Shallow landslides triggered by heavy rainfalls are slope instabilities, developed in the most superficial eluvial layers, involving the first 2 m from the ground level. A crucial predisposing factor in shallow landslides occurrence is the soil water content, generally measured trough sensors installed in the first soil layers. However, despite being a very precise approach, this monitoring technique provides for a site-specific dataset. An integrated method to extend the hydrological characterization from site-specific to slope scale is presented, combining geotechnical analyses, field data monitoring, and geophysical investigations, in two experimental test sites located on Italian Apennines. Ten Electrical Resistivity Tomographies (ERT) of the first soil horizons were performed through different array geometries (2D-3D-Time-Lapse), calibrated and interpreted basing on stratigraphic logs, trenches, and monitored soil water content field data. The test sites colluvial covers composition was analyzed and compared to resistivity values to build conceptual hydrogeological models of the deep-water circulation. In addition, two time-lapse (4D) ERT surveys were performed in both test sites simulating very intense precipitations, to determine the resistivity variations at different soil drainage conditions, thus estimating the average bulk permeability. Bulk permeability can be also a useful input parameter for slope stability models, widely employed in engineering practices. This integrated method proved to be very useful for the hydrogeological characterization of the subsoil at slope scale, where it is susceptible to slope instability, improving the knowledge of water circulation, as well as the bulk permeability heterogeneities, which are shallow landslides triggering parameters.

An integrated hydrochemical and geophysical study of the saline paleo-water uprising into the alluvial aquifer of the Oltrepò Pavese plain sector (Po Plain, northern Italy) is presented. This study involved hydrochemical analysis of groundwater, assessment of well logs, and one-, two- and three-dimensional electrical geophysical surveys. The studied area was selected for its characteristic hydrogeological setting. The alluvial aquifer is strongly conditioned by the presence of a buried tectonic discontinuity along which the saline waters are mainly distributed. These waters rise along the discontinuities in the bedrock and flow into the overlying alluvial aquifer. Contamination from saline waters is not spatially and vertically homogeneous within the aquifer. The spatial distribution of Na–Cl waters suggests the existence of plumes of highly mineralized waters that locally reach the aquifer, diffuse and mix with freshwaters. The saline waters show a dilution during upward migration, which is due to mixing with the shallow fresh groundwater. Highly mineralized groundwater is identified even at very shallow depth in correspondence with each plume. On the other hand, there is a lower degree of contamination in those sectors of the aquifer that are further away from the structural discontinuities and this lesser contamination generally only involves the deeper parts of the aquifer.

A pseudo-3D electrical resistivity tomography (ERT) survey has been carried out to detect cavities at the Neolithic/Palaeolithic site of Grotta Scaloria, close to Manfredonia, Apulia, Italy. Scaloria Cave has a rich history of archaeological research of more than 80 years and is one of the most important Neolithic complexes in the Mediterranean. Synthetic data modelling allowed to check the adequacy of the geophysical method and to develop a proper experimental setup at the survey design stage. Indeed, the results of the field data inversion revealed high resistivity anomalies which can be related to cavities and provided a good definition of the main geological structures and boundaries. Moreover, the results suggest that unknown and speleological unexplored cavities are still present at the Scaloria Cave study site. These findings may provide further insights on pseudo-3D ERT applicability, particularly for cavity detection. Furthermore, the approach used in this study yields fruitful information for further archaeological survey design and for the interpretation of ERT investigations targeting similar geological features and structures.