The assessment of drought duration, severity, and its impact on groundwater resources can be achieved through the integrated analysis of climatic indices and groundwater level fluctuations. This study investigates the effects of drought periods on groundwater within distinct sectors of the Castelporziano Estate aquifer. Utilizing data from two meteorological stations and the Estate's piezometric monitoring network, a comprehensive analysis was conducted. The availability of extensive thermo-pluviometric and piezometric records (1995-2024) facilitated the computation of the Standardized Precipitation-Evapotranspiration Index (SPEI) and the Standardized Groundwater Index (SGI), enabling the evaluation of their variations over the past 30 years.
Prior research has established the presence of a main aquifer, exhibiting seasonal fluctuations primarily driven by local meteoric inputs, with base flow sustained by contributions from the regional aquifer. The Coastal and Central sectors, mainly recharged by local precipitation, show a different decline in piezometric levels. Comparative analysis of the SPEI calculated for two weather stations, one situated along the coast and the other in the inland sector of the Estate, revealed significant variations, which prove decisive in the recharge processes of these sectors. The Coastal sector exhibited a consistent pattern of alternating wet and dry periods until 2016, followed by a sustained drought period extending to 2023. These fluctuations are reflected in groundwater levels, as evidenced by the SGI, which has registered continuous negative values since 2016, reaching its minimum values in 2024. In the Central sector, the SPEI indicates a protracted drought from 1999 to 2008, resulting in a persistent reduction of piezometric heads. Consistent negative SGI values since 2008 corroborate the enduring water deficit in this sector, with a discernible exacerbation observed in the last three years, correlating with the SPEI trend.

Low-permeability fractured rocks constitute the bedrock of many regions worldwide. Due to the extreme heterogeneity and anisotropy, these rocks show very complex and varied drawdown-time trends when subjected to pumping. Understanding these trends is crucial for operational decisions, such as utilizing wells for water supply or managing dewatering operations in mining sites. This study examines nine pumping tests in an andesitic bedrock formation. The tests were carried out in wells of varying depths (30 - 260 m) in a region where groundwater circulation is not always continuous in the network of discontinuities. The tests lasting between 9 and 68 hours were generally carried out at constant flow rate (0.4-6 L/s) with measurements of drawdown in the pumping well and, in some cases, in an observation well. The drawdown data versus time have been analyzed through semi-log plots, the smoothed time series’ have then been represented on bi-log plots together with the first derivative of the drawdown. The trends of the drawdown and its derivative have been compared with theoretical curves, and interpretation was refined using flow dimension sequence analysis. The results show very different responses of the aquifer to pumping, which are affected by the interconnection of discontinuities, the presence of multiple hierarchical networks of discontinuities and of dykes that bisects a country-rock aquifer.
Data from pumping tests was integrated by earth tides groundwater response from 6 piezometers and by additional information deriving from RQD available for 400 boreholes to obtain a probability distribution of the hydraulic parameters to be used as prior information in numerical modelling.