NASA / UC Irvine / NCAR

Variations in total water storage from normal, in millimeters, in the Tigris and Euphrates river basins, as measured by NASA's Gravity Recovery and Climate Experiment satellites, from January 2003 through December 2009. Reds represent drier conditions, while blues represent wetter conditions.

Freshwater resources in the water-stressed Middle East are rapidly declining at a time when global climate change is projected to make the region even drier, scientists report in a new study.

Between 2003 and 2009, parts of Turkey, Syria, Iraq, and Iran along the Tigris and Euphrates river basins lost 117 million acre feet of stored water, according to gravity measurements taken by a pair of wedge-shaped satellites. That’s nearly the equivalent of all the water in the Dead Sea. 

"It is a pretty big water loss,” Jay Famiglietti, a hydrologist at the University of California Irvine, told NBC News. "And (the Middle East) is right up there with some of the most water-stressed regions of the world."

Since ground-based data on water usage in the Middle East is difficult to obtain, Famiglietti and colleagues used NASA’s Gravity Recovery and Satellite Experiment (GRACE) to understand how much water mass moved out of the region. 

Then, using satellite images of changes in lake and reservoir water levels, the researchers accounted for about a fifth of the water loss. Computer models of soil moisture and snowpack drying accounted for another fifth. The rest was due to groundwater pumping, primarily for irrigation purposes, Famiglietti said.

Groundwater pumping increased during 2007, when the region experienced a drought, which is a normal response to dwindling surface water supplies, he noted. Such droughts, he added, are expected to increase in the future in response to global climate change.

"So, it is probably a pretty good idea for us to begin thinking about managing the available water resources more carefully, thinking about how to sustain them for the long term," Famiglietti said.

In particular, he said the region needs to begin to pay closer attention to groundwater. The study indicates groundwater withdrawals are high, but what is unclear is how much water is actually in the ground.

Sandra Postel is director of the Global Water Policy Project, which promotes the preservation and sustainable use of freshwater. In an email to NBC News, she said the best opportunity for the Middle East is joint management of shared rivers and aquifers.

"Because water flows across and under political boundaries, it can be used over and over again if managed effectively," she said. "In this way water use is optimized to create greater overall benefits for all parties. If those benefits are then shared equitably among all the parties, water can be a force for peace and trust-building."

Water management in the Middle East is tricky, noted Katalyn Voss, lead author of the paper and a water policy fellow at the Center for Hydrologic Modeling. Turkey has jurisdiction over the Tigris and Euphrates headwaters and controls how much water flows downstream to Syria, Iran, and Iraq.

Turkey’s control of water distribution to the adjacent countries has already caused tension. For example, during the 2007 drought, it continued to divert river water to irrigate its crops, which put pressure on the downstream neighbors.

"Both the United Nations and anecdotal reports from area residents note that once stream flow declined, the northern part of Iraq had to switch to groundwater," she said in a news release. "In a fragile social, economic, and political environment, this did not help."

Findings are to be published online Feb. 15 in the journal Water Resources Research.

John Roach is a contributing writer for NBC News. To learn more about him, check out his website.