A sustained increase in spring discharges was monitored after the 2016 Central Italy seismic sequence in the fractured carbonate aquifer of Valnerina–Sibillini Mts. The groundwater surplus recorded between August 2016 and November 2017 was determined to be between 400 and 500 × 10⁶ m³. In fractured aquifers, the post‐seismic rise in spring discharges is generally attributed to an increase in bulk permeability caused by the fracture cleaning effect, which is induced by pore pressure propagation. In the studied aquifers, the large amount of additional discharge cannot only be attributed to the enhanced permeability, which was evaluated to be less than 20% after each main seismic event. A detailed analysis of the spring discharge hydrographs and of the water level at five gauging stations was carried out to determine the possible causes of this sudden increase in groundwater outflow. Taking into account the geological and structural framework, a conceptual model of a basin‐in‐series has been adopted to describe the complex hydrogeological setting, where the thrusts and extensional faults have clearly influenced the groundwater flow directions before and after the seismic sequence. The prevalent portion of the total post‐seismic discharge surplus not explained by the increase in permeability has been attributed to changes in the hydraulic gradient that caused seismogenic fault rupture and the disruption in the upgradient sector of the aquifer. The additional flow calculated through the breach of the pre‐existing hydrostructural barrier corresponds to approximately 470 × 10⁶ m³. This value is consistent with the total discharge increase measured in the whole study area, validating the proposed conceptual model. Consequently, a shift in the piezometric divide of the hydrogeological system has been induced, causing a potentially permanent change that lowers the discharge amount of the eastern springs.

This paper describes the contents of the new Hydrogeological Map of the City of Rome (1:50,000 scale). The map extends to the entire municipality (1285 km²) and is based on both the most recent scientific studies on the groundwater field and new survey activities carried out in order to fill the data gaps in several areas of the examined territory. The map is the result of a combination of different urban groundwater expertise and Geographic Information System (GIS)-based mapping performed using the most recent available data and has been produced with the intention of furnishing the City of Rome with the most recent and updated information regarding groundwater.

Springs play a key role in the hydrology of mountain catchments and their water supply has a considerable impact on regional livelihood, biodiversity, tourism, and power generation. However, there is still limited knowledge of how rain and snow contribute to the recharge of Alpine springs. This study presents a four-year investigation of stable isotopes in precipitation and spring water at the scale of a 240 km² wide dolomitic massif (Dolomites, Italian Alps) with the aim of determining the proportions of snowmelt and rain in spring water and to provide insights on the variability of these contributions in space and time. Four precipitation sampling devices were installed along a strong elevation gradient (from 725 to 2660 m a.s.l.) and nine major springs were monitored seasonally. The monitoring period comprised three extreme weather conditions, i.e., an exceptional snowpack melting period following the highest snowfall in 30 years, an intense precipitation event (386.4 mm of rain in 48 h), and one of the driest periods ever observed in the region. Isotope-based mixing analysis revealed that rain and snowmelt contributions to spring water were noticeably variable, with two main recharge time windows: a late spring–summer snowmelt recharge period with an average snowmelt fraction in spring water up to 94 ± 9%, and a late autumn–early winter period with a rain fraction in spring water up to 68 ± 17%. Overall, during the monitoring period, snowmelt produced high-flow conditions and sustained baseflow more than rain. We argue that the seasonal variability of the snowmelt and rain fractions during the monitoring period reflects the relatively rapid and climate-dependent storage processes occurring in the aquifer. Our results also showed that snowmelt fractions in spring water vary in space around the mountain group as a function of the elevation of their recharge areas. High-altitude recharge areas, above 2500 m a.s.l., are characterized by a predominance of the snowmelt fraction (72% ± 29%) over the rain contribution. Recharge altitudes of approximately 2400 m a.s.l. also show a snow predominance (65 ± 31%), while springs recharged below 2000 m a.s.l. are recharged mostly from rain (snowmelt fraction of 46 ± 26%). Results from this study may be used to develop more accurate water management strategies in mountain catchments and to cope with future climate-change predictions that indicate a decline in the snow volume and duration in Alpine regions.

Co-seismic changes in groundwater regime are often observed after moderate to strong earthquakes. The 24 August 2016 M_w 6.0 extensional Amatrice earthquake, which was the first event of a long-lasting seismic sequence, including the 30 October 2016 M_w 6.5 Norcia event, triggered a significant discharge alteration to the Pescara di Arquata spring, located in the Umbria-Marche Apennines (Northern Apennines, Central Italy) and exploited for drinking purposes. During the first five months after the first mainshock, an extra flow of about 30% was recorded, while both water chemistry and temperature did not show significant changes. Thereafter, the spring discharge decreased significantly, and at the end of 2019 it was still lower than normal. The Standardized Precipitation Index (SPI) indicates that these low mean monthly discharge values are not related to particularly dry conditions. The increase in post-seismic depletion coefficients indicates that the aquifer empties faster than it did during the inter-seismic period. The observed transient increase and subsequent decrease of discharge are consistent with a transient, earthquake-related increase in hydraulic conductivity.