Let me tell a little history about the Canal du Midi, and suggest an unusual walk.
Construction of the Canal du Midi started one year before the Great Fire of London. That’s less than eighty years after the defeat of the Spanish Armada. No wonder the Journal des Savants of 7th June 1688 said it was worth traveling from the ends of the world to see it.
The energy and imagination of Pierre-Paul Riquet combined with the political environment of the reign of Louis XIV to bring this project to life, but the concept existed a millennium and a half earlier. The Roman emperors Nero and Augustus discussed it, and so did Charlemagne, Francois I, Charles IX and Henri IV. Each of these commissioned a study, which led to several attempts at building a canal. Each was abandoned without demonstrating an approach that was feasible.
There were strong motives for these rulers of France to take the project seriously, although the inland waterway would be about 400 Km long and its highest point would be just under 200 metres above sea level. Let’s look at some of them.
Firstly, the sea route around Spain is about 3,000 Km, so the canal route is only about one sixth as long. But why float the cargo instead of carrying it by land? Nowadays, with road and rail freight able to make the journey in a few hours, this is not justified – most inland waterways have become leisure facilities. However, there was no way to use wheels to transport large freight loads until the nineteenth century.
Secondly, storms were frequent and each year many of the ships either foundered at sea or were driven ashore.
Thirdly, pirates preyed on the slow-moving cargo vessels along much of the route.
Clearly, a short, safe cargo route between the Atlantic and Mediterranean ports of France would be valuable to both the merchants and their government. Pierre-Paul Riquet was the first man who had the wealth, influence, determination and skills to create one. Under the Ancien Regime, before the French Revolution, certain people were granted the right to collect taxes. Pierre-Paul Riquet was such a person, for part of the Languedoc region, which gave him the necessary wealth, influence and local knowledge to combine with his exceptional ability to manage both people and advanced technical projects.
The lazy river Garonne provided a navigable route from the Atlantic port of Bordeaux to the city of Toulouse. However, the Garonne flowed so slowly because Toulouse was not much higher above sea level than Bordeaux. To get from Toulouse to the Mediterranean, the waterway had to cross a watershed 190 meters above sea level.
By Riquet’s time, people knew how to use locks to run a canal over a hill. His challenge was to find a source of water to keep those locks filled even during the summer, when natural springs weakened or even dried up completely.
Riquet spent a long time exploring the area around the ridge known as the Montagne Noire which now forms the southern boundary of the Parc du Haut Languedoc. It was while he was checking out a source called la Fontaine de la Grave that a stone fell across the stream, creating a small dam. Eventually, this overflowed at the edges, creating one stream down each side of the watershed.
This event is said to have triggered his decision to create a reservoir big enough to provide water throughout the dry summer months, and positioned to feed the locks on both sides of the watershed. The final design required the creation of a 6 million cubic metre artificial lake – the Bassin de Saint-Ferreol, now a popular recreational area – to collect water from several streams. This was connected by a 34 Km rigole (a man-made feeder stream) which collected water from two other streams as it meandered down to a small local header pond at Naurouze, alongside the top lock.
If you can find a driver willing to drop you and then pick you up a few hours later (perhaps some of your family or group would prefer to wander round Castelnaudary and have a lazy coffee while you walk about 16 Km), try walking the footpath along the rigole . Half of it is probably enough for one day. On the A61 autoroute from Toulouse to Carcassonne, take exit 20 (Villefranche-de-Lauragais) or exit 21 (Castelnaudary) and pick up the N113. Near Labastide-d’Anjou, look for signs to the Obélisque de Riguel. This monument is next to the point at which the rigole enters the octagonal reservoir used to refill the top lock. Ask your driver to wait for you where the rigole crosses the D1 between the hamlets of Airoux and les Pagets, or at St Paulet if you are feeling a little more energetic.
There is an excellent series of Discovery videos about the construction of the Canal du Midi on How Stuff Works.