Ardeche (river)

See also: Ardeche

The Ardèche (in Occitan Ardecha ) is a river of the south of the France, affluent right of the the Rhone. It gave its name to the department which it sprinkles, but its catchment area relates to also the Lozere and the Gard.

Geography

It takes its source in the Vivarais, close to the collar of Chavade, in the forest of Mazan on the commune of Astet. After Aubenas and Ruoms, it receives the Chassezac, then is inserted starting from Vallon-Pont-d'Arc in the famous throats which it itself dug. It joined the Rhone upstream Pont-Saint-Esprit.

Principal affluents and tributaries of a tributary

  • Auzon

  • Lignon
  • the Line
  • the Beaume
  • the Chassezac
    • the Proud
    • the Terminal
  • Drobie
  • Fontaulière
  • Claduègne
  • Ibie
  • Volane

Hydrology

Its medium flow is of 65 m/s, but the Rivière knows violent risings in spring and the autumn and periods of very low waters in summer. At the time of exceptional risings, as in 1827,1890 and 1924, it can reach 7.800 m/s and its level to go up to the dimension record of 21,4 meters in the throats.

Flows

The interannual medium flow of Ardeche was observed and calculated over one 26 years period to Saint-Martin-in Ardèche. It is assembled to 63,4 m ³ a second for a surface of basin of 2  240 km ², are the very great majority of its area catchment (2  430 km ²). The river present of the seasonal fluctuations of flow typical of the Cevennes mode, with high waters of autumn and winter at double top, carrying the average monthly flow at the first top of 93 m ³ in October, then after a fall to 76 m ³ in December, a new going top from 96 to 102 m ³ in January - March (with an in January maximum). A fast fall of the flows follows, finishing in one period of low water level in July - August involving a fall of the monthly medium flow up to the level of 12 m ³ in July.

The VCN3 can fall until 2,5 m ³, in the event of dry decennial period. The VCN3 is the past minimal quantity or minimal flow over three days consecutive.

As for the risings, they can be extremely important, at the point to be become legendary (generally following the Cevennes storms). Indeed, the QIX 2 or calculated flow of rising biennial and the QIX 5 or flow calculated for a quinquennial rising is worth 1  respectively; 800 and 2  600 m ³ a second, which is enormous. The QIX 10 or calculated flow of decennial rising, even more gigantic, is of 3  100 m ³ a second, while the QIX 20 and QIX 50 are assembled at the almost fabulous levels of respectively 3  600 and 4  300 m ³ a second (see note).

Instantaneous maximum flow recorded with Saint-Martin-in Ardèche east of 4  500 m ³ a second (two thirds of the medium flow of the Danube), while the daily maximum flow is worth 2  506 m ³ a second.

The Lame of water past in the catchment area of the river is of 897 millimetres annually, which is very high. The specific flow (Qsp) is assembled thus at 28,3 liters a second and per square kilometer of basin.

Vocal waiter

The Préfecture of the Ardèche brought into service since the month of June 2005, a vocal Serveur whose objective is to diffuse messages of information regularly in order to allow the follow-up of any serious event of civil security having started a Crisis cell /veille. Accurate informations on the Raw evolution of the S

Departments and main cities crossed

Tourist sites

  • the Gorges of Ardeche

  • the Cave Chauvet-Bridge-with Arc
  • Swallow-hole Cave of Forest the

References

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