Karez - A Middle Eastern Irrigation Technique
KARIZ
A long underground water tunnel dug into arid or semi-arid land to provide a source of irrigation water. The qanat (foggara in North Africa and the Levant, falaj in the United Arab Emirates and Oman, kariz in Iran) is an ancient Middle Eastern technique that supports large settlements in harsh environmental conditions.
Unlike surface water runoff, which can dry up for periods during the rainy season and the growing season, underground channels discharge continuously. This is essential in areas with a winter rainy season and a growing season that coincides with the rainy season.
In karez making, the tunnel is started at the bottom and a slope is created to bring water up to the top of the gallery. It is then dug back and at some points it may be rerouted to flow at different levels, for example to create an underground waterfall.