Contribution isotopique (18O, 2H, 3H) à la compréhension des mécanismes d'écoulement des eaux de Surface et des eaux souterraines en Vallée d'Aoste (Italie)

Isotopic contribution (18O, 2H, 3H) in the understanding of the flow pattern in surface water and groundwater in the Aosta valley (Italy)

Abstract

In a comprehensive study dealing with the water resources in the Aosta valley isotope analyses have been carried out on precipitation, runoff waters and groundwaters. The main targets were to provide: the evidence of the effective infiltration, the evaluation of sublimination and evaporation losses from the surface of the glaciers, the delineation of the recharge areas and of the origin of surface and groundwater flows, the input of glacier underflow in the recharge of the aquifers, the estimation of the turnover time of the different water bodies. The main results drawn from two hydrologic cycles span time exhibit the complexity of the hydrologic system of the Aosta valley as linked to: - the humid air masses circulation (oceanic or Mediterranean origin, presence of successive mountains barriers, ...) - the relative orientation and geographic situation of the valleys versus these circulations - the role of the glaciers and their associate rocky substratum in the qualitative and quantitative change in their outflow.