La grotte de la Mine (Haute-Savoie) : structuration et fonctionnement hydrogéologique du vallon de Bise

Abstract

The Mine cave and the hydrology of vallon de Blse (french north prealps). Three dye-tracing experiments were performed in the Bise valley, in the Chablais region of Haute-Savoie, France. The first two, at sink holes where water from mountain lakes disappeared, and the third one, in an underground river, inside the Mine cave. The water came out at the multiple springs of the Ouvertures, some 3km away. The average velocity of the tracer, about 150 m/h, and the amount of dye recovered, show that the underground drainage system is not well developed, the water circulation being probably phreatic, although a vadose behavior, e.g. in the Mine cave, is active in some parts of the system. The underground system is quite old, part of it having been beheaded, mainly through glacial erosion. Some speleothems from the accessible part of the underground drainage system give an age of more than half a million of years. That number is in agreement with my geomorphological observations of the surrounding landscape. The experiment showed also that the Ouvertures springs are contaminated by germs from the cattle pasturing in the valley meadows. Considering their future captation, a safety perimeter is proposed.