In Ardestan, Iran, there is a Qanat with two levels of water lying over each other, called the Moon Qanat. The 1st level is 30 meters deep, and the 2nd level is 27 meters deep, so the high difference is 3 meters. The soil formation of Moon Qanat is such that the water from 2nd level does not penetrate the lower level.
The strangest qanat in Iran is the two-storey qanat of Moon-e Ardestan that was built approximately 800 years ago; it has ordinary wells together with different mother wells and side wells.
The Structure of Moon Qanat
The Qanat of Mun (Moon Qanat) is a 2km long, two-story qanat, having two main tunnels with one mother well each. The lowest tunnel is 30m down and is separated by the above tunnel by 3m of elevation. This top tunnel goes through a half circle path when it reaches the vertical shafts. The layer between the tunnels is impermeable, so water does not leak between them . However, the tunnels do share all other wells besides their mother wells. The entire Moon Qanat has 30 shafts that are spaced 42.4m apart. Its average outward flowrate is 50 liters per second.
“Ancient Iranians invented a new system to bring the groundwater to the surface using gravitational force”, called “Qanat”
What is Qanat?
The qanat is a method for developing and supplying groundwater and consists of a gently sloping tunnel, cut through alluvial material, which leads water by gravity flow from beneath the water table at its upper end to a ground surface outlet and irrigation canal at its lower end. Qanats are constructed by the hand labour of skilled workers known as Muqannis using techniques which have altered little since qanat construction began.
The qanat system within an area represents a traditional response to the problem of water supply and irrigation and is a particularly characteristic feature of the landscape of Iran.
Qanat is an underground gallery that conveys water from an aquifer or a water source to less elevated fields. In practice, a Qanat consists of a series of vertical shafts in sloping ground, interconnected at the bottom by a tunnel with a gradient more gentle than that of the ground. The first shaft (mother well) is sunk, usually into an alluvial fan, to a level below the groundwater table. Shafts are sunk at intervals of 20 to 200 meters in a line between the groundwater recharge zone and the irrigated land. From the air, a Qanat system looks like a line of anthills leading from the foothills across the desert to the greenery of an irrigated settlement.
The Story of Moon Qanat
The famous Qanat, in the Mun district, is the world’s only two-story qanat. Legend says that once a qanat-builder from Yazd stopped in Mun for a night. In the morning before departure, he told the locals that he had heard the murmur of underground waters and encouraged them to build a qanat on the site he had shown. On his way back, he stopped in Mun again and was very surprised to see that the qanat had been built on a difterent level from what he had suggested. The construction started anew, and another floor of the Moon Qanat came into being. Remarkably, the water of the two canals never mixes.