Hydrodynamic Characterization of the Perrot Spring (Aosta Valley, Italy) Combining Spring and Meteorological Data

This study characterizes the Perrot Spring (Aosta Valley, Italy), aiming to analyze meteorological data in order to define its hydrodynamic behavior in a context of climate variability. A time-series analysis of Spring discharge, water temperature, electrical conductivity, and stable isotopes was carried out by comparing them with meteorological variables, including precipitation, snow height, and air temperature, over the period 2022–2026. Decadal trends in meteorological variables were also assessed for the period 2002–2026, and the Maillet recession coefficients of the Spring were determined. The analysis revealed significant meteorological variability, with decadal trends showing increasing annual mean air temperatures and decreasing snow height. The absence of temporal variability in the isotopic composition of the Spring, despite the relevant discharge fluctuations, suggests the existence of a groundwater circulation system that promotes effective mixing of infiltrating precipitation within the aquifer. The Spring response to infiltration inputs exhibits a dual behavior. First, the Spring reacts rapidly, with discharge doubling within a few hours. Second, Spring discharge is proportional to precipitation occurring during the previous 100 days, reacting more slowly. Spring water temperature and electrical conductivity do not appear to be significantly affected by meteorological variability. In conclusion, the comparison between Spring and meteorological data suggests that the Spring exhibits a good short-term resilience to seasonal dry periods, but the observed decadal meteorological trends could still pose a future threat.