The Persian Qanats are the underground aqueduct made by Iranians. Persian Qanats are linked to Persian Gardens in Iran architecture and urbanism.
Qanat is an underground channel to move water slowly from water well to surface for drinking and irrigation. Though we can find this kind of strange and wonderful structures in other countries too, the origin of it is Iran. The number of Qanats in Iran is not exactly known, but 3700 Qanats are dynamic and active today among which 11 of them have been registered as a world heritage on UNESCO. These fascinating structures which are the symbol of Iranian ancestors’ innovative thoughts and lifestyles are an enigma for most people around the world. In this piece of writing, I do my best to familiarize you with these artworks made with a combination of love, recognition, and engineering and architectural science.
Qanats which were technically developed by ancient Iranians were built by some skilled labors with hand labor and handed down from fathers to sons. The history of these fascinating well-made technology dates back to the early 1st millennium BC.
This old system of water supply acts as an underground aqueduct consisting of a deep well and vertical access shafts. Still, Qanats generate credible water supply for human irrigation in arid, semi-arid and hot climates such as Yazd and Kerman. The value of this unique system is related directly to the volume, the quality, and also regularity of water flow.
The small tribal groups gently started to move onto the Iranian plateau. This place used to experience less rain falling compared to their homeland. They were accustomed to cultivation which was possible with rivers and stream water, so they begin to search for groundwater, instead. On the Plateau dry seasons were severe and more regular. In general, most of the annual rainfall happened from October to April. Thus, ancient farmers tried to notice the flow of water and recognize that the accumulated water in miners' tunnels and wells had not dried. They made a deal with miners to task them with the construction of tunnels. To see if the water from different places and put in channels could be sufficient for irrigation. Ancient Iranian farmers water using distracted miners from copper extraction. Thus, they established the basic system of underground water conduit to irrigate agricultural lands in hot and dry climates.
Qanats included some galleries with 1.4 meters high and 0.5 meters wide. The wells which served also to let access to repairman and builders had vertical ventilation and were connected with drainage galleries and lead to drainage channels. Qanat galleries could have the length up to several kilometers.
Qanat building required a deep understanding of underground engineering and geology. Observance of qanat’s gradient or angle in drainage galleries was one of the most important and basic conditions for generating a Qanat. If the angle is too small it wouldn’t permit a current to flow and if it was too deep it would result in excessive destruction and erosion of conduits. On average, drainage galleries of on meter could give 0.3 to 0.6 water liters per second.
The length of the strand depends on normal conditions and these conditions depend on ground slope and depth of mother wells. On the other hand, the lower the underground water level, the greater the depth of mother wells. The most important factor in determining the length of the Qanats is the ground slope.
Calculation of slope levels, technical details of building and repairmen of galleries was so significant that authorities of the time had introduced legal regulations regarding them. This knowledge quickly spread from Iran into other parts such as central Asia and Southern Caucasus, Arabian Peninsula, United Arab Emirates and also Even North Africa.
If you look at Qanats from the sky, you will see a row of craters that pass through the dry areas of foothills to reach the green site that is a village or a city. These craters are not Qanats themselves, but wells or what is called well bars that lead to long channels or Qanats. But these wells are not made for water extraction, but digging Qanats. Qanats are beneath these wells under the ground. In this awesome invention, you do not need to raise a rope every time you raise the soil once and the water comes out of the ground automatically.
Interestingly, there are some special structures along with some Qanat areas. These structures were home for people who were involved in making Qanats. They were called Moqani, which means a person who makes Qanat. Since Qanats usually had long length Moqanies could not go home after they finished the work every day due to fewer facilities for commuting at that time. Thus, they Made some home along with the place they were working which is called “Bokn” in Yazd. Bokns usually consisted of three rooms, a kitchen, a living room and a room for putting their work tools. Since the weather in dessert places is usually hot, the Bokn making had its special structure to prevent hot weather. First, they dug a corridor along one well bar, then dug the home at the end of the corridor. All 3 rooms of Bokns had chimneys to condition the air. Bokns had different shapes and sizes.
Almost most of the cities in Iran have Qanat. As recorded by some authorities and documents there are more than 37000 active Qanat strands in Iran. You can imagine how many of them have been destroyed or are inactive. All East Azerbaijan province in the northwest, Kurdistan province in the west, Baluchestan province in the northwest, Guilan province in North and Kish island in the south possess this ancient heritage. But Iran desert cities have the greatest number of Persian Qanats. These provinces are Kerman, Yazd, Khorasan, Isfahan, and Markazi. The reason is understandable. These cities experience low waterfall during the year. Thus, the water is not so abundant on the ground which made last centuries residents look for water under the ground. Bam city in Kerman province is the city that has the most of these structures in Iran. Akbar Abad and Ghasem Abad Baravat Qanats are located in this city.
Even today you can find most of these ancient Qanats surviving in Iran which has been welcome to the historian, scientists, and tourists from around the world. Here we are the eleven Persian Qanats which have been registered in UNESCO as a world heritage.
Qasabeh Qanat, Gonand, Khorasan
Qanat of Baladeh, Ferdows, Khorasan
Qanat of the Moon, Ardestan, Isfahan
Qanat of Vazvan, Meymeh, Isfahan
Mozd Abad Qanat, Shahin Shar, Isfahan
Hasam Abad-e Moshir Qanat, Mehriz, Yazd
Qanat of Zarch, Fahraj, Yazd
Qanat of Gowhariz, Joupar, Kerman
Akbar Abad & Ghasem Abad, Baravat, Kerman
Ebrahim Abad Qanat, Moshkabad, Arak