Gild (river)

Geography

Its valley separates the mounts from the Forez, with the east, and the mounts of the Livradois, in the west.

Its official source is on the territory of Saint-Bonnet-the-Borough, with the locality “Wood of Berny”, at an altitude of: 1065 Mr. It is initially called brook of Berny then brook of Aubianges before taking his final name on his arrival on the territory of Doranges.

It crosses Ambert well off its borough and Courpière just apart from its historical center, and passes moreover in the vicinity immediate of Sauviat, Néronde, Peschadoires, Thiers, Noalhat, Dorat and Puy-Guillaume.

Its confluence with Combining it is with the height of Ris upstream of Saint-Yorre (close to Vichy) and downstream from Puy-Guillaume.

Two hydroelectric stations were built to profit from its flow: power station known as of Sauviat ( with horse on the commune of Saint-Flour ) and power station of Olliergues.

Gilds constitutes the true backbone of the Regional natural park Livradois-Drill. Its flow strongly decreased since the XIXe century, in consequence of the intensive afforestation practiced in the mounts of Livradois and of Drill, devoted during long centuries to activities of pasture. The reduction in this flow thus involved the disappearance of hundreds of mills located on Gilds and its affluents, thus accelerating disappearance, in the Arrondissement of Ambert, of paper industry, formerly famous in whole France.

Affluents

Its principal affluents are:

the Dolore (left bank)
the Faye (Right Bank)
the Couzon (Right Bank)
the Durolle

Hydrology

The annual medium flow of Gilds, calculated over 17 years with Dorat (of 1991 to 2007), is of 20,0 m ³ a second for a surface of basin of: 1523 km ². The river present of the fluctuations seasonal of flow, with risings winter-spring from 26,0 to 31,4 m ³, December to April included and maximum in February, and a low water level of end of be-beginning of autumn, July to September, characterized by a fall of the monthly medium flow up to 5,09 m ³ in August (ref.: ).

With the low water level the VCN3 can fall until 0,82 m ³, in the event of dry period quinquennial, that is to say 820 liters a second, which is not too severe, and normal compared with the average of the rivers of the basin of the Loire (see note).

As for the risings, they can be important, but without too much excess as it is often the case of the Western affluents of the Loire or, worse, the Cevennes rivers. The QIX 2 and QIX 5 or calculated flows of biennial and quinquennial rising are worth respectively 190 and 250 m ³ a second. The QIX 10 or calculated flow of decennial rising is of 300 m ³ a second, the QIX 20 of 340 m ³, while the QIX 50 was not calculated fault of duration of sufficient observation to determine it validly (see note).

The recorded maximum instantaneous flow with Dorat during this period, was of 356 m ³ a second on April 17th, 2005, while the recorded maximum daily output was of 296 m ³ a second on December 3rd, 2003. If one compares the first of these values on a QIX scale of the river, one notes that this rising was of a vicennial nature, and thus hardly exceptional.

The Lame of water past in the basin of Dore is of 415 millimetres annually, which is relatively high in France and definitely higher than the overall average of the catchment area of the the Loire (243 millimetres). The specific Débit (Qsp) is assembled at 13,1 liters a second and per square kilometer of basin.

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