Land subsidence, a silent but extremely dangerous phenomenon, has become one of the most serious environmental crises Iran has faced in recent years. Land subsidence is the gradual lowering of the Earth’s surface due to various geological and anthropogenic factors. In Iran, the main causes of land subsidence are the overexploitation of groundwater resources and a sharp decline in the groundwater level. Many experts therefore refer to it as a “silent earthquake” because the effects, although slow, are extremely destructive, and the damage caused is virtually irreparable.
Subsidence in Iran
According to the Geological and Mineral Resources Organization of Iran, many Iranian plains are experiencing land subsidence at an alarming rate. The global average is about 4 mm per year , reaching 30–40 cm per year in some areas of Iran .
The plains of Tehran, Varamin, Kerman, Isfahan, Mashhad, Yazd, and Kermanshah are among the areas most affected by subsidence in Iran. The plains surrounding the capital, where millions of people live and vital infrastructure is protected, are seriously at risk. If these events continue, not only agricultural land will be destroyed, but buildings, roads, railways, power lines, and even the country’s cultural heritage will be irreparably damaged.
The role of groundwater in land subsidence
Iran’s climate is characterized by low rainfall and aridity . Average annual rainfall is around 250 millimeters, less than one-third of the global average. Groundwater is therefore an important strategic resource for human consumption, industry, and agriculture.
However, in recent decades, more groundwater has been extracted than it can reabsorb. Illegal well drilling , water-intensive agricultural practices, and declining rainfall have led to a sharp decline in the groundwater level. As the groundwater level drops, air fills the spaces between soil particles and other sediments. These spaces gradually harden, eventually leading to the subsidence of the Earth’s surface.
This phenomenon is essentially irreversible . Contrary to popular belief, the compacted layer cannot be restored by reintroducing the water withdrawn from the aquifer. In other words, the aquifer’s storage capacity is irreversibly reduced.
Consequences of land subsidence
Land subsidence is not limited to changes in the terrain , but has a variety of consequences:
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Damage to infrastructure : cracks in buildings, breaks in gas and water pipes, damage to railways and roads.
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Historical monuments in danger : Many historical sites in Isfahan, Rayy and Yazd are threatened by landslides.
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Declining agricultural productivity : Declining agricultural land leads to a loss of fertility.
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Increased risk of flooding : Due to changes in the natural slope of the terrain and the creation of deep cracks, rainwater flows away as surface runoff instead of infiltrating into the ground.
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Decreasing groundwater capacity : The capacity of groundwater aquifers is constantly decreasing due to ground pressure.
An example of land subsidence in Iran
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Tehran, Sahel and Ramin : Land subsidence in these areas is reported to be reaching 36 centimetres per year, and it is believed that such a rate could lead to a multi-faceted crisis.
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Isfahan: In some areas such as Parkar and Shahinshahr, the landslide destroyed buildings and even left deep cracks in the ground.
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Yazd and Kerman : These two provinces are facing one of the most serious crises due to intensive pistachio cultivation and overexploitation of groundwater.
The connection between climate change and land subsidence
In addition to overexploitation, climate change is exacerbating the problem. Rising temperatures and reduced rainfall have reduced natural groundwater recharge in recent years. Recurrent droughts have further increased the pressure on groundwater resources and the local population’s dependence on them.
Solutions to mitigate and manage land subsidence
Overcoming this national crisis requires a comprehensive, multifaceted plan. Key solutions include:
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Water management : reducing groundwater abstraction, installing smart water meters in wells, and sealing unauthorized wells.
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Changing cropping patterns : In dry regions, crops that require less water, such as rice and watermelons, are being planted instead of crops that require a lot of water.
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Development of new irrigation methods : use of drip and sprinkler irrigation systems instead of conventional irrigation.
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Water recycling and reuse : particularly in the industrial sector and urban green spaces.
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Artificial recharge of extensive aquifers : diversion of surface runoff and flood water into aquifers.
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Public awareness raising : Training and information of farmers, citizens and administrators to change their attitudes towards water use.
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Continuous monitoring : Use of remote sensing technology and satellite data to closely monitor subsidence rates.
Assessing the impact of contaminants on reverse osmosis membrane performance
Finally
Land subsidence in Iran has reached a level that constitutes a national crisis and a threat to regional security . This phenomenon is directly linked to the overexploitation of groundwater. This demonstrates that only improved water management and a change in consumption habits can solve this problem.
While some consequences are irreversible, prevention and management measures can slow the spread of the crisis. The survival and development of many regions of Iran undoubtedly depend on how we manage our land and water resources today.