To make use of the limited amounts of water in arid region, the Iranians developed man-made underground water channels called qanats (kanats). In fact, qanats may be considered as the first long-distance water transfer system. Qanats are an ancient water transfer system found in arid regions wherein groundwater from mountainous areas, aquifers and sometimes from rivers, was brought to points of re-emergence such as an oasis, through one or more underground tunnels. The tunnels, many of which were kilometers in length, had designed for slopes to provide gravitational flow. The tunnels allowed water to drain out to the surface by gravity to supply water to lower and flatter agricultural land.
The United Nations and other organizations are encouraging the revitalization of traditional water harvesting and supply technologies in arid areas because they feel it is important for sustainable water utilization. A qanat is a gently sloping subterranean conduit, which taps a water-bearing zone at a higher elevation than cultivated lands. 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 and allow the population to live in desert area.
A qanat system has a profound influence on the lives of the water users. It allows those living in a desert environment adjacent to a mountain watershed to create a large oasis in an otherwise stark environment.