Roman Aqueducts of Zaghouan-Carthage: Ancient Water Supply Infrastructure in Tunisia
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Country: Tunisia
Civilization: Byzantine, Roman
Remains: Infrastructure
History
The Roman Aqueducts of Zaghouan-Carthage, located near present-day Mohammedia in Tunisia, were constructed by the Romans to channel water from springs near Zaghouan, approximately 60 kilometers south of Carthage. This infrastructure was essential for supplying the ancient city of Carthage, a major urban center in Roman North Africa. The aqueduct’s construction is generally associated with the early 2nd century AD, particularly linked to Emperor Hadrian’s visit in 128 AD, which coincided with the end of a prolonged drought. Another significant phase of use is connected to the inauguration of the Baths of Antonius in 162 AD, which required a dependable water source.
Throughout its history, the aqueduct experienced repeated destruction during military conflicts. It was damaged during the Vandal siege of Carthage in 439 AD, reflecting the turmoil of the late Roman period in North Africa. Later, the Eastern Roman Empire under Emperor Justinian undertook efforts to reconquer and restore the region, including repairs to the aqueduct. The Arab conquest of Carthage in 698 AD also led to damage, but the aqueduct was restored after each major conflict, demonstrating its continued importance.
In the medieval period, specifically the 13th century, a Hafsid ruler extended a branch of the aqueduct to his palace in Manouba. This extension served to irrigate gardens, indicating a shift in the aqueduct’s function from urban water supply to agricultural and leisure uses. From the 16th century onward, the aqueduct fell into neglect and was increasingly dismantled for building materials. Its elevated sections were largely destroyed or repurposed as a stone quarry.
In the 19th century, French engineers undertook restoration efforts to revive the aqueduct’s water channel. In 1859, the water conduit was repaired to supply the city of Tunis, with damaged elevated sections replaced by modern pressure pipes. This restoration allowed the aqueduct to resume operation by 1862. The site and its surroundings have since been recognized for their ecological value, serving as nesting sites for various bird species.
Remains
The aqueduct’s remains extend over a vast area and include a complex system of water channels, arcades, and cisterns. The main water source is a sacred fountain structure at Djebel Zaghouan, built on an artificial terrace open to the north. This fountain complex dates to Roman times and was designed to collect and purify spring water before it entered the aqueduct. The terrace is enclosed on its southern side by a crescent-shaped portico approximately four meters wide, featuring a Roman concrete core clad with limestone blocks. The portico’s outer wall is divided into 26 sections by engaged columns alternating with niches that once held statues.
Opposite each engaged column stands a full sandstone column supporting a vaulted peristyle made of porous travertine covered with marble. The vault’s exterior was sealed with a waterproof mortar known as opus signinum. The portico floor was decorated with mosaics, and the central cella, constructed of limestone and clad in marble, housed the spring itself. Five springs emerge within the terrace area, their waters collected in an underground basin beneath the terrace. This basin functioned both as a water intake and a settling basin to remove impurities.
The aqueduct channel extends approximately 132 kilometers, including tributaries, with a total elevation drop of 264 meters over about 90 kilometers from Zaghouan to Carthage. The channel maintains an average gradient of 0.3 percent. Its cross-section measures roughly 90 centimeters wide and 130 centimeters high, vaulted on top. The channel walls consist of Roman cement clad with sandstone blocks and lined internally with waterproof opus signinum. Ventilation was provided by small square openings in the vault, while circular depressions at the base served as sedimentation basins requiring regular maintenance.
The aqueduct crosses three plains on arcades: a five-kilometer stretch on the plain of Oudna, including a now-demolished double arcade bridge 125 meters long and 33 meters high; a two-kilometer arcade on the plain of Miliane reaching up to 20 meters in height; and a ten-kilometer arcade on the plain of La Soukra, also up to 20 meters tall. These arcades supported the water channel across flat terrain.
At Carthage, the aqueduct discharged water into two large cistern complexes. The La Malga cisterns, dating to the 1st century AD, had a capacity of about 51 million liters. The Bordj Djedid cistern, consisting of 18 barrel-shaped basins, held between 25 and 30 million liters and supplied the Baths of Antonius. The precise archaeological details of how water was distributed from the aqueduct to these cisterns remain unclear.
Today, well-preserved sections of the aqueduct’s arcades survive near Oudna and Mohamedia. Other parts, especially near Carthage, have been largely destroyed or repurposed, with standing masonry almost entirely absent due to destruction from the 17th century onward. The site’s cavities provide nesting sites for falcons and other birds, contributing to its designation as an Important Bird Area.
