The Nine Locks of Fonseranes
This is the most spectacular structure on the Canal du Midi, and the most visited tourist site in Hérault. The series of 8 locks and 9 basins, called the ‘Octuple’, allows boats to navigate a difference in level of 21.50 metres in a distance of 300 metres. As in all the locks along the Canal du Midi, the basins are oval: this shape makes the stone walls better able to withstand the pressure of the water pouring in.
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The Fonseranes water slope
Water slopes, which are often found on canals in the north, act as a replacement for locks. Their advantage is that they allow the passage of large barges, which was impossible in the 9 locks’ basins. The principle: a barge enters a chamber filled with water, which is moved either upstream or downstream by a motorized engine on pneumatic tyres, and then released. At Fonséranes, it came too late: commercial traffic was already in decline. The water slope was abandoned shortly after the work was completed, some 20 years ago.
The Canal Bridge
At the foot of Fonseranes hill, the Canal du Midi ran up against the River Orb: barges had to cross the river to get back onto the canal on the other side, at Port Saint-Sauveur. But the Orb’s violent floods caused many boats to be wrecked. The canal branch towards the Orb was sealed off and the canal’s water and its traffic was diverted along a canal bridge over the Orb, 28m wide and 240m long, which was inaugurated in 1858
The Pont de Caylus
This is the last structure along the Canal du Midi in the Béziers Méditerranée area. It’s a «Riquet bridge», built in the 17th century at the same time as the canal, but raised in the 1970s to allow high barges to pass under it.
The Malpas Tunnel (Nissan-lez-Ensérune)
Built in one year, the breakthrough at Malpas (which means ‘bad step’) is one of Paul Riquet’s great civil engineering achievements, and is a symbol of his obstinacy. At the foot of the Ensérune mountain, it involved carving a canal tunnel measuring 173m long, 8.5m high and 6m wide through a crumbling hillside in order to avoid a long detour. Riquet built the tunnel despite a veto from Colbert, who had ordered the work to be stopped.