Deep cracks in the earth’s surface or vast and deep holes that suddenly happen under people’s feet in towns and villages are signs of the phenomenon of land subsidence. Subsidence has now become an environmental, social, and economic threat in the world.
According to the results of the ‘Mapping, the global threat of land subsidence’ article published earlier this year in the journal Science, 19 percent of the world’s population lives in areas exposed to subsidence. Also, 12 percent of the world’s GDP, which is about $8.17 trillion, is produced in areas prone to subsidence.
Subsidence is not only a direct threat to human life and property but also exacerbates flood damage and can even lead to permanent loss of land with various land uses damage to infrastructure and buildings, as well as damage to the environment.
The phenomenon of land subsidence is not the issue of a particular country or logic, but on all continents, some areas are prone to subsidence. North America, Asia, Europe, and South Australia are prominent examples of regions involved with the subsidence phenomenon.
Reports about the damages of this phenomenon show that the economic consequences of subsidence are not just speculation. For example, despite the subsidence phenomenon, the risk of flooding in the world’s coastal cities will reach $635 billion annually by 2050.
The economic consequences of subsidence can be investigated in two categories: direct and indirect. Critical infrastructure such as water management, transportation, energy, and communications are damaged by subsidence, and this is just one of the direct consequences of subsidence.
Damage and destruction of residential buildings and factories is another direct consequence of subsidence in the economy. These damages impose the cost of repair, migration, and uncertainty on the economy. Other direct consequences of subsidence can be considered as its destructive impact on the environment, cultural-historical sites, as well as damages caused by declining performance.
On the other hand, indirect consequences of subsidence can also affect the economy. Among them are increased flood risk, reduced agricultural production, and social and healthcare challenges. According to estimates, $77.7 billion of Iran’s GDP is at risk of subsidence.
Of Iran’s 609 plains, about 500 have fresh waters, all of which are facing subsidence. The results of the latest monitoring on the plains of Iran show that there is currently no plain in the country where freshwater is available but does not face the phenomenon of subsidence.
The reason for this is the indiscriminate harvesting of water from aquifers and the lack of management of water resources by the government.
It is not unexpected that next year’s studies will show that the northern cities of Gilan and Mazandaran have also been added to the total cities involved in subsidence risk, cities that are even not facing drought.
In the plains of Tehran, the rate of subsidence has decreased compared to the previous five years, but its extent has increased. The most dangerous province in the country in terms of subsidence is Isfahan province and Isfahan is the only metropolis in the country that subsidence has penetrated the city.
Therefore, not only can subsidence be considered as a threat to the historical-cultural centers of this province, but also the tourism economy of Isfahan, followed by the livelihood of residents, is threatened by the phenomenon of subsidence.
The most basic way to deal with land subsidence is to reduce water harvesting from underground water resources. Because due to proper administration and control by the government the only solution left for the country is the management of consumption from underground water resources because the loss and damages are not easily reversible.