Loire
The Loire ( , , ; ; ; ; ) is the longest river in France and the 171st longest in the world. With a length of , it drains , more than a fifth of France's land, while its average discharge is only half that of the Rhône.
It rises in the so ...
in the
Nouvelle-Aquitaine
Nouvelle-Aquitaine () is the largest Regions of France, administrative region in France by area, spanning the west and southwest of Metropolitan France. The region was created in 2014 by the merging of Aquitaine, Limousin, and Poitou-Charentes ...
and
Pays de la Loire
Pays de la Loire (; but can also mean 'Lower Loire') is one of the eighteen administrative regions of France, located on the country's Atlantic Ocean, Atlantic coast. It was created in the 1950s to serve as a zone of influence for its capital an ...
regions of western
France
France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
. The Thouet rises at Secondigny, close to the source of the Sèvre Nantaise, and joins the Loire just to the west of Saumur. It is long, and drains an area of .
The river's name derives from the ancient Gallic word for tranquil.
Course of the river
The Thouet rises in the Gâtine Vendéenne, the most southern outcrop of the
Armorican Massif
The Armorican Massif (, ) is a geologic massif that covers a large area in the northwest of France, including Brittany, the western part of Normandy and the Pays de la Loire. It is important because it is connected to Dover on the British side o ...
, at altitude. The Armorican Massif is made up of volcanic and metamorphic rocks dating back to the Paleozoic era. This impermeable land does not result in any important
aquifer
An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...
s but is an area of significant rainfall runoff. From the source to Parthenay the river flows in a generally east–west direction.
To the east of Parthenay, the river turns north and flows on a generally northward heading for the rest of its course. Between Saint-Loup-Lamairé and Thouars, the river flows onto the Paris Basin, an area of
sedimentary rock
Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...
s where successive marine deposits of periods from the
Triassic
The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...
tributaries
A tributary, or an ''affluent'', is a stream or river that flows into a larger stream ('' main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which the ...
of the River Thouet are:
* The Viette, at Parthenay on the right bank
* The Palais, at Parthenay on the left bank
* The Cébron, at Saint-Loup-Lamairé on the left bank
* The Thouaret, near Taizé on the left bank
* The Argenton, at Saint-Martin-de-Sanzay on the left bank
* The Losse, at Montreuil-Bellay on the right bank
* The Dive, at Saint-Just-sur-Dive on the right bank.
For much of its length, the Thouet is paralleled by the GR 36long-distance walking route, which connects Ouistreham, on the coast of the
English Channel
The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busi ...
Spain
Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...
. This stretch of the path traces the footsteps of pilgrims from
Brittany
Brittany ( ) is a peninsula, historical country and cultural area in the north-west of modern France, covering the western part of what was known as Armorica in Roman Gaul. It became an Kingdom of Brittany, independent kingdom and then a Duch ...
and
Normandy
Normandy (; or ) is a geographical and cultural region in northwestern Europe, roughly coextensive with the historical Duchy of Normandy.
Normandy comprises Normandy (administrative region), mainland Normandy (a part of France) and insular N ...
on their way to
Santiago de Compostela
Santiago de Compostela, simply Santiago, or Compostela, in the province of Province of A Coruña, A Coruña, is the capital of the autonomous communities of Spain, autonomous community of Galicia (Spain), Galicia, in northwestern Spain. The city ...
The Thouet was once navigable between its confluence with the Loire and Montreuil-Bellay. The first mention of navigation on the river dates from 1430 when an assembly of merchants in Saumur suggested the creation of a navigation over this stretch of the river, requiring the creation of passages through three mill weirs. It is possible that boats were already carrying goods on the river before that date, the cargo being transferred between boats at each obstacle.King Charles VII authorised the start of work by
letters patent
Letters patent (plurale tantum, plural form for singular and plural) are a type of legal instrument in the form of a published written order issued by a monarch, President (government title), president or other head of state, generally granti ...
, financing the work by allowing the lords of Montreuil-Bellay to raise a tax on wine that would pass through their land. In the 15th and 16th centuries, the passage through the weirs probably took the form of flash locks. The later pound lock may have been introduced towards the end of the 16th century, and it is known that three pound locks were in use on the river by 1608. A project to make the river navigable up to Thouars was proposed in 1746 but was never executed.
The Dive, a tributary of the Thouet, was canalised in 1834 to create the Canal de la Dive. As part of this development, two modern pound locks with straight sides and mitred gates were built on the Thouet, downstream of the confluence with the Dive. A third modern lock was built at the same time on the Thouet, but upstream from the confluence of the Dive. These locks had dimensions of length, width, and a draught of .
However the new navigation soon faced competition from better roads and the railway, which appeared in the region in 1874. The maximum boat size imposed by the locks proved insufficient, and a proposed enlargement to the larger Freycinet gauge was never realized. The last commercial navigation on the river was in 1920.