Versoix (river)

	Versoix
	The Versoix in Versoix
	Data
Water code	FR : V0360500 , CH : 123
location	France , Ain department and Switzerland , canton of Geneva
River system	Rhone
Drain over	Rhone → Mediterranean
source	at Divonne-les-Bains ; 46 ° 21 ′ 47 ″ N , 6 ° 6 ′ 35 ″ E
Source height	approx. 600 m
muzzle	at Versoix in Lake Geneva Coordinates: 46 ° 16 '30 " N , 6 ° 10' 15" E ; CH1903: 502 275 / 125618 46 ° 16 '30 " N , 6 ° 10' 15" O;
Mouth height	372 m above sea level M.
Height difference	approx. 228 m
Bottom slope	approx. 8.4 ‰
length	27 km
Catchment area	89 km²

The Versoix is a 27 km long river that has its source on French territory and flows into Lake Geneva near Versoix in the Swiss canton of Geneva . It drains a section of the plateau between Lake Geneva and the Jura and belongs to the catchment area of the Rhone . The area of the catchment area of the Versoix is 89 km².

geography

The headwaters of the Versoix are located at around 600 m in the foothills of the first Jura chain in the commune of Divonne-les-Bains in the French department of Ain . The uppermost section of the stream is called the Divonne . The Versoix initially flows eastwards through the village of Divonne-les-Bains and shortly afterwards it reaches a wide valley at 465 m, which is separated from Lake Geneva by the ridge of Chavannes. Here the stream turns with a sharp curve to the south-south-west and now flows for a longer stretch parallel to the west bank of Lake Geneva, forming the state border between Switzerland and France for over 9 km. In the wide valley basin there are large swamp areas, which the Versoix, whose gradient is now less than 0.1%, crosses with numerous meanders .

Only below Sauverny does the Versoix gradually begin to sink into the surrounding plateaus. The Oudar , which rises in the Pays de Gex on the southern slopes of the Jura, flows here from the west . The Versoix now draws another curve, flows south-east and crosses over entirely to Swiss territory (canton Geneva). It is located in a valley that is around 15 to 20 m deeper than the adjacent areas and has a flat floodplain that is up to 300 m wide. At La Bâtie it receives the second noteworthy inflow with the Creuson . South of the small town of Versoix, the river of the same name flows into Lake Geneva with a small alluvial cone .

The Versoix flows over long distances in a stream bed, the natural or near-natural state of which has been preserved. Despite the use of the water since the Middle Ages, the banks are only built in the Divonne-les-Bains and Versoix area.

Hydrology

The Versoix has a nivopluvial discharge regime . Floods can occur in spring during the snowmelt in the Jura and later in the year during strong thunderstorms or prolonged rainfall. Fed by the karst body of water in the Jura, the Versoix still carries a relatively large amount of water compared to other rivers of similar length, even after longer dry periods. The mean annual runoff at Versoix is 3.7 m³ / s.

fauna

Trout , bullhead and grayling can be found in the Versoix . The first beaver reintroduction project in Switzerland started in 1956 on the natural course of the river. The population has since established itself here.

History and use

The river name was first mentioned in 1319 under the name Aqua Versoye . Later the names Versoya (1497), Versois (1730) and Versoie (1906) appeared. The name is derived from the old French word versoi or bersoye (hiding place, wickerwork of willow rod).

As early as Roman times, part of the spring water of the upper Versoix was diverted and led to the town of Colonia Iulia Equestris (Nyon) via an aqueduct .

The water power of the Versoix has been used to operate mills and hammer mills since the Middle Ages . In the 16th century the paper mills took their place (especially at Divonne-les-Bains, Sauverny and La Bâtie). The La Bâtie paper mill closed in 1880. After that there was a paper mill at Versoix, which had to give up its operations in 2000.

Water is drained from the Versoix in three different places. This was partly done in the Middle Ages in order to supply small streams that flow directly into Lake Geneva and hardly carry any water in the summer with a water capacity that is as constant as possible, sufficient for use by mills as well as for irrigation of the agricultural areas. These include the canal drainage to the Greny (flows into Lake Geneva at Coppet ) and Brassu (flows from Céligny ) and the Canal de Crans , which feeds the Nant du Pry at Crans-près-Céligny . With the third canal, inaugurated in 1785, the water of the Versoix from La Bâtie is carried over 5.4 km along the northern slope of the valley for industrial and irrigation purposes to Versoix-la-Ville, which was newly established at that time.

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