NASA’s
Startling Satellite Data Shows Massive Drop In Mideast Freshwater
Reserves During Warming-Driven Drought
17
March, 2013
By
Alan Buis, Steve Cole, and Janet Wilson, via NASA
A
new study using data from a pair of gravity-measuring NASA satellites
finds that large parts of the arid Middle East region lost freshwater
reserves rapidly during the past decade.
Scientists
at the University of California, Irvine; NASA’s Goddard Space
Flight Center in Greenbelt, Md.; and the National Center for
Atmospheric Research in Boulder, Colo., found during
a seven-year period beginning in 2003 that parts of Turkey, Syria,
Iraq and Iran along the Tigris and Euphrates river basins lost 117
million acre feet (144 cubic kilometers) of total stored freshwater.
That is almost the amount of water in the Dead Sea. The researchers
attribute about 60 percent of the loss to pumping of groundwater from
underground reservoirs.
The
findings … published Friday, Feb. 15, in the journal Water
Resources Research,
are the result of one of the first comprehensive hydrological
assessments of the entire Tigris-Euphrates-Western Iran region.
Because obtaining ground-based data in the area is difficult,
satellite data, such as those from NASA’s twin Gravity Recovery and
Climate Experiment (GRACE) satellites, are essential. GRACE is
providing a global picture of water storage trends and is invaluable
when hydrologic observations are not routinely collected or shared
beyond political boundaries.
“GRACE
data show an alarming rate of decrease in total water storage in the
Tigris and Euphrates river basins, which currently have the second
fastest rate of groundwater storage loss on Earth, after India,”
said Jay Famiglietti, principal investigator of the study and a
hydrologist and professor at UC Irvine.
“The rate was especially striking after the 2007 drought. Meanwhile, demand for freshwater continues to rise, and the region does not coordinate its water management because of different interpretations of international laws.”
“The rate was especially striking after the 2007 drought. Meanwhile, demand for freshwater continues to rise, and the region does not coordinate its water management because of different interpretations of international laws.”
Famiglietti
said GRACE is like having a giant scale in the sky. Within a given
region, rising or falling water reserves alter Earth’s mass,
influencing how strong the local gravitational attraction is. By
periodically measuring gravity regionally, GRACE tells us how much
each region’s water storage changes over time.
“GRACE
really is the only way we can estimate groundwater storage changes
from space right now,” Famiglietti said.
The
team calculated about one-fifth of the observed water losses resulted
from soil drying up and snowpack shrinking, partly in response to the
2007 drought. Loss of surface water from lakes and reservoirs
accounted for about another fifth of the losses. The majority of the
water lost — approximately 73 million acre feet (90 cubic
kilometers) — was due to reductions in groundwater.
“That’s
enough water to meet the needs of tens of millions to more than a
hundred million people in the region each year, depending on regional
water use standards and availability,” said Famiglietti.
Famiglietti
said when a drought reduces an available surface water supply,
irrigators and other water users turn to groundwater supplies. For
example, the Iraqi government drilled about 1,000 wells in response
to the 2007 drought, a number that does not include the numerous
private wells landowners also very likely drilled.
“Water
management is a complex issue in the Middle East — an area that
already is dealing with limited water resources and competing
stakeholders,” said Kate Voss, lead author of the study and a water
policy fellow with the University of California’s Center for
Hydrological Modeling in Irvine, which Famiglietti directs.
“The
Middle East just does not have that much water to begin with, and
it’s a part of the world that will be experiencing less rainfall
with climate change,” said Famiglietti. “Those dry areas are
getting dryer. The Middle East and the world’s other arid regions
need to manage available water resources as best they can.”
Study
co-author Matt Rodell of Goddard added it is important to remember
groundwater is being extracted unsustainably in parts of the United
States, as well.
“Groundwater
is like your savings account,” Rodell said. “It’s okay to draw
it down when you need it, but if it’s not replenished, eventually
it will be gone.”
GRACE
is a joint mission with the German Aerospace Center and the German
Research Center for Geosciences, in partnership with the University
of Texas at Austin. NASA’s Jet Propulsion Laboratory, Pasadena,
Calif., developed the GRACE spacecraft and manages the mission for
NASA’s Science Mission Directorate, Washington. For more about
GRACE, visit:
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