Canal du Midi

The Canal du Midi (; ) is a long canal in Southern France (french: le Midi). Originally named the ''Canal royal en Languedoc'' (Royal Canal in Languedoc) and renamed by French revolutionaries to ''Canal du Midi'' in 1789, the canal is considered one of the greatest construction works of the 17th century.

The canal connects the Garonne to the Étang de Thau on the Mediterranean and, along with the long Canal de Garonne, forms the Canal des Deux Mers, joining the Atlantic to the Mediterranean.

Strictly speaking, ''"Canal du Midi"'' refers to the portion initially constructed from Toulouse to the Mediterranean – the Deux-Mers canal project aimed to link together several sections of navigable waterways to join the Mediterranean and the Atlantic: first the Canal du Midi, then the Garonne which was more or less navigable between Toulouse and Bordeaux, then the Garonne Lateral Canal built later, and finally the Gironde estuary after Bordeaux.

Jean-Baptiste Colbert authorized the start of work by royal edict in October, 1666, with the aim of developing the wheat trade, under the supervision of Pierre-Paul Riquet, and construction lasted from 1666 to 1681, during the reign of Louis XIV. The Canal du Midi is one of the oldest canals of Europe still in operation (the prototype being the Briare Canal). The challenges in these works are closely related to the challenges of inland water transport today. The key challenge, raised by Pierre-Paul Riquet, was to convey water from the Montagne Noire (Black Mountains) to the Seuil de Naurouze, the highest point of the canal.

The Canal du Midi was inscribed as a UNESCO World Heritage Site in 1996, because of its outstanding engineering and artistic design, and it was designated as an International Historic Civil Engineering Landmark in 2016.

Introduction

Location and profile of the canal

The Canal du Midi is located in the south of France, in the departments of Hérault, and Haute-Garonne. Is long, starting in the west at Port de l'Embouchure, Toulouse and terminating in the east at a place called ''Les Onglous'', Marseillan, where the canal opens into the étang de Thau (between Agde and Sète).

The Canal du Midi is a summit-level canal, climbing from Toulouse on the Atlantic side over a distance of to the Seuil de Naurouze or summit level, where the feeder canal enters. The total rise is , and the summit level is at an altitude of . This difference in level down to the sea is covered over the remaining distance of from Naurouze to Les Onglous on the Étang de Thau.

The design canal depth is with a minimum of . The draft allowed is although regular users advise that even with boats will occasionally touch the bottom because of silt deposits in many places. The width on the surface is on average with variations between and . Finally, the width of the canal bed is .

This longitudinal profile of the Canal du Midi shows it rising from Toulouse (1) to the Seuil de Naurouze (2), then dropping down to Castelnaudary (3), Carcassonne (4) and Trèbes (5). The canal continues to Béziers after the passing through the Fonserannes Locks (6), then Agde (7), to finish at Sète on the étang de Thau (8).

The longest canal pound is between Argens Lock and the Fonserannes Locks, while the shortest Canal pound is between the two Fresquel locks.René Gast, ''The Canal du Midi and the Canals from the Atlantic to the Mediterranean'', éditions Ouest-France, 2000, , p. 22

Legal status

For historical reasons, the Canal du Midi has a unique legal status, which was codified in 1956A. Homont, noted by the Conseil d'État, ''Ministry of Public Works and Transport c. Dame Boudet'', 3 May 1963, ''Judicial Topics: administrative right'', 1963, p. 489-490. in the ''Public Code of waterways and inland navigation'', then in the ''General code of the property of public persons''. Under Article L. 2111-11 of the Code, the public domain of the canal is determined by reference to the fief once granted to Pierre-Paul Riquet and limits were set by the official report drawn up in 1772. The staff quarters and warehouses, as well as the Lampy reservoir, were also added. Articles L. 2124-20 to L. 2124-25 set out the rules relating to the maintenance of the canal which is generally the responsibility of the public entity that owns it, with the participation of communes and, in some cases, waterside residents.

Under the Act of 27 November 1897, the State of France owns the Canal du Midi and its management is delegated to the public body Voies Navigables de France, attached to the Ministry of Transport.

History

Abandoned projects

The building of a canal was an old idea. Numerous and sometimes utopian projects were devised to build a canal between the Atlantic Ocean and the Mediterranean Sea. Leaders such as Augustus, Nero, Charlemagne, François I, Charles IX and Henry IV had dreamed of it, as it is a true political and economic issue. King François I brought Leonardo da Vinci to France in 1516 and commissioned a survey of a route from the Garonne at Toulouse to the Aude at Carcassonne.

The construction of such a structure would save vessels (of trade but also the king's galleys) and goods from sailing around the Iberian Peninsula which could take a month to complete. At that time shipping was fraught with dangers such as piracy and the Barbary pirates.Franck Ferrand, ''The Great adventure of the Canal du Midi'', transmitted in ''Au cœur de l'histoire'' on Europe 1, 29 May 2013

The most realistic projects were presented to the King in the 16th century. A first draft was presented by Nicolas Bachelier in 1539 to the Estates of Languedoc''Canal du Midi''
Structurae, consulted on 20 August 2007. then a second in 1598 by Pierre Reneau and finally a third project was proposed by Bernard Aribat de Béziers in 1617. These projects were abandoned because they did not give enough thought to the water supply for the canal and provided a system of diversion of water from Pyrénées rivers too complex or impossible to implement. In 1650 another engineer also proposed to divert water from the Ariège to Cintegabelle to bring a non-navigable canal to Pech-David near Toulouse. Again, the question arose of how to carry water to the Seuil de Naurouze at a greater height than that of Toulouse.

The projects were not launched for fear of losing too much money and conviction of the human impossibility to dig such a canal. The major problem was how to supply the summit sections with enough water.Chandra Mukerji, ''Impossible Engineering'' Princeton: Princeton University Press, 304 pages, Jean-Denis Bergasse ''Le Canal du Midi'' Cessenon: J-D Bergasse 1982-1984, .

Nevertheless, Pierre-Paul Riquet, a wealthy collector of salt tax in Languedoc proposed a more convincing project than his predecessors. When Louis XIV received his proposal through the Archbishop of Toulouse (Charles-François Anglure of Bourlemont) in 1662 he saw the opportunity to deprive Spain of part of its resources, and the opportunity to mark his reign with an imperishable work.

English translation:

Study of the project

Compared to canals, managing rivers is difficult but only one canal is required between the Atlantic Ocean and the Mediterranean Sea. Unlike a river, it is easier to manage the flow of a canal to ensure a constant flow of traffic throughout the year.

The Canal du Midi is a summit-level canal because it must pass over a height between two valleys. The construction of this canal required passage through the Seuil de Naurouze or the Seuil de Graissens.

Thirty years passed from the start of planning to the commencement of work: a similar project was also studied by a committee of which Riquet's father was a member.

Highlights

In 1660, Riquet found the solution to the main problem: the water supply to the summit point to feed both sides of the canal. His idea was to get water flowing from the Montagne Noire. His important knowledge of the hydrography of the Montagne Noire and Sor allowed him to imagine an ingenious irrigation system. He was inspired by the French engineer Adam de Craponne who had implemented the same system for the Craponne Canal.

For this, he planned to recover the mountain waters in dams and reservoirs and then forward them to the Seuil de Naurouze through channels crossing the Seuil de Graissens. The water from the Sor passing near Revel was the main supply envisaged by Riquet. Other rivers from the Montagne Noire were also part of the system such as the Alzeau, the Laudot, the Rieutort, the Bernassonne, and the . The Montagne Noire is a region with twice the rainfall of the plain of Lauragais with 1400 millimetres per year at around above sea level. To store the river water he planned to create three basins: the Reservoir of Lampy-Vieux, a hexagonal harbour basin at Naurouze, and the Bassin de Saint-Ferréol with a large earth dam across the mouth of the valley of the Laudot stream.

In 1664, during the study of the project, the Estates of Languedoc asked Riquet to put into practice his idea experimentally. He then built a test channel diverting water from the Sor to the Seuil de Naurouze. It was the Rigole de la plaine which he completed in 1665 and used to prove that it is possible to bring water to the highest points of the course of the canal.Michel Cotte, ''Canal du Midi, marvel of Europe'', Paris: Belin, 2003, 191 pages, , p. 26. This was the event that reassured the Committee of Experts that the king had set up on site to inspect the choices and plans prepared by Riquet. From that moment Louis XIV knew that the canal was technically feasible.

Inaccuracies by Pierre-Paul Riquet

Riquet studied in depth the supply of water to the canal at the Seuil de Naurouze. His study appeared rigorous and included a pilot phase with the construction of the Rigole de la plaine to substantiate his claim. The project still remained unclear in many respects especially the route of the canal. This route was not final and was not precise as it would be today for a highway project or high-speed railway. Only the directions of the route were known and plotted on a map. Changes in the route could be made by the Contractor depending on the difficulties he encountered on the ground.

On the Atlantic side, he proposed several layouts: one to pass by Castres and Revel through the Seuil de Graissens and Agout. In fact, this river was already under development for navigation. Another route would pass by the Girou river and avoid Toulouse as in the preceding route. On the Mediterranean side, the route was not set. He would use the Fresquel until the Aude but the arrival on the coast was first intended to be at Narbonne then at Sète.

In 1663 Riquet conducted field studies to finally fix the path on the Atlantic side by the seuil de Naurouze along the valley of the Hers-Vif to Toulouse downstream of the Garonne. The navigable part of the river is downstream of Bazacle which was a ford in the centre of Toulouse, blocking navigation. The canal could not consider not going through the economic heart of the region so therefore the final route was via Castres and the Girou.

Study techniques

Pierre-Paul Riquet had no technical training and learnt on the job. He regularly practised experiments and field observations. His technique remained highly empirical because at that time applied science and hydraulic techniques through laws or concepts had not been mastered. Even so, Riquet had a scientific approach as he systematically took measurements of flow and made calculations of volumes. In addition, to overcome his technical shortcomings, he was surrounded by many technicians such as Hector Boutheroüe, François Andreossy surveyor and cartographer, and Pierre Campmas an expert in water flows.

He set up experiments to prove that it was possible to bring the water to the Seuil de Naurouze from the river Sor in the Montagne Noire. At his own expense, of 200,000 livres, he built a test canal, only two feet wide, and on the 9 November 1665 he opened the flow successfully. When the canal was authorized the next year, this test rigole would become the Rigole de la plaine. He also built on his property in Bonrepos a model of the canal with locks, tunnels, and ''épanchoirs'' (spillways) reproducing the slopes and feeding all with water.

Political and economic context

The economic situation of the country was quite difficult at the time. When Colbert became minister he believed that domestic and international trade was not in favour of the Kingdom of France. The Dutch could take better advantage of trade and economic activity in the country. The prices of Grain dropped a lot and wine production fell in 1660. This crisis caused depreciation of land values and small farms were going bankrupt. In addition, the region of Languedoc experienced religious conflict during the Fronde. It was difficult to implement a policy in this area and in particular to introduce taxes such as the salt tax.

Colbert then saw Pierre-Paul Riquet and his project as a way to pursue a policy of economic expansion in the service of absolutism in Languedoc. In fact, Riquet proposed himself to implement the salt tax and to build the Canal du Midi. Thus, the construction of the canal would permit the creation of a direct passage between the Mediterranean Sea and the Atlantic without passing through the Strait of Gibraltar controlled by the Spaniards, the aim being to destroy the Spanish trade and establish a commercial flow through Languedoc. The Languedoc region had many resources such as wheat, wine from Minervois, woollen cloth, silk, and salt which producers were struggling to export due to lack of trade. By passing through the Canal du Midi, Colbert hoped to distribute goods in the different regions of ''le Midi'' to strengthen royal power and open up Toulouse and its region.

The edict of Louis XIV and the financing of the project

Despite a project that seemed precarious, Colbert authorized commencement of work by a royal edict in October 1666 after the approval of a committee of experts that looked at the route of the canal for several months. The project benefited significantly from the appointment of an engineer for fortifications and hydraulics – Louis Nicolas de Clerville – who used his influence with Colbert to start the project. The decree specified the authorization of the construction of the canal, its issuing of invitations to tender, and its awarding to the designer, Pierre-Paul Riquet, and his descendants. It also gave rights of expropriation to Riquet and describes the possibility of creating mills, warehouses and housing for the operation of the canal. The project formed a tax-exempt "fief" whose owner had the rights of fishing and hunting. Finally, it describes the operating procedures including the introduction of tolls, traffic organization, and ownership of vessels. The king decided to cede the ownership and operation of the facility in a particular order to overcome the potential drawbacks of a work so great. This system ensured the continued maintenance and operation of the canal even if the state's finances are at their lowest.

The work was launched in two phases each called an "enterprise". The first enterprise of connecting Toulouse to Trèbes was estimated at 3.6 million livres. The finances of the State, however, were not very sound and the Estates of Languedoc were not willing to fund such a project for fear that their funds would be used for unexpected expenses. So, in exchange for the ownership and operation of the canal, Pierre-Paul Riquet proposed to finance part of the works from his own funds. The rest was to be paid by the State in exchange for profits that Riquet earned from the salt tax. The second enterprise of works between Trèbes and the étang de Thau in December 1668 cost 5.832 million livres plus a million more livres for the resumption of work on the port of Sète.

Ultimately, while the initial budget was six million livres, all the work together would cost between 17 and 18 million livres of the time, 40% was advanced by the King, 40% by the province, and 20% by Riquet himself, who became the owner. His descendants continued to pay two million livres for over 50 years.

Construction of the canal

At the age of 63, Riquet started his great enterprise, sending his personal engineer, François Andreossy, and a local water expert, Pierre Roux, to the Montagne Noire to work on the water supply. This supply system successfully fed the canal with water where it crossed the continental divide, replacing water that drained toward the two seas. The system was a masterpiece of both hydraulic and structural engineering, and served as an early ratification of Riquet's vision. It was also a major part of the massive undertaking.

Work began on the first "enterprise" on 1 January 1667 with the construction of the trough of the Rigole de la plaine then continued on 15 April 1667 with the laying of the first stone of the Lac de Saint-Ferréol.René Gast, ''The Canal du Midi and the Navigable waterways from the Atlantic to the Mediterranean'', Rennes: Ed. Ouest-France, 2000, 125 pages, , p. 18. Originally Riquet wanted to build a dozen reservoirs but the Commissioner General of fortifications, Louis Nicolas de Clerville, asked him to replace them with a single reservoir. This was a great novelty at the time – no reservoir-lake of this magnitude had ever been built before.

Some of Clerville's men with experience in military engineering came, to build the huge dam for the single reservoir, the Bassin de St. Ferréol, on the river Laudot. The Laudot is a tributary of the Tarn in the Montagne Noire some from the summit of the proposed canal at Seuil de Naurouze. This massive dam, long, above the riverbed and thick at its base was the largest work of civil engineering in Europe and only the second major dam to be built in Europe, after one in Alicante in Spain. It was connected to the Canal du Midi by a contoured channel over long, wide with a base width of . It was eventually equipped with 14 locks in order to bring building materials for the canal down from the mountains and to create a new port for the mountain town of Revel.

In November 1667 an official ceremony laid the foundation stone of the Garonne lock in Toulouse in the presence of representatives of the Parliament of Toulouse, the ''Capitouls'' (sheriffs), and the Archbishop of Toulouse, Charles-François d'Anglure de Bourlemont. A first filling of water was made between the seuil de Naurouze and Toulouse during the winter of 1671–1672 and the first boat traffic could begin. In 1673 the section from Naurouze to Trèbes was completed marking the end of the first "enterprise".

From 1671 the second enterprise began linking Trèbes to the Mediterranean Sea and to build the port of Sète (then called ''Cette'', the location was chosen and the port constructed by Clerville). This part of the canal posed problems at the junction between the étang de Thau and Trèbes because the canal must cross the course of the Hérault