Furan

Geography

Furan takes its source with 1 160 meters of altitude in the commune of the Bessat in the department of the the Loire, with 10 kilometers upstream of the town of Saint-Etienne. It is thrown in the the Loire out of Right Bank, on the level of the commune of Andrézieux-Bouthéon.

Affluents

Its principal affluents are the Onzon and the Malval.

Crossed cities

Furan crosses thirteen communes of which:

Bessat
Tarentaise
Rochetaillée (common partner of Saint-Etienne)
Saint-Etienne
Fouillouse
Andrézieux-Bouthéon

Hydrology

Furan is a rather abundant river, but also extremely irregular, as the majority of the rivers of the east of the basin of the Loire, though regularized well by the dams Rochetaillée. Its flow was observed during one 40 years period (1968-2007), with Andrézieux-Bouthéon, locality located at the level of its confluence with the the Loire. The catchment area of the river is of 178 km ².

The interannual medium flow or module of the river with Andrézieux-Bouthéon is of 2,46 m ³ a second.

Furan presents seasonal fluctuations of flow little marked, at least since the construction of the stoppings. The high waters are held in winter and in spring carrying the average monthly flow on a level located between 2,53 and 3,36 m ³ a second, from November to May included (with a first in November maximum, and a second, more important, in May). As of June, the flow falls quickly to the low waters of summer which have in July place and August, involving a fall of the monthly medium flow going up to 1,57 m ³ in August. But the fluctuations of flow are more marked according to the years.

With the low water level, the VCN3 can fall until 0,270 m ³, in the event of dry period quinquennial, that is to say 270 liters a second, which is hardly severe, but would be it much more without the contribution of the reserves created by the stoppings. The VCN3 is the past minimal quantity or minimal flow over three days consecutive.

As for the risings, they can be extremely important taking into account the small size of the river and its catchment area, and are proportionally not less than the risings of the other rivers of the mounts of the Lyonese and of the whole of the edge is basin of the Loire. The QIX 2 and QIX 5 are worth respectively 59 and 80 m ³ a second. The QIX 10 or calculated flow of decennial rising is of 93 m ³ a second, the QIX 20 of 110 m ³ and the QIX 50 of 120 m ³ (see note).

The recorded maximum instantaneous flow with Andrézieux-Bouthéon during this 40 years period, was of 142 m ³ a second on May 1st, 1977, while the value maximum day laborer was of 62 m ³ a second on May 26th of the same year. By comparing the first of these values with the various QIX of the river, it appears clearly that this rising largely higher than raw the cinquantennale was calculated by the QIX 50, and thus very exceptional.

On the whole, Furan is an abundant river, following the example of the whole of the rivers tributary of the Loire and resulting the well sprinkled heights of the Eastern edge of the Massif Central. The Lame of water past in its catchment area is of 437 millimetres annually, which is largely higher than the overall average of France all confused basins, and as well sure to the average of the basin of the the Loire (244 millimetres). The specific Flow of the river (or Qsp) reached the high figure of 13,8 liters a second and per square kilometer of basin.

Equipment

Two Barrage S were built out of built stones with Rochetaillée in the department of the Loire of which the first under the reign of Napoleon III. These two stoppings bear the name of the “Pit of Hell” for the first (1866) and of the “Step of Riot” for the second (1878). The first is a stopping which was used for a long time at the same time with the support of low water level, the drinking water adduction and the fight against the risings. This last vocation took the top since the stopping was emptied completely in 2003. The second is used as auxiliary drinking water supply for the town of Saint-Etienne.

Furan is mainly covered in the crossing of Saint-Etienne (either approximately 7 km) where it is also used as sewers. It reappears with the free air only in the north of Saint-Etienne in the district of the Terrace . Furan traverses approximately 5 km before arriving at the purification plant known as of the Porchon , bordering on the communes of Fouillouse and Andrézieux-Bouthéon. 10% of waste water are transported by the collectors until the purification plant and 90% by the river.

The Furania village

With the the Middle Ages, “Furania”, the village on Furan, the current town of Saint-Etienne indicated.

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