Apr 15, 2019

California’s Central Valley is Sinking

As farmers drill for water, California’s Central Valley continues to sink. However, according to a recent study, it can be saved.

As farmers drill for water, California’s Central Valley continues to sink. However, according to a recent study, it can be saved.
As farmers drill for water, California’s Central Valley continues to sink. However, according to a recent study, it can be saved.

Stanford University researchers believe they have identified the best way to replenish the shrinking aquifers beneath California’s Central Valley.

According to The Sacramento Bee, the groundwater beneath the Central Valley has been steadily depleting, particularly as the state’s $50 billion agricultural industry relied on it during a series of droughts. Each year, more water exits the aquifer than goes into it.

The study from Stanford’s School of Earth, Energy and Environmental Sciences found that unless action is taken, the ground in that region will sink more than 13 ft over the next 20 years, according to The Sacramento Bee.

“There is a time delay in the system,” said Rosemary Knight, Stanford geophysicist and senior author on the study. “The only way we can stop it is to be strategic about what we do with our available recharge water.”

Knight said the Central Valley is in the midst of “a perfect storm” of conditions — including little rain, rising temperatures and an abundance of clay, which is prone to subsidence, or caving in — that will contribute to ground collapse.

According to The Sacramento Bee, much of that clay, which compacts as it dries out, is loaded with arsenic that could be pumped into the water supply. In order to “recharge” the aquifers, farmers have taken to strategic flooding of their fields and orchards.

“The key question is where does the water go?” Knight said. “If you’re going to flood a farmer’s field, you should be sure it’s going to work.”

The approach recommended by the study relies on “a marriage of two types of remote sensing data” that analyzes sand and clay layers in the ground, according to the Bee. It could be applied across large agricultural regions at relatively low cost, according to a statement announcing the report.

According to the Bee, as researchers collect more data, they will be able to predict where the ground is most at risk of sinking. The authors said this will be vital in the future.

“As groundwater demand grows globally due to climate change, more basins are experiencing land subsidence, making it essential that we can accurately model the impacts of groundwater depletion and design effective management strategies to reduce or avoid subsidence,” the authors concluded in the study.

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