A giant sinkhole about 60 metres deep has made a surprise appearance in western Iran. The sinkhole opened up on August 19 near the small village of Kerdabad, in the Kabudrahang county of the western province of Hamadan. It has terrified both locals and experts, who say this phenomenon shows that groundwater tables have been badly damaged.
The images of this giant hole in the earth are even more chilling due to its location: the sinkhole is only one kilometre from a village with more than 2,000 residents, and only a few more kilometres from a solar power station, a thermal power plant and a major national highway.
CORRECTION (3/9/2018): The original version of this article published Aug. 27 cited erroneous estimations of the size of the sinkhole. We estimate its diameter to be approximately 100 meters.
A shepherd who witnessed the pit’s creation described it to Iran’s state media:
It was about 3 pm and I was just 20 metres away from where the pit would open up. Suddenly I heard a strange, deep noise and saw lots of dirt flying up in the air. One second the hole wasn’t there, and the next second it was. People in the village are now afraid – what if it happens again, but this time in the village? We ask the authorities to find a solution for us.
This is not the first time this phenomenon has occurred in the region – it is actually the 13th giant sinkhole to have appeared in Kabudrahang county in two decades. So far, none of them have opened up inside villages or cities, but some have come close.
According to Iran’s Tasnim news agency there are 90 sinkholes in all of the country, including 25 in Hamadan province.
"Sinkholes pose a huge risk to the people"
Amir Shemshaki is the director general of the bureau of geohazards, engineering and environmental geology at the Geology Survey and Mineral Exploration of Iran, which is a national agency.
These sinkholes are caused by large domes under the earth that collapse in on themselves. They usually take place in sedimentary layers, mostly in calcium or lime.
There are many natural and human-made reasons that can lead to these collapses. The natural reasons include large amounts of water washing through them, or simply that they become too heavy over time. Human-made reasons include overconsumption of ground water – if the dome’s structure is too dry, it weakens – as well as the presence of wastewater with high levels of PH, which can cause calcium and lime to dissolve.
In Kabudrahang county, there are several factors combined: there’s an overconsumption of groundwater, it has a high PH, and the ground formation is based on lime, which dissolves easily.
To prevent the formation of sinkholes, the agriculture in this region must be adapted. Water consumption must be reduced via more effective irrigation practices.
According to the Hamadan province water company, there are at least 1,000 illegal water walls serving 120,000 hectares or agriculture in Kabudrahang county, and this has reduced groundwater levels by 40 meters in the past 20 years.
According to Nasser Karami, an Iranian physical climatologist based in London, “In less than 50 years, Iran has used up 70 percent of its groundwater supply, which took a million years to build up.”
Sinkholes pose a huge risk to the people living in [Kabudrahang county]. So we must closely monitor urban development and carry out careful surveys so that any plans for construction in risk-prone areas can either be stopped or relocated.
Iran has been hit by drought for five decades running. According to the Iran Meteorological Organisation, 90 percent of its territory is currently experiencing drought, although the levels differ from region to region.