Conny Waters – AncientPages.com – Researchers have unraveled the intricate history of the ancient aqueduct system in Arles, Provence.
Barbegal aqueduct. Image credit: maarjaara – CC BY 2.0
The team based their research on aqueduct carbonates – limescale deposits – that had accumulated in the aqueducts, basins, and lead pipes, as well as lumps of aqueduct carbonate used as building aggregate in the roof of the Baths of Constantine.
Once, Arles (attested as Arelate). a coastal city and commune in the South of France, was a favorite city of Emperor Constantine I, who built baths there, substantial remains of which are still standing.
Dr. Gül Sürmelihindi from the Institute of Geosciences at JGU, who conducted the study, said that this research demonstrates the operational mechanisms of a Roman aqueduct over several centuries.
The study shows how it was periodically transformed by the Romans, efficiently maintained and modified, thereby serving as one of the most lucid examples of a sustainable water management from antiquity.
Professor Dr. Cees Passchier from the Institute of Geosciences at Mainz University explained that this study differs from previous research by exploring the complex water supply system of ancient Arles, rather than focusing solely on one aqueduct.
The investigation covers multiple aqueducts, a basin, and various interconnected water structures within the city, providing a comprehensive understanding of its historical infrastructure.
For some time, there had been hypotheses regarding the connections between various components of the city’s water supply system.
Recent research has now confirmed these theories with concrete evidence from the Arles water system archives. The results prove the long-lasting functionality of the Roman aqueduct in Arles. Starting around 3 BCE, this aqueduct sourced water from the southern slopes of the Alpilles hills to supply the city of Arles.
After nearly a century, an additional aqueduct was constructed on the northern side of the same hills. The water from this new aqueduct merged with that of its southern counterpart in an existing basin belonging to the original aqueduct.
With the opening of the northern aqueduct, the role of the southern one changed; it was redirected to power a large 16-wheeled complex of water mills at nearby Barbegal.
This finding was confirmed by researchers in an earlier study through carbonate analysis.
Another important discovery emerged from the collapsed ceiling pieces of the Baths of Constantine in Arles, shedding light on their previously unknown water source. Researchers identified aqueduct carbonates within these fragments, which were traced back to the northern aqueduct.
This evidence suggests that when Emperor Constantine commissioned the construction of the baths in the early fourth century AD, this aqueduct was likely restored. The chipped-off carbonates from this restoration were then repurposed as building material for the bath’s roof, according to Sürmelihindi.
Through their research, the team successfully addressed the previously unresolved question of how water was supplied to the bath and determined the operational period of the Roman aqueduct. They found that it was in use at least until the baths were constructed, as evidenced by carbonate deposits from the aqueduct being used in its construction.
It is likely that the aqueduct continued to function well into the fifth century AD, up until it was disrupted by invading Franks and Burgundians.
The discovery of large lead pipes from Roman times, found across the bed of the Rhône River in the 19th century, sparked considerable debate regarding their function.
A key question was determining the direction in which these pipes transported water. Understanding this aspect is crucial for insights into Roman engineering and water management practices.
Researchers solved this key question using carbonates,which are deposits with similar isotopic compositions to those in the aqueducts’ north and south branches were found in the lead pipes, confirming that an inverted siphon from the Arles aqueduct supplied the Trinquetaille quarter across the river.
“Without the aqueduct carbonate archives, it would be impossible to reconstruct these relationships” said Passchier.
“But because the deposits are heavily contaminated with clay, they cannot be dated using standard dating technologies. Instead, we analyzed stable oxygen and carbon isotopes from the carbonates and cross-correlated the isotopic profiles to see the times of their simultaneous deposition,” added Sürmelihindi.
“This allowed us to identify the same annual layers in the carbonates and thus determine their relative depositional periods and thus the historical timing of modifications and changes made to the Arles water supply system.”
The researchers from Johannes Gutenberg University Mainz (JGU), the University of Oxford, and the University of Innsbruck published their findings in the renowned scientific journal Geoarchaeology.
Written by Conny Waters – AncientPages.com Staff Writer