Rissani, Morocco
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What is a Qanat?
A qanat - called a khettara in Morocco, galleria in Spain and karez in Pakistan and Afghanistan - is an irrigation system that carries water from an underground bed to a village or farm. Unlike canals, qanats are underground tunnels. They are used in hot, arid places with a high rate of evaporation. Qanats were developed by the Persians in about 800 BC and are quite simple in design. Each qanat has a series of dry wells or shafts connected to a gently sloping tunnel. The shafts provide air and access for repair. And they prevent collapse. The tunnel's downward slope ensures gravity does all the work. The gentle slope curbs the water's speed. And because qanats draw water from an upland aquifer, an underground reservoir in a mountain or hill, their tunnels meet the surface when they reach the fields. |
