In this paper, previous works on the three-dimensional hydrostratigraphic characterization and two-dimensional groundwater flow modeling at the regional scale for the Salento peninsula (southeastern Italy) are shown to provide a fundamental basis for an overall conceptualization of the multi-layered aquifer system of the Taranto Gulf (northwestern Salento). This is done by identifying source terms and providing a preliminary estimate of different balance terms, based on available data and information. Then, a further characterization will be provided using three-dimensional groundwater flow models and calibration techniques based on the solution of an inverse problem. As a result the hydraulic features of the deep karst aquifer can be mapped; the stresses due to human water-demanding activities and the occurrence of the saltwater intrusion phenomenon were analyzed and possible weaknesses of the conceptual and of the preliminary numerical model pointed out.

This paper deals with the reconstruction of buried targets exhibiting both dielectric and magnetic characteristics, starting from GPR data collected at the interface air/soil. The problem is tackled under a two-dimensional geometry by means of linear scalar inverse scattering and the performances of the approach will be outlined against experimental data.

The evaluation of the accuracy or reasonableness of numerical models of groundwater flow is a complex task, due to the uncertainties in hydrodynamic properties and boundary conditions and the scarcity of good-quality field data. To assess model reliability, different calibration techniques are joined to evaluate the effects of different kinds of boundary conditions on the groundwater flow in a coastal multi-layered aquifer in southern Italy. In particular, both direct and indirect approaches for inverse modeling were joined through the calibration of one of the most uncertain parameters, namely the hydraulic conductivity of the karst deep hydrostratigraphic unit. The methodology proposed here, and applied to a real case study, confirmed that the selection of boundary conditions is among the most critical and difficult aspects of the characterization of a groundwater system for conceptual analysis or numerical simulation. The practical tests conducted in this study show that incorrect specification of boundary conditions prevents an acceptable match between the model response to the hydraulic stresses and the behavior of the natural system. Such effects have a negative impact on the applicability of numerical modeling to simulate groundwater dynamics in complex hydrogeological situations. This is particularly important for management of the aquifer system investigated in this work, which represents the only available freshwater resource of the study area, and is threatened by overexploitation and saltwater intrusion.

Detection of underground cavities is a very important phase in the process of mitigating the risk related to sinkholes in karst, as well as in urban settings with presence of man-made cavities. At this aim, we explore in this study the combination of hydro-stratigraphic, geomorphological and geophysical study, integrated by caving explorations and surveys. Hydro-stratigraphy and geomorphology include thematic surface mapping, multi-year analysis of aerial photographs and archival research, underground surveys and examination of borehole and well data. Geophysical surveys may rely on different methods such as electrical resistivity tomography, ground penetrating radar, seismic surveys and microgravity measurements. Depending upon the local geology, as well as depth and feature of the underground cavities, the above techniques may be used alternatively or in combination to obtain the best results in the identification of the voids. The importance of integrating different methodologies and techniques is pointed out by discussing the potentiality and the drawbacks of each adopted methods.

Geophysical methods for archaeological exploration, in Italy, date back to the Fifties with the pioneering work of Fondazione Lerici, and still many surveys are carried out to find new sites or to plan the future activity in an open archaeological excavation. The conservation of the cultural heritage, art, crafts or buildings, involves constant restoration works. High resolution geophysics and micro geophysics techniques may contribute to facilitate the restoration of artworks or historical building elements. With respect to the management of a museum, micro geophysics techniques can contribute to evaluating the possibility and the precautions that have to be taken when moving artefacts either for a museum reorganization or for temporarily lending a masterpiece to an exhibition.

GPR survey was used as a non-invasive geophysical technique for civil-engineering. This survey was performed in the test site of XIII International Conference “GPR 2010”, Lecce (Italy). In order to simulate subsurface archaeological and engineering targets several objects, of different materials and geometries, was buried in the subsurface. A small building was built in the area using different construction techniques for different walls, both ancient and modern. GPR method can detect such superficial bodies or different walls with a relative efficiency depending on the field context, the dielectric properties of the host material and the nature and size of the bodies. In this work we have carried out two test. The first to verify the 900 MHz antenna resolution to estimate layers thickness of the sack walls typical of the Salento (Lecce, Italy). The second test to assess the 400 MHz antenna resolution to detect target of engineering interest in the first few meters. Very useful is also the use of three-dimensional data volumes and time slices for interpretation.

In Cutrofiano, in the southern part of the Salento Peninsula, Apulia, Italy, a Pleistocene calcarenitic sequence was quarried by digging extensive networks of galleries along the geological succession most suitable for the quarrying activity. These caves represent a potential hazard for the built-up environment due to the occurrence of underground instability that may propagate upward and eventually reach the surface, causing sinkholes. In this work we propose integrated interdisciplinary methods for cavities detection. The methodology was applied at a test area located along a major road near Cutrofiano using geological and electrical-resistivity tomography and microgravity geophysical methods.

This paper focuses on the impacts of contemporary geomorphological processes on fruition activities in a karst area of Salento (Apulia, southeastern Italy). The work illustrates the results of studies in a sinkhole field at Nociglia, in the Lecce province, recently recognized as a geosite and where shallow phreatic speleogenesis operates close to the water table level with the formation of karst caves, successive roof collapse, formation of wide caverns, and sinkhole development at the surface. All these features threaten the nearby infrastructures including a province road. Salento has a great number of active sinkholes related to natural and anthropogenic cavities. To assess the potential danger from sinkholes, it is important to identify and monitor the main factors contributing to the formation process. A multi-disciplinary approach, comprising geological, geomorphological, and geophysical analyses, is necessary to obtain a omprehensive knowledge of these complex phenomena in karst areas. Geophysical methods can be of great help to monitor the processes and for identifying and mapping features related to the underground voids, by detecting contrasts in physical properties, such as density and electrical resistivity, with the surrounding sediments. The territory of Nociglia demonstrates that monitoring is essential for the safe exploitation of these type of geomorphosites .

Sinkholes and land subsidence are among the main coastal geologic hazards. Their occurrence poses a serious threat to the man-made environment, due to the increasing density of population, pipelines and other infrastructures along the coasts, and to the catastrophic nature of the phenomena, which generally occur without any premonitory signs. To assess the potential danger from sinkholes along the coast, it is important to identify and monitor the main factors contributing to the process. This article reports a methodology based on sequential stratigraphic, hydrogeological and geophysical investigations to draw up a susceptibility map of sinkholes in coastal areas. The town of Casalabate situated in the Apulia region (southern Italy), affected by a long history of sinkhole phenomena, is here presented as an example. The approach proposed is based on sequential stratigraphical, geomorphological and geophysical surveys to identify the mechanisms of sinkhole formation and to provide a zonation of the areas in which further sinkhole phenomena may likely occur. Interpretation of the ground penetration radar and electrical tomography profiles has enabled us to identify the potentially most unstable sectors, significantly improving the assessment of the sinkhole susceptibility in the area. The proposed methodology is suitable to be exported in other coastal areas where limestone bedrock is not directly exposed at the surface, but covered by a variable thickness of recent deposits.

The control exerted by the hydrostratigraphic structure on aquifer recharge, groundwater flow and discharge along the coastal areas of a Mediterranean basin (Salento peninsula, about 5,000 km2 wide, southern Italy) is assessed through the development and application of a groundwater flow model based on the reconstruction of the hydrostratigraphic architecture at the regional scale. The hydrostratigraphic model, obtained by processing surface and subsurface data, is applied to map the top of the main aquifer, which is hosted in the deep hydrostratigraphic unit corresponding to Cretaceous and Oligocene limestones with complex geometrical relationships with the sea. It is also used to estimate the aquifer recharge, which occurs by percolation through overlying younger sediments with low permeability. These data are completed with information about the soil use to estimate water abstraction for irrigation and with literature data to estimate the water abstraction for drinking and industrial purposes. The above-sketched conceptual model is the basis for a finite difference groundwater 2D pseudo-stationary flow model, which assumes the following fundamental approximations: the fractured and karst limestone hydrostratigraphic unit can be approximated, at the model scale, as a continuous medium for which the discrete Darcy’s law is valid; the transition zone between salt and fresh water is so small with respect to the grid spacing that the Ghyben–Herzberg’s approximation for a sharp interface can be applied. Along the coastline different boundary conditions are assigned if the top of the limestone hydrostratigraphic unit lies either above the sea level (the aquifer has a free surface and fresh water is drained), or below the sea level (the aquifer is under pressure and the contact with sea occurs off-shore). The groundwater flow model correctly predicts the areas where the aquifer is fully saturated with salt water.

This paper deals with the reconstruction of buried targets exhibiting both dielectric and magnetic characteristics, starting from GPR data collected at the interface air/soil. The problem is tackled under the Born Approximation. In particular, two dimensional migration and linear inversion results will be compared versus experimental data and three dimensional representations of the reconstructions achieved from both methods will be shown.

Mediterranean areas are characterized by complex hydrogeological systems, where management of freshwater resources, mostly stored in karstic, coastal aquifers, is necessary and requires the application of numerical tools to detect and prevent deterioration of groundwater, mostly caused by overexploitation. In the Taranto area (southern Italy), the deep, karstic aquifer is the only source of freshwater and satisfies the main human activities. Preserving quantity and quality of this system through management policies is so necessary and such task can be addressed through modeling tools which take into account human impacts and the effects of climate changes. A variable-density flow model was developed with SEAWAT to depict the "current" status of the saltwater intrusion, namely the status simulated over an average hydrogeological year. Considering the goals of this analysis and the scale at which the model was built, the equivalent porous medium approach was adopted to represent the deep aquifer. The effects that different flow boundary conditions along the coast have on the transport model were assessed. Furthermore, salinity stratification occurs within a strip spreading between 4km and 7km from the coast in the deep aquifer. The model predicts a similar phenomenon for some submarine freshwater springs and modeling outcomes were positively compared with measurements found in the literature. Two scenarios were simulated to assess the effects of decreased rainfall and increased pumping on saline intrusion. Major differences in the concentration field with respect to the "current" status were found where the hydraulic conductivity of the deep aquifer is higher and such differences are higher when Dirichlet flow boundary conditions are assigned. Furthermore, the Dirichlet boundary condition along the coast for transport modeling influences the concentration field in different scenarios at shallow depths; as such, concentration values simulated under stressed conditions are lower than those simulated under undisturbed conditions.

The present work illustrates the results of studies in a sinkhole field at Nociglia (Salento sub-region, Apulia, SE Italy) where the shallow phreatic speleogenesis operates close to the water table level with formation of karst caves, successive roof collapse, formation of wide caverns and sinkhole development. All of this creates serious problems to the nearby infrastructures, including a province road. Salento has a great number of active sinkholes, related to natural and anthropogenic cavities. Their presence is at the origin of several problems to the built-up environment, due to the increasing population growth and development pressures. In such a context, the detection of cavities, and the assessment of the sinkhole hazard presents numerous difficulties. A multidisciplinary approach, comprising geological, geomorphological and geophysical analyses, is necessary to obtain comprehensive knowledge of the complex phenomena in karstic areas. Geophysical methods can be of great help to identify and map the features related to the underground voids, likely evolving to sinkholes, by detecting contrasts in physical properties such as density and electrical resistivity, with the surrounding sediments. At the same time, recognition of the presence of sinkholes by geophysical methods has to adapt to the different geological conditions, and to take advantage of the integration among the several methodologies available

In this paper, a simple methodology is proposed to assess the geothermal potential of the underground of the Salento peninsula (southern Italy) at the regional scale, by calculating the equivalent thermal performance of the subsoil, which expresses the thermal power that is potentially extractable and useful to heat or cool a building. Since the possibility of exploiting the underground as a heat reservoir depends on the physical properties and water saturation of rocks, previous detailed studies on the hydrostratigraphic setup of the region are the basis for this analysis of geothermal potential. The results show that the underground of the Salento peninsula has great potentialities for heating of buildings, except for some coastal areas because the saltwater intrusion phenomenon could cause problems for the realization of low-enthalpy geothermal energy systems.