Southern California actually 'breathes' water

Credit: Bryan Riel and Mark Simons

To survive, humans need to breathe oxygen. But in order for Southern California to thrive, it needs to breathe... water?

Researchers at the California Institute of Technology have gathered hundreds of satellite images from 1992 through 2011. The images, turned into a GIF, show how the ground in the southern part of the world's fifth largest economy rises and falls when groundwater is pumped in and out of aquifers beneath the surface.

"What we see through the rising and falling of the ground surface is the elastic response of the land to regular changes in groundwater level," says lead author Bryan Riel in a statement.

Riel, who is now a geophysicist at NASA's Jet Propulsion Laboratory, continued: "Because we have data over a long period of time, we were also able to isolate long-term surface deformation signals, including subsidence of the land that seems to be caused by compaction of clay layers in response to background variations in groundwater withdrawal."

The results of the findings have been published in the April 20 edition of Water Resources Research.

The data, which was captured by radar from the European Space Agency, focuses on San Fernando to Irvine, just minutes north of California's exquisite Newport Beach in Orange County. The aquifers in this region supply much of the water for the state's local farms and residents throughout the year.

While an impressive visual nonetheless, the fluctuation has actually been less dramatic than in recent years. This is due to regulators focusing more on replenishing the aquifers and less on depleting them.

"At the beginning of the study period, we see big sinusoids—higher highs and lower lows," said Caltech's Mark Simons  in the statement. "Toward the later half of the study, that flattens out a bit, indicating that water control districts were more actively managing aquifers, and making sure to put water back into them instead of just taking it out."

The change in fluctuations began after Gov. Jerry Brown signed the Sustainable Groundwater Management Act into law in 2014, which says that "groundwater managers need to avoid permanent lowering of the ground level."

Follow Chris Ciaccia on Twitter @Chris_Ciaccia