“The government blames the current crisis on changing climate [but] the dramatic water security issues of Iran are rooted in decades of disintegrated planning and managerial myopia,” says Keveh Madani, a former deputy head of the country’s environment department and now director of the United Nations University’s Institute of Water, Environment and Health. 

To meet growing water shortages in the country’s burgeoning cities, “Iran was one of the top three dam-builders in the world” in the late 20th century, says Penelope Mitchell, a geographer at the University of Arizona’s Global Water Security Center. Dozens were built on rivers too small to sustain them. Rather than fixing shortages, the reservoirs have increased the loss of water due to evaporation from their large surface areas, she says, while lowering river flows downstream and drying up wetlands and underground water reserves. 

Today, many of the reservoirs behind those dams are all but empty. Iran’s president made his call to relocate the capital after water levels in Tehran’s five reservoirs plunged to 12 percent of capacity last month. 

Iran’s neighbors are exacerbating the crisis. In Afghanistan, the source of two rivers important to Iran’s water supplies (the Helmand and Harirud), the Taliban are on their own dam-building spree that is reducing cross-border flows. The Pashdan Dam, which went into operation in August, “means Afghanistan can control up to 80 percent of the average stream flow of the Harirud,” says Mitchell, threatening water supplies to much of eastern Iran, including Iran’s second largest city, Mashhad.

While surface waters suffer, the situation underground is even worse. In the past 40 years, Iranians have sunk more than a million wells fitted with powerful pumps. The aim has been to irrigate arid farmland to meet the country’s goal of food self-sufficiency in a hostile world of trade sanctions. But the result has been rampant overpumping of aquifers that once held copious amounts of water.  

The majority of Iran’s precious underground water reserves have been pumped dry, says Madani. He estimates a loss of more than 210 cubic kilometers [50 cubic miles] of stored water in the first two decades of this century. 

Iran is far from alone in overpumping its precious national water stores. But a recent international study of 1,700 underground water reserves in 40 countries found that a staggering 32 of the world’s 50 most overpumped aquifers are in Iran. “The biggest alarm bells are in Iran’s West Qazvin Plain, Arsanjan Basin, Baladeh Basin, and Rashtkhar aquifers,” says coauthor Richard Taylor, geographer at University College London. In each, water tables are falling by up to 10 feet a year.

Agriculture is the prime culprit, says Mitchell. In Iran, some 90 percent of the water abstracted from rivers and underground aquifers is taken for agriculture. But as ever more pumped wells are sunk, their returns are diminishing.

Analyzing the most recently publicly available figures, Roohollah Noori, a freshwater ecologist until recently at the University of Tehran, found that the number of wells and other abstraction points had almost doubled since 2000. But the amount of water successfully brought to the surface fell by 18 percent. In many places, formerly irrigated fields lie barren and abandoned.

As reservoirs empty and wells fail, the country’s hydrologists say Iran is on the verge of “water bankruptcy.” They forecast food shortages, a repetition of water protests that spread across the country in the summer of 2021, and even a water war with Afghanistan over its dam-building. And a long-discussed plan to move the capital from Tehran to the wetter south of the country is now “no longer optional” but a necessity, because of water shortages, says Iran’s president. No detailed plans have yet been drawn up, but the Makran region on the shores of the Gulf of Oman is seen as the most likely location for the project. 

This is a tragic turnaround for an arid country with a proud tradition of sophisticated management of its meager water resources. Iran is the origin and cultural and engineering heartland of ancient water-collecting systems known as qanats. 

Qanats are gently sloping tunnels dug into hillsides in riverless regions to tap underground water, allowing it to flow out into valleys using gravity alone. They have long sustained the country’s farmers, as well as being until recently the main source of water for cities such as Tehran, Yazd, and Isfahan. But today only one in seven fields are irrigated by the tunnels.

Iran has an estimated 70,000 of these structures, most of which are more than 2,500 years old. Their aggregate length has been put at more than 250,000 miles. The Gonabad qanat network, reputedly the world’s largest, extends for more than 20 miles beneath the Barakuh Mountains of northeast Iran. The tunnels are more than 3 feet high, reach a depth of a thousand feet, and are supplied by more than 400 vertical wells for maintenance. 

Unlike pumped wells, qanats are an inherently sustainable source of water. They can only take as much water as is replenished by the rain. Yet such has been their durability that they were often called “everlasting springs.”

This Persian technology spread far and wide from China to North Africa and Spain, which exported the idea to the Americas. Many qanats have fallen out of use, deprived of water by pumped wells. Some countries, such as Oman, are reviving them as the most viable water resources in many arid regions. 

But in their homeland, there is no such action. Iranian hydrologists estimate that in the past half century, around half of Iran’s qanats have been rendered waterless through poor maintenance or as pumped wells have lowered water tables within hillsides. Noori found that groundwater depletion began in the early 1950s and “coincided with the gradual replacement of Persian qanats… with deep wells”.

“History will never forgive us for what [deep wells] have done to our qanats,” says Mohammad Barshan, director of the Qanats Center in Kerman. 

Besides overpumping, a second reason why Iran’s underground water reserves are slipping away is that less water is seeping down from surface water bodies and soils to replenish them. Noori found a 35 percent decline in aquifer recharge since 2002. 

One reason is climate change. Droughts have combined with warmer temperatures that reduce winter snow cover, which is a major means of groundwater replenishment in the mountains. But Noori identifies “human intervention” as the main cause — especially dams and abstractions for irrigation that dry up rivers, natural lakes, and wetlands, whose seepage is another major source of recharge.  

Lake Urmia in northwest Iran was once the Middle East’s largest lake, covering more than 2,300 square miles. But NASA satellite images taken in 2023 showed it had almost completely dried up. Similarly, the Hamoun wetland, straddling the Iran-Afghan border on the Helmand River, once covered some 1,500 square miles and was home to abundant wildlife, including a population of leopards. Now it is mostly lifeless salt flats.  

The loss of such ecological jewels makes a mockery of Iran’s status as the host of the 1971 treaty to protect internationally important wetlands, named after Ramsar, the Iranian city where it was signed. 

Another factor in the reduced recharge, says Noori, is the introduction of more modern irrigation methods aimed at getting more crops from less water. Farmers are being encouraged to line canals and irrigate crops more efficiently. But this greater “efficiency” has a perverse consequence: It results in less water seeping below ground to top up aquifers. 

Hydrologists warn that much of the damage to aquifers is permanent. As they dry out, their water-holding pores collapse. As qanats dry up, they too cave in. 

At the surface, this is causing an epidemic of subsidence. According to Iranian remote sensing expert Mahmud Haghshenas Haghighi, now at Leibniz University in Germany, subsidence affects more than 3.5 percent of the country. Ancient cities once reliant on qanats, such as Isfahan and Yazd, are seeing buildings and infrastructure damaged on a huge scale. Geologists call it a “silent earthquake.” 

But, while surface structures can be repaired, the geological wreckage underground cannot. “Once significant subsidence and compression occurs, much of the… water storage capacity is permanently lost and cannot be restored, even if water levels later rise,” says Mitchell.

What can be done to ward off Iran’s water bankruptcy? Many Iranian hydrologists believe there needs to be a massive switch of funding from dams and wells to repairing qanats, which Barshan says “remain the best solution for Iran’s ongoing water crisis,” and recharging the aquifers. 

Aquifer recharge was long advocated by Iranian hydrologist Sayyed Ahang Kowsar, who died last year. Forty years ago, when a professor of natural resources at Shiraz University in southern Iran, he developed a successful pilot project that channeled occasional extreme mountain floods to recharge underground water beneath the Gareh-Bygone Plain. 

Iran is estimated to lose at least a fifth of its rainfall to flash floods that flow uncollected into the ocean. Kowsar found that as much as 80 percent of those floodwaters could be redirected into aquifers. Yet hydrologists say the idea of tapping this water has been almost entirely rebuffed by the government.  

Critics such as Kowsar’s son Nik, a water analyst now working in the U.S., say officials are closely aligned with politically well-connected engineers bent on constructing ever more big projects such as dams. Their latest is a complex and expensive scheme to desalinate seawater from the Persian Gulf and pump it through some 2,300 miles of pipelines to parched provinces. A link to Isfahan opened this month. But, while the water is valuable for heavy industries such as steel, the high cost of desalination, pipes, and pumping makes it far too expensive for agriculture.

Something has to give. More dams make no sense when the rivers are already running dry. More pumped wells make no sense when there is no water left to tap. They just hasten water bankruptcy.

Politically, the country’s ambition for food security through self-reliance needs to be rethought, hydrologists say. There is simply not enough water to achieve it in the long run. Madani and others call for farmers to switch from growing thirsty staple crops such as rice to higher-value, less water-intensive crops that can be sold internationally in exchange for staples. But that requires Iran to lose its current political status as an international pariah and rejoin the global trading community.