Tuesday, April 21, 2009
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.
Posted by Naj