In recent years, Iran grappled with challenges due to the overexploitation of groundwater, causing land subsidence and posing a threat to its precious historical sites, including the legendary terrace of Persepolis. Once the ceremonial capital of the ancient Persian Empire, Persepolis, established by Darius I in 518 BCE, stands as a testament to the architectural and cultural grandeur of the time. However, the surrounding Marvdasht Plain, situated less than half a kilometer from the Persepolis terrace, experienced alarming rates of land subsidence, threatening the stability of these ancient ruins. BBC News reports that the iconic carvings hewn into the stone structures, which endured for over 2,500 years, are now under threat as the plains around them sink by hundreds of millimeters annually.
The phenomenon is not isolated to Persepolis alone. Many of Iran's World Heritage sites, such as Pasargadae and the city of Yazd, lie perilously close to areas undergoing similar subsidence issues. "Only through detailed on-site assessments can the potential impact on these sites be fully determined, but it will certainly happen someday," stated Professor Mahdi Motaghi from the Helmholtz Centre for Ocean Research Kiel. According to Motaghi, the primary driver of this subsidence is the "excessive and unsustainable extraction of groundwater," as reported by Alwasat News. This unsustainable practice not only causes the land to sink but also contributes to the desertification of the region.
Land subsidence is exacerbated by periods of drought and rising temperatures, further reducing groundwater replenishment. Since the 1970s, Iran saw over 70% of its groundwater reserves depleted, and for decades consumed more water than its natural resources could replenish, as noted by Professor Motaghi.
As roads, canals, and pipelines tilt and bend due to the sinking land, the resulting infrastructure problems are both costly and damaging. In Tehran, parts of the city have been sinking by approximately 25 centimeters annually, demonstrating the widespread nature of this issue across Iran.
Efforts to mitigate these challenges include using radar technology to monitor subsidence closely. Researchers utilize this technology to measure even minute changes in the Earth's surface, explained Motaghi. Moreover, Iran pledged to cut its national water consumption significantly over the next several years by implementing strategies such as reuse and improved irrigation techniques.
The measures taken by other countries offer potential solutions. For example, after the 1980s, Bangkok saw its subsidence rate decrease from 120 millimeters annually to less than 20 millimeters in many areas by the 2000s, following government-imposed restrictions on groundwater pumping. Such international examples provide a possible roadmap for Iran as it seeks to preserve both its water resources and its invaluable historical heritage.
"There is no magic key - but experience proves that policies bear fruit," said Andrew Pearson from the International Center for Groundwater Resources Assessment. However, Iran's ambitious goals are currently thwarted by international sanctions, bureaucratic obstacles, and scarce investments, as noted by observers.
The preparation of this article relied on a news-analysis system.