Now, detailed satellite images reveal the extent of the problem, including that some parts of the Iranian capital are falling by as much as 25 centimetres a year, and that the collapse is spreading to encompass the city’s international airport . Geoscientists Mahdi Motagh and Mahmud Haghshenas Haghighi, both at the GFZ German Research Centre for Geosciences in Potsdam, used satellite data to monitor subsidence across the Tehran region between 2003 and 2017.
Previous work had shown that Tehran is sinking and had linked the sinkage to the depletion of groundwater aquifers, which are being sucked dry to irrigate nearby farmland and serve greater Tehran’s 13 million or so residents . The latest data put new figures on the problem. The western Tehran Plain — a mix of Tehran’s urban sprawl, satellite cities and agricultural land — is subsiding at a rate of 25 centimetres per year, and the Varamin Plain, an agricultural region to the southeast of the city, is subsiding at a similar rate. The city’s international airport — located southwest of Tehran — is sinking 5 centimetres annually (Source: https://www.nature.com/).