How it began
The qanat, also called kariz, is a water supply system developed in ancient Iran about 3,000 years ago. The historian Henri Goblot argued that it grew out of mining: early Iranians put to use the water that miners wanted to drain away, somewhere in the northwest of present-day Iran near the Turkish border, and the method then reached the Zagros Mountains. An inscription of the Assyrian king Sargon II records that in 714 BCE he found a green and prosperous district near Lake Urmia that had no river and was watered in this way.
How it works
A mother well is sunk into an aquifer, usually in an alluvial fan at the head of a valley. From it an almost horizontal tunnel runs underground with a gentle slope, so that water flows by gravity alone, often over many kilometers, to an exit from which channels distribute it to the fields of the shareholders. A line of vertical shafts, which look like craters from above, gives access for digging and repair. The levels, gradient and length are calculated by traditional methods handed down among skilled qanat workers.
How it spread
Under the Achaemenid kings, anyone who built a qanat or restored an abandoned one was freed from tax for up to five generations, and the technique spread across the Iranian plateau and beyond. On the order of Darius a qanat was built at the Kharga Oasis in Egypt. The same system is known as karez in Afghanistan and Pakistan, foggara in Algeria, khettara in the Atlas Mountains and falaj in Oman and the United Arab Emirates. After the coming of Islam even Mecca gained a qanat.
Who pushed back
Qanats needed constant upkeep and suffered when rulers neglected them. Sources report that they were abandoned in the Seleucid era and that the Parthian kings cared less for them than the Achaemenids and Sasanians did. In the 13th century the Mongol invasion left many qanats ruined and dry, until the Ilkhanid ruler Ghazan Khan and his Persian minister Rashid al-Din took steps to revive them.
Where it stands today
In the middle of the 20th century an estimated 50,000 qanats were in use in Iran, and a 2005 count recorded 34,355. The qanat at Gonabad still supplies drinking and farm water to nearly 40,000 people after some 2,700 years. In 2016 UNESCO inscribed eleven Iranian qanats on the World Heritage List as The Persian Qanat. They remain active water carriers, managed under a traditional communal system of sharing.
