The river flows through three French regions: Bourgogne-Franche-Comté, Doubs, Jura and Saône-et-Loire. It is named after the Doubs river. The river also flows through Swiss cantons of Neuchâtel and Jura. It is a major tributary of the Saône and therefore a tributary of the Rhône .
Its length is 453 km , of which 430 km on French territory and 85 km on Swiss territory. The river is the tenth longest in Europe and fourth in France after the Marne and Saône. It is also the ninth longest in Switzerland.
The river originates in Mouthe, a town in the Jura massif. It flows mainly northeast at first. After reaching the Belfort Gorge, it changes direction and flows southwest to its confluence. It joins the Saône at Verdun-sur-le-Doubs , at an altitude of 175 m.
The waters of the Doubs enter the Mediterranean via the Saône (from Verdun-sur-le-Doubs to Lyon) and then via the Rhône (from Lyon to the Mediterranean), completing a river course of 1 032 km, of which 999 km are on French territory, making it the longest river course in the Rhône basin.
Ecology
The riverbed of the Doubs has a diverse morphology, with canyons and basins fed by karst tributaries. It has never been channelized. The small channel maintains its natural form for much of its upper reaches, often on the floor of a wooded valley, except at the large dams. The bed of the river is heterogeneous. These characteristics make the Doubs high in biological potential, but the karst environment makes it vulnerable to possible pollution from the groundwater that feeds the springs.
The Doubs is no longer a wild river: its hydrological regime (originally ‚pluvio-nival‘) and water quality are marked by anthropisation. the natural flow and ecological continuity are significantly altered by three hydroelectric dams (the Châtelot dam, built in 1953 and with a concession until 2028. Refrain dam (1909, licensed until 2032) and Goule dam (1898, licensed until 2024). The disappearance of some natural dams, the change in temperature or sediment dynamics can also be observed (DIREN Franche-Comté, 1994). Nutrients have also eutrophized the river, to the detriment of the fish potential and the overall ecopotency of the environment.
CSP-INRA studies from 1994 to 1999. CSP study from 2003 to 2005…) by comparing the current status with what is assumed to be a good ecological status for the biocenotype corresponding to the study station, or rather with a developed reference system („statistically on a number of non-polluted sites“).
Several species of trout (rainbow and large), pike, grayling, perch, etc., are present in the river, but at densities that fall far short of the theoretical ecological potential of the river.
