Coastal areas have become increasingly vulnerable to groundwater salinization, especially in the last century, due to the combined effects of climate change and growing anthropization. In this study, a novel methodology named GALDIT-SUSI was applied in the floodplain of the Volturno River mouth for the current (2018) and future (2050) evaluation of seawater intrusion accounting for the expected subsidence and groundwater salinization rates. Several input variables such as digital surface model, land use classification, subsidence rate and drainage system have been mapped via remote sensing resources. The current assessment highlights how areas affected by salinization coincide with the semiperennial lagoons and inland depressed areas where paleosaline groundwaters are present. The future assessment (2050) shows a marked increase of salinization vulnerability in the coastal strip and in the most depressed areas. The results highlight that the main vulnerability driver is the Revelle index, while predicted subsidence and recharge rates will only slightly affect groundwater salinization. This case study indicates that GALDIT-SUSI is a reliable and easy-to-use tool for the assessment of groundwater salinization in many coastal regions of the world.

Land subsidence (LS) is becoming one of the major problems in coastal and delta cities worldwide. Understanding the current LS situation and the research trends is of paramount importance for further studies and addressing future international research networks. We analyzed the LS-related literature available from the Scopus database. The use of a single database avoided the redundancy of articles, while excluding some subject areas was useful to obtain only studies related to LS. By using VOSviewer and CiteSpace tools, we conducted a bibliometric analysis by considering title, keywords, and abstract to identify the temporal development, the geographical origin, and the area of study of the research. The results revealed a considerable heterogeneity of approaches, thematics, study areas, and research output trends. China, the US, and Italy are the major contributors to the scientific production, but the higher number of articles is not always related to the extension of the LS phenomenon in these countries. The monitoring approach differs worldwide, and univocal modeling is still lacking; from the analysis of the keywords, it is clear that the focus of most studies is on the relationship with the hydrological/hydrogeological aspects. Since the 2000s, however, the development of SAR technologies has boosted the study of the phenomenon from a different point of view.

In the Mediterranean area, several alluvial coastal plains, developed after the Holocene transgression, are affected by subsidence. The Volturno alluvial-coastal plain, along the eastern Tyrrhenian Sea (southern Italy) is characterized by subsidence rates determined through InSAR data analysis and ranging between 0 and <−20 mm/year in an area of about 750 kmq across the Volturno River. Inside this area, the pattern of subsidence shows sites with apparently anomalous localized subsidence. To understand the driving mechanisms of this process, a lithostratigraphic reconstruction was provided focusing on the spatial distribution of the horizons considered weak by a geotechnical point of view; then, the subsidence map was overlain spatially with geological data in a Geographic Information System (GIS) environment. The spatial analysis highlighted the major ground deformation occurring within the outer boundary of the incised paleo-valley, corresponding to the Holocene alluvial/transitional filling that overlies a compaction-free Pleistocene basement. Inside this general trend, differential compaction was detected corresponding to the thick occurrence of clay and peat deposits, suggesting that the subsidence rate registered in the plain are due in part to the consolidation of primary settlements of soft and compressible soils that characterize the subsoil of these areas, and in large part to the secondary consolidation settlements.

In Campania (southern Italy), the widespread presence of anthropogenic cavities in the subsoil of the Neapolitan and Caserta provinces is well known. In these towns, the underground quarrying activities were performed for centuries to extract volcanic tuffs for buildings. The urban developments have sealed many signals of the presence of cavities and their real extent is almost unknown, thus representing a geological hazard and contributing to the subsoil instability of many places. This contribution will show the main cavity typologies recognized across an area north of Naples according to the geological characteristics of the subsoil. The main aim of the study is the cataloging of the cavities and the analysis of the city subsoil as their presence may easily trigger the collapse of the shallow or deeper soils. Moreover, the recognition and sustainable reuse of cavities contributes to enhancing the cultural and touristic promotion of a territory. In this study, a database framework was elaborated that includes all the possible architectural, geological and geotechnical elements of the cavities. Data were managed in a GIS environment in order to provide a useful tool for monitoring and managing the cavities for risk mitigation and tourism enhancement.

Landslides are one of the most serious problems affecting large parts of the world. There are two approaches that are used to study the organization of these land cover features: firstly, an approach utilizing lithostratigraphic tools, where soils are described and interpreted in accordance with specific geological/lithological patterns, and, secondly, through pedological instruments, where the pedogenetic patterns are identified, and the sequences are identified via standardized criteria and organized according to modern classification systems. In the present review, a comparison between the two above approaches is outlined, using the Campania Apennine reliefs (Southern Italy) as the reference environment because they are periodically and dramatically affected by mass movements mainly associated with rainfall events. These reliefs are strongly influenced by the products emitted by the Phlegraean Fields and the Somma–Vesuvius volcanoes. These products affect surface structures either through their direct alteration, with the formation of pedogenized products, or through their reworking, mainly stimulated by rainfall events, which is also responsible for the movement of pedogenized materials along the slopes. This results in complex surface architectures, knowledge of which is a crucial step in the assessment of robust monitoring systems. This review covers the Cervinara area, located in the central portion of the Campania Apennines, which was overwhelmed by dramatic landslide events in 1999. Our aims were to critically analyze the impact and the potential of lithostratigraphic and pedological approaches in studying the soils of the area in question and to provide an inventory of the scientific papers in which, with different aims, descriptions and interpretations of the local soil covers are reported. We examined and selected the national and international literature available in major scientific online databases, and these were split into groups on the basis of citations and type of approach. The reviewed literature showed that the stratigraphic approach was by far the most preferred, although significant potential was offered by pedological tools in this field of investigation. A high number of hydraulic and geotechnical articles was also found, in comparison to geological and pedological papers, which confirmed the significant levels of interest in the land cover type in question, specifically regarding landslide processes, and in their role in risk mitigation practices. On the whole, the latter approach has been proven to offer a greater exploration potential through the use of rigorous classification systems and, thus, the possibility of identifying and correlating soil properties over large areas.

The present study focused on the relationships between subsidence and geological and geotechnical features of the Volturno River alluvial and coastal plain (northern Campania, Italy). Subsidence rates were determined through InSAR data analysis. A lithostratigraphic reconstruction was provided for the Holocene succession that overlay a continuous, thick, volcaniclastic unit (Campania Grey Tuff) deposited 39 ka B.P. The digital surface model carried out for this unit showed a palaeovalley morphology, allowing the reconstruction of the palaeodrainage network and a better modeling of the stratigraphic architecture of the post-CGT deposits. The subsidence map was overlain spatially with geological data. In the whole plain, the major ground deformations affect the sedimentary piles filling the palaeovalley engraved in the volcanic compaction-free basement. Inside the general subsidence trend, differential compaction was detected within these deposits corresponding to the occurrence of clay and peat of different thicknesses, suggesting that the subsidence rates are due in part to the primary consolidation and in large part to the secondary consolidation.