Stone walls uncovered along the Nile reveal ancient engineering marvel

Some of these groins were submerged beneath the Aswan High Dam reservoir, but their existence was rediscovered through travelers' diaries from the 19th century, a 200-year-old map, and archives of aerial photographs. 

Many of these river groins now reside in ancient, dry Nile channels within the desert, indicating their historical significance. “The occurrence of these walls in channels that dried out thousands of years ago strongly suggests some of this engineering was in response to waning flows and the need to expand the riparian area suitable for agriculture,” said Jamie Woodward, Professor of Physical Geography at the University of Manchester and co-author of the study.

The team utilized radiocarbon and luminescence dating techniques to determine that some of these walls date back over 3,000 years. This evidence suggests that indigenous Nubian communities and later inhabitants of towns established by the ancient Egyptian state implemented this form of landscape engineering to adapt to changing river flows caused by climate change.

Enduring legacy and monumental barrages

The river groins served as barriers that captured fertile silts during the Nile's annual inundation, enabling agricultural activities without artificial irrigation. 

“From speaking with farmers in Sudanese Nubia, we also learnt that river groins continued to be built as recently as the 1970s, and that the land formed by some walls is still cultivated today,” said Dr. Dalton. “This incredibly long-lived hydraulic technology played a crucial role in enabling communities to grow food and thrive in the challenging landscapes of Nubia for over 4000 years.”

In addition to the smaller river groins, the research team identified massive stone walls within the Nile, some measuring up to five meters thick and 200 meters long. These monumental barrages played a pivotal role in directing river flow and facilitating boat navigation through hazardous Nile rapids. By connecting ancient Egypt and Nubia, these structures contributed to the movement of resources, armies, people, and ideas along the Nile.

Dr. Neal Spencer, Deputy Director at the Fitzwilliam Museum (University of Cambridge) and Director of the Amara West Research Project emphasized the importance of interdisciplinary research in uncovering enduring traditions, technologies, and agricultural practices within Nubia. By complementing the biased information present in the ancient Egyptian textual record, this study provides valuable insights into the rich history of the Nile Valley.

The discovery of these ancient river groins highlights the remarkable ingenuity of ancient civilizations but also deepens our understanding of their interactions and adaptations to changing environments.

Study Abstract:

Across a 1000-km stretch of the River Nile, from the 1st Cataract in southern Egypt to the 4th Cataract in Sudan, many hundreds of drystone walls are located within active channels, on seasonally inundated floodplains or in now-dry Holocene palaeochannel belts. These walls (or river groynes) functioned as flood and flow control structures and are of a type now commonly in use worldwide. In the Nile Valley, the structures have been subject only to localised investigations, and none have been radiometrically dated. Some were built within living memory to trap nutrient-rich Nile silts for agriculture, a practice already recorded in the early 19th century C.E. However, others situated within ancient palaeochannel belts indicate construction over much longer time frames. In this paper, we map the distribution of these river groynes using remote sensing and drone survey. We then establish their probable functions and a provisional chronology using ethnoarchaeological investigation and the ground survey, excavation and radiometric dating of the structures in northern Sudan, focusing on the Holocene riverine landscape surrounding the pharaonic settlement of Amara West (c. 1300–1000 B.C.E.). Finally, we consider the historical and economic implications of this form of hydraulic engineering in the Nile Valley over the past three millennia.