Rhône valley

The Rhône ( , ; Occitan: ''Ròse''; Arpitan: ''Rôno'') is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and Southeastern France before discharging into the Mediterranean Sea ( Gulf of Lion). At Arles, near its mouth, the river divides into the Great Rhône () and the Little Rhône (). The resulting delta forms the Camargue region.

The river's source is the Rhône Glacier, at the east edge of the Swiss canton of Valais. The glacier is part of the Saint-Gotthard Massif, which gives rise to three other major rivers: the Reuss, Rhine and Ticino.

The Rhône is, with the Po and the Nile, one of the three Mediterranean rivers with the largest water discharge.

Etymology

The name ''Rhône'' continues the Latin name ( Greek ) in Greco-Roman geography. The Gaulish name of the river was or (from a PIE root *''ret-'' "to run, roll" frequently found in river names).

Names in other languages include ; ; ; ; ; and .

The Greco-Roman as well as the reconstructed Gaulish name is masculine, as is French . This form survives in the Spanish/Portuguese and Italian namesakes, and , respectively. German has adopted the French name but given it the feminine gender, . The original German adoption of the Latin name was also masculine, ; it survives only in the Upper Valais ( dialectal ).

In French, the adjective derived from the river is , as in (literally "the furrow of the Rhône"), which is the name of the long, straight Saône and Rhône river valleys, a deep cleft running due south to the Mediterranean and separating the Alps from the Massif Central.

Navigation

Before railroads and highways were developed, the Rhône was an important inland trade and transportation route, connecting the cities of Arles, Avignon, Valence, Vienne and Lyon to the Mediterranean ports of Fos-sur-Mer, Marseille and Sète. Travelling down the Rhône by barge would take three weeks. By motorized vessel, the trip now takes only three days. The Rhône is classified as a Class V waterway for the section from the mouth of the Saône at Lyon to the sea at Port-Saint-Louis-du-Rhône. Upstream from Lyon, a section of the Rhône was made navigable for small ships up to Seyssel. , the part between Lyon and Sault-Brénaz is closed for navigation.

The Saône, which is also canalized, connects the Rhône ports to the cities of Villefranche-sur-Saône, Mâcon and Chalon-sur-Saône. Smaller vessels (up to CEMT class I) can travel further northwest, north and northeast via the Centre-Loire-Briare and Loing Canals to the Seine, via the Canal de la Marne à la Saône (recently often called the " Canal entre Champagne et Bourgogne") to the Marne, via the Canal des Vosges (formerly called the "Canal de l'Est – Branche Sud") to the Moselle and via the Canal du Rhône au Rhin to the Rhine.

The Rhône is infamous for its strong current when the river carries large quantities of water: current speeds up to are sometimes reached, particularly in the stretch below the last lock at Vallabrègues and in the relatively narrow first diversion canal south of Lyon. The 12 locks are operated daily from 5:00 a.m. until 9:00 p.m. All operation is centrally controlled from one control centre at Châteauneuf. Commercial barges may navigate during the night hours by authorisation.

Course

The Rhône begins as the meltwater of the Rhône Glacier in Valais, in the Swiss Alps, at an altitude of approximately . From there it flows southwest through Gletsch and the Goms, the uppermost valley region of the Valais before Brig. In the Brig area, it receives the waters of the Massa from the Aletsch Glacier, the longest glacier of the Alps, and shortly after, it receives the waters of the Vispa, the longest affluent in Valais. After that, it flows onward through the valley which bears its name and runs initially in a westerly direction about thirty kilometers to Leuk, then southwest about fifty kilometers to Martigny.

Down as far as Brig, the Rhône is a torrent; it then becomes a great mountain river running southwest through a glacial valley. Between Brig and Martigny, it collects waters mostly from the valleys of the Pennine Alps to the south, whose rivers originate from the large glaciers of the massifs of Monte Rosa, Dom, and Grand Combin, but also from the steeper slopes of the Bernese Alps to the north, and the Mont Blanc massif to the west. As a result, the Rhône Valley experiences a drier climate than the rest of Switzerland, being sheltered by the three highest ranges of the Alps, making Valais the driest and largest wine region of the country.

At Martigny, where it receives the waters of the Drance on its left bank, the Rhône makes a sharp turn towards the north. Heading toward Lake Geneva (), the valley narrows near Saint-Maurice, a feature that has long given the Rhône valley strategic importance for the control of the Alpine passes. The Rhône then marks the boundary between the cantons of Valais (left bank) and Vaud (right bank), separating two parts of the historical region of Chablais. It then enters Lake Geneva near Le Bouveret, where the water flows west.

On the left (south) bank of Lake Geneva, the river Morge joins at the village of Saint-Gingolph, and also marks the French-Swiss border. Westward, the Dranse (unrelated to the Drance) enters the lake with its preserved delta, and then the Hermance marks another French-Swiss border. Between the Morge and Hermance, the lake is divided by the two countries along its centreline, with the left bank in France. The remainder of the lake is Swiss, including the entire right (north) bank. Here, the tributaries are the Veveyse, the Venoge, the Aubonne, the Morges, among other smaller rivers.

Lake Geneva ends in the city of Geneva, where the lake level is controlled by the . The average discharge from Lake Geneva is . Below the dam, the Rhône receives the waters of the Arve, fed by the Mont Blanc massif, with a visibly higher sediment load and much lower temperature.

After a total of in Switzerland, the Rhône continues west, entering France and the southern Jura Mountains. It turns toward the south, past Lac de Bourget, which the Rhône drains via the Canal de Savières. Continuing generally westward, the Rhône then receives the waters of the Valserine, enters the reservoir created by the Génissiat Dam, and is then joined by the Ain.

Reaching Lyon, the most populous city on its course, the Rhône receives its biggest tributary, the Saône, with an average flow of , compared to the Rhône's at this point. From this confluence, the Rhône follows a southward course. Along the Rhône Valley, it is joined on the right (western) bank by the rivers Eyrieux, Ardèche