The quanats of Iran

A traveler flying over Iran can see plainly that the country has an arid climate. The Iranian plateau is largely desert. Most of Iran (excepting areas in the northwestern provinces and along the southern shores of the Caspian Sea) receives only six to 10 inches of rainfall a year.

Other regions of the world with so little rainfall (for example the dry heart of Australia) are barren of attempts at agriculture. Yet Iran is a farming country that not only grows its own food but also manages to produce crops for export, such as cotton, dried fruits, oilseeds and so on. It has achieved this remarkable accomplishment by developing an ingenious system for tapping underground water. The system, called qanat (from a Semitic word meaning “to dig”), was invented in Iran thousands of years ago, and it is so simple and effective that it was adopted in many other and regions of the Middle East and around the Mediterranean.

The qanat system consists of underground channels that convey water from aquifers in highlands to the surface at lower levels by gravity. The qanat works of Iran were built on a scale that rivaled the great aqueducts of the Roman Empire. Whereas the Roman aqueducts now are only a historical curiosity, the Iranian system is still in use after 3,000 years and has continually been expanded. There are some 22,000 qanat units in Iran, comprising more than 170,000 miles of underground channels. The system supplies 75 percent of all the water used in that country, providing water not only for irrigation but also for house-hold consumption. Until recently (before the building of the Karaj Dam) the million inhabitants of the city of Tehran depended on a qanat system tapping the foothills of the Elburz Mountains for their entire water supply.

Some 3,000 years ago the Persians learned how to dig underground aqueducts that would bring mountain ground water to the plains. Today (NB: = 1968!) the system provides 75 percent of the water used in Iran.

Discoveries of underground conduits in a number of ancient Roman sites led some modern archaeologists to suppose the Romans had invented the qanat system. Written records and recent excavations leave no doubt, however, that ancient Iran (Persia) was its actual birthplace. As early as the seventh century B.C. the Assyrian king Sargon II reported that during a campaign in Persia he had found an underground system for tapping water in operation near Lake Urmia. His son, King Sennacherib, applied the “secret” of using underground conduits in building an irrigation system around Nineveh, and he constructed a qanat on the Persian model to supply water for the city of Arbela. Egyptian inscriptions disclose that the Persians donated the idea to Egypt after Darius I conquered that country in 518 B.C. Scylax, a captain in Darius’ navy, built a qanat that brought water to the oasis of Karg, apparently from the underground water table of the Nile River 100 miles away. Remnants of the qanat are still in operation. This contribution may well have been partly responsible for the Egyptians’ friendliness to their conqueror and their bestowal of the title of Pharaoh on Darius.

References to qanat systems, known by various names, are fairly common in the literature of ancient and medieval times. The Greek historian Polybius in the second century B.C. described a qanat that had been built in an Iranian desert “during the Persian ascendancy.” It had been constructed underground, he remarked, “at infinite toil and expense … through a large tract of country” and brought water to the desert from sources that were mysterious to “the people who use the water now.” More