The jewel of the first superpower in the world is sinking

Persepolis has already suffered “irreversible damage”. It is not an exclusive phenomenon to Iran, but the scale is different, and puts several historical sites at risk.

The columns and stairs of sculpted stone of the terrace of Persepolisthe ceremonial capital of the former Persian Empire (c. 550 BC – 330 BC), survived for 2500 years, but now the soil around the place classified as a world heritage by UNESCO is sink.

The terrace was built on solid rock. Some parts may move only a few millimeters. But the gently inclined plains surrounding the fragile ancient stone structures formed with sediments deposited by running water. And now they are sinking tens of centimeters per year.

Marvdasht’s plain soil in Iran began to fragment, and the cracks are increasing. It is less than half a kilometer of the terrace and up to ten meters from another historical location, Naqsh-e Rostam.

“There are cracks on Earth, in the vicinity of Persépolis and Naqsh-e Rostam, which can be attributed to the degree of terrain subsidence”-the difference in the speed to which the soil is sinking-explains Mahmud Haghos Haghigni of the Institute of Photographia and Geoinformation at Leibniz University in Germany.

“Regarding Persépolis, I read news in the press about slits and other signs of damage. But without a comprehensive study, we cannot attribute them directly to the degree of subsilding. The terrace is in a relatively stable geological formation at the foot of the mountain,” he describes.

“Jewel” of the first superpower in the world

The United Nations Organization for Education, Science and Culture has classified Persepolis as World In 1979. their “magnificent ruins” are “among the greatest archaeological sites in the world,” according to UNESCO.

“Known as the Ayamenide set jewelry [persa] In the domains of agriculture, urban planning, construction technology and art, the real city of Persépolis is an archaeological site without equivalent and represents a unique testimony of one of the oldest civilizations.”

This civilization would become the Persian Empire, often described as the First superpower in the world. At its height, it covered a vast area that extended from Libya to the west to India, to the east.

Many of the other 28 Iranian locations classified as a world heritage are also located in areas where the soil is sinking. Include Pasárgathe original capital of the Persian Empire, and the historic city of Iazde. Authorities warn of the risks of subsidence in Isfahanequally World Heritage of UNESCO. Its bridges and mosques are found next to areas of sinking.

And the transiranial railroad, with 1,394 km long, crosses several sinking basins, which can cause distortions in the rails. The line was classified as a world heritage in 2021.

Running Against Time

Soil subsility is a slow process, and its detection can be difficult until fissures appear on the walls and foundations. Researchers use radar and compare images over time.

“This technology measures very subtle changes on the earth’s surface of only a few millimeters,” explains Professor Mahdi Motagh of the Leibniz University GFZ University Center of Geosciences.

Your team observed worrying differences at the depth of subsidy in Persepolis, Naqsh-e Rostam and in nearby places. Elements excavated directly on limestone, such as Naqsh-e Rostam, remain for now stable, but the neighboring plain is sinks quickly.

“On the border between the historical place rocky and the plain, we observed a strong gradient in the displacement field, which causes great slits and cracks on earth,” explains the professor.

“Irreversible damage has already occurred in some places. We observed a slit that directly crosses the zoroastro cube [em Naqsh-e Rostam] and that damaged him. ”

Only detailed evaluations on the ground can reveal when other locations will be affected, explains Motagh. But “that, inevitably, it will happen one day“, The newspaper.

Exhausted groundwater

“The main cause of land subsission in Iran is the excessive and unsustainable extraction of groundwater, which causes soil sinking and the advancement of desertification,” explains Motagh.

When water is pumped in excess underground layers-known as aquifers-the soil is compressed and the surface sinks, sometimes permanently.

A Drought and climate heating aggravate the problembecause less water returns to the underground. And Iran is one of the countries that are faster losing their aquifers.

The country has consumed for decades more water than nature replies. First he sold out rivers and reservoirs, then resorted to underground reserves.

Iranian aquifers have been strongly explored since the 1970s. It is estimated that more than 70% of their reserves are already sold out.

“Several pairs -reviewed studies show that the Iran is one of the largest consumers of groundwater in the world”Says Andrew Pearson of the International Center for Aquifer Resources Evaluation (IGRAC).

“About 90% of the water used in Iran is intended for agriculture,” he explains, “and excessive extraction, aggravated by drought, is the main cause of exhaustion.”

Impacts far beyond historical places

A recent national analysis concluded that about 56,000 square kilometers of Iranian lands are measurable – the equivalent of 3.5% of the country.

Some zones of the capital, Tehran, have been sink about 25 centimeters a year for several decades. In Rafsanjan (in the southeast of the country, known for its extensive pistatus plantations), it is estimated that aquifers are extracted from 300 million cubic meters of water per year, due to over-exploitation.

And as the soil sinks, roads, channels and tubes include and deform, generating serious infrastructure problems.

Iran is not the only

The difficulties faced by Iran are serious but not exclusive.

A, (Indonesia) and the Central Valley of (USA) have already registered, in certain periods, sinks of up to 100 mm per year. What distinguishes the Iranian case is the depth and scale of the phenomenon, as well as the amount of historical places at risk.

“Due to the geological context, subsidy in Iran is often accompanied by surface cracks and runs, which can extend to kilometers and reach several meters deep, with serious consequences for structures and infrastructure,” says Professor Pietro Teatini of the University of Padua in Italy.

Many other countries in the Middle East and North Africa – namely Egypt, Saudi Arabia, Israel and the occupied Palestinian territories – face similar problems. The region is one of the most affected by water stress worldwide.

UNESCO has organized technical seminars and meetings with government representatives in countries such as Indonesia and Vietnam. There are also planning initiatives in the Philippines, but political circumstances limit similar work in Iran.

Water Resources Management

A UNESCO spokesman told BBC News that the lessons learned in Spain, Mexico, China and Indonesia show that subsidenceOnce started, it is practically irreversible. Therefore, sustainable groundwater management is essential in arid regions such as Iran.

Experts agree on the need for integrated management of aquifer resources, but warns of social and political obstacles. In regions dependent on agriculture, abrupt cuts can have severe consequences.

“It is necessary to combine geoscience with engineering and the preservation of historical heritage,” says Motagh. “But it’s not easy, and to achieve significant cooperation with Iranian institutions is still particularly difficult.”

Iran pledged to reduce national water consumption by 45 billion cubic meters per yearover seven years, through reuse, gout irrigation to gout and improvement of supply. But these ambitious goals are locked by international sanctions, bureaucracy and lack of investment.

In August, the BBC contacted the Iran’s Ministry of Foreign Affairs, the country’s consulate and embassy in London, asking for comments on Iranian water resources management plans. No answer.

The measures adopted in other parts of the world to face subsilding may serve as an example to Iran on how to keep water and its historical heritage.

In the 1980s, parts of the Thai capital, Bangkok, were sank about 120 mm per year. But after the government introduced pumping limits, tariffs and monitoring, aquifer levels have risen and subsilding has reduced to 10–20 mm per year, or less, in many regions during the 2000s. “It’s not a magical change, but it shows that policy works,” concludes Andrew Pearson.