Garonne

The Garonne (, ; in Occitan, Catalan and Spanish: Garona; ) is a river in southwest France and northern Spain, with a length of 602 km (341 miles).

Geography

Source

the Garonne turns northward (out of sight), and after 12 km receives water from the Joèu (Pic Aneto).]]

The Garonne's headwaters are to be found in the Aran Valley in the Pyrenees, though three different locations have been proposed as the true source: the Uelh deth Garona at Plan de Beret (), the Ratera-Saboredo cirque ), or the slopes of Pic Aneto (Salterillo-Barrancs ravine according to the season).

The Uelh deth Garona (1,862 m a.s.l.) has been traditionally considered as the source of the Garonne. From this point a brook (called the Beret-Garona) runs for 2.5 km until the bed of the main upper Garonne valley. The river runs for another 38 km until the French border at Pont del Rei (40.5 km in total).

The Ratera-Saboredo cirque is the head of the upper Garonne valley, and its upper lake (2,600 m a.s.l.) is the origin of the Ruda-Garona river, running for 16 km until the confluence with the Beret-Garona brook, and another 38 km until the French border at Pont del Rei (54 km in total). At the confluence, the Ruda-Garona carries 2.6 m3/s of water. The Ratera-Saboredo cirque has been pointed by many researchers as the origin of the Garonne.

The third thesis holds that the river rises on the slopes of Pic Aneto, at 2,300 m a.s.l. and flows by way of a sink hole known as the Forau de Aigualluts () through the limestone of the Tuca Blanca de Pomèro and a resurgence in the Val dera Artiga above the Aran Valley in the Spanish Pyrenees. This underground route was suggested by the geologist Ramond de Carbonnières in 1787, but there was no confirmation until 1931, when caver Norbert Casteret poured fluorescein dye into the flow and noted its emergence a few hours later away at Uelhs deth Joèu ("Jove's eyes" ) in the Artiga de Lin on the other side of the mountain. From Aigualluts to the confluence with the main river at the bed of the upper Garonne valley (800 m a.s.l.), the Joèu has run for 12.4 km (16 more to get to the French border), carrying 2.16 m3/s. of water, while the main river is carrying 17.7 m3/s.

Despite the lack of universal agreement upon definition for determining a stream's source, the United States Geological Survey, the National Geographic Society, and the Smithsonian Institution agree that a stream's source should be considered as the most distant point (along watercourses from the river mouth) in the drainage basin from which water runs. The use of new technologies such as DEM, GIS, GPS or orthophotography has made much easier to specify the accurate length of rivers

The Ratera-Saboredo cirque is the "most distant point (along watercourses from the river mouth) in the drainage basin from which water runs", and the source of the Garonne, according to the United States Geological Survey, the National Geographic Society, and the Smithsonian Institution convention upon determining a stream's source.

Course

The Garonne follows the Aran Valley northwards into France, flowing via Toulouse and Agen towards Bordeaux, where it meets the Gironde estuary. The Gironde flows into the Atlantic Ocean (Bay of Biscay). Along its course, the Garonne is joined by three other major rivers: the Ariège, the Tarn, and the Lot. Just after Bordeaux, the Garonne river finally meets the Dordogne, forming the Gironde estuary, which after approximately empties into the Atlantic Ocean. Other tributaries include the Save and the Gers.

The Garonne is one of the few rivers in the world that exhibit a tidal bore. Surfers and jet skiers can ride the tidal bore at least as far as the village of Cambes, from the Atlantic and even further upstream.

Towns along the river

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Aran Valley (Spain): Vielha

Haute-Garonne (31): Saint-Gaudens, Muret, Toulouse

Tarn-et-Garonne (82): Castelsarrasin

Lot-et-Garonne (47): Agen, Marmande

Gironde(33): Langon, Bordeaux, Blaye, Le Verdon-sur-Mer

Charente-Maritime (17): Royan

Main tributaries

Following the flow of the river: {| |- valign="top" |

Pique

Ourse

Neste

Salat

Volp

Arize

Louge

|

Ariège

Touch

Save

Gimone

Hers-Mort

Tarn

Arrats

|

Gers

Baïse

Lot

Dropt

Ciron

Gat mort

Devèze

|

Jalle de Blanquefort

|}

Navigation

The Garonne plays an important role in inland shipping. The river not only allows seagoing vessels to reach the port of Bordeaux but also forms part of the "Canal des Deux Mers", linking the Mediterranean Sea to the Atlantic Ocean, allowing a shorter and safer way for goods to pass from the agricultural areas of the South of France to the Atlantic.

From the ocean, ships pass through the Gironde estuary until the mouth of the Garonne (to the right of the Dordogne when sailing upstream). The Garonne remains navigable for larger vessels up to the "Pont de Pierre" (Stone Bridge) in Bordeaux. River vessels can sail upstream to Castets-en-Dorthe, where the Garonne Lateral Canal (Canal Latéral à la Garonne) joins the river.

Prior to the building of the Garonne Lateral Canal, constructed between 1838 and 1856, river shipping used the Garonne itself as far as Toulouse. However the navigation of the upper river was very uncertain, and this stretch of the river is no longer considered navigable. Instead the lateral canal takes the ships through 53 locks to the town of Toulouse, where the canal meets the Canal du Midi, the next stage of the "Canal des Deux Mers".

The Garonne Lateral Canal was subject to one of the largest infrastructure works in Europe, when it was adapted to the standardized barge size of 38 by , during the last century. French minister Freycinet ordered that all major canals used for long distance transport be suitable for vessels of those standard dimensions. The extension of all of the former locks to the new standard length was carried out throughout the lateral canal. The other half of the Canal des Deux Mers, the Canal du Midi, partly escaped this operation, because by the time the works had reached the area where the most locks were situated, commercial traffic on the canal had almost disappeared. The works were stopped, leading to the cultural heritage status of the United Nations that has made the Canal du Midi famous. (Source: NoorderSoft Waterways database)

See also

List of rivers of Europe

References

External links

French Waterways - River Garonne Information on the navigable lower Garonne

Category:Rivers of Catalonia Category:Rivers of France * Category:Charente-Maritime Category:Gironde Category:Haute-Garonne Category:Lot-et-Garonne Category:Tarn-et-Garonne