Recently, water levels in the main reservoirs serving Tehran dropped to dangerously low levels. This sharp decline forced officials to admit that the city may no longer be sustainable. As a result, plans to relocate the capital to wetter coastal regions are gaining urgency. Although such a move would take decades and cost enormous sums, water scarcity leaves few alternatives.
While low rainfall triggered the latest emergency, scientists point to deeper causes. Over the past half century, Iran built hundreds of dams to control rivers and store water. Many of these dams sit on rivers too small to support them. Instead of solving shortages, they created new problems.
Large reservoirs lose massive amounts of water through evaporation, especially in hot climates.
Over the last four decades, Iran drilled more than a million deep wells. Powerful pumps pulled water from aquifers to irrigate farmland and supply cities. The goal was to achieve food self-reliance and reduce dependence on imports.
As aquifers drain, the ground above them collapses. This process causes land subsidence, where the surface slowly sinks. Roads crack, buildings tilt, and pipelines break. Because it happens gradually, scientists call it a “silent earthquake.”
Unlike surface damage, underground collapse cannot be fixed. Once soil layers compress, they permanently lose their ability to store water. Even heavy rainfall cannot restore that lost capacity.
Iran hosts about 70,000 qanats, many over 2,500 years old. Together, they stretch hundreds of thousands of miles underground. For centuries, they supplied cities and farms in some of the driest landscapes on Earth. Today, about half of these qanats no longer function. Poor maintenance weakened many tunnels. More importantly, deep wells lowered water tables below the qanats, leaving them dry. As water disappeared, tunnels collapsed, erasing a key part of Iran’s water heritage." msn
