The source of the river lies at above sea level in the Vivarais, near the Col de la Chavade, in the forest of Mazan in the commune of Astet. After the towns of Aubenas and Ruoms, it collects the Chassezac and the Beaume and plunges into its famous gorge below Vallon-Pont-d'Arc. It flows into the Rhône at Pont-Saint-Esprit.
Departments and communes
The Ardèche flows through the following departments and communes:
The most important tributaries and subtributaries to the Ardèche River include:
Hydrology
The river has an average discharge of but experiences severe floods, called "coups de l'Ardèche", in spring and autumn and periods of very low water in summer. During flood events in 1827, 1890, and 1924, it reached and the water level rose to a record in the gorge. Despite the Ardèche's short length, the flow of the river at is relatively high—higher than the Gardon at, the Cèze, the Hérault, or the Agout —major rivers south of the Massif Central but much longer.
Rates of flow at Saint-Martin d'Ardèche
The inter-annual average flow of the Ardèche was observed and calculated over a period of 26 years at Saint-Martin d'Ardèche. It amounted to for a surface basin of —i.e. the vast majority of its watershed of. The river has seasonal fluctuations: a typical flow around the Cevennes, with high water in autumn and winter being double the normal, brings the average monthly flow at the first peak of in October then, after falling to in December, a new peak occurs from in January–March. A rapid decline in flow rate follows ending in a dry period in July–August resulting in a decrease of the average monthly rate to the level of in July. The VCN3 can drop to in a dry year. Floods can be extremely important. The Qix 2 and Qix 5 are respectively which is high. QIX 10 is while QIX 20 and QIX 50 respectively rise to. The maximum instantaneous flow recorded in Saint-Martin d'Ardèche has been , while the maximum recorded daily rate was. The runoff curve number flowing into the catchment of the river is annually, which is very high. The specific flow reaches 28.3 litres per second per square kilometre of the catchment.
Flows of waterways in the Ardèche catchment
Voice server
The prefecture of Ardèche has provided a voice server since June 2005 whose objective is to regularly disseminate information messages to allow monitoring of any significant event that might trigger a civil security crisis or standby alert. Precise information on the evolution of any flood is provided.
Peculiarity
The Ardèche receives water from the Loire river via the "La Palisse" flood barrier and the Lake d'Issarlès. Effectively, the water is collected to feed the EDF hydroelectric plant at Montpezat-sous-Bauzon and is subsequently piped into the Fontaulière river, a tributary of the Ardèche, near the town of Aubenas.
Hydronymy
Several ancient inscriptions about a college of nautes in associated rivers have been discovered in the Gard. It is possible that the two rivers concerned are the Ardèche and the Ouvèze. The identification of these two rivers is still pending. However, if it does involve the Ardèche river, the spellings Hentica, then Ardesca have been attested.
Protected areas
The Ardèche is protected along almost all of its course. These protected areas are:
The Gorges de l'Ardèche - The Gorges de l'Ardèche is located between the villages of Vallon-Pont-d'Arc and Saint-Martin-d'Ardèche. The road along the north rim of the gorge has views into the gorge and over the river.
Pont d'Arc - A natural stone bridge across the river near the town of Vallon-Pont-d'Arc forms the natural to the Gorges de l'Ardèche.
Chauvet Cave - This limestone cave, which is named after its discoverer, is in the Gorges de l'Ardèche. It contains early Stone Age cave paintings of great variety and expressiveness. Since the cave is not open to the public, photographs of cave paintings are displayed in an exhibition in Vallon-Pont d'Arc.
