Currently the worst affected areas have been agricultural regions, such as the pistachio growing area on the Rafsanjan Plain in central Iran.
Digging Deeper for Water
Farmers consistently have to dig deeper wells every year, said Kourosh Mohammadi, from Tarbiat Modarres University in Tehran, Iran, who wasn't involved in the study.
Iran's cities are showing the strain too.
"In urban areas such as Tehran, residential blocks have also been affected by subsidence," Motagh said. Cracks are appearing in buildings, roads, and pipelines, added Mohammadi.
To make matters worse, the loose, dry soil is making earthquakes more dangerous, because the ground shakes more easily, according to Motagh.
An Old Problem
Iran isn't alone in facing these problems.
"This is quite consistent with similar basin subsidence that occurred in the western United States [near San Jose in the San Francisco Bay Area, in the Great Valley, and other basins in California] in the 20th century," said Roland Burgmann, from the University of California, Berkeley, who wasn't involved with the study.
Nowadays cities such as San Francisco import their water from the Sierra Nevada mountains. Similar mitigation schemes, along with better management of water supplies, may help ease the problem in Iran. But Burgmann thinks it is going to be tough.
"This can only be mitigated by finding water elsewhere or by drastically reducing water use for agriculture, industry, and personal use, neither of which will be easy in Iran or many other countries facing similar water crises," he said.
Climate change may exacerbate the problem, according to Motagh. Climate models predict a reduction in rainfall and an expansion of existing arid and semi-arid regions, such as Iran.
Motagh speculates that water removal and subsequent subsidence is likely to become an issue in many Middle Eastern countries.
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