Ancient Egypt is recognized for being one of the first hydraulic civilizations in history: they had control over irrigation canals, dams and transportation that was essential for erect and maintain a centralized kingdom for more than three thousand years in a fertile strip surrounded by desert. In the Old Kingdom period (c. 2700–2200 BC), the Egyptians built seven enormous pyramids representing approximately 25 million tons of rock cut, transported and fitted in less than 150 years. How they did it remains a mystery.
In that period the pharaohs they ordered stone blocks to be moved at a rate equivalent to 50 tons per hour sustained for decades. There are several hypothesesbut none are satisfactory enough to explain that performance, especially at the beginning. The origin of everything is in Saqqara: the Step Pyramid of Pharaoh Djoser It is the oldest of the great pyramids and the first built entirely of carved stone. This is precisely where a multidisciplinary team proposes for the first time that water was the driving force of its construction.
The hydraulic hypothesis. What the research team led by Xavier Landreau proposes is a kind of hydraulic elevator formed by three large structures from the Zoser complex. The Gisr el-Mudir functioned as a retention dam, the southern Dry Trench was the settling tank and the twin shafts (connected by a 200 meter underground tunnel) constituted the lifting mechanism: a huge float that would have raised the blocks from inside the pyramid in cycles of filling and emptying.
Water from the desert wadis was channeled and filtered before reaching the vertical wells. When filled, the water buoyantly raised a platform on which the blocks rested, allowing them to be deposited on the upper levels without the need for external ramps and with less labor effort.
Why is it important. Firstly, because it provides a coherent functional explanation for three structures at Saqqara whose purpose was not entirely clear. The analysis brings together hydrology, archeology and civil engineering to integrate all these elements into a unified and logical system, possibly making the Saqqara complex the oldest hydraulic infrastructure in history.
If the hypothesis is confirmed, it would leave behind the hegemonic belief of ramps and a large amount of labor as a universal solution for building pyramids. A hydraulic lifting system implies efficient management of resources, energy and logistics, by significantly reducing labor. Additionally, it involves even more advanced knowledge of hydraulics. The next question is clear: are there more pyramids in Egypt built like this?
Context. Saqqara is on a limestone plateau west of the Nile. How the research team mappedto the west of the complex there was a potential watershed of 400 square kilometers linked to the wadi Taflah, an ancient tributary of the Nile already documented on 18th century maps. This point is important because although today it is a desert plateau, studies of sediments from the complex itself show that during the reign of Djoser the area received intense seasonal runoffwith enough kinetic energy to deposit sediments of water origin inside the structures. In short, there was water available and in quantity.
Other historical hypotheses. The most consolidated theories about the construction of the pyramids point to ramps with different geometries combined with levers and sleds. For Giza for example, Jean-Pierre Houdin proposed an interior spiral ramp. For Saqqara, studies collected in the paper itself suggest that the Dry Pit was the main limestone quarry, with short ramps on each side as a supply mechanism. As for the twin wells, the dominant interpretation until now was funerary: the royal tomb of Djoser and the abode of his ka. As for the dry grave, it was considered a quarry or had a ritual function.
How have they done it. This research team has not excavated anything: it has combined satellite images of Airbus Pléiadeselevation models from the French IGN and the QGIS GIS to reconstruct the paleohydrology of the environment. From here, they generated 3D models of the complex’s internal architecture with quite popular commercial software such as SolidWorks or SketchUp. Regarding the hydraulic mechanism, they developed their own deliberately simple numerical model to estimate the water consumption and carrying capacity of the system.
Yes, but. Using existing data has been both its greatest strength and also its greatest virtue, as the team recognizes. That is, although their study integrates basin topography, hydraulics and internal architecture, they have not accessed the wells or dated the sediments directly. On the other hand, from the perspective of the study of Egypt, stating that the wells are not funerary contradicts decades of consolidated interpretation. On the other hand, it raises a structural question: if those who made the first pyramids in Egypt mastered this hydraulic technology, why are the pyramids after Giza increasingly smaller and poorer?
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Cover | Charles J Sharp
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