Petra: lost city of the ancient world
Christian Augé and Jean-Marie Dentzer
2000 AD p 59-62
The mastery of water
To create a city, one begins by assuring the availability of fundamental resources, especially water. Petra has springs that flow continually, but these provide only a nominal output. The collection of rainwater had to augment this supply. But in this semiarid desert climate, rain is very infrequent. It was therefore necessary to gather it on the broadest surface possible. This may explain why the city lies at the bottom of a broad, sloping bowl, surrounded by steep cliffs.
When rain falls upon a basin 54 square miles (92 square kilometers) in area, on hard terrain that absorbs very little, water will amass in a few hours in considerable and sometimes dangerous amounts. Rainfall into the basin of Petra flows along the course of the unchanneled Wadi Musa, which also continually carried water into the city from the Ain Musa, the most abundant spring in the area.
A systematic exploration of the entire zone of Petra has revealed a great variety of sophisticated structures for the collection, control, and distribution of water. Conceived with intelligence, these were based on close analysis of the topography, which is highly irregular. Water collected from the surfaces of the rocks was carried by rock-cut channels, or occasionally conduits constructed of stone, or covered with stone slabs, into open-air reservoirs or closed cisterns.
Some of these waterworks were modest in size and could be maintained by a small number of people at the domestic level. Larger systems included dams, organized in chains, that blocked the gorges leading into the basin and supplied the reservoirs. These installations were complemented by a network of long-distance conduits that carried water to Petra from the most important springs in the area, which rose several kilometers away at the edge of the plateau, to districts well above the water level of the Wadi Musa. This system reveals an impressive technical mastery. A project of such large scope was surely beyond the capabilities of a small community.
An extensive network of water pipes was implemented in the northeastern and southeastern sectors of the city to collect, channel, and distribute the water from springs located several miles away. Top: these water ducts are depicted in a sketch by Rene Saupin. Extant elements of the conduits indicate that they were built on a smooth, carefully calculated slope that reveals a remarkable command of hydraulic technology. Above: a piece of terra-cotta pipe; conduits were either pipes or gutters carved into the rock and rendered watertight by a hydraulic plaster made of lime, sometimes mixed with clay.
Another impressive public project was the protection of the narrow passage of the Siq from the violent flooding to which it was exposed. This was accomplished by diverting the overflow of the Wadi Musa through a tunnel into a tributary. The Nabataeans clearly mastered water conservation and management at Petra in progressive stages.
(Petra: lost city of the ancient world, Christian Augé and Jean-Marie Dentzer, 2000 AD, p 59-62)
By Steve Rudd: Contact the author for comments, input or corrections.
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