Journans (river)

Journans
Data
Water code	FR :  V0410560
location	France , Auvergne-Rhône-Alpes region
River system	Rhône
Drain over	Lion  → Allondon  → Rhône  → Mediterranean
source	at Colomby de Gex 46 ° 19 ′ 38 ″  N , 6 ° 3 ′ 6 ″  E
Source height	approx.  1380  m
muzzle	at Saint-Genis-Pouilly in the Lion Coordinates: 46 ° 15 ′ 36 "  N , 6 ° 3 ′ 6"  E 46 ° 15 ′ 36 "  N , 6 ° 3 ′ 6"  E
Mouth height	approx.  450  m
Height difference	approx. 930 m
Bottom slope	approx. 62 ‰
length	15 km
Catchment area	146 km²
Right tributaries	Varfeuille , Janvion
Small towns	Gex , Saint-Genis-Pouilly

The Journans , known in its lower reaches as the Grand Journans , is an approximately 15-kilometer-long river in the Allondon catchment area in the French Ain ( Auvergne-Rhône-Alpes region ), in the Pays de Gex , northwest of the city of Geneva . After the confluence of the Grand Journans and Lion , the flowing water takes on the name Lion, although the latter has covered a significantly shorter distance than the Journans until the merger. The Journans is mentioned for the first time in 1397 as Aqua de Jornan ; from 1730 the spelling Journan has been handed down.

geography

The headwaters of the Journans are located in the Haut-Jura Regional Nature Park at around 1380 m in the municipality of Gex on the steep eastern slope of the Colomby de Gex . At the weak point of a fault line running across the Jura chain, the erosion was able to break up the hard rock layers, so that over time a characteristic evacuation basin , the Creux de l'Envers, formed. This basin is enclosed in the north by the heights around the Col de la Faucille , in the west by the crests of Mont Rond and Colomby de Gex and in the south by Mont Chanais.

The Journans first flows through the Creux de l'Envers to the northeast, before it draws an arc of around 90 ° and passes the narrow point of the Portes Sarrazines between Mont Chanais and the heights of the Col de la Faucille. At Gex the stream reaches the foot of the Jura. On the first five kilometers of its route, the Journans overcomes an altitude difference of around 800 meters.

Below Gex, the Journans emerges from a notch valley slightly cut into the slopes at the foot of the Jura into the Geneva basin, which is characterized by Quaternary deposits. It now flows southwards through a flat flood plain that is partially moored. Part of the water seeps away in the zone between Gex and Ségny . The only noteworthy side streams are the Varfeuille and Janvion, both of which flow from the right.

The flowing water divides in the predominantly wooded marshland between the villages of Brétigny and Veraz. The main part flows further south through the plain and receives the name Grand Journans, while a small part (especially during floods) is diverted to the southeast, then runs parallel to the Grand Journans as the Petit Journans and flows into the Lion after 3.3 km. A short time later, the Grand Journans also united with the Lion in the municipality of Saint-Genis-Pouilly . Although the Lion has only covered 5 km to this point (in contrast to the 15 km of the Journans), the stream is still called the Lion. After a further four kilometers, this flows into the Allondon near the Swiss border.

Hydrology

The Journans has a nivopluviales flow regime with strongly fluctuating water levels. Floods can occur in spring during the snowmelt in the Jura and later in the year during strong thunderstorms or prolonged rainfall. At Gex, the mean annual runoff is around 0.33 m³ / s, with the monthly mean fluctuating between 0.07 m³ / s in August and 0.69 m³ / s in April. At 29 km, the Journans-Lion-Allondon river system is the longest surface watercourse in the Allondon catchment area. At the confluence of the Lion in the Allondon, however, the latter generally carries a larger amount of water, as it has its source in a karst spring at the foot of the Jura.

Web links

Commons : Journans  - collection of images, videos and audio files

Remarks

1. ↑ Source geoportail.fr (1: 16,000)
2. ↑ mouth geoportail.fr (1: 32,000)
3. ↑ ^{a b c} The information on the length of the river is based on the information on the Journans from SANDRE (French), accessed on January 3, 2012, rounded to full kilometers.