Groundwater response to local climate variability: hydrogeological and isotopic evidences from the Mt. Amiata volcanic aquifer (Tuscany, central Italy)

Groundwater bodies constitute important water supplies as they are considered to be the safest and most reliable sources for drinking water. Although they commonly show complex dynamics, they may provide information on climate variability, being sensitive at both local and global climate conditions. Currently, the shallow aquifer hosted in the Mt. Amiata volcanics represents the most important freshwater reservoir of southern Tuscany (central Italy). Nevertheless, such a groundwater system is still poorly constrained, despite the hydrogeological and geochemical investigations carried out in the last decades. In this work literature and new hydrogeological and water stable isotopic data from both rainfall and groundwater are reviewed with the aim to better understand how the Mt. Amiata aquifer responds to the meteoric recharge and evaluate the impact of climate variability on this significant groundwater body. Isotopically, a good agreement between the rainfall and the groundwater system was observed, suggesting that the aquifer can be used as a proxy for local climate changes.