Massif du Mont-Blanc : identification d'une structure aquifère majeure

The Mont-Blanc Massif: identification of a water-bearning important structure

GEOLEP, Ecole Polytechnique Fédérale de Lausanne - Actuellement au BRGM, Service Eau

Abstract

The hydrogeology of Alpine crystalline massifs is still strongly unknown. The knowledge of groundwater reserves is important as far as tourism is developing in these regions. The Mont-Blanc road tunnel allows us to observe the crystalline massif at a large depth. This underground work has crossed over, during the drilling, a major water-bearning structure, at the origin of large water inflows (1000 t/s). The large discharge rates now still present (200 t/s) indicate that the concerned tectonic accident is at the origin of an important and permanent water resource. Observations made on the concerned water inflows permit to determine the behaviour of this water-bearing structure in the middle of the Mont-Blanc Massif.