once covered the Sierra. Filled with porous materials, experts believe they could act as a high-speed expressway to transport diverted floodwaters deep into the aquifer.

“And so, there are water managers now looking at how they could use an existing aqueduct or an irrigation canal or a series of irrigation ditches, to move water to prime locations for recharge. “, explains Knight.

A prime location is a paleo valley site discovered near Fresno. Kassy Chauhan is managing director of the North Kings Groundwater Sustainability Agency and director of the Fresno Irrigation District. She says planners hope to potentially use the new data to help plan critical groundwater recharge programs, in an area hard hit by the state’s current drought.

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“And that’s really what it’s all about when the rain and the heavy, wet seasons come…we want to be able to put as much water in the basement as possible,” Chauhan says.

To achieve this, Knight is using a new grant to combine aerial surveying with ground data to create an online mapping system. The aim is to help everyone from water agencies to farmers identify locations that could be optimized for groundwater recharge.

“There is so much space below the ground surface where we can store water. And in some ways, the worse our groundwater situation gets. The lower the water levels go, the more we have to space for storage,” Knight points out.

The researchers say versions of the technology can also be used effectively in smaller areas to locate optimal water recharge sites in areas such as orchards or agricultural fields. Perhaps, greatly expanding how California manages its water supply.

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