Azergues

The Azergues is a French river which runs in the Département of the Rhone. It is one of the Affluent S of the the Saone which crosses the mounts of the Beaujolais. Its name would come from the Arab wadi zerga which means “blue water”.

Geography

Azergues has two sources, the first located on the territory of the commune of Chénelette, the second with Hen-the-Écharmeaux, both in the mounts of the Beaujolais wine, each one giving rise to a river called Azergues. One considers with the PIKE PERCH that the principal branch is that of Chénelette, the second being tributary first under the name of " brook Azergues". Upon the departure, the river adopts a rather rectilinear direction south-south-east but obliquing gradually towards full south-east. Arrived at the level of the locality of Lozanne, it carries out a radical change of orientation, and takes from now on the direction of north. It is thrown in the the Saone on the level of the commune of Anse, with six kilometers in the south (downstream) of Villefranche-sur-Saône.

Affluents

the Soanan (Right Bank)
the Brévenne (Right Bank)

the Turdine (left bank)

Hydrology

The flow of Azergues was observed over one 43 years period (1965-2007), with Lozanne, city of the Département of the Rhone located at less than fifteen kilometers of its confluence with the the Saone with Anse. The catchment area of the river is there of 792 km ², which represents more than 96% of the totality of this basin.

The interannual medium flow or module of the river is of 7,51 m ³ a second.

Azergues presents seasonal fluctuations of flow rather important. The high waters are located in autumn and in spring, and carry the average monthly flow on a level from 9,16 to 15,8 m ³ a second, from November to April included (with a first top in December and a second in February), and low waters of summer, July to September, with a fall of the average monthly flow up to the level of 1,79 m ³ in August.

With the low water levels, the VCN3 can fall until 0,21 m ³, in the event of dry quinquennial period. Let us recall that the VCN3 is the past minimal quantity or minimal flow over three days consecutive.

In addition the risings of Azergues can be important. The recorded maximum instantaneous flow was of 495 m ³ a second on May 17th, 1983, while the value maximum day laborer was of 251 m ³ a second on December 2nd, 2003. The QIX 2 and QIX 5 are worth respectively 110 and 170 m ³. The QIX 10, or calculated flow of decennial rising, is assembled to 210 m ³ a second, and the QIX 20 is worth 230 of them. As for the QIX 50, it is of 290 m ³ (see note). That means that statistically there must be a rising of 110 m ³ a second every two years and of 170 m ³ every five years.

As comparison, let us recall that the QIX 10 of the the Eure to Louviers is worth 96 m ³ a second, while its QIX 50 is of 130 m ³. One notices thus that the QIX 10 like the QIX 50 of Azergues, small river equipped with a small basin of 792 km ², are moreover of the double of those of the Eure, whereas the catchment area of this last is more than five times wider.

The Lame of water past in the basin of Azergues is assembled to 300 millimetres annually, which is a little lower than the overall average of France, but definitely lower than the average of the totality of the basin of the Rhone (670 millimetres with Valence) like the Saone (501 millimetres in Lyon). The specific Débit (or Qsp) is of 9,5 liters a second and per square kilometer of basin.

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