The secretary of Iran’s Natural Disaster Task Force has said hundreds of large plains in the country are at risk of subsidence due to decreased level of underground water.
Ali Baitollahi, secretary of the nationwide working group, which was set up in 2002 and answers to the Interior Ministry, told ISNA news agency that no fewer than 609 tracts of land are vulnerable to landslides and cave-ins.
“This destructive phenomenon is directly related to groundwater depletion,” he said. “If the level of groundwater aquifers decreases, the ground level goes down.”
Furthermore, Baitollahi said, the process was irreversible: “If the subsidence such a level that all the aquifers become empty and dense, even if it rains and snows thousands of times in the coming years, the rainwater will no longer penetrate the soil.”
As well as worsening droughts, Baitollahi warned that subsidence could have a major impact on industrial infrastructure and power grids. Pylon foundations in such areas as Varamin, Eshtehard and Qom have already been weakened by reduced elevation.
"Land subsidence under oil and gas transmission lines will cause them to rupture,” Baitollahi said, “and will lead to hazards and loss of life."
Tehran and Iranian Cities Already Feeling the Effects of Subsidence
Baitollahi quoted a recent study that, he said, had examined the records since 1999 and established that over the past 20 years, elevation levels southwest of Tehran, at the intersection of the Azadegan Expressway and Saeedi Highway, had notably decreased.
Two other areas south of Tehran, including a 30 sq km zone on the way to Shahriyar and a 25km by 15km area of the Varamin plain, also showed “serious” subsidence.
In 2018 at least five major sinkholes opened up in Tehran in the Shahran area, Payambar Street, Ghiam Square, Mohammadieh Square, and the Molavi crossroads. In some cases they were fatal. The collapses made headlines around the world and at the time, Iranian officials immediately called for improved water management methods.
The agricultural community will be affected by subsidence because if water remains on the surface, nutrients will not find their way into the soil, turning fertile plains into deserts.
But Baitollahi warned that the most dramatic immediate effects could be observed in metropolitan areas such as Tehran, Isfahan, Kerman and Mashhad. Apart from the sinkholes, subsistence causes high-rise building structures to weaken, with potentially devastating consequences.
Beitollahi, who is also a member of Tehran’s Road, Housing and Urban Development Research Center, told ISNA he believed it was not too late. He criticized water-intensive farming methods for products such as watermelons and pointed out that subsidence had been reduced to near-zero in countries like Japan through planned action. “Unlike earthquakes,” he said, “landslides can be controlled.”