Aqueduc Souterrain de Briord

Useful Information

Location:	D19, 01470 Briord. From Briord D79a towards Verizieu, turn left on D19, after 1 km park at the necropolis sign. Follow single lane gravel road on the other side, 5 minutes walk. (45.787300, 5.465126)
Open:	no restrictions. [2022]
Fee:	free. [2022]
Classification:	Water Supply
Light:	Incandescent Electric Light System
Dimension:	L=197.20 m, W=1.50 to 2.50 m, H=2 to 3 m. East entrance: A=241.25 m asl. West entrance: A=240.50 m asl.
Guided tours:	self guided
Photography:	allowed
Accessibility:	no
Bibliography:
Address:	Aqueduc Souterrain de Briord.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then. Please check rates and details directly with the companies in question if you need more recent info.

History

1650	first written mention.
1904	delared a historical monument.

Description

The Aqueduc Souterrain de Briord is an almost 200 m long tunnel which crosses the colline de Briarette (Briarette hill). It was a canal for freshwater for the important Roman village Vicus Brioratensis at the shores of the Rhone river, which was built in Gallo-Roman times. The water originated from the Brive, a small river which flows through a valley parallel to the course of the Rhône to the east of Briarette hill. There is a theory that it was constructed during the time of Marcus Aurelius (121 to 180) but there is no evidence.

The tunnel was dug from both ends at the same time using picks. The two tunnels met with an axial offset of 11.50 m and a vertical offset of 2 m. The vertical offset is today difficult to see, as the tunnel was later used for a pipe, and for this purpose the floor was leveled. Most likely the offset is a result of the misalignment of the miners, but there is also the possibility that it was deliberate in order to attenuate the water flow.

The canal was not only a means to transport the water, it also served as a cistern or reservoir. A dam, built somewhere at the southern exit, resulted in a high and constant water level in the aqueduct, as shown by the single watermark at the walls. To bring water from the Brive a canal was built at the northern exit of the tunnel. From the southern exit of the tunnel there is a height difference to the city of 35 m, which is enough to operate mills, but so far no remains have been found.

The tunnel was built in karstified limestone, and so small caves were discovered. There is a karstic chimney in the middle of the ceiling which has been explored by speleologists. They discovered that it had not been entered during the construction of the tunnel.