Saltwater intrusion is a growing threat for coastal aquifers and agricultural practices in low-lying plains. Most of the farmlands located between the margin of the Southern Venice lagoon and the Northern Po delta, Italy, lie a few meters below mean sea level and are drained by a large network of artificial channels and hydraulic infrastructures to avoid frequent flooding and allow agricultural practices. This work proposes an assessment of the vulnerability to saltwater intrusion, following a new concept of the hazard status, resulting in combining the depth of the freshwater/saltwater interface and the electrical resistivity of the shallow subsoil. The sensitivity of the farmland system was assessed by using ground elevation, distance from freshwater and saltwater sources, permeability, potential runoff, land subsidence, and sea-level rise indicators. Relative weights were assigned by a pairwise comparison following the Analytic Hierarchy Process approach. The computed vulnerability map highlights that about 30% of the farmlands is under strong and extreme conditions, 28% between marginal and moderate, and 40% under negligible conditions. Results from previous vulnerability assessments are discussed in order to explain their differences in terms of hazard status conceptualization and sensitivity characterization of farmland system.

Complex freshwater–saltwater exchanges characterize most Holocene groundwater aquifers in low-lying coastal plains around the world, particularly in mechanically drained territories. This is due to the combination of several factors that control groundwater dynamics, including the high variability of the Holocene coastal deposits that host the shallow aquifers and the water management practices. The relationships between the stratal architecture of sedimentary deposits and the vertical changes in the salinity of the phreatic aquifer are poorly studied although they represent an issue of primary importance for a sustainable use of water resources and for agriculture. This research work is focused on the influence of sedimentary constraints, i.e., stratigraphic discontinuities and related changes in permeability in shaping salinity stratification into the unconfined aquifer at the southern margin of the Venice lagoon (Italy). Nine sites have been investigated by collecting sediment cores for facies analysis and monitoring water electrical conductivity in piezometric wells. The results show that buried channelized sandy deposits can enhance salinity mitigation of the phreatic aquifer in conjunction with precipitations and sufficient freshwater supply from nearby rivers and irrigation channels. Our analyses also reveal that the differences in stratigraphic architecture of the upper 10 m of the subsoil determine different fresh–saltwater dynamics of the phreatic aquifer. In particular, three possible behaviors can occur: (i) where the subsurface is characterized by the presence of a thick, up to 5 m, paleochannel, a freshwater lens is always present in the most surficial part of the phreatic aquifer; (ii) where the subsurface is composed by fine-grained sediments of marsh and lagoon paleo-environment, the phreatic aquifer tends to be salt-contaminated over its entire thickness; (iii) where the subsurface contains thin, up to 2–3 m, paleochannel deposits, the fresh–saltwater dynamics of the most surficial part of the phreatic aquifer varies more during the year, as a result of seasonal precipitation trend. The provided characterization of saltwater dynamics represents the basis for planning mitigation measures to improve the farmland productivity of the Venetian coastal plains.

Land degradation is a growing concern in arid and semi-arid regions, posing severe threats to ecosystem stability, agricultural productivity, and rural livelihoods due to the combined effects of natural processes and human activities. This study examines the role of Opuntia ficus-indica (OFI), a drought-resistant cactus, in mitigating land degradation and enhancing ecosystem resilience in central Tunisia using Landsat 5 and 9 satellites with 30 m spatial resolution. Spatio-temporal dynamics of land use/land cover (LULC) and variations in key spectral indices sensitive to vegetation and soil conditions were analyzed over the period from 2000 to 2024. Using a remote sensing-based multi-index framework, Land Degradation Index (LDI) maps were generated for 2000–2010 and 2010–2024 sub-periods. Change detection analysis revealed a marked reduction in moderate-to-severe land degradation, particularly in areas characterized by OFI expansion. NDVI values associated with OFI increased significantly, from less than 0.1 in 2000 to about 0.18 in 2024, indicating enhanced vegetation vigor and improved adaptive capacity under semi-arid climatic conditions. To further assess species performance, correlation analyses were conducted between NDVI-OFI values and topographic variables, including elevation and terrain curvature. Results show a strong positive relationship between NDVI-OFI and elevation, with a clear temporal improvement from 2000 to 2024. In addition, NDVI values were highest in convex terrain forms (0.2), highlighting OFI’s ability to thrive in erosion-prone and topographically exposed environments. Findings confirm the effectiveness of OFI in reversing land degradation processes, supporting restoration through an integrated approach combining multi-temporal remote sensing and topographic analysis. The study highlights the potential of OFI as a cost-effective and scalable nature-based solution for land rehabilitation in semi-arid regions.

Saltwater intrusion increasingly jeopardizes groundwater in low-lying coastal plains worldwide, where the combined effects of sea-level rise, land subsidence, and hydraulic regulation further exacerbate aquifer vulnerability and threaten the long-term sustainability of freshwater supplies. To move beyond sparse and fragmented piezometric observations, we propose “integrated coastal supersites”: wells equipped with multiparametric sensors and multilevel piezometers that couple high-resolution vertical conductivity–temperature–depth (CTD) profiling with continuous hydro-meteorological time series to monitor the hydrodynamic behavior of coastal aquifers and saltwater intrusion. This study describes the installation of two supersites and presents early insights from the first monitoring period, which, despite a short observation window limited to the summer season (July–September 2025), demonstrate the effectiveness of this approach. Two contrasting supersites were deployed in the coastal plain between the Brenta and Adige Rivers (Italy): Gorzone, characterized by a thick, laterally persistent aquitard, and Buoro, where the aquitard is thinner and discontinuous. Profiles and fixed sensors at both sites reveal a consistent fresh-to-saline transition in the phreatic aquifers and a secondary freshwater lens capping the confined systems. At Gorzone, the confining layer hydraulically isolates the deeper aquifer, preserving low salinity beneath a saline, tidally constrained phreatic zone. Groundwater heads oscillate by about 0.2 m, and rainfall events do not dilute salinity; instead, pressure transients—amplified by drainage regulation and inland-propagating tides—induce short-lived EC increases via upconing. Buoro shows smaller water-level variations, not always linked to rainfall, and, in contrast, exhibits partial vertical connectivity and faster dynamics: phreatic heads respond chiefly to internal drainage and local recharge, with rises rapidly damped by pumping, while salinity remains steady without episodic peaks. The confined aquifer shows buffered, delayed responses to surface forcings. Although the monitoring window is currently limited to 2025 through the summer season, these results offer compelling evidence that coastal supersites are reliable, scalable, and management-critical relevance platforms for groundwater calibration, forecasting, and long-term assessment.

Natural compaction of Holocene deposits is one of the main processes contributing to land subsidence in low-lying coastal environments. Its quantification has been challenging until now because of difficulties inherent to monitoring land displacements in coastal and transitional environments and disentangling the various processes that superpose to produce the observed total displacement. A significant step forward has been made possible by interferometric processing of Synthetic Aperture Radar (InSAR), specifically Persistent Scatterer Interferometry (PSI). InSAR retrieves land displacement from satellites without needing direct access to the coastland where inner water basins, watercourses, wetlands, and the lack of infrastructure make ground-based monitoring techniques almost impossible to use. PSI detects thousands of measurable radar reflectors per square kilometer over large areas. This high spatial resolution helps disentangle the causes of the observed displacements and, consequently, understanding where natural compaction is a key factor. In this chapter, we review relevant case studies and discuss the outcomes of the research carried out in the coastland of the Po River plain, northern Adriatic Sea, Italy. Specifically, we focus on the low-lying farmlands and wetlands in the Po delta and the tidal marshes of the Venice Lagoon. L-, C-, and X-band SAR data are integrated to increase the effectiveness in retrieving information on scattered small infrastructures, vegetation, and wet zones. Integration with in situ data, such as the sediment deposition age, differential compaction at a few depth intervals, and accretion rates, reveals a significant correlation between natural compaction rates and the marsh age. Such dataset is then used to develop a specific accretion-natural compaction model to forecast the resilience of these transitional environments to anthropogenic stressors and sea level rise due to climate change.

The Mediterranean region is experiencing severe environmental pressures due to climate change, population growth, agricultural intensification, and desertification. Impacts will be exacerbated in the coming decades and require adaptation strategies to increase the resilience of ecosystems and counteract land degradation. Throughout the Mediterranean, desertification combined with reduced freshwater availability will be the main factors limiting agricultural production, driving the need for alternative low-water demanding crops. Some Neglected and Underutilized Species (NUS), typical of the Mediterranean area and already used by rural populations, are adapted to grow under drought conditions, in combination with other soil limiting factors, such as high salinity, reduced nutrient inputs, and desertification. These species have the potential to ameliorate soil quality and to be a viable alternative for farmers, especially smallholders, to generate economic value.The VENUS project (i.e. ConVErting marginal lands of the Mediterranean basin into productive and sustainable agroecosystems using low water demanding Neglected and Underutilized Species) aims to demonstrate the environmental potential of introducing NUS, known for their resilience under extreme conditions, and their economic potential as marketable products, including food, cosmetics, and energy applications. Specifically, 10 pilot sites have recently been established in 7 Mediterranean countries (Greece, Italy, Morocco, Tunisia, Egypt, Jordan and Algeria) to collect data on biotic and abiotic factors regulating the NUS production systems, to test the suitability and sustainability of NUS, and to assess the impact of their cultivation on soil health quality. The local results obtained at the pilot sites, combined with an analysis of the distribution of the most recent databases available in the literature of key abiotic/climatic factors across the Mediterranean, will be useful for the scalability and transferability assessment of NUS production systems to a wider scale. Furthermore, NUS production system at each site will be analysed to assess their quality for various market applications (i.e., food, cosmeceutical and pharmaceutical, and energy production), and social acceptance with the final aim of producing a set of commercially viable and sustainable business models at partners’ pilot regions and countries, providing alternatives to farmers struggling with water scarcity and other limiting factors.FundingThis work was conducted in the framework of the project VENUS - “ConVErting marginal lands of the Mediterranean basin into productive and sustainable agroecosystems using low water demanding Neglected and Underutilized Species” funded by the PRIMA programme (Grant Agreement No. 2312) supported by the European Union’s Horizon 2020 research and innovation programme.