Satellite missions from 2003 to 2009, supplemented by remote-sensing data and output from land surface models, show a decrease in volume of the region’s freshwater reserves of 143.6 cubic kilometers during the 7-years of the study. This rate of water loss is among the largest liquid freshwater losses on the planet during this period. The 143.662.8 km3 loss during the 7-year study period is nearly equivalent in volume to the entire Dead Sea, which has an average volume of 147 km3.
The analyses presented suggests that groundwater depletion is the largest single contributor to the this observed negative trend, accounting for approximately 60 percent of the total volume of water lost, the majority of which occurred after the onset of drought in 2007.
Why is this not surprising? For one, a complex system of trans-boundary, groundwater aquifers underlies this region. Secondly, domestic and international monitoring, regulation, and data-sharing related to these groundwater aquifers are sorely lacking. While the region is subject to harsh environmental conditions, an absence of effective monitoring and management across borders leaves little basis for establishing strategies for conserving these precious, natural resources.
But if countries do not openly share information on water use, especially aquifer withdrawals, how can one verify these results? Extracting groundwater at a faster rate than it can be naturally replenished has some clearly observable effects, such “subsidence”, a geological term that describes the sinking of the earth’s surface. Reports of land subsidence due to over-abstraction of groundwater in places like Teheran, Iran, are well-documented. One can also use information on newly-constructed wells, such as the 1000 wells reportedly dug by the Iraqi government from 2007 to 2009 due to a decline in surface water availability.
On a side note, negative trends in volumetric losses in snow water and soil moisture in this same time period accounted for 20 percent of the observed water losses. However, both snow water and soil moisture loss are recognized to be largely climate-driven and are expected to be in further steady decline in the foreseeable future.
What do these results bode for the future of water in the Middle East? Traditionally, lack of trans-boundary cooperation, especially with little to no incentives for neighbors upstream to participate, has often led to downstream neighbors reverting to non-renewable groundwater supplies to satisfy demand.
These latest revelations will "even the playing field" in two very important ways. The first is that the 20 percent of observed water losses due to climate impacts may affect upstream and downstream neighbors more equitably than surface water abstractions do. The second, even , more important one, is that the technology mix of satellite, remote sensing, land surface models, and meteorological data makes individual government self-reporting on water abstractions, irrelevant. Data-driven models can approximate true values of surface as well as groundwater withdrawals. They are an objective source of information that all stakeholders can have equal access to.
How, or will, this affect groundwater withdrawal choices? Who knows? But we can measure it much more easily than before. And that puts us one step closer to understanding the gap between water supply and water demand in each of our Middle Eastern countries. There is very little mystery about what is happening, or indeed why it is happening. There is cause for alarm, but the hard evidence is also a potential foundation for a regional effort to manage and conserve a precious yet dwindling resource.