Iran’s ‘Qanat’ Irrigation Tunnels Become UNESCO World Heritage Sites

UNESCO’s World Heritage Committee has recently inscribed 11 Iranian treasures on its list of World Heritage sites. They’re neither mosques, nor monuments, nor majestic royal palaces: they are qanats, those ancient irrigation tunnels that have allowed water to be delivered for centuries to the country’s most parched and arid regions. The oldest of these qanats was built more than 2,500 years ago, and the most recent, 200 years ago. Their particular technology distinguishes them from the 33,000 other qanats existing in Iran today.

400px-insideqanat-near-isfahanUNESCO experts approved the 11 qanats’ inscription on the World Heritage List in July after considering the age, architecture, depth and length of each of them. They are located in six of the country’s provinces: Razavi Khorasan, South Khorasan, Yazd, Kerman, Markazi, and Isfahan. Here is a link to the corresponding UNESCO web page:

Qanat technology was developed in Persia over 3,000 years ago, later spreading eastward and westward, according to a July report by Radio France Internationale.

The qanat is an underground channel that is dug practically horizontally with a gentle slope to ensure the flow of water. It is designed to capture ground water and channel it outwards.

Its construction begins with the drilling of a mother well that guarantees the quality and volume of the water table. The digging of the gallery starts downstream to reach the mother well. The drilling of a series of vertical shafts or intermediary wells at 50 to 100 meters intervals permits the evacuation of the debris from the excavated gallery and ensures its ventilation. The gallery can be several kilometers long, or even tens of kilometers long.

The qanat is a reliable and consistent source of water in arid and semi-arid regions. The name comes from the Akkadian word for reed. It was picked up by Semitic languages such as Aramaic and Arabic, and non-Semitic languages such as ancient Greek and Latin. Though absent in ancient Persian, it is commonly used in modern Persian — as is its Persian equivalent Kariz or Kahriz.

330px-qanat_cross_section-svgMany historians agree that qanat technology was developed in Persia – meaning pre-Islamic Iran – more than 3,000 years ago. Cyrus the Great (the Achaemenid emperor who ruled from around 559 B.C. to 530 B.C.) introduced it in Oman, and his successor Darius (who ruled from 550 B.C. to 486 B.C.) in the Egyptian oases.

It spread eastward from Afghanistan to India and China, and westward to Morocco, Algeria and Libya in North Africa. It was even introduced in Palermo, the capital of Sicily, during the Moorish occupation. The Romans spread it across the Middle East and all the way to Tunisia, and it was passed on by the Arabs to Spain and Morocco.

One of the 11 sites inscribed on UNESCO’s World Heritage List is the Qasabeh qanat of the city of Gonabad, in the Razavi Khorasan province of northeastern Iran. It is also known by its Persian name Kariz-e Keykhosrow. It is one of the oldest qanats in the world; experts believe it was built between 700 and 500 B.C. It is made up 427 intermediary wells. The depth of its mother well is 320m, and its underground gallery is 131,035m long.

In his Safarnameh, or travelogue, Nasir Khosrow (1003-1077) states that this particular qanat was built by order of Kay Khosrow, a legendary king — who, in some interpretations, is none other than Cyrus the Great.

The Zarch qanat is also inscribed on the World Heritage List. Measuring 71 kilometers long, it is the longest qanat in Iran, and is made up of 2,115 intermediary wells or inspection shafts which enable the qanat’s cleaning and repair. The Zarch qanat is also the oldest in Iran. Its construction dates back approximately 3,000 years.

Qanats have the advantage of being resilient to natural disasters such as earthquakes and floods, and are not really affected by rainfall levels. They also resist human disasters, such as wartime destruction.

aerialIt seems that the ancient Persians solved the problem of the equitable distribution of qanat water by using the clepsydra (a water-operated time-measuring device). Callisthenes, who accompanied Alexander the Great during his Asian campaign in the 3rd century B.C., notes that in the villages, farmers would appoint one of their own to oversee the equitable distribution of the qanat’s water. The designated representative would sit on a podium next to the water outlet, place a small container with a little hole inside a larger container of water, and when the small container was filled up (one or more times), he would change the course of the water and channel it towards another farmer’s stream. This would indicate that the clepsydra was widely used at the time in Persia. Its invention probably has something to do with the development of qanat technology by the Persians in the first place.

All told, there are an estimated 33,000 operational qanats in Iran today, compared to approximately 50,000 in the mid-20th century. That decline is attributable to a countrywide over-consumption of water since the advent of the Islamic Republic. The drilling of countless unauthorized wells and the haphazard construction of dams has contributed significantly to the drying up of water tables. Read the original RFI report