Engineering series 3: Canal du Midi


This article is a short abstract about a once groundbreaking civil engineering work, which however became wholly obsolete in the 20th century: Le canal du Midi in South France.

I took a short glimpse at parts of this construction, which essential 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.

Le canal du Midi (“The canal of the South) offers since that period of the early modern age a convenient navigable connection from the Mediterranean Sea to the Atlantic ocean1.

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

The alternative – the Strait of Gibraltar – yet offered such a connection, as a matter of fact. But shipping was risky, took more time, and could be very expensive due to differing political circumstances.

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

To connect 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 as the basic development and construction work was initiated, after decades of geographical examinations and research activities.

Civil engineering

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, contrived 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 .

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

To regulate the water supply for the canal, the reservoir Bassin de Saint-Ferréol was created, which is today together 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 alongside the canal, which overall length sums up to two hundred and forty kilometers.

Hence this allows cargo-ships a convenient opportunity to navigate 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 (plane trees for the most part). This in particular provides the necessary longevity for the canal-banks.

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 importance for goods and passenger traffic.

In these days, the canal is almost entirely utilized for touristic purposes, with cycling or renting a boat as most popular activities3.

3 everyone can easily rent one of those houseboats and chug down the canal since there is no license required

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