In Iran, the area around Tehran is literally sinking. Stressed by a 30-year drought and hollowed out by excessive water pumping, the parched landscape near Iran’s capital has begun to open. Massive holes appear in the countryside. Fissures and crevices occur along roads.
The condition is called “land subsidence.” It poses a grave danger.
“Land subsidence is a destructive phenomenon,” says Siavash Arabi. The measurement expert at Iran’s cartography department says he can identify “destruction of farmland, cracks of the Earth’s surface, damage to civilian areas in cities, wastewater lines, cracks in roads, and damages to water and natural gas pipes.”
Why is it happening?
Tehran sits high on a semi-arid plateau. Over the last 100 years, the city has grown to be a sprawling metropolis of 13 million people.
All those people put pressure on water resources. Now add a longstanding drought. Last year, for example, the nation saw only 6.7 inches of rain. So Iranians went underground for water.
Aquifers are underground water reservoirs. Drilling down and then pumping up water became a necessity. But over-reliance on aquifers left empty caverns beneath the surface.
“When you pump water from under the ground surface, you cause some empty space to be formed in the soil,” Arabi explains. “Gradually, the pressure from above . . . leads to sinking of the ground.”
Iranian authorities have measured up to 8.6 inches of annual subsidence near the capital. Normal sinking would be only as high as 1.1 inches per year. Even greater levels have been measured elsewhere in the country. Some sinkholes in western Iran are as deep as 196 feet.
The sinking also threatens vital infrastructure, like Tehran’s Imam Khomeini International Airport. Tehran’s oil refinery, a key highway, automobile manufacturing plants, and railroads all sit on sinking ground.
Geopolitics play a role in the crisis. Since 1979, Iran has sought to become self-sufficient. (See Iranian Revolution Anniversary.) It hoped to thwart international sanctions imposed by other countries that didn’t favor Iran’s severe Islamist rule. That attempt at self-sufficiency includes agriculture and food production. The problem, however, comes in inefficient water use on farms.
Iranian authorities are cracking down on illegal wells to prevent further sinkholes. They are also exploring using desalination plants along the Persian Gulf. But desalination comes with problems of its own. (See Brine Problems.) Meanwhile, Israeli Prime Minister Benjamin Netanyahu—who opposes Iran’s current government—released an online video offering his country’s water technology to help.
“The Iranian regime shouts: ‘Death to Israel,’” Netanyahu said. “Israel shouts: ‘Life to the Iranian people.’”
Iran shrugged off the offer. But solutions to the water crisis will be difficult to find.
(An aerial view shows a massive hole caused by drought and excessive water pumping in western Iran. Note the car, circled at upper right, for scale. AP Photo)