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Digital rock physics offers powerful perspectives to investigate Earth materials in 3D and non-destructively. However, it has been poorly applied to microporous volcanic rocks due to their challenging microstructures, although they are studied for numerous volcanological, geothermal and engineering applications. Their rapid origin, in fact, leads to complex textures, where pores are dispersed in fine, heterogeneous and lithified matrices. We propose a framework to optimize their investigation and face innovative 3D/4D imaging challenges. A 3D multiscale study of a tuff was performed through X-ray microtomography and image-based simulations, finding that accurate characterizations of microstructure and petrophysical properties require high-resolution scans (≤ 4 μm/px). However, high-resolution imaging of large samples may need long times and hard X-rays, covering small rock volumes. To deal with these limitations, we implemented 2D/3D convolutional neural network and generative adversarial network-based super-resolution approaches. They can improve the quality of low-resolution scans, learning mapping functions from low-resolution to high-resolution images. This is one of the first efforts to apply deep learning-based super-resolution to unconventional non-sedimentary digital rocks and real scans. Our findings suggest that these approaches, and mainly 2D U-Net and pix2pix networks trained on paired data, can strongly facilitate high-resolution imaging of large microporous (volcanic) rocks.

Groundwater bodies in the urbanized and densely populated aquifers or coastal floodplains may be subjected to groundwater rebound (GR), often causing serious risks of groundwater flooding (GF) to underground structures and infrastructures. This paper shows the results of a study carried out in the Naples' periurban area (Italy) to: investigate the dynamics and features of GR and GF phenomena, map flooded sites during 2013–2015 period, and provide an interpretative analysis of the factors that control the GF of private buildings and agricultural lands. At the municipality scale, since 1990 and until 2015, a remarkable and widespread GR was observed, with magnitude up to +16.54 m, triggering an unexpected GF of basements of buildings and agricultural soils. Field surveys proved that there is a time delay of the GF, ranging from 17 to 20 years, compared to the start of GR. Moreover, inhomogeneous distribution of flooding episodes is controlled by anthropogenic and natural factors. The obtained results are fundamental to design mitigation measures to GF hazard, and offer new perspectives to make Naples' periurban area more robust, smart and resilient against this new hydrogeological risk, undervalued by Italian legislation and local authorities.

Nowadays the phenomenon of global warming is unequivocal, as confirmed by the latest reports of the IPCC and studies of the climate-change impacts on ecosystems, global economy, and populations. The effect of climate change on groundwater is a very relevant task especially for regions dependent chiefly on groundwater availability, as for the southern Italy. In such a territorial framework, to achieve a detailed hydro-climatological characterization, an Ensemble of 15 RCMs (E15) derived from the EURO-CORDEX project was analyzed considering two IPCC Representative Concentration Pathways (RCP4.5 and RCP8.5). The E15 was calibrated over the period (1950–1996) by a statistical comparison with data observed by the regional meteorological network managed by the former National Hydrological Service (SIMN), Department of Naples. The effects of climate change on air temperature (T), precipitation (P) and, consequently, on actual evapotranspiration (ETR) and effective precipitation Pe (P – ETR) were analyzed until 2100. The latter was considered as a proxy of groundwater recharge of the principal aquifer systems, represented chiefly by the karst aquifers. As a principal result, it was found that the E15 is basically able to reproduce the observed annual precipitation (OBS P ) and mean annual air temperature (OBS T ), being characterized by a very similar frequency distribution. Accordingly, an inferential statistical approach was performed for calibrating E15 precipitation (E15 P ) and air temperature (E15 T ) based on the compensation of the difference with OBS P (+ 7%) and OBS T (− 16%). The E15 projects a reduction in precipitation and an increase in air temperature under both RCPs, with a divergence point between the two scenarios occurring by about 2040. As a principal result, Pe shows declining trends for both RCP scenarios, reaching a decrease of the 11-yrs moving average down to − 20%, for RCP4.5, and − 50%, for RCP8.5, even if characterized by relevant inter-annual fluctuations.

In many Italian regions, and particularly in southern Italy, karst aquifers are the main sources of drinking water and play a crucial role in the socio-economic development of the territory. Hence, estimating the groundwater recharge of these aquifers is a fundamental task for the proper management of water resources, while also considering the impacts of climate changes. In the southern Apennines, the assessment of hydrological parameters that is needed for the estimation of groundwater recharge is a challenging issue, especially for the spatial and temporal inhomogeneity of networks of rain and air temperature stations, as well as the variable geomorphological features and land use across mountainous karst areas. In such a framework, the integration of terrestrial and remotely sensed data is a promising approach to limit these uncertainties. In this research, estimations of actual evapotranspiration and groundwater recharge using remotely sensed data gathered by the Moderate Resolution Imaging Spectrometer (MODIS) satellite in the period 2000–2014 are shown for karst aquifers of the southern Apennines. To assess the uncertainties affecting conventional methods based on empirical formulas, the values estimated by the MODIS dataset were compared with those calculated by Coutagne, Turc, and Thornthwaite classical empirical formulas, which were based on the recordings of meteorological stations. The annual rainfall time series of 266 rain gauges and 150 air temperature stations, recorded using meteorological networks managed by public agencies in the period 2000–2014, were considered for reconstructing the regional distributed models of actual evapotranspiration (AET) and groundwater recharge. Considering the MODIS AET, the mean annual groundwater recharge for karst aquifers was estimated to be about 448 mm·year−1. In contrast, using the Turc, Coutagne, and Thornthwaite methods, it was estimated as being 494, 533, and 437 mm·year−1, respectively. The obtained results open a new methodological perspective for the assessment of the groundwater recharge of karst aquifers at the regional and mean annual scales, allowing for limiting uncertainties and taking into account a spatial resolution greater than that of the existing meteorological networks. Among the most relevant results obtained via the comparison of classical approaches used for estimating evapotranspiration is the good matching of the actual evapotranspiration estimated using MODIS data with the potential evapotranspiration estimated using the Thornthwaite formula. This result was considered linked to the availability of soil moisture for the evapotranspiration demand due to the relevant precipitation in the area, the general occurrence of soils covering karst aquifers, and the dense vegetation.

Defining the origin of ground deformation, which can be a very challenging task, may be approached through several investigative techniques. Ground deformation can originate in response to both natural (e.g., tectonics) and anthropic (e.g., groundwater pumping) contributions. These may either act simultaneously or be somewhat correlated in space and time. For example, the location of structurally controlled basins may be the locus of enhanced human-induced subsidence. In this paper, we investigate the natural and anthropic contributions to ground deformation in the urbanized area of the inner Sarno plain, in the Southern Apennines. We used a multidisciplinary approach based on the collection and analysis of a combination of geomorphological, stratigraphical, structural, hydrogeological, GPS, and DInSAR datasets. Geomorphological, stratigraphical, and structural data suggested the occurrence of a graben-like depocenter, the Sarno basin, bounded by faults with evidence of activity in the last 39 ka. Geodetic data indicated that the Sarno basin also experienced ground deformation (mostly subsidence) in the last 30 years, with a possible anthropogenic contribution due to groundwater pumping. Hydrogeological data suggested that a significant portion of the subsidence detected by geodetic data can be ascribed to groundwater pumping from the alluvial plain aquifer, rather than to a re-activation of faults in the last 30 years. Our interpretation suggested that a positive feedback exists between fault activity and the location of area affected by human-induced subsidence. In fact, fault activity caused the accumulation of poorly consolidated deposits within the Sarno basin, which enhanced groundwater-induced subsidence. The multidisciplinary approach used here was proven to be successful within the study area and could therefore be an effective tool for investigating ground deformation in other urbanized areas worldwide.

This paper summarizes the results of a study focused on the hydrogeological characterization and recognition of groundwater resources in continental southern Italy, developed under the European INTERREG IIC Programme. The study reconstructed up-to-date scientific knowledge regarding aquifers, groundwater circulation schemes and groundwater resources exploitation in the administrative regions of southern Italy included in the Objective I (Molise, Campania, Basilicata, Puglia and Calabria). In this paper, the methodological approaches applied to synthesize and homogenize bibliographic data collected from the hydrogeological literature and to set a regional hydrogeological mapping are described. Results presented are three hydrogeological maps, 1:300,000 scale, showing hydrogeological units and groundwater flow schemes that are relevant in the regional hydrogeological context, and a brief description of principal types of aquifer and groundwater resources of continental southern Italy.

Hydrogeology of the lower sector of the Basento and Cavone river basins (southern Italy), has been little studied so far, although this area plays a strategic role being an agricultural area, for the production of wheat and organic olive oil, and represents a historical economic pole, with the presence of an industrial area and several extraction sites of natural gas. In this paper, starting from official Italian geological maps, a hydrogeological conceptual model and geodatabase were developed through hydrogeological characterization of lithological formations, analysis of topographic cartography and satellite images, as well as an extensive hydrogeological survey. The results are represented by a hydrogeological map at the 1:50,000 scale, hydrostratigraphic cross-sections, groundwater flow schemes, and a groundwater database. These are valuable tools for knowledge and may be used as a reference for future hydrogeological studies, as well as planning and decision-making in groundwater management.

Shallow aquifers of coastal and internal alluvial plains of developed countries are commonly characterized by the challenging management of groundwater resources due to the intense agricultural and industrial activities that determine a high risk of groundwater contamination. Among the principal origins of pollution in these areas are agricultural practices based on the amendment of soils by nitrate fertilizers, which have been recognized as one of the most severe environmental emergencies for which specific policies and regulations have been issued (e.g., EU Directive 2006/118/EC). In such a framework, the results of research aimed at assessing the specific vulnerability of shallow alluvial aquifers to nitrate fertilizer pollutants by coupled process-based and empirical approaches are here proposed. The research focused on assessing the specific vulnerability to nitrate pollution of a shallow alluvial aquifer of the Campania region (southern Italy), which was selected due to its representativeness to other recurrent hydrogeological settings occurring in alluvial plains of the region and worldwide. In this area, 1D hydro-stratigraphic models of the unsaturated zone were reconstructed and applied for simulating the transport of nitrate pollutants at the water table and estimating the associated travel times. Numerical modeling was carried out by the finite differences VS2TDI code and considered a 10-year time series of rainfall and evapotranspiration as well as typical local farming practices of nitrate fertilizer input. Results of the travel time calculated for the 1D hydro-stratigraphic models considered and at different depths were recognized as a proxy to assess the specific vulnerability to nitrate fertilizer pollution. Among the principal outcomes is an empirical multiple correlation between the travel time of the nitrate fertilizer pollutant, water table depth, and equivalent saturated hydraulic conductivity of the unsaturated zone or hydraulic resistance, which was used to assess the travel time at the distributed scale over the whole area studied as well as the related specific vulnerability. Given such results, the coupled process-based and empirical approach is proposed as generally applicable for assessing and mapping groundwater vulnerability in shallow aquifers, for which detailed stratigraphic and piezometric data are available.

Karst aquifers provide drinking water for 10% of the world’s population, support agriculture, groundwater-dependent activities, and ecosystems. These aquifers are characterised by complex groundwater-flow systems, hence, they are extremely vulnerable and protecting them requires an in-depth understanding of the systems. Poor data accessibility has limited advances in karst research and realistic representation of karst processes in large-scale hydrological studies. In this study, we present World Karst Spring hydrograph (WoKaS) database, a community-wide effort to improve data accessibility. WoKaS is the first global karst springs discharge database with over 400 spring observations collected from articles, hydrological databases and researchers. The dataset’s coverage compares to the global distribution of carbonate rocks with some bias towards the latitudes of more developed countries. WoKaS database will ensure easy access to a large-sample of good quality datasets suitable for a wide range of applications: comparative studies, trend analysis and model evaluation. This database will largely contribute to research advancement in karst hydrology, supports karst groundwater management, and promotes international and interdisciplinary collaborations. Measurement(s) hydrographic feature • fluid flow rate Technology Type(s) digital curation Factor Type(s) geographic location • year Sample Characteristic - Environment karst • spring • groundwater Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.11336507

The assessment of groundwater vulnerability to pollution is becoming even more important all over the world due to the increase of impacts of human activities on groundwater resources and the related risks to the human health, economics, and the environment. Owing to the variability of methods known for estimating groundwater vulnerability, basically depending on hydrogeological parameters considered and the scale of analysis, the comparison of results of different methods appears straightforward for identifying the best approach in a given hydrogeological condition and reference scale. In such a view, this work attempts to assess the groundwater vulnerability of the Terminio Mt. karst aquifer, by applying four different groundwater vulnerability methods, index-based, and comparing results in order to identify the best performing one in karst environments. The study aquifer, located in the Picentini Mts Regional Park (Campania region, southern Italy) represents a strategic drinking water resource since Roman times and hosts massive groundwater resources which outflow mainly from tapped basal and subordinately perched springs. The peculiar characters of the study karst aquifer, which favour direct infiltration and groundwater recharge processes, as well as the occurrence of industrial, agricultural and grazing activities, make it very vulnerable to groundwater pollution, thus requiring a proper and careful territorial management. Beside the most frequently and generally used methods for assessing groundwater vulnerability, such as the DRASTIC and SINTACS, also DAC and COP methods specifically designed for karst aquifers were applied and mutually compared. Results of SINTACS, DRASTIC and DAC methods show groundwater vulnerability maps of the Terminio Mt. karst aquifer as chiefly characterized by two classes of intrinsic groundwater vulnerability, varying between the medium and high degrees. Furthermore, high and extremely high values of groundwater vulnerability were found in areas controlled by the shallow depth of the water-table. Instead, the COP method resulted as the most effective in identifying the endorheic areas and the related karst morphologies as very high groundwater vulnerability zones, therefore the most suitable in capturing specific hydrogeological features of karst areas that control groundwater pollution and vulnerability. Results obtained will support decision tools aimed at the land use planning and protection of karst aquifers from pollution in karst areas.