California is getting ready to enter the hottest and driest months of the year, but it’s armed this year, at least, with a rainy season that resulted in nearly average precipitation for parts of the state. The largest reservoirs in Northern California are brimming, and urban water suppliers will be getting something of a reprieve on statewide mandatory conservation requirements.
About 90 percent of the state still suffers from some kind of drought conditions, though, and many experts suggest it will take two or three consecutive winters like the most recent to snap California’s drought.
But one expert believes we’ll need much more than that.
In the Los Angeles Times last month, hydrologist Jay Famiglietti, a senior water scientist at the NASA Jet Propulsion Laboratory and a professor at the University of California, Irvine, wrote that even a few years of increased precipitation, “won’t make a dent in this little-discussed reality: California suffers from chronic water scarcity.”
This issue of chronic water scarcity goes back long before California’s current drought and isn’t simply related to a lack of precipitation.
“What I really mean is that most of the water that we use is to grow food and we don’t have enough to do that, which is why we see the groundwater depletion that we do,” said Famiglietti. “That’s why we are literally running out of water. We’re trying to grow food for the nation using only California water and it’s killing us.”
Farmers in California produce about half the country’s fruits, vegetables and nuts. And many other crops are exported, too. The state is responsible for 80 percent of the world’s almond supply.
Growing food in the arid Central Valley requires irrigation, and farmers rely, in part, on groundwater. How much groundwater is pumped is related to the availability of surface water. Due to drought and environmental concerns, surface deliveries via the State Water Project and Central Valley Project (CVP) are often curtailed. Low deliveries of surface water result in higher amounts of groundwater pumping.
“One of the purposes of constructing the Central Valley Project was to offset groundwater overdraft in the early part of the 20th Century,” said Mike Wade, executive director of the California Farm Water Coalition. “It’s a no-brainer that today’s management of the CVP putting environmental priorities ahead of people without regard to social and economic impacts has taken us all the way back to the 1920s-era groundwater problems.”
Groves of citrus trees sit below a barren hillside in Tulare County, outside of Porterville, Calif. Some farmers are getting only a tiny fraction of their historic surface water, and so are drilling ever-deeper, draining the groundwater. (AP)
Satellite data from NASA’s GRACE (Gravity Recovery and Climate Experiment) mission has revealed big losses in groundwater in California’s Central Valley aquifer. As a result, the ground in many places is sinking. One area of the Tulare basin sank more than a foot in only eight months. Groundwater levels are continually setting record lows. The Department of Water Resources reported, “There are many areas of the San Joaquin Valley where recent groundwater levels are more than 100ft [30m] below previous historical lows and correspond to areas of recent subsidence.”
The problem is not just in California’s Central Valley. A study by Famiglietti and colleagues published last summer found that of the world’s 37 biggest aquifers, more than half had tipped past the point of sustainability.
“They are being depleted, some of them pretty rapidly,” said Famiglietti. “All of those aquifers are being used to support food production.”
Globally, about half the water that we use for agriculture comes from groundwater.
“So that’s why they are being depleted and the fact that they are being depleted points to huge, huge challenges to our food production around the world,” he said. “We better get thinking about it. Many of those aquifers are tapping into fossil groundwater that is not going to be replaced in our lifetimes or anyone else’s lifetimes.”
As crucial as groundwater is, it remains poorly understood, managed and regulated. “In the developing world, oversight is often non-existent,” wrote Famiglietti in Nature Climate Change. In parts of the U.S. we’re not much better off, either. California didn’t pass a law to monitor groundwater use until 2014, and the law’s implementation will take decades. The state also lacks accurate data on the amount of groundwater resources.
Increasing the understanding of the groundwater situation and implementing management solutions is fast becoming paramount as climate change impacts will likely further stress many of the aquifers that are already in trouble.
“One of the biggest things is that we are actually seeing the wet areas of the world getting wetter, and the dry areas of the world getting drier,” said Famiglietti. Research from the Intergovernmental Panel on Climate Change suggests this scenario happening by the end of the century, “but we are seeing it now,” he said. “In the last five or six years the pattern has become very clear in our GRACE data.”
Areas of high latitude and low latitude are getting wetter, and the area between is getting drier. The line between wet and dry runs right through California (and the middle of the United States). As dry areas get less precipitation, they will need to rely more on groundwater, which will cause further stress to aquifers. “You throw in a little population growth and I think it’s just a mess,” said Famiglietti.
Solutions to the problem are multifaceted. For Wade, the most obvious relates to surface water. “Unless we fix surface supply problems, managing groundwater under new sustainability rules will result in the loss of hundreds of thousands of acres of farms that grow food for the market,” he said.
In his article in Nature, Famiglietti called for a four-fold approach to tackle the problem, which includes greater efficiency in agricultural water use, better exploration of aquifers to get a realistic accounting of water resources, combining surface and groundwater management, and sharing information across political boundaries on aquifer levels and groundwater withdrawals.
While the current drought in California creates additional stress on groundwater, it also creates an opportunity for public awareness. “The drought highlights the [groundwater] problem. That’s when we really appreciate it a little more,” said Famiglietti. “But the problem has always been there and it’s always going to be there. And it’s very clear when we look at our data over the long term. We are literally draining the bank account.”