TEHRAN - Land subsidence in the plains of Iran has affected the country's historical and archaeological monuments. The main cause of land subsidence in Iran is the excessive groundwater withdrawal for agricultural, industrial, and urban irrigation purposes.

This has led to the emptying of groundwater and reduced access to water for domestic and agricultural purposes. Land subsidence has affected about 3.5 %b of the area of Iran until 2024, which if we consider the area of the plains, to be about 15 % of the total area of Iran - about 23 % of the plains of Iran experiences some level of land subsidence. 

Note that about 10 % of 400 plains in which land subsidence has been reported are plains that are sinking at a rate of more than 10 centimeters per year. 

The provinces of Tehran, Isfahan, Fars, Khorasan-e Razavi, and Kerman are among the most important regions in which the most amounts of subsidence have been reported. The first subsidence report in Iran was from Rafsanjan Plain, Kerman province, in 1977, where the subsidence rate is about 37 centimeters per year as of 2024. 

In Alborz province and the cities of Savojbolagh and Nazarabad experience subsidence of 29 and 27 centimeters per year, respectively. The subsidence has also affected the historical sites of Iran, such as the Naqsh-e Jahan square of Isfahan, ancient mosques, Takht-e Jamshid (Persepolis), and Naqsh-e Rostam collection. Land subsidence has also affected Iran's infrastructures, including airports, roads, and railways. 

The most important measure that can help to reduce the speed of land subsidence is to reduce the extraction of groundwater.  In order to improve land use planning, implementation of sustainable water management methods, installation of smart monitoring systems on water pumps and wells, prohibition of drilling of deep wells and suspension of unauthorized wells, controlling agricultural products, and banning the cultivation of water-intensive crops may help the land subsidence risk reduction.

Subsidence in areas with rich historical and archeological heritage has become an important concern. Many of the historical buildings such as Takht-e Jamshid (Persepolis), Naqsh-e Rostam in Fars, and Golestan Palace in southern Tehran, and various mosques and bazaars are made of materials that may not withstand significant subsidence. 

As the ground settles unevenly, cracks appear in the walls, ceilings, and foundations. The destruction of these buildings affects not only their physical condition but also the heritage of the culture they represent. 

Many places are of significant historical value for their cities and regions and are an important part of the national identity of that region. Restoration projects should consider the strengthening of the structure against future subsidence while maintaining historical authenticity, with the expertise of several disciplines, including engineering, archeology, and archaeological rehabilitation. 

According to recent observations, in 2024, subsidence occurred at 300 meters distance to Takht Jamshid and at a distance of 10 to 15 meters from Naqsh-e Rostam. In addition, Naqsh-e Rostam, especially the Cube of Zoroaster has been exposed to manual soil settlement and the leveling of the area. These observations raise concerns about the sustainability of important ancient sites in Iran. Subsidence can cause the creation of cracks and fissures that endanger the sturdiness of these buildings.

Visible damage in the Naqsh-e Rostam includes cracks to different depths, sometimes up to 50 cm. Despite the effort to fill them with sand, it has been observed that these cracks have expanded. 

The continuation of these gaps shows that the building conditions are getting worse, which may eventually lead to further damage to the Cube of Zoroaster. The importance of the culture of Takht-e Jamshid and Naqsh-e Rostam cannot be overstated because they are the components of the identity of the nation. 

Subsidence affects not only physical structures but also stone reliefs and precious tombs, which date back to the kings of ancient times such as Darius the Great and Xerxes. The rate of subsidence progress is slow. Since these sites face increasing risks due to environmental factors such as rainfall and the reduction of groundwater levels, their preservation is increasingly important and essential.

Due to a lack of financial resources and management problems for the protection of sites in crisis, the efforts to carry out repairs have been very slow. The preventive measures against more subsidence were always ongoing. Specialized teams have visited these sites for monitoring and restoration efforts. 

A coherent plan to control the situation is necessary according to the level of land subsidence that has affected the plains including the surrounding areas of Fars province where Takht-e Jamshid and Naqsh-e Rostam are located. 

Sustainable water management methods include stopping extraction from deep wells and methods of controlling groundwater extraction, including water level monitoring, and limiting the amount of water to be pumped. The promotion of rainwater harvesting techniques can help to reduce the reliance on water sources. 

Reforestation and soil protection by planting vegetation around these dark places can help to stabilize the soil structure, reduce erosion, and improve water retention in the soil.  Installing an accurate monitoring system will help to compare the satellite images, for example, InSAR technology, to localize the momentary tracking of the earth's movement should be provided. Regular geological surveys of subsurface data help to control subsidence. 

Public awareness campaigns about the importance of sustainable development and management can strengthen community participation in conservation efforts. Involving the residents of the region through workshops or training programs may help better understanding and cooperation among the various sectors of house building, agriculture, animal husbandry, and civil engineering. 

Implementation of strict regulations regarding land use near the ancient areas of Takht-e Jamshid and Naqsh-e Rostam helps to minimize the subsidence acceleration facts.

The Ministry of Cultural Heritage has carried out this monitoring work, but in order to prevent the spread of subsidence in the archaeological sites, it has to cooperate with several ministries, including the Ministry of Energy and the Ministry of Jihad of Agriculture. 

The implementation of the laws against the illegal extraction of water for long-term sustainability is an important task force of the Ministry of Energy and the Ministry of Interior. The restoration projects by the Ministry of Cultural Heritage should be started by observing the protocols for repairing the damaged areas caused by the subsidence.

Cooperation with international organizations for technical support in restoration efforts can help restore and rehabilitate archaeological sites by sharing the knowledge of international scientists. University research - currently underway - should be directly supported financially and technically to develop innovative solutions for land subsidence management, and the development of new technologies in the form of local solutions will help the issue.

Partnerships with universities or research institutes can facilitate the transfer of knowledge about best practices at the global level. Upgrading existing infrastructure to resist potential changes caused by subsidence protects both cultural heritage sites and local communities. The implementation of drainage systems that manage surface water effectively can prevent excess moisture in soil instability. The development of systems that are specifically aimed at protecting cultural heritage sites against environmental threats should be done at the national level.

International organizations such as UNESCO may provide frameworks to preserve these valuable places and at the same time address environmental concerns. The participation of local communities in the decision-making processes related to land-use management ensures that the solutions are culturally appropriate and widely accepted. Voluntary programs focused on conservation efforts can foster a sense of ownership among residents of their historic sites.