An investigation of the aqueduct of Valente 426 kilometers long, which supplied Constantinople – present-day Istanbul -, has revealed knowledge about how this structure was maintained, which was used for 700 years.
It seems that the channels had been cleaned of carbonate deposits until just a few decades before the infrastructure was abandoned. In addition, these tasks were carried out without the water supply being interrupted thanks to a double channeling.
In 324 d. C., the Roman Emperor Constantine the Great made Constantinople the new capital of the Roman Empire. Although the city is at the crossroads of land and sea routes of geopolitical importance, the fresh water supply was a problem.
Therefore, a new aqueduct to supply Constantinople from springs 60 kilometers to the west. As the city grew, this system expanded in the 5th century to springs that are located 120 kilometers from the city in a straight line. This gave the aqueduct a total length of at least 426 kilometers, which made it the longest in the ancient world. The aqueduct consisted of domed masonry canals large enough to walk on, built of stone and concrete; 90 large bridges and many tunnels up to 5 kilometers long.
A team from the Johannes Gutenberg University of Mainz led by geoarchaeologist Gül Sürmelihindi studied the carbonate deposits of this aqueduct, that is, the lime that was formed in the running water, which can be used to obtain important information about the management of the water and the palaeoenvironment at that time.
The researchers found that the entire aqueduct system contained only thin carbonate deposits, representing approximately 27 years of use. However, from the annals of the city it is known that the aqueduct system operated for more than 700 years, until at least the twelfth century.
“This means that the entire aqueduct must have been maintained and cleaned from deposits during the Byzantine Empire, even shortly before it stopped working, “explained Sürmelihindi it’s a statement. Carbonate deposits can block the entire water supply and must be removed from time to time.
Although the aqueduct is of late Roman origin, the carbonate found in the canal is from the Byzantine Middle Ages. This prompted the researchers to think about possible cleaning and maintenance strategies, because cleaning and repairing a 426-kilometer canal means that it cannot be used for weeks or months, while the city’s population depends on its water supply.
They then found that 50 kilometers of the central part of the water system is built as dual channels, with one aqueduct channel above the other, crossing two-story bridges. “It is very likely that this system has been configured to allow cleaning and maintenance operations,” said Passchier. “It would have been an expensive but practical solution,” he added.
Unfortunately for the research team, it is no longer possible to study the exact operation of the system. One of the most imposing bridges, that of Balligerme, It was blown up with dynamite in 2020 by treasure hunters who mistakenly believed that they could find gold in the ruins.