Underground dating secret pdf
Thus a qanat cannot cause significant drawdown in an aquifer because its flow varies directly with the subsurface water supply.When properly maintained, a qanat is a sustainable system that provides water indefinitely.westward across North Africa and into Cyprus, Sicily, Spain, and the Canary Islands.
In these locations, qanats in Iran, with their 170,000 miles of underground conduits all built by manual labor, deliver a total of 19,500 cubic feet of water per second - an amount equivalent to 75 percent of the discharge of the Euphrates River into the Mesopotamian plain.
The main qanat tunnel sloped gently down from pre-mountainous alluvial fans to an outlet at a village.
From there, canals would distribute water to fields for irrigation.
The Chinese, while acknowledging a possible Persian connection, find an antecedent to the qanats were an important factor in determining where people lived.
The largest towns were still located at low elevations on the floors of intermontane basins and in broad river valleys.
If the soil is firm, no lining is required for the tunnel.