Engineering series 2: Canal du Midi


The following text outlines a once groundbreaking civil engineering work that became an example of obsolete engineering art in the 20th century: Le canal du Midi, lying in the very south of France.

I took short glimpses at parts of this construction, whose substantial elements were built at the end of the 17th century, during a few days trip to Narbonne and a stay in Toulouse, where the river Garonne is directly jointed with the canal.

“The canal of the South” offers since that period of the early modern age an expedient navigable connection from the Mediterranean Sea to the Atlantic Ocean1.

The alternative, the Strait of Gibraltar, offered yet such a connection, as a matter of fact. But shipping was risky, took longer, and could be very expensive at times depending on political circumstances.

Toulouse, the river Garonne and Le pont Neuf ("New bridge")
Toulouse, the river Garonne and Le pont Neuf (“New bridge”)

Connecting the Atlantic Ocean with the Mediterranean Sea was a desire for centuries since the classical antiquity.

But It was not until the end of the 17th century when the basic development and construction work was finally initiated, after decades of geographical examinations and research activities.

1 the Garonne is navigable between Toulouse and Bordeaux, the latter situated at the Atlantic Ocean. So the canal had to connect Toulouse with the Mediterranean Sea

Building the canal

The most urgent question was about the allocation of water to create the canal in a largely difficult terrain.

The engineer Pierre-Paul Riquet (who passed away just a few months before the canal’s official opening in 1681), the builder and one of the financiers of the project, conceived a delicate system of water-supply from the surrounding area to transform the deepest depressions in the region into a navigable canal.

Le canal du Midi
Le canal du Midi

After several years of planning and construction work, the structure connected Toulouse with Carcassone and Beziers, and the last station for the canal water was the Etang de Thau2.

To regulate the water supply for the canal, the reservoir Bassin de Saint-Ferréol was created, today along with the canal du Midi a World Heritage Site.

A multitude of aqueducts, dams, tunnels and locks are integral parts of the canal (locks are intended to compensate the differences in water levels), whose overall length sums up to two hundred and forty kilometers.

Hence cargo-ships can navigate conveniently from the Atlantic Ocean to the Mediterranean Sea, and vice versa.

Mediterranean Sea near Narbonne
Mediterranean Sea near Narbonne

A further core element of the structure are numerous trees planted alongside the banks (the great majority plane trees). This in particular provides the necessary longevity for the canal-banks.

2 the technically slightly shorter route to Narbonne was not realized for various reasons

The canal becomes obsolete

Le canal du Midi retained its economic significance until the 20th century. Then railway and railroads diminished more and more its relevance for goods and passenger traffic.

In these days, the canal is almost entirely utilized for touristic purposes, with cycling or chugging downstream on small boats as popular activities.