A qanat is a water management system used to provide a reliable supply of water to human settlements or for irrigation in hot arid and semi-arid climates. The technology is known to have developed in ancient Persia, and then spread to other cultures, especially along the Silk Road.

Qanats are constructed as a series of well-like vertical shafts, connected by gently sloping underground tunnels. This technique allows water to be transported long distances in hot dry climates without losing a large proportion of the source water to seepage and evaporation. As the water must run downwards under gravity, the destination must be lower than the source, which is typically an upland acquifer or stream.

About four-fifths of the water used in the plateau regions of Iran is brought to use in this way. However, because agriculture is less and less practiced in Iran, the qanats that are being made now are not as effective as those made in the past due to deteriorating knowledge of how to make them.

Common variant spellings/transliterations of qanat in English include kanat, khanat, kunut, kona, konait, ghanat, ghundat.

Alternative terms used to describe such structures in Asia and North Africa are karez, kakuriz, chin-avulz, fugara, mayun, falaj.

See also ancient natural refrigerators in Persia called yakhchal.

External links

• WaterHistory.org Article on Karez in Turpan, Xinjiang, China
• World Wildlife Fund Editorial on Karez in Afghanistan