This is an aerial view of an ancient irrigation system originating in Persia (Qanat). The picture is taken in 1978 by the award winning award-winning Swiss photographer Georg Gerster .
The 'holes" in the picture are a series of well-like vertical shafts. These are connected by gently sloping tunnels. The objective is to transport the subterranean water in a manner that efficiently delivers large quantities of water to the surface without need for pumping. The water drains relying on gravity, with the destination lower than the source. This allows 1) the water to be transported long distances in hot dry climates without losing a large proportion of the source water and 2) to transport water in the mountains, where the surface water cannot flow "up" the "bumps".
Qanat finders, builders, managers (do you call them "diviners" in English?) used to be highly respected in old times in Iran. They would be hired as modern-day consultants, and their travel paid to architect the Qanat systems across the land.
Wikipedia has a rather nice and pictorial explanation of their history and propagation across different cultures.
3 comments:
This sounds a lot like an artesian-well system which obtains its pressure by being fed miles away by a mountain system's water runoff into a strata of rock which has an impermeable layer below. Water can be transported far from the mountains in the strata and can either be tapped into from above or, sometimes, flows out naturally if the strata reaches surface. I drink from an artesian well daily although drilling 100 meters down was necessary to hit the strata. Good water, though, from the rockies in western US.
http://www.fardanews.com/fa/pages/?cid=80917
aussi:
Irrigation et Drainage dans l'Antiquite
Qanats et canalisations souterraines en Iran, en Egypte et en Grece, seminaire tenu au College de France sous la direction de Pierre Briant.
par Pierre Briant
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