Search Results (10,213)

Across Africa, drought seldom occurs alone. Rainfall deficits often coincide with heat, rapid soil moisture loss and reduced streamflow, producing compound events whose impacts exceed those of any single driver. This review synthesises station observations, satellite and reanalysis products, and climate model simulations to clarify where such events are most common, how they form, how they affect societies and ecosystems, and how risks are changing. A practical tiered definition tailored to African conditions is outlined and applied to identify five recurrent hotspots: the Sahel, the Greater Horn of Africa, southern Africa, the margins of the Congo Basin and the Guinea Coast. The review sets out a physically consistent sequence that links basin-scale sea surface temperature anomalies to shifts in monsoon circulation, and then to land processes that amplify and prolong heat and dryness through reduced evapotranspiration and soil-moisture memory. Documented impacts include lower crop and pasture productivity, pressure on rivers, reservoirs and groundwater, stress on hydropower and wider consequences for food and energy security. Compound drought frequency across these hotspots has risen by 18–55% since 1980, with the probability of the most severe events roughly doubling at 1.5 °C of global warming and tripling at 3 °C. The review highlights near-term priorities, including compound-aware monitoring, sub-seasonal-to-seasonal early warning and conjunctive water management. Full article

Tourism development in the Yucatán Peninsula has long been dominated by coastal mass tourism, resulting in environmental pressure and pronounced spatial imbalances. In response, increasing attention has been directed toward diversification strategies based on inland and nature-based attractions. Among these, cenotes—karst sinkholes connected to regional groundwater systems—have emerged as a distinctive tourism resource. This paper introduces the concept of cenotourism as a form of nature-based and geoculturally embedded tourism centred on cenotes and their associated karst environments. The analysis combines conceptual development with empirical evidence from a large-scale tourism survey conducted in Yucatán (n ≈ 2800). The findings suggest that cenotes constitute a meaningful component of tourists’ activity portfolios, with 24.6% of respondents declaring an intention to visit them. Cenotourism contributes to diversification and appears to support the redistribution of tourist flows toward inland areas, while simultaneously increasing exposure to highly sensitive groundwater systems. These results point to a clear sustainability trade-off, although its magnitude may vary depending on local governance conditions. While cenotourism may strengthen local economies and reduce pressure on coastal destinations, it also introduces risks related to groundwater contamination, cultural commodification, and uneven benefit distribution. Such outcomes depend strongly on governance conditions, including visitor management, environmental monitoring, and community participation. By conceptualizing cenotourism as an integrative framework linking tourism demand, environmental vulnerability, and governance processes, the study contributes to understanding tourism development in groundwater-dependent systems. The findings emphasize the need for context-specific management approaches and situate cenotourism within broader water-sensitive tourism planning. Full article

Arsenic-contaminated groundwater is a major environmental concern, particularly in northern Argentina. Here, Microbacterium oxydans AE038-20, isolated from arsenic-rich groundwater, was investigated to elucidate its tolerance and transformation capacity. Growth assays showed that the strain tolerates inorganic arsenic [As(III), As(V)] and methylarsenite [MAs(III)] without significant inhibition. Speciation analyses revealed progressive oxidation of As(III) to As(V), reaching near-complete conversion after 10 days. Similarly, MAs(III) was fully oxidized to MAs(V). Genome sequencing identified ars-related determinants, including arsR, arsC, putative arsenite efflux systems, and arsP, supporting detoxification via arsenate reduction and arsenite efflux. Proteomic analyses confirmed the expression of proteins related to arsenic resistance, oxidative stress response, and metal transport. However, no canonical arsenite oxidases were detected at either the genomic or proteomic level. Despite this, M. oxydans AE038-20 exhibited clear arsenic oxidation activity. The detection of pigment-associated proteins and in vitro oxidation assays suggest an alternative mechanism potentially mediated by redox-active pigments. These findings highlight an alternative pathway for arsenic transformation in environmental bacteria. Full article

Hydrogeochemistry is a practical and low-impact tool for mineral exploration that relies primarily on groundwater as sampling media. It is particularly valuable for blind or deeply buried deposits where surface geochemical methods are ineffective, as groundwater acts as a natural integrator of geochemical signals from depth. This study presents a PRISMA 2020-compliant systematic review of hydrogeochemical exploration practices published between 1946 and 2025, synthesizing 118 empirically screened case studies from diverse geological and climatic settings. The review evaluates the geochemical processes governing aqueous dispersion halos, including sulphide oxidation, water–rock interaction, redox controls, and physicochemical speciation, and assesses how these processes influence pathfinder behaviour and anomaly expression. Quantitative synthesis highlights consistent patterns in hydrogeochemical footprints across major mineral systems and demonstrates the effectiveness of thermodynamically informed and multivariate interpretation strategies over simple concentration-based approaches. Emerging trends identified include the growing application of non-traditional stable isotope fractionation, nanoparticle geochemistry using single-particle ICP-MS, and integration of hydrogeochemical datasets with GIS, geophysics, and machine learning-based prospectivity modelling. Unlike recent narrative reviews, this study provides a fully reproducible, structured evaluation of the global evidence base and formalizes a standardized end-to-end workflow. Full article

Groundwater is a key strategic resource underpinning water security, and its effective management requires reliable, high-frequency monitoring data. In mountainous regions such as the flysch Carpathians in southern Poland, natural springs are particularly sensitive indicators of aquifer system dynamics. This study analyzes the role of springs in the national groundwater observation and research network and identifies barriers to the implementation of automated monitoring of spring discharge. The research covered 28 springs operating within the regional monitoring network of the Polish Geological Institute—National Research Institute in the Carpathian region. Classical hydrogeological spring classifications were applied and complemented with proprietary criteria addressing formal-legal, technical, and environmental conditions affecting the feasibility of automation. The results show that all of the analysed springs exhibited a Meinzer’s variability index (V) exceeding 100%, and numerous objects showed a coefficient of variation (CV) above 150%, providing quantitative evidence that standard weekly manual measurements statistically fail to capture rapid flow dynamics and peak discharge events. To bridge the gap between hydrodynamic observations and monitoring logistics, this study introduces a novel methodological contribution: the F-T-S-N screening framework. This proprietary, multi-criteria classification quantifies Formal-legal, Technical, Structural, and Nature-environmental barriers to telemetry implementation. The application of this framework demonstrates that the main obstacles to modernization are non-technological. The proposed classification serves as a practical, transferable tool that supports the rational planning of monitoring network automation in other mountainous regions with similar hydrogeological conditions. Full article

This study assessed photovoltaic (PV) soiling losses at Alamogordo, New Mexico, USA, located within the Chihuahuan Desert and near the White Sands gypsum dune field, a region with frequent dust events. Soiling material collected from PV module surfaces showed seasonal variations in mineral composition, with quartz being the main component during the fall season and calcite predominating during the spring. All samples collected during the following spring season contained large amounts of gypsum, indicating transport from White Sands, supported by HYSPLIT back-trajectories and surface wind data. Soiling materials collected from PV module surfaces generally had a mineral composition similar to that of the surrounding local soils. The mean particle size of collected soiling material samples ranged from 8 to 21 µm, with ~90% of particles being dust (<50 µm) and ~10% of the soiling particles being sand (>50 µm). Despite Alamogordo experiencing 22 dust events during this study, soiling-related power losses were relatively low, about 2% to 3%, much lower than reported for Global Dust Belt locations. The prevailing south-to-southwest winds and their gusts acted as a passive cleaning mechanism, as they were aligned with the front of the PV modules and likely resuspended particles off panel surfaces. Additionally, relatively low rainfall (about 2.2 mm per hour) was effective in restoring PV performance. These findings suggest that, due to the relatively low soiling losses observed, frequent cleaning may not be necessary at this location, resulting in potential savings in maintenance costs over the long-term operation of the PV system. Full article

Stochastic inputs are essential for incorporating hydrological variability in water resources assessment, planning, and management. However, most studies focus on the generation of precipitation and temperature, precipitation and streamflow, and precipitation and evaporation, with limited incorporation of groundwater levels. This study assessed the ability of the Variable Length Block (VLB) bootstrapping model for simultaneously generating stochastic sequences of rainfall, evaporation, and groundwater levels. The performance of the model was assessed by comparing single statistics of historical time series located within the box plots of 100 annual and monthly stochastically generated time series. The model preserved eight of the nine statistics adequately, except for skewness, across all variables, with historical values for evaporation and groundwater levels falling below and above the interquartile range for 12 months. All the historic statistics for rainfall, evaporation, and groundwater levels were within the interquartile ranges of the box plots for 83, 71, and 71% of the time, respectively. The historic statistics for rainfall, evaporation, and groundwater levels were within the box plot ranges for 100, 98, and 99% of the time, respectively. These findings indicated reasonably successful generation, and the VLB generator was therefore considered applicable for the stochastic generation of multiple hydrometric data types. Full article

Population growth and unplanned land use significantly contribute to transforming natural hazards into disasters. Earthquake-induced losses of life and property are often linked to inadequate planning decisions. The city center of Şanlıurfa provides a recent example, where the 6 February 2023 earthquake resulted in 340 fatalities and substantial material damage. Variations in urban planning over different periods have caused disaster risk to fluctuate even across short distances. This study examines Şanlıurfa’s urban development in terms of earthquake vulnerability. Using Geographic Information Systems (GIS) and the Analytic Hierarchy Process (AHP), the earthquake risk map reveals elevated risk in areas near fault lines and regions with high groundwater levels. Approximately 7% of the area is classified as very low risk, 54% as low risk, 37% as moderate risk, and 2% as high risk. Limited consideration of disaster-focused planning has led to both planned and unplanned developments in hazardous zones. Consequently, construction should prioritize low-risk areas, with necessary precautions applied in high-risk zones when unavoidable. Full article

Land subsidence (LS) is a widespread geoenvironmental problem driven by both natural processes and human activities. Identifying the main factors controlling LS susceptibility and their spatial contribution patterns is essential for LS management and mitigation. In this study, an interpretable earth observation framework was developed for the North China Plain (NCP) to quantify both spatial and non-spatial contributions of dominant LS drivers. Land displacement was derived from Sentinel-1A SAR images using Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) processing. The displacement map was then combined with nine geoenvironmental variables to construct an LS susceptibility model using the eXtreme Gradient-Boosting (XGBoost) algorithm. The model performed well, with an R² of 0.96, an EVS of 0.96, and an MAE of 2.25 mm/yr. SHapley Additive exPlanations (SHAP) analysis was employed to quantify feature contributions and their effects on LS susceptibility. The results show that a deep groundwater level (DGL) was the dominant factor, followed by elevation and a shallow groundwater level (SGL). The effect of DGL was strongest when it ranged from −75 to 20 m. Elevation showed a clear effect on LS occurrence when values fall between 30 and 50 m. Relatively high subsidence sensitivity was mainly observed in areas where SGL was below −7 m. Interaction effects, particularly those between DGL and elevation and between DGL and SGL, further increased LS susceptibility in specific areas. The highest predicted susceptibility occurred in areas with DGL below −20 m and elevations below 30 m. Higher susceptibility was also identified where DGL was high and SGL ranged between −20 and −10 m, and where DGL was low and SGL ranged from 15 to 20 m. In contrast, factors such as slope and aspect had limited influence at the regional scale. The contributions of the predominant factors show obvious marginal effects and significant spatial heterogeneity to LS susceptibility. The results clarify where and how key factors shape subsidence and can inform targeted mitigation measures and urban planning by local authorities. Full article

In the United States, most urban areas are served by sewers and wastewater treatment plants, while septic systems remain common in rural regions, in lower-density communities, and in areas with lower levels of public services. The policy frameworks for septic system management are complex and variable, involving multiple key actors and levels of government and varying considerably from place to place. This research seeks to characterize the septic system management practices in two New York State watersheds: The first study area is located in central New York (the Lower Seneca River watershed) and comprises communities with greater reliance on surface water, and the second is in eastern New York on Long Island (Peconic Estuary Watershed), where groundwater is the primary source of drinking water. Since homeowner practices play a central role in outcomes, we also investigate homeowners’ understandings of their septic systems (also called onsite wastewater treatment systems, or OWTS). The methods used include policy analysis as well as qualitative research methods (interviews, focus groups, and survey research) to characterize homeowners’ perceptions and understandings, including their awareness of grant programs for septic system upgrades and replacement. The results show that most septic system owners hold only partial understandings of their systems. Their awareness of the connections between septic system management and groundwater protection is limited, with noted differences across watersheds. The study findings can inform future planning initiatives, as they illustrate the value of placing community water system understanding at the forefront of outreach efforts. Full article

Physicochemical and microbiological parameters are important indicators of drinking water quality. This study assessed the quality of groundwater used for drinking in four regions of Kosovo at 16 locations using an integrated assessment framework that combined physicochemical, microbiological, and Water Quality Index (WQI) approaches. The results reveal substantial spatial variability in water quality. While most physicochemical parameters remained within recommended limits, elevated values of total dissolved solids (up to 2792.5 mg/L), electrical conductivity (up to 2768.5 µS/cm), nitrate (up to 60.75 mg/L), and phosphate (up to 0.875 mg/L) were observed at several locations, indicating localized hydrogeochemical and anthropogenic influences. Dissolved oxygen levels were generally low (0.68–5.49 mg/L), reflecting limited aeration conditions in groundwater systems. Microbiological analysis revealed critical contamination, with Escherichia coli concentrations up to 299.9 CFU/100 mL, and all sampling sites exceeded permissible limits, indicating widespread fecal pollution and rendering the groundwater unsafe for direct consumption. WQI assessment further confirmed this condition, where 93.75% of locations were classified as medium quality using the NSF-WQI method, whereas the WA-WQI method categorized 68.75% of samples as poor and 6.25% as very poor. The novelty of this study lies in the integrated evaluation of hydrogeochemical processes and microbiological contamination using dual WQI methods and multivariate statistical analysis, providing a comprehensive understanding of groundwater degradation pathways. The findings are significant for policymakers, environmental managers, and public health authorities, highlighting the urgent need for groundwater treatment, improved sanitation infrastructure, and sustainable water resource management strategies in vulnerable regions. Full article

Coal resource exploitation may alter hydrogeological conditions and influence the occurrence and migration of coal-derived organic contaminants in mining regions. Among these contaminants, naphthenic acids (NAs) have received increasing attention, whereas their occurrence and environmental behavior in coal mining areas remain insufficiently understood. For the first time in an open-pit coal mining setting, this study systematically investigated the concentrations and molecular compositions of NAs in surface water, groundwater, and source-related water samples from the Shenfu Coalfield, a representative mining area in China. NAs were detected in all samples, with concentrations exhibiting clear spatial variability. Groundwater consistently contained substantially higher NA levels than surface water, and elevated concentrations in downstream river reaches coincided spatially with groundwater discharge zones, identifying groundwater as a key reservoir and transport pathway for NAs in the mining-affected watershed. Principal component analysis further revealed compositional similarities among groundwater, coal-washing wastewater, and certain surface-water samples, indicating contributions from both coal-bearing strata and coal-processing activities. These findings highlight the necessity of incorporating NAs into routine mine-water monitoring and groundwater protection programs in open-pit coal mining regions. Full article

Coal gasification slag (CGS) is rich in Si-Al-Ca components and thus has potential for ceramic utilization, but associated heavy metals may pose environmental risks. In this study, CGS from Yili (Xinjiang, China) was used as the major raw material (80 wt%), with clay and waste glass as additives, to prepare ceramsite by firing green pellets (8–12 mm) at 1000–1200 °C. The phase evolution, microstructure, and heavy-metal migration were characterized, and the leaching safety was evaluated. Increasing temperature leads to progressive quartz consumption, enrichment of feldspar-type crystalline phases, and liquid-phase sintering, which together enhance densification. The apparent density and single-particle compressive strength exhibit an “increase-then-decrease” trend with temperature and reach maxima at 1150 °C, where the compressive strength is 15.38 MPa. Heavy-metal behavior is element-specific: As and Zn show stronger volatilization, whereas Mn, Ba, Ni, and Cu are largely retained in the solid phase; Cr shows intermediate, temperature-dependent volatilization. After firing at ≥1150 °C, the leached concentrations of Cr, Mn, Ni, Cu, Zn, As, and Ba under the sulfuric acid–nitric acid test (HJ/T 299-2007) are below the Class III limits of the Chinese Groundwater Quality Standard (GB/T 14848-2017). Considering phase/structure evolution, mechanical performance, and short-term heavy-metal leaching, 1150 °C is identified as the preferred firing temperature in this work. Full article

At around 8:40 a.m. on 17 July 2024, the Wanshuitian landslide in the Three Gorges Reservoir Area (TGRA) experienced a deformation failure characterized by thrust load-caused deformations and high-speed sliding. Using geological surveys and unmanned aerial vehicle (UAV) photography, this study divided the Wanshuitian landslide area into five zones: sliding initiation (A1), secondary disintegration (A2), main accumulation (B1), right falling (B2), and left falling (B3) zones. Through monitoring data analysis and GeoStudio-based numerical simulations, this study revealed the mechanisms behind the landslide failure mode characterized by slope sliding approximately along the strike of the rock formation under the coupling effect of hydrological and geological conditions. The results indicate that factors inducing the landslide failure include the geomorphic feature of alternating grooves and ridges, the lithologic assemblage characterized by interbeds of soft and hard rocks, the slope structure with well-developed joints, and the sustained heavy rains in the preceding period. In the Wanshuitian landslide area, mudstone valleys are prone to accumulate rainwater, which can infiltrate directly into the weak interlayers of rock masses and soften the rock masses. Multi-peak rain events with a short time interval serve as a critical factor in groundwater recharge. Within 17 days preceding its failure, the Wanshuitian landslide experienced a superimposed process of heavy and secondary rain events with a short interval (four days). Rainwater from the first heavy rain event failed to completely discharge during the short interval, while the secondary rain event also caused rainwater accumulation. These led to a continuous rise in the groundwater table, a constant decrease in the shear strength of the slope, and ultimately the landslide instability. Since the landslide sliding in the dip direction of the rock formation was impeded, the main sliding direction of the landslide formed an angle of 88° with this direction. This led to a unique failure mode characterized by slope sliding approximately along the strike of the rock formation. Based on these findings, this study proposed characteristics for the early identification of the failure of similar landslides, aiming to provide a robust scientific basis for the monitoring, early warning, and prevention and control of the failure of similar landslides. Full article

During the excavation of tunnels in deeply buried underground hydropower stations, complex geological and construction conditions significantly increase the risk of sudden groundwater inflow, and the accuracy of groundwater inflow calculations remains low. This study takes the deeply buried underground powerhouse of a hydropower station as the engineering background and meticulously characterizes the underground powerhouse chamber group and its associated drainage facilities. On this basis, the study couples the geological model with the water flow model to systematically simulate the seepage field characteristics under complex conditions, including the pre-excavation, excavation, and operational phases. The water inflow at different parts of the powerhouse during the excavation phase is predicted. The results show that different rainfall conditions significantly affect the water inflow, with the inflow increasing as rainfall intensity rises. The maximum water inflow occurs in the storage reservoir area under heavy rainfall conditions, reaching 13,043.7 m³/d. During the operation phase, the external water pressure is greatly influenced by rainfall conditions, with the maximum pressure head of the water delivery pipeline from the underground powerhouse area to the reservoir section reaching 882.78 m under heavy rainfall. These findings provide a reference for future engineering construction. The results of this study offer theoretical and engineering references for groundwater inflow prediction and comprehensive control in deeply buried underground powerhouses under complex conditions. Full article