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Introduction to the Rhone

Between you and I…

My source lies in Switzerland in the Saint-Gothard massif, at an altitude of 2,300 m, from which I flow until reaching the Mediterranean Sea. I am 810 km long, 72 km of which crosses Lake Geneva, the largest lake in Western Europe. A course scattered with irregularities: elbows and rocky ravines, floodplains and steep slopes. Famous for my impetuosity, I have often spilled out of my bed, causing major damage. Humans very quickly wanted to tame me, channel me to reduce my floods and exploit what I offer to the maximum, meaning using me as a navigable waterway, a source of energy, and water for cities and fields. Now, more attention is given to preserve my biodiversity, my landscapes and enhance my uses so that I continue to serve and sustainably develop the territories I cross. Me, the impetuous, powerful Rhone or Rotten shared by France and Switzerland!

A little history


I was born 55 million years ago, from the creation of the Rhone Valley: a huge rift caused by the separation of the Earth’s crust. Following marine, riverine and lagoon episodes, it was the drying up of the Mediterranean Sea that allowed me to gouge out my bed. My cohabitation with humans was peaceful until the end of the middle-ages. During the Gallo-Roman period, along with the Saone, I was even one of the busiest corridors of the Roman Empire after the Nile, between Arles and Lugdunum, the capital of Gaul. In the middle-ages, I was used to transport salt, metals, wood and cereals.

With the Little Ice Age, beginning at the start of the 14th century and lasting until the end of the 19th century, I became tumultuous: heavy rains, advancing glaciers, the inflows of my tributaries: my floods became devastating.

In the middle of the 19th century, humans got together to develop me, tame my behaviour to protect farmland and towns and make navigation safer. In Switzerland, these actions were called “correction”. In France, starting in 1884, the chief engineers of the Rhone, Jacquet and Girardon, perfected systems to regularise my flows by installing spur dikes, training dikes, protection dikes, groynes, etc. The 1950s saw the addition of other developments (dams, hydropower plants, locks and more dikes) built by the CNR, the Compagnie Nationale du Rhône. On the Swiss side, it was a project to build a railway between Valais and Italy in the 1860s that led to the construction of dikes to contain me.

On both sides of the border, a new chapter began twenty years ago with great attention given to the study of my water and the restoration of natural habitats.


Technical information

  • Source: the Furka Glacier, in the alpine massif of Saint-Gothard
  • Mouth: Camargue delta – Mediterranean Sea
  • Average discharge: 251 m3/s at the outlet of Lake Geneva; 1,800 m3/s along the French course
  • Total length: 812 km (290 km in Switzerland and 522 km in France)
  • Watershed: 97,800 km2 (including 7 800 km² in Switzerland)
  • Countries crossed: Switzerland, France
  • Main tributaries: Vispa, Grande Eau, La Veveyse, La Venoge, Versoix, Arve in Switzerland; Ain, Saône, Isère, Ardèche, Drôme, Durance, Gard in France.

A cross-border watershed

I ignore geographic boundaries and have always made available my many uses to both countries: hydroelectricity production, irrigation of farmland, drinking water, navigation, cooling nuclear power plants, exosystemic services, leisure, etc.

Nevertheless, coordination proved necessary on either side of the border. This was already the case between the two main hydroelectricity operators:

  • The Services Industriels de Genève (SIG) which manages the river’s discharges as a function of the regulated levels of Lake Geneva, and the Canton of Geneva’s need for hydroelectricity production;
  • The Compagnie Nationale du Rhône, the concession holder of the river from the Swiss border to the Mediterranean, which fulfils three missions: navigation, irrigation and hydroelectricity production.

This cooperation above all focuses on managing the sediment carried in enormous quantities by one of my tributaries, the Arve: operations to flush these sediments (silt, sand, etc.) take place every 3 to 4 years, from the Swiss dam of Verbois, to prevent them from accumulating on my bed and increasing the flood risks. Coordinated management is necessary so that the French operator assists these operations with its own installations and that the safety of the surrounding population is ensured and the impacts on the environment limited

The effects of climate change and the intensification of water use will require stronger cross border governance in the near future, to ensure sustainable and coordinated management of both the uses and the preservation of my ecosystem. Disputes could occur without a common and global vision of the stakes I represent!

Considering my future

My future is above all that of my source: at present my glacier is losing from 5 to 7 metres in thickness every year, under the effects of climate change. The experts estimate a reduction by half from now to 2030 and its disappearance by 2100.

Le Glacier du Rhône – © Camille Moirenc

Ice melting and the increase of extreme meteorological events will certainly weaken me: in winter, the snow lasts only in the high mountains and greater evaporation of water will reduce my natural discharge. By 2050, I will have structurally less water, from -10% to -40%. Already, in 2017, a year of severe drought, my average discharge was 30% lower than that of the last twenty years.


My water resources will then give rise to major conflicts, particularly if withdrawals for agriculture and industrial activities continue to increase.


My future is also that of the fauna and flora that I host, which my managers and political decision-makers want to preserve and enhance, especially for tourism and improving the living environment of the surrounding population. The combat against all kinds of micropollutants originating from agricultural, industrial and domestic activities – including plastics – remains vital.

To understand all this better, a journey downstream is required!

Discovering the Rhone

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