California Drought Caused Sierra Nevada To Grow An Inch, NASA Researchers Say

While the recent California drought was definitely bad for numerous lawns and farms in the Golden State, it apparently resulted in the iconic Sierra Nevada mountain range growing close to an inch, according to new data from NASA’s Jet Propulsion Laboratory.

According to the Los Angeles Times, JPL researchers monitored the mountain range with about 1,300 GPS stations, hoping to determine how its elevation changed in a four-year period from October 2011 to October 2015. Based on the differences in height, the mountains lost about 10.8 cubic miles of water in those four years, or just about enough water to support Los Angeles for 45 years.

Commenting on his team’s findings, JPL research scientist Donald Argus explained how precipitation trends could cause mountains to shrink or grow. When rain, snow, and other forms of precipitation build up on the surface, mountains tend to give way and lose some height. But when there is a lack of water on the surface, similar to what happened in this decade’s California drought, the opposite happens, as mountains grow a bit taller due to the loss of water weight.

“It’s like a bathroom scale,” Argus told the Sacramento Bee on Thursday.

“When you took the water off, it rose.”

Overall, the California drought resulted in the Sierra Nevada rising 24 millimeters, or close to an inch. However, the Los Angeles Times added that the Sierra has since regained almost half of the water it had previously lost, which caused it to shrink about a half-inch since October 2015.

Prior to the release of NASA’s findings earlier in the week, researchers were already aware that the Sierra Nevada had a tendency to lose or gain some height. One theory that sought to explain these fluctuations revolved around the phenomenon of “tectonic uplift,” or the slow and steady shifting of Earth’s tectonic plates. While this did play a role in the mountain range’s one-inch height increase, the study indicated that only a fraction of this gain was due to tectonic uplift.

A second theory suggested that intense groundwater pumping had caused the height increase in the Sierra Nevada. As explained by the Sacramento Bee, farmers in California’s Central Valley had engaged in groundwater pumping during the drought, which resulted in parts of the valley floor sinking. NASA’s study confirmed that this also contributed to the height increase, but not as much as the lack of water and snow from 2011 to 2015.

In a statement, study co-author and JPL senior water scientist Jay Famiglietti stressed that the role of mountains in storing water is something that has yet to be explored in full. But with the release of his team’s findings, he hopes that the techniques used in the research will encourage scientists to address unanswered questions surrounding mountain groundwater and its behavior.

“What does the water table look like within mountain ranges? Is there a significant amount of groundwater stored within mountains? We just don’t have answers yet, and this study identities a set of new tools to help us get them.”

Even if those questions do get answered, the fact remains that mountain water is largely inaccessible, Famiglietti said in an interview with the Los Angeles Times. Given how the drought caused the Sierra Nevada to lose so much water and add a bit to its height, he believes that determining the pathways mountain water travels through is especially important in California and other regions that are prone to such events.

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