Iranian jube pictures
After the Arab conquests of the Aryan lands, the Arabs called the system a 'qanat'.
However, the system continued to be called kareez in the eastern Aryan lands including the neighbouring eastern Turkic lands.
It is not unusual to find several underground kareez running parallel to one another, or to find a freshly constructed kareez constructed close to an older disused one.
Water collected in this manner, while probably not suitable as drinking water is useful as irrigation water.
In Persian, a spring is called sarab meaning the head or start of water or stream or cheshmeh.] The kareez are difficult, laborious and time consuming to build and maintain.
Every 20 to 35 metres, the muqannis sink vertical shafts.
The distance between the shafts is determined by the excavation effort required to create a shaft, the excavation effort required to carry the tunnel debris back to the shaft and the amount of air needed to sustain a worker.
Kareez tunnels can have a 0.5 to 0.1% slope gradient.