Groundwater response to precipitation extremes: the case of the "Vaia" storm (Eastern Italian Alps)

Extreme precipitation events are expected to increase in intensity in Alpine regions due to climate change. While many studies have analyzed the impact of these phenomena on flooding risk, very few deal with their effect on groundwater. This work analyzes the hydrograph response of three springs to an extreme storm, which occurred in Northern Italy in October 2018. We observed that the newly infiltrated storm water contributed to feeding the winter baseflow, increasing its volume up to 85 % compared to normal conditions. It was also found that the response of groundwater to heavy precipitation seems to be influenced by the type of media. A high-altitude spring belonging to the fractured carbonate aquifer shows a quick response to the storm input, while springs outflowing at the base of the mountain slopes (mixed fractured carbonate and porous deposits) exhibit a delayed response. Results are important when analyzing future water availability and to better understand the impact of extreme events on groundwater flow.