Coise (river)

Geography

It takes its source in the department of the the Rhone (69) in the south of Holy-Catherine and is thrown in the the Loire with Montrond-the-Baths, in the department of the the Loire (42).

Departments and principal crossed localities

the Rhone (69): Holy-Catherine, Saint-Symphorien-on-Coise
the Loire (42): Saint-Galmier, Montrond-the-Baths

Principal affluents

the Potensinet , Right Bank, length 10 kilometers, which joins in the north of Larajasse
the Couzon , left bank, 11 kilometers, which joins in the south-west of Saint-Symphorien-on-Coise
the Gimond , Right Bank, 14 kilometers, which joins in the south of Chazelles-on-Lyon
the Gimond (even name) , left bank, 14 kilometers, which sprinkles Gimond and joins in the north of Saint-Medard-in-Drill
the Gérinière , left bank, 12 kilometers, which sprinkles Saint-Bonnet-the-Oules and join in the west of Saint-Galmier
the Anzieux , Right Bank, 15 kilometers, which sprinkles Bellegarde-in-Drill and joins with Montrond-the-Baths

Hydrology

Coise is a river provided rather well, like the majority of the rivers of the Eastern edge of the Massif Central. Its flow was observed during one 40 years period (1961-2000), with Saint-Medard-in-Drill, locality of the department of the the Loire located at a score of kilometers of its confluence with the the Loire. The catchment area of the river is there of 181 km ², that is to say more or less 90% of the totality of this last.

The interannual medium flow or module of the river with Saint-Medard-in-Drill is of 1,61 m ³ a second.

Coise present of the seasonal fluctuations of flow marked enough, and its mode can be divided into two periods. The high waters of winter-spring are one seven months period beginning in November and finishing in May. It is characterized by average monthly flows going from 1,85 to 2,54 m ³ a second (with an in January maximum). The low waters take place in summer, by July to September included, and are accompanied by a fall of the monthly medium flow going up to 0,47 m ³ in August, which remains still consistent for such a small river.

With the low water level, the VCN3 can however fall until 0,009 m ³, in the event of dry period quinquennial, that is to say 9 liters a second, which is severe, the river being then tiny room to a thin net (see note).

As for the risings, they can be very important, characteristic shared by the majority of the rivers of the east of the Massif Central (Aron, Arroux, Azergues, Furan etc). Thus the QIX 2 and QIX 5 or calculated flows of biennial and quinquennial rising are worth respectively 22 and 36 m ³ a second. The QIX 10 or calculated flow of decennial rising is of 45 m ³ a second, the QIX 20 of 54 m ³, while the QIX 50 is assembled to 65 m ³ a second (see note).

The maximum instantaneous flow recorded with Saint-Medard-in-Drill during the period of observation, was of 114 m ³ a second on July 1st, 1977, while the value maximum day laborer was of 74,5 m ³ a second on May 17th, 1983. By comparing the first of these values on a QIX scale of the river, one notes that this rising was much more than cinquantennale, undoubtedly more than centennial, but in all the cases completely exceptional.

Coise is a fairly abundant river. The Lame of water past in its catchment area is of 281 millimetres annually, which is certainly lower than the overall average of France all confused basins, but higher than the average of the basin of the the Loire (244 millimetres). The specific Débit of the river (or Qsp) posts of this fact the figure of 8,9 liters a second and per square kilometer of basin.

Random links: