Flash-Floods in Petra
Since Nabataean times the Siq, a narrow gorge cutting through the sandstone formations of the Petra Region, which is the main entrance to the ancient city, is affected by seasonal flash-floods during winter. The upper hills flanking the Siq collect about 1 million cubic meters. The Nabataeans had a complete water management system to contain this threat.
In the nineties, the director of Cultech proposed to the Petra National Trust (PNT) a project in which a study of the problem. He supervised the study conducted by PNT with the collaboration of The Middle East Engineering Management Company. The study revealed many ancient dams, cisterns, agricultural terraces, and wadi barriers (retaining walls to protect the flanks of stream-beds. Wadi means valley in Arabic). The Director then implemented a study over the wider are in the upper hills overlooking the whole site. The size of the watershed affecting the Siq entrance to the city was found to be 55 square kilometres. A watershed is an area whose rainfall flows and collects in one single point, possibly causing a potential flash-flood threat that depends on its area and the rainfall intensity in any given time. Uncontrolled rain form the 55 square kilometres would flow in the Siq and can cause serious threats to the tourist in the Siq. In the early sixties, several French tourists lost their lives when a sudden torrential flash flood took them by surprise.
To solve the problem, the Department of Antiquities resorted to the ancient Nabataean engineering skills. A tunnel which had been blocked over the years by debris was reopened and the threat in the Siq was completely removed. This is not the only example of Nabataean ingenuity when it comes to management of the precious and scarce water resources that were available in the semi arid region of Petra. Their skills in water harvesting and water transport through channels and water pipes cannot be contested. For more information please read this article published in “Near Eastern Archaeology”.