QANAT KAREZ AS SALT LEACHING SYSTEMS

DAVID BLOCH, Engineering, SALT ARCHIVE, TELAVIV, Israel

More than 150,000 thousand QANAT KAREZ sweet water distribution systems including more than 200,000 kilometers of tunnels exist in the Middle East. They are operated incorrectly losing uncontrolled quantities of water. The original ancient design was to direct water to arid zone SABKHA basins in order to leach salt deposits by recrystallising and precipitating the salts as a pure thick crust. They are used today only for domestic water supply. The engineering and construction of these systems involved an extremely heavy investment, in extreme desert conditions. The human cost of building these systems could only have been justified by the value of the salt products resulting from the irrigation and flooding mechanisms. This forgotten technology is no longer in use and the misunderstanding has caused the misuse and inefficiency of the water supplies of many communities which still rely on the ancient Qanat.