Drugeon

The Drugeon is a French Rivière Massif of the Jura running in the department of the Doubs. It is an affluent of the Doubs, therefore a tributary of a tributary of the the Rhone by Doubs and the the Saone.

Geography

It takes its source in the Marais of Malpas and of Be worth-and-Chantegrue and throws itself in the Doubs with the locality All-Wind located at the north of Pontarlier. The altitude of the basin of Drugeon varies from 805 meters to 1.080 meters.

Hydrology

Drugeon is a rather abundant river, like the majority of the rivers of the basin of the Saone. Its flow was observed during one 41 years period (1967-2007), with Vuillecin, locality very close to its confluence with the Doubs. The catchment area of the river is there of 191 km ² is it quasi totality of this one.

The interannual medium flow or module of the river with Vuillecin is of 3,29 m ³ a second.

Drugeon presents seasonal fluctuations of flow very little marked, with one period of high waters going from the autumn in spring and characterized by average monthly flows located between 3,77 and 4,60 m ³ a second, from November to April included (with an in February maximum). As of at the end of April, the flow decreases slowly to lead to the period of the low waters which proceeds in July and in August, bringing a fall of the monthly medium flow going up to 1,96 m ³ to August.

With the low water level the VCN3 can fall until 0,180 m ³, in the event of dry quinquennial period, that is to say 180 liters a second, which cannot be described as really severe (see note).

The risings can however be rather important. The QIX 2 and QIX 5 or calculated flows of biennial and quinquennial rising are worth respectively 30 and 39 m ³ a second. The QIX 10 or calculated flow of decennial rising is of 46 m ³ a second, the QIX 20 of 52 m ³, while the QIX 50 is assembled to 59 m ³ a second (see note).

The recorded maximum instantaneous flow with Vuillecin during this period, was of 53 m ³ a second on March 14th, 1981, while the recorded maximum daily output was of 47,9 m ³ a second the same day. If one compares the first of these values on a QIX scale of the river, one notes that this rising of a vicennial nature and by no means exceptional, was thus intended to repeat oneself every 20 years on average.

The Lame of water past in the catchment area of Drugeon is of 545 millimetres annually, which is largely higher than the overall average of the France all basins confused, but as higher as the average of the basin of the the Saone (501 millimetres in Lyon). The specific Débit of the river (or Qsp) consequently posts the very solid figure of 17,2 liters a second and per square kilometer of basin.

A basin of great ecological interest

One counts there an exceptional flora (49 protected spaces) and a remarkable fauna for France (142 vertebrate and 9 protected invertebrates). It presents in particular many Tourbière S. It was classified special protection zone (ZPS) in January 1999.

Fauna of the basin of Drugeon

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