California Is Still (Literally) Sinking

March 8th 2017

Kyle Fitzpatrick

Desperate times call for desperate measures and, amid a drought, that typically means: turning to groundwater.

In California, a multi-year drought may be coming to an end, but sources of groundwater are still quite sore after being tapped excessively for drinking water and corporate agriculture.

Droughts have some severe side effects.

California’s reliance on groundwater in trying times has led to the sinking of the state — literally. As ATTN: reported in 2015, depleting groundwater has caused thousands of miles in the state to uniformly sink by as much as two inches a month, according to imagery from NASA.

Two years after this initial finding, NASA’s Jet Propulsion Laboratory has released new findings: the state is still sinking as a result of depleting groundwater resources. This problem is widespread, creating “subsidence bowls” of depressed land from Fresno County to the Sacramento Valley. Hundreds of square miles of land have sunk as much as two feet.

This problem isn’t new, but it's particularly bad right now.

Beyond the 2015 findings, subsidence has been an ongoing problem in areas where groundwater is heavily relied upon. Cathleen Jones, Radar Scientist at JPL and co-author of the recent JPL report, told ATTN: the new findings are concerning but unfortunately nothing new.

“We’ve been looking at [subsidence] since 2013 but it’s been going on for a lot longer than that,” Jones told ATTN:. “I can’t say exactly how long but probably as long as there’ve been people using groundwater in the Central Valley. There’s been a loss of compaction of the aquifers in some areas and that’s caused the ground to subside.”

While a sinking state may sound abstract, the effects are fairly clear since it quite literally means the land is compacting into the earth. “The effects are better seen across a broad scale,” Jones explained. “You would see that bridges would not have as much clearance over water anymore. You would see pooling of water when it rains. The scale of subsidence is kind of broader than a single house. A single house sitting on this land: all of it would subside.”

Subsidence can subside, though.

If groundwater resources are replenished and monitored during droughts, the effects of subsidence can be mitigated or avoided altogether. That’s not necessarily what’s happening, as Jones shared with ATTN:. “Whenever there’s a drought, people have to turn to groundwater as their water supply.... The problem is not that people are using groundwater at all — it’s that there’s not feedback between the consequences of how fast they withdraw the groundwater or where they withdraw or when and the collateral damage of some kind.”

Jones stressed that many aquifers are composed of multiple layers of clay and, accordingly, compact and re-expand when they are filled with water. However, some collapse after becoming too depleted.

“The worst thing that could happen is that you lose the capability to store water when you collapse an aquifer,” Jones says. “That’s not going to be fixed. I can rebuild a road but I can’t rebuild the aquifer.”

Considering droughts are becoming a nationwide issue — and are likely another byproduct of climate change — what's happening in California should serve as a warning.

"You’d be surprised how many states have severe drought in the last few years,” Jones said. “It’s not just California, it’s not even just the Western states: this is a big deal across the United States.”