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NASA satellite data find freshwater losses in Middle East
Reprinted From Prevention Web: http://www.preventionweb.net/english/professional/news/v.php?id=31209&a=email&utm_source=pw_emailWashington
-- 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
Scientists at the University of California at Irvine (UC 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, parts of Turkey, Syria, Iraq and Iran along
the Tigris and Euphrates river basins lost 117 million acre feet (144
cubic kilometers) of its 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
The findings, to be 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 that 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
"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, principle 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."
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 rought, 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. For more about GRACE, visit: