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Deterioration in the groundwater quality is prevalent in many parts of the eastern and north-eastern India; however, little attention has been paid for its assessment. In order to evaluate the groundwater suitability in the north-eastern region of India, this study was carried out in Barpeta District of Assam. The groundwater samples were collected from various locations to represent the overall water quality of the district. Suitability was assessed in terms of its usability for drinking and irrigation. It was found that the groundwater samples are contaminated with high amount of arsenic, which refers that water is unfit for consumption as well as agricultural activities. Hydrogeological studies revealed that regional geological factors might be responsible for excess arsenic concentration in the region. Overall, groundwater quality was found to be alkaline having moderate hardness with high amount of iron, manganese, and lead as well.

Sea level rise presents a range of hazards, including rising groundwater tables, salinization, and subsurface flooding, which threaten subsurface infrastructure in coastal communities. Groundwater shoaling inundates basements, tunnels, and utility networks, and mobilizes contaminants, while salinization accelerates corrosion and deteriorates water quality. Hydrogeologic studies increasingly assess these hazards, but few consider exposure and vulnerability to evaluate the overall risk, which is critical for adaptation planning. This commentary offers a perspective on the need to develop subsurface risk assessment tools for coastal zones by building on existing groundwater hydrology knowledge and adapting current risk analysis frameworks for coastal communities. We highlight essential data sets, infrastructure needs, and interdisciplinary collaborations required to implement these frameworks. Finally, we outline a path forward that includes (a) well‐defined, local‐scale risk analyses of specific infrastructure categories, (b) scale up through the creation of accessible, web‐based coastal groundwater observatories and shared monitoring networks, and (c) advances toward the long‐term development of digital twins that integrate real‐time sensing, satellite data, and machine learning to anticipate subsurface hazards at regional scale. All require sustained interdisciplinary collaboration among academia, government institutions, and coastal communities.

This paper deals with updated results coming from hydrogeological studies carried on the framework of the SECOSUD Phase II, called “Conservation and equitable use of biological diversity in the SADC region (Southern African Development Community), a project supported by the Italian Ministry of Foreign Affairs in the SADC, whose focus area includes South Africa Development Countries. The main goal of the SECOSUD Phase II Project is the definition and implementation of scenarios for sustainable development, aimed at an equitable conservation of biodiversity resources and, as a consequence of this target, the hydrogeological characterization, with the groundwater recharge assessment, of this area and its buffer zone. Limpopo National Park is one of the jewels in the crown of Mozambique’s protected areas. As a matter of fact, sustaining the conservation of biodiversity, due to its complexity and multiple drivers, which stress it, is on first a matter of water environment assessment, as most ecosystems are highly dependent on the hydrological cycle and groundwater availability. After gathering regional and local geological data, which let us set up a detailed geological map of the area under study, pointing out the main outcropping geological units, with their main hydrogeological properties, the methodological approach adopted has been to assess the potential infiltration, applying the Inverse Hydrogeological Budget Technique, performed for the focus area. Because of the lack of meteorological data referred to Limpopo National Park, it has been applied a spatial distribution of precipitation measurements, collected in many gauge stations, located in the Kruger National Park during the last 54 years, which represent an interesting rainfall historical series. The target of the study has been to assess a trend of meteorological data with the aim of understanding how precipitations could affect groundwater recharge, and their influence on groundwater availability. The estimation of groundwater recharge is the tool for suggesting better water management in the area, aimed to preserve as much biodiversity as people living in the buffer zone.

Australian commonwealth, state and territory geological surveys possess information on over 3 million drillhole logs. In addition to mineral exploration drilling, extensive drillhole datasets exist from oil and gas exploration and hydrogeological studies. Other countries no doubt have similar data holdings. Together these legacy drillhole datasets have the potential to significantly enhance constraints on regional 3D geological models and improve our understanding of subsurface architecture, but have limited use in their current form as many if not most drill logs lack stratigraphic information, containing only lithological descriptions. This study develops open-source codes and methodologies for stratigraphy recovery (determining the ordered sequence of stratigraphic units) from drillhole lithological data by introducing a search algorithm that systematically explores all geologically plausible stratigraphic orderings for individual drillholes, combined with a solution correlation algorithm that compares the topological relationships of stratigraphic units across multiple drillholes to identify geologically consistent solutions and reduce uncertainty. The algorithms combine constraints from lithological descriptions with stratigraphic relationships automatically derived from regional maps. In addition, the method quantifies uncertainty by generating multiple plausible stratigraphic interpretations, providing critical insights for resource estimation, scenario analysis, and data acquisition strategies. The application of our method to a dataset of 52 drillholes from South Australia demonstrated its ability to make useful predictions of stratigraphic solutions and quantifying associated uncertainties. These results not only validate our approach but also highlight opportunities to refine current stratigraphic descriptions and provide a valuable new source for regional 3D geological modelling.

Developing conceptual models is a critical step in hydrogeological studies that should utilise multiple lines of evidence and data types to minimise conceptual uncertainty, particularly in data-sparse systems. This study used new and existing major ion and isotope (O, H, Sr, C) data sets to refine a previous hydraulic-head-based conceptual model of the Galilee Basin (Australia). The analyses provide evidence for the locations of recharge and discharge areas and determine hydrochemical processes along flow paths to improve understanding of potential source waters to the Doongmabulla Springs Complex (DSC) and to infer mixing within, or exchange between aquifer units. There was good agreement between previously inferred recharge and discharge areas defined using hydraulic head data and interpretations from hydrochemical evolution along groundwater flow pathways, at least where data were available. Major ion and isotope data suggest that the DSC likely receives water from both a relatively shallow, local flow path and a deeper regional flow path. This observation is relevant to previous concerns about threats to the DSC, as mine-induced drawdown may impact the relative contributions to spring discharge from different recharge sources and aquifers. Silicate weathering in the deeper Clematis Formation and Dunda Beds, and evapotranspiration in the overlying Moolayember Formation have strong control on the total dissolved solids content. These findings suggest that the Clematis Formation and Dunda Beds are hydrochemically distinct from the Moolayember Formation, with limited exchange between these aquifers, which has important implications for model conceptualisation and ongoing monitoring of mining activities in the Galilee Basin.

Bedrock mapping is essential for understanding seismic amplification, particularly in sediment-filled valleys or basins. However, this can be hard in urban environments. We conducted a geophysical investigation of the sediment-filled Bolzano basin in Northern Italy, where three valleys converge. This study uses low-impact, single-station geophysical methods suitable for urban areas to address the challenges of mapping in such environments. A dataset of 574 microtremor and gravity measurements, along with three seismic reflection lines, allows for the inference of the basin’s deep bedrock morphology, even without direct stratigraphic data. The dataset facilitates a detailed analysis of the spatial patterns of resonance frequencies and amplitudes, revealing 1D and 2D characteristics of the resonances. Notably, 2D resonances predominate along the Adige valley, i.e., the deepest part of the basin with depths up to 900 m. These 2D resonances, which cannot be interpreted through simple 1D frequency-depth relationships, are better understood by integrating gravity data to develop a depth model. The study identifies resonance frequencies ranging from 0.27 to over 3 Hz in Bolzano, affecting different building types during earthquakes. Maximum resonance amplitudes occur at lower frequencies, specifically at 2D resonance sites, therefore primarily impacting high structures. The 2D resonances are directional, with the most significant amplification occurring longitudinally along the valley axes. The resulting 3D bedrock model aids in seismic site response modeling, hydrogeological studies, and geothermal exploration and provides insights into the geological history of the basin, highlighting the role of the Adige Valley as a major drainage pathway.

As climate change intensifies, water supplies are declining and groundwater is increasingly being exploited worldwide to meet increased population needs, industrial growth, and agricultural development. Groundwater exploration relies mainly on hydrogeological studies, often supported by geophysical techniques (e.g., geoelectrical methods). Although these techniques can be cost-effective and time-efficient, they can be difficult to implement due to topographical effects or localized heterogeneities. Furthermore, when using ground-based geophysical measurements, it is impossible to survey large regions with dense coverage. We, therefore, require a means of targeting geophysical campaigns. The combination of Geographical Information System (GIS) and remote-sensing (RS) data can facilitate the identification of areas with high groundwater potential and suitable locations for geophysical surveys. In this study, we illustrate how GIS, RS, and geophysical surveys can be utilized for assessing potential groundwater resources. The study is based on two phases: a RS–GIS groundwater prospect modeling and a detailed geoelectrical survey (40 vertical electrical soundings, VES) for aquifer description in the El-Hamiz watershed (Algeria). The GIS–RS model was developed to highlight potential groundwater areas and locate the site of VES measurements. Furthermore, the geoelectrical data and hydrochemical analysis helped to determine the aquifer characteristics (depth to water table, saturated zone thickness, and aquifer resistivity). This study highlights the effectiveness of a combined use of RS–GIS modeling and geophysical data to improve the understanding of groundwater availability and its quality.

Groundwater-level monitoring networks provide vital information for hydrogeological studies. Including exploited domestic wells in these monitoring networks can provide a low-cost means of obtaining a broader set of data; however, the use of these sites is limited because the frequent pumping of these wells generates outliers in the recorded time series. Here a slope criterion is applied to identify and remove outliers from groundwater-level time series from exploited domestic wells. Nonetheless, eliminating outliers creates a problem of missing values, which biases the subsequent time series analysis. Thus, 14 imputation methods were used to replace the missing values. The proposed approach is applied to groundwater-level time series from a monitoring network of 20 wells in the Lanaudière region, Québec, Canada. The slope criterion proves very effective in identifying outliers in exploited domestic wells. Missing values generated by outlier removal can reach up to 99% of the recorded data. Among the characteristics of the missing value pattern, the gap size and the position of the gaps along the time series are the most important parameters that affect the performance of the 14 imputation methods. Of the imputation methods tested, linear interpolation and Stineman interpolation, and then Kalman filtering, were the most effective. The present study demonstrates that exploited domestic wells can be used for groundwater monitoring by removing the outliers and imputing the missing values.

Groundwater availability, management and protection are great challenges for the sustainability of groundwater resources in the scattered rural areas of the Atlantic regions of Europe where groundwater is the only option for water supply. This report presents a hydrogeological study of the coastal granitic area of Oia in northwestern Spain, which has unique geomorphological and hydrogeological features with steep slopes favoring the erosion of the weathered granite. The hydrogeological conceptual model of the study area includes: (1) the regolith layer, which is present only in the flat summit of the mountains; (2) the slope debris and the colluvial deposits, which are present in the intermediate and lowest parts of the hillside; (3) the marine terrace; and (4) the underlying fractured granite. Groundwater recharge from rainfall infiltration varies spatially due to variations in terrain slope, geology and land use. The mean annual recharge estimated with a hydrological water balance model ranges from 75 mm in the steepest zone to 135 mm in the lowest flat areas. Groundwater flows mostly through the regolith and the detrital formations, which have the largest hydraulic conductivities. Groundwater discharges in seepage areas, springs, along the main creeks and into the sea. The conceptual hydrogeological model has been implemented in a groundwater flow model, which later has been used to select the best pumping scenario. Model results show that the future water needs for domestic and tourist water supply can be safely provided with eight pumping wells with a maximum pumping rate of 700 m3/day.

In the drylands of Northern Mendoza, Argentina, water supply depends on rivers and groundwater. Climate change makes this region vulnerable due to the snow-glacial-melt regime of the main rivers and populations being concentrated in “irrigated oasis” areas. This article synthesizes hydrogeological knowledge of Northern Mendoza, from the Andes to the eastern plains. The study collected hydrogeological information (published and unpublished) from 1974 to 2020 and analyzed the groundwater situation in the context of climate change. Northern Mendoza comprises fractured and clastic aquifers. Hydrogeological studies (mainly technical reports from the 1980s and 1990s) focused on clastic aquifers to support agricultural activities. These studies included general hydrochemical characterization and localized contamination surveys. Also, they included estimations of groundwater reserves and hydraulic parameters. The hydrogeology of mountain and foothill areas is mostly unknown. Further work is needed: quantification of groundwater resources, surveys of contamination and overexploitation of the confined and unconfined aquifers, better understanding of the surface-water/groundwater interaction, and an efficient monitoring network. The lack of updated information and a sustainable groundwater management strategy in irrigated areas has created legal conflicts among groundwater users, pollution problems, and high pressure on this finite resource. Besides, the poor current groundwater knowledge limits the regional economic development and the enforcement of protection measures against water contamination and overexploitation. Although the impacts of climate change on groundwater resources are globally uncertain, the adaptation to this change requires an improvement in the understanding of groundwater, professionalization of its management, and incorporation of technological advances in hydrogeology issues and water uses.