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Origin and history

The Roman aqueduct of Briord, also called the Gallo-Roman aqueduct of Briarette, is a remarkable ancient vestige located in the department of Ain, on the commune of Briord. This monument, classified in 1904, is distinguished by its tunnel-aqueduct, nearly 200 metres long, dug in a limestone hill to bring water from the Brivaz River to the Gallo-Roman Vicus of Brioratensis. Only its underground part is now known, with a 2.7 metre wide entrance and a variable height between 1.6 and 2.7 metres.

The aqueduct captured water from the Brivaz in Montagnieu, crossed the hill Saint Didier, and ended near the former Gallo-Roman necropolis of the Plants. Its layout presents a right-angled elbow, interpreted as the meeting point of the two teams of miners who dug from each end. The 32-metre elevation between the water intake and the outlet suggests an unusually strong slope for a Roman aqueduct, with remains of stone blocks at the location of the water intake, perhaps the remains of a dam or hydraulic development.

Discovered at the beginning of the 20th century, the tunnel was first explored in 1853 by Alexandre Sirand, who found graffiti dating back to the 16th century, testimonies of previous visits (Pingon 1550, Cointet 1552). In 1900, Father Jacquand organized a partial clearance of the tunnel, allowing Abbés Marchand and Morgon to study its structure. Ranked a historic monument in 1904, the aqueduct received subsidies in 1905 for its complete clearing, led by Mr. Chevelu in 1906. No ancient inscription was found, but a paleo-Christian fragment, re-used later, was discovered around 1980.

The construction techniques reveal a digging in compact limestone, with traces of burin on the walls indicating simultaneous work from both entrances. Fr. Marchand hypothesized that the observed deviation would result from the miners' attempts to locate each other, while Adrien Blanchet suggested a voluntary sinuosity to reduce the current's strength. In 2019, a collective of surveyors undertook a 3D digital modelling of the pipeline, marking a new stage in his study.

The aqueduct illustrates Roman engineering in water supply, adapted here to a rugged relief. Its classification as a historical monument and successive excavations underline its heritage importance, although its aerial route remains unknown. The vestiges accessible today offer a rare testimony of Gallo-Roman hydraulic techniques in the Auvergne-Rhône-Alpes region.

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