Science
World’s Aquifers Losing Replenishment Race, Researchers Say
From
the Arabian Peninsula to northern India to California’s Central Valley,
nearly a third of the world’s 37 largest aquifers are being drained
faster than they are being replenished, according to a recent study led by scientists at the University of California, Irvine. The aquifers are concentrated in food-producing regions that support up to two billion people.
A companion study
indicates that the total amount of water in the aquifers, and how long
it will last at current depletion rates, is still uncertain. “In most
cases, we do not know how much groundwater exists in storage” to cover
unsustainable pumping, the study said. Historical estimates, it argues,
probably have unrealistically overstated total groundwater volume.
“We’re
depleting one third or more of the world’s major aquifers at a pretty
rapid clip,” said Jay S. Famiglietti, a professor of earth system
science at the University of California, Irvine, and a leading
researcher for the two studies. “And there’s not as much water there as
we think.”
Graphic
Your Contribution to the California Drought
The average American consumes more than 300 gallons of
California water each week by eating food that was produced there.
Dr.
Famiglietti and his colleagues found that eight to 11 of 37 major world
aquifers are overstressed, meaning they are losing much more water than
man or nature returns to them.
The
new studies do not come as a surprise to hydrologists like Jerad Bales,
chief scientist for water at the United States Geological Survey. But
for him and other experts, an open question is whether the governments
and individuals who control groundwater can or will work to gain more
knowledge about the extent of the resource and how much use is
sustainable.
Another
question is whether those with responsibility for managing the aquifers
will act to limit groundwater use, particularly if groundwater is
essential to their livelihoods.
“We
still have a ways to go in terms of learning how, and having the
willpower, to manage our groundwater systems,” Dr. Bales said. “We need
to think about it more. Water — people all over the world think, ‘If
it’s under my property, it’s my resource.’ But it affects everybody.”
Pradeep
Aggarwal, who leads the isotope hydrology division of the International
Atomic Energy Agency in Vienna, said in an interview that there was
growing recognition of the extent of groundwater depletion but that the
problem remains “an orphan.”
“Unless the government has an alternative to provide for their livelihoods, who is going to stop it?” Dr. Aggarwal said.
A
farmer, he added, will figure that “my livelihood depends on pumping
that water — if I stop pumping it, my neighbor keeps pumping it.” The
problem of groundwater depletion, he said, cannot be solved by
individuals. “This requires action on a larger scale,” Dr. Aggarwal
said.
The
stress on the most-used groundwater, measured over broad geographies by
a NASA satellite that has provided 13 years of data, is a matter of
real concern because, as the study said, “groundwater is currently the
primary source of freshwater for approximately two billion people.”
Another
scientist, Marc Bierkens, who holds a chair in earth surface hydrology
at the Department of Physical Geography at Utrecht University in the
Netherlands, estimated that about 20 percent of the world’s population
depended on crops irrigated by groundwater. In 2012, he published a
study in the journal Nature that pointed to the same groundwater overuse
reflected in the NASA data.
“Humans
are overexploiting groundwater in many large aquifers that are critical
to agriculture, especially in Asia and North America,” the Bierkens
study said.
Details
about individual aquifers are hard to come by. The data from NASA’s
twin Gravity Recovery and Climate Experiment (Grace) satellites cannot
show a level of detail below 150,000 square kilometers.
Dr.
Famiglietti, who is also senior water scientist at NASA’s Jet
Propulsion Laboratory, said that for the managers who have some control
over the use of aquifers, the data from Grace is “too coarse” to provide
useful data for local decisions. “They are waiting for us to do the
research — we call it downscaling it to a resolution they can use, that
makes it actionable for them,” he said.
The
volume of water in 11 of the 37 aquifers studied has declined over more
than a decade, according to the study, which was just published in the
journal Water Resources Research.
The
researchers looked at what appeared to be the loss of groundwater in
the aquifers — many of the most stressed are in arid or semiarid regions
— and examined how the water has been used, whether for irrigation,
supplying the daily needs of large populations or for industrial
purposes.
“Quantifying
our understanding of how we use water in the world is very important,
especially when the resource becomes limited,” Dr. Famiglietti said.
“It’s important to understand where the big users are because that is
key to affecting management in the future.”
A very insightful essay bringing to the surface the very very
delicate balance that exists on our planet between flora & fauna.
The Earth must maintain this balance so that the Earth's
very poignant beauty and purpose and function~~~~is SUSTAINED.
Its
impact on the economy, pollution, and the focus on Climate; The
Conversation---makes this worthy substance, for continued enthusiasm, and
consideration
Lou Marconi (SuiteLou0819)
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