Quantifying the effects of global warming on spring discharge and assessing future discharge trends along the Apennines (Italy)

Global warming affects atmospheric and oceanic energy budgets, altering the Earth’s water cycle. Groundwater, as the primary source of fresh water in the hydrosphere, is a vital resource for ecological, environmental, and societal needs. In countries like Italy, where springs are a predominant water source, it is crucial to assess their resilience to climate-induced changes in recharge for ensuring water supply and ecosystem preservation. The Mediterranean region, already experiencing reduced recharge and increased droughts, is a climate change hotspot. In particular, the Apennines in Italy, located at the heart of the Mediterranean, have observed significant climate impacts in recent decades. This PhD project presents a century-long analysis of discharge patterns from key springs along the Apennines to quantify the long-term effects of climate change and forecast future scenarios. Three main approaches were employed: the first combined experimental and historical analyses to evaluate the long-term effects of climate change on the flow rate of Nadìa Spring in the Northern Apennines, demonstrating its resilience during droughts. The second approach used multiregression analysis to investigate the relationship between recharge parameters and discharge at Sanità Spring (Southern Apennines) and Ermicciolo Spring (Amiata Mountain), aiming to forecast flow for 2040-2070 using projected meteorological scenarios. The third approach applied Long Short-Term Memory machine learning models to predict short- and long-term discharge at Sanità and Ermicciolo Springs. In addition to these, four other springs were investigated to assess climate change impacts over multi-decadal timescales. The results of this research provide a quantitative understanding of the relationship between climate drivers and spring flow rate, allowing for the projection of discharge scenarios and evaluation of future groundwater availability along the Apennines.