Aqueducts are very impressive examples of the art of construction in the Roman Empire. Even today, they still provide us with new perspectives on the aesthetic, practical and technical aspects of construction and use. Scientists from Johannes Gutenberg University in Mainz (JGU) investigated the longest aqueduct at the time, the 426-kilometer-long Valens Aqueduct feeding Constantinople, and revealed new information on how this structure has been maintained over time. It appears that the canals had been cleaned of carbonate deposits only a few decades before the site was abandoned.
The late Roman aqueduct provided water to the people of Constantinople
The Roman Empire was ahead of its time in many ways, with a strong commitment to building infrastructure for its citizens that we still find fascinating today. This includes architecturally inspired temples, theaters and amphitheatres, but also a dense road network and impressive ports and mines. “However, the most revolutionary technical achievement of the Roman Empire lies in its water management, especially its long-distance aqueducts which supplied water to towns, baths and mines,” said Dr Gül Sürmelihindi of the geoarchaeology group of the University of Mainz. . Aqueducts were not a Roman invention, but in the hands of the Romans these long-distance aqueducts developed and spread widely in one of the greatest empires in history.
Almost all the towns of the Roman Empire had an adequate supply of fresh running water, in some cases in fact with a larger volume than is the case today. “These aqueducts are best known for their impressive bridges, like the Pont du Gard in southern France, which are still standing today after two millennia. But they are mostly impressive because of the way the construction problems went. been solved, which would be discouraging. even for modern engineers, “said Professor Cees Passchier of the JGU. More than 2,000 long-distance Roman aqueducts are known to date, and many more are waiting to be discovered. he study undertaken by Dr Gül Sürmelihindi and his research team focuses on the most spectacular late Roman aqueduct, the water supply pipes of Constantinople, now Istanbul in present-day Turkey.
Carbonate deposits provide information on Byzantine water management
In 324 AD, Roman Emperor Constantine the Great made Constantinople the new capital of the Roman Empire. Although the city sits at the geopolitically important crossroads of land and sea routes, the supply of fresh water was a problem. A new aqueduct was therefore built to supply Constantinople from sources located 60 kilometers to the west. As the city grew, this system was extended in the 5th century to sources that are even 120 kilometers from the city in a straight line. This gave the aqueduct a total length of at least 426 kilometers, making it the longest in the ancient world. The aqueduct consisted of vaulted masonry canals large enough to cross, built of stone and concrete, 90 large bridges, and numerous tunnels up to 5 kilometers long.
Sürmelihindi and his team studied the carbonate deposits of this aqueduct, i.e. the limestone that has formed in running water, which can be used to gain important information on water management and the paleoenvironment at that time. The researchers found that the entire water system contained only thin deposits of carbonate, representing about 27 years of use. From the city’s annals, however, it is known that the aqueduct system operated for over 700 years, until at least the 12th century. “This means that the entire aqueduct must have been maintained and cleared of deposits during the Byzantine Empire, even shortly before it ceased to function,” Sürmelihindi explained. Carbonate deposits can block the entire water supply and should be removed from time to time.
A 50 kilometer double construction was probably built for maintenance
Although the aqueduct is of late Roman origin, the carbonate found in the canal is from the Byzantine Middle Ages. This got researchers thinking about possible cleaning and maintenance strategies – as 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 out that 50 kilometers of the central part of the water system is double-constructed, with one aqueduct channel above the other, crossing two-story bridges. “It is very likely that this system was put in place to allow for cleaning and maintenance,” Passchier said. “It would have been an expensive but practical solution.”
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 Ball? Germ, was dynamite destroyed in 2020 by treasure hunters who mistakenly believed they could find gold in the ruins.