Abstract Groundwater resource availability is essential for both human needs and ecosystem equilibrium. In the context of ongoing climate change, the water table in the Castelporziano Presidential Estate has shown a significant decline in recent years. To understand this phenomenon, a 30-year analysis of groundwater level trends was conducted. A first comparison of water table fluctuation with rainfall variations does not explain the lowering of the piezometric levels, especially in the central zone of the study area. By comparing the changes in water table levels and soil water content over time with the Standardized Precipitation and Evapotranspiration Index (SPEI at 12 and 3 months temporal scale), a strong correlation among recharge and exhaustion phases and the cycling through wet and dry periods has been inferred, confirming the crucial role of evapotranspiration. Despite the absence of -trend in rainfall, the clear raising trend of temperature triggered higher evapotranspiration values. This process has reduced the water surplus available for aquifer recharge. Nevertheless, the groundwater resilience allows the water table to react to the first multi-year period of drought (1999–2008) in the following years. Unfortunately, since 2016 this fragile equilibrium has been menaced by a new prolonged drought period, having negative consequences on the water table, which is strongly decreasing. The Standardized Groundwater Index SGI values confirm negative conditions since 2008, reaching the most negative values in recent observation years. This crisis, supported by the reduction of the soil moisture during last decade, has likely contributed to the strong problems registered in the Castelporziano forest since 2016. Graphical abstract
Chiara et al. (Fri,) studied this question.