Groundwater warning in California a wake-up call for Canada: FamigliettiA team of scientists who pioneered methods to observe changes in global groundwater stores over the past two decades using a specialized NASA satellite mission has made a surprising discovery about the aquifers that supply California’s Central Valley region.
Jan 9, 2023
Despite the Sustainable Groundwater Management Act (SGMA) adopted in 2014 to prevent over-pumping and stabilize the aquifers, the groundwater depletion rate has accelerated to a point where the resource could disappear over the next several decades. SGMA gives the state’s local groundwater management districts until 2042 to reach sustainability goals.
Renowned water scientist Dr. Jay Famiglietti (PhD), lead researcher of a scientific team that in late December published a paper in the prestigious Nature Communications journal detailing what their analysis indicates, has a blunt message:
“All around the world, we have been kicking the can down the road for a long time on effectively managing groundwater. Now we are at the end of the road, and it’s a dead end.”
Among the world’s most productive agricultural areas, California’s Central Valley grows most of the produce consumed across North America. To do that it relies heavily on aquifers – as much as 100 per cent during droughts. While groundwater has been disappearing from the region for almost a century, the increasing rate of drawdown in recent years is completely unsustainable, Famiglietti said.
“If that water disappears, so does food production. That means less produce, higher prices, shortages, and other shocks to food systems,” said Famiglietti, professor emeritus in hydrology at the University of Saskatchewan (USask) and former executive director of USask’s Global Institute for Water Security.
“My fear is that if we wait 20 years to bring these aquifers to sustainability, there may not be anything left,” he said. “So, speeding up the implementation period may be worth considering, because there appears to be a rush to pump as much as possible before the hammer comes down.”
His team analyzed nearly two decades of data collected by NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite and the GRACE Follow-On satellite. Their research shows groundwater losses during 2019-2021—the driest three-year period in California’s history—were 31 per cent faster than in two previous drought periods of 2006-2011, and 2011 to 2017. This rate is also five times greater than the long-term average rate of depletion since 1962.
Deep groundwater took geologic time of millions of years to accumulate, Famiglietti said, and the current scale and pace of the depletion means that recharging the supply is virtually impossible.
“We talk about managed aquifer recharge and replenishing some of these aquifers. But that’s a small amount of water and it’s close to the surface. This is industrial scale mining of groundwater, with virtually no chance on human time scales to replace the losses.”
The impacts of depletion far extend beyond food production, he said. A big issue is the subsidence (sinking) of the ground, which can potentially affect about one-quarter of the Central Valley.
Water for desert cities, including in major U.S. cities such as Las Vegas, Phoenix, Tucson, and Salt Lake City, will be also more scarce, he said.
Accompanying the disappearance of groundwater, there is ecological damage as wetlands are drained, and as streams run dry. And as water tables fall, costs increase to dig deeper wells and pump groundwater higher, creating affordability problems for people who need to access the water. As well, the poorer quality of the deep water makes expensive treatment necessary for drinking it.
What’s happening in the Central Valley is also happening in the Lower Colorado Basin, the southern part of the High Plains Ogallala Aquifer, the Middle East, in India and Bangladesh, and several other major food-producing regions around the world, he said.
This depletion of groundwater should be a wake-up call for Canada, where more than half of the population relies on groundwater for drinking, and for Saskatchewan, which is striving to double its food production capacity, said Famiglietti.
“Currently we’re OK, but if we want to increase food production and we want to be doing it on an annual, sustainable basis, that means irrigation and that means having continuous access to water. To me that means groundwater.”
He notes that South Saskatchewan River water is nearly over-allocated already, as is the water in many of Canada’s rivers, so care must be taken to avoid Saskatchewan becoming another California or Colorado River Basin.
“We have to think about how much groundwater we need for sustainable food production, and then to manage to balance that with changing surface water availability so that we can do it for centuries, not just for a few decades.” https://news.usask.ca/articles/research/2023/groundwater-warning-in-california-a-wake-up-call-for-canada-famiglietti.php?mc_cid=08a280c977&mc_eid=30488675cb