by Darya Golestani

Normally first cities and civilizations were settled next to rivers or fountains. But there are so many archaeological sites which are really far from these water sources. So what did people do?

At first, they decided to transfer water from its sources to their place of living. Later, well digging was invented and used to supply water. And after that at the beginning of the first millennium B.C. Persians invented Qanats which are elaborate tunnel systems for extracting groundwater. They used these Qanats to supply water for dry mountain basins of present day Iran. They dug Qanat tunnels by hand, just large enough to fit the person who was digging. Qanat has a main tunnel which slopes gently from pre-mountain alluvial fans to an outlet at a village. From there, by the help of irrigation canals water is distributed to fields. These amazing structures allowed Persian farmers to succeed despite long dry periods and there was no surface water.

Qanat water delivery system Has at least 3 advantages for more information ask your tour guide.

A Qanat is a sustainable system that provides water indefinitely when it’s properly maintained. The self-limiting feature of a Qanat prevents significant drawdown in an aquifer. Water flows continuously in a Qanat, and although some winter water is used for domestic use, much larger amounts of irrigation water are needed during the daylight hours of the spring and summer growing season. In these two seasons, night flow may be stored in small reservoirs at the mouth of the qanat and held there for daytime use.

1- Tunnel’s infiltration part
2- Tunnel’s water conveyance part
3- Open channel
4- Vertical shafts
5- Storage pond
6- Irrigation area
7- Sand and gravel
8- Soil layers
9- Surface of groundwater

Construction:

Qanats are constructed by specialists. A windlass is set up at the surface and the excavated soil is hauled up in buckets. The spoil is dumped around the opening of the shaft to make a small mound: the latter feature keeps surface runoff from entering the shaft bringing silt and other contamination with it.
A vertical shaft 1 meter in diameter is dug out. Then, a gently sloping tunnel is constructed which transports water from groundwater wells to the surface some distance away. If the soil is loose, reinforcing rings which are called Nā, and they are installed at intervals in the tunnel to prevent cave-ins. Nā is usually made by burnt clay. Periodic cleaning and maintenance work is necessary due to mineral, salt, and other deposits which accumulate in the channel.

 

 

Sources:
1. Janebollahi, M.S, 2017, “Qanat Technology and Culture”, Roshanan, p.26
2. “the Qanat: A living history in Iran, Ahmadi. H, Nazari. A,Malekian. A, September 2007
3. “Biodiversity in Qanats, Rezaei. K, Azarinzand. H, October 2008