Ouvrages du Libron
Coordinates: 43°18′03″N 03°24′15″E / 43.30083°N 3.40417°E
Ouvrages du Libron (English: Works of Libron) is a structure like no other on the Canal du Midi. It allows the Libron River, near Agde in south-west France, to traverse the Canal du Midi. At the point of intersection, the Libron is more or less at the same level as the Canal du Midi so a traditional aqueduct was not an option. The problem was further exacerbated by the Libron's propensity to flash flood up to twenty times a year. The problem was originally solved by the building of a pontoon aqueduct known as the Libron Raft which utilised a flush-decked barge to protect the canal channel in times of flooding however this was replaced by the present structure in 1855.
The Canal du Midi was opened in 1681, a year after the death of its designer and implementer Pierre-Paul Riquet. Between its opening and the creation of the Ouvrages du Libron, the Libron would periodically overflow and fill the canal with silt and debris. During periods of flooding, a special flush-walled barge would be placed in the canal, like a raft, with high walls on either end, forming a large walled area that would allow the Libron to flow over the canal without depositing its silt and trash. Canal traffic was unable to pass whilst the barge was in place and would have to wait for the flood to recede and the barge to be removed.
In 1855, the Ouvrages du Libron (Works of Libron) were built to better allow the two streams to coexist. The engineer Urbain Maguès designed a structure that allowed the Libron to be directed in such a way as to allow a canal boat to safely pass and to limit the mud and debris being deposited into the canal by the flooding river.
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