Here’s what you’ll learn when you read this story:
-
The ‘Ain Braq aqueduct, which supplied water to ancient Petra, was thought to have only one conduit, or channel, until the recent discovery of a second one.
-
Although most of the lead pipe is no longer present in the conduit, its former extent can be inferred by matching its footprint to fragments of lead pipe still present in the area.
-
Long and narrow, this pipe was most likely used as an inverted siphon, with the water passing through a collection tank before flowing through a series of tanks.
The importance of finding water supplies in a harsh desert climate is a central theme in Frank Herbert’s classic science fiction novel. Dune (and in the most recent film adaptation by Denis Villeneuve). Rising from dusty sands and carved out of red sandstone, Jordan’s ancient city of Petra recalls the desert landscapes and stone edifices of Herbert’s distant sci-fi desert planet. But Petra already had aqueducts and water systems thousands of years ago that predated those of the fictional Arrakis – so no one in Petra ever needed a suit to survive.
Petra was an urban center of the ancient world, despite its location in a semi-arid climate that brought almost no rain. It was the capital of the Nabatean kingdom until it became part of the Roman province of Arabia in the early 2nd century AD. As an important administrative and commercial center, Petra needed water for purposes beyond keeping people alive. Its hydraulic systems filled baths, kept gardens and agriculture thriving, gushed from a sacred fountain known as a nymphaeum, and filled basins in temples, sanctuaries, and tombs. Now, on the southeastern edge of the abandoned city, archaeologists have discovered that the ‘Ain Braq aqueduct that runs through the massive Jabal al-Madhbah in Petra was even more sophisticated than previously thought.
As part of a 2023 excavation carried out as part of the urban development project of ancient Petra, a research team led by Niklas Jungmann of the Humboldt-Universität zu Berlin studied the system that brought water to Petra. These included cisterns, basins, a reservoir with a dam and the ‘Ain Braq aqueduct. In the course of their research, Jungmann and his team discovered something that the aqueduct had hidden for millennia. It featured not just one, but two different main pipes that kept water flowing into Petra. Researchers have long known about the first canal lined with terracotta pipes to carry water to the city. What the researchers did not expect was to uncover the imprint of a second pipe that once held a pressurized lead pipe that supplied water to the pools and reservoirs on az-Zantur Hill.
“The discovery of numerous water structures on the plateau directly above the cliff slopes, with the presumed aqueduct channel and dam, raised broader questions about the engineering and chronology of this area,” Jungmann said in a study recently published in Levant. “That [the existence of a second conduit] was not mentioned in previous research, examining how the aqueduct penetrated the city became a primary focus of the research.”
Measuring approximately 380 feet (116 meters) in length, the newly discovered pipeline used a welded metal pipe that was made of lead and encased in mortar. Additional evidence that the Nabateans used a lead pipe in the second conduit include its significantly larger diameter compared to the terracotta pipes found in the area and the regular surface of the impression it left behind in the underlying stone, as opposed to the irregular surface impression typical of channels that held terracotta pipes. A later excavation supported this hypothesis when Nabataean pipe blocks were discovered during a survey of the city center. In the hardened mortar was a section of lead pipe, whose imprint texture and dimensions matched those of the previous find and left no doubt as to the general composition of the second main aqueduct.
Jungmann concluded that such a long and narrow lead pipe was probably used as an inverted siphon in the ‘Ain Braq aqueduct. It was buried in concrete to carry water under the city, bypassing surface obstacles. The water in the system would have passed through a collection tank before entering the two aqueduct pipes. Previously, one theory posited that the pipeline might have made a detour to deliver water to another part of the city before reaching its destination. However, it was found that the pipeline is heading west, probably to reach the reservoirs of the az-Zantur hill. A bypass would not have been viable either, as only an unbroken pipe generating sufficient internal pressure can allow water from a siphon to flow from the sump to the basin or tank it was supposed to fill.
“Overall, this study underscores the potential for further research into Nabataean water management,” Jungmann said. “While some hypotheses have been proposed above about the two branches of the aqueduct in the city, more fieldwork is needed to provide a fuller understanding of the distribution system and its evolution over time.”
You may also like