Search Results (855)

The groundwater resources are increasingly stressed in the Islamabad–Rawalpindi metropolitan area of Pakistan due to unplanned urbanization, growth of industries, and inadequate waste management. In this study, the aquifer vulnerability was evaluated in the productive alluvial zone of Islamabad Watershed using a Geographic Information System (GIS)-based DRASTIC model and critically comparing it with independent measured contamination of groundwater, which is a common weakness in many machine-learning-based DRASTIC studies considering the vulnerability index as the model input. The data from 21 boreholes supplied by the Capital Development Authority (CDA) were used to map seven hydrogeological parameters in ArcGIS Pro at a 30 m resolution. The DRASTIC Index values ranged from 69 to 188, with 12.9% of the mapped watershed (209.3 km²) being rated as Very High vulnerability, mainly in the shallow western urban alluvium where water tables are below 5 m. Single-parameter sensitivity analysis showed that the most influential factors of the index were impact of the vadose zone (S_i = 1.14) and depth to water table (S_i = 1.09). A Random Forest model was trained on independently measured nitrate instead of the DRASTIC Index, but had a poor predictive skill (cross-validated R² = 0.08), and the SHapley Additive exPlanations (SHAP) analysis suggested that increased vulnerability (shallow water table and high recharge) was correlated with lower nitrate concentrations. The inverse relationship between groundwater intrinsic vulnerability and measured nitrate was statistically significant when compared to 233 groundwater samples collected at the same locations during two different campaigns (2018 and 2024) (pooled Pearson r = −0.27, p < 0.001; Spearman ρ = −0.19, p = 0.007; Kruskal–Wallis H = 14.10, p = 0.003). Levels of nitrate in both Low and Moderate vulnerability zones (6.0 and 7.7 mg/L, respectively) were higher than in Very High zones (3.4 mg/L). The inverse direction was consistent across both campaigns and robustly significant in the 2024 dataset (ρ = −0.33, p < 0.001), which covered a wider contamination gradient; in the 2018 dataset, only the parametric test was significant. Nitrate showed no significant difference between land-use classes (H = 7.23, p = 0.065) and was found as a few individual high concentrations, suggesting that these were not diffuse loading issues or intrinsic susceptibility, but were likely influenced by point sources. These results show that intrinsic DRASTIC vulnerability is useful to identify areas vulnerable to potential future contamination, but does not explain the current distribution of contamination in this aquifer, which is influenced by point-source loading and residence-time effects. To provide effective groundwater protection, intrinsic vulnerability assessment must be complemented with specific monitoring of point sources. Full article

Water scarcity poses significant challenges to urban water management for long-term sustainability in hyper-arid regions. This study presents a longitudinal assessment of water demand and supply dynamics in Sharjah, United Arab Emirates, from 2016 to 2022 using operational data obtained from the Sharjah Electricity, Water and Gas Authority (SEWA). Temporal trends in water production, sectoral consumption, and source transitions were evaluated using descriptive statistics and operational performance metrics: Demand–Production Ratio (DPR), Operational Production Margin (OPM), Production Adequacy Index (PAI), Source Dependency Ratio (SDR), and Seasonal Variability Index (SVI). Results showed that Sharjah maintained a production capacity consistently exceeding billed consumption, with an average DPR of approximately 72% and a PAI of 1.0. Desalinated water became the dominant supply source (~90%), while groundwater reliance declined substantially to support aquifer conservation. The residential sector accounted for approximately 62% of total water demand, highlighting the importance of demand-side management strategies. Seasonal variability analysis indicated peak demand during summer months, while desalination capacity supported relatively stable supply conditions throughout the year. The findings provide localized empirical insights into urban water management, supply diversification, and long-term water security in a hyper-arid Gulf city. Full article

Daily groundwater-level prediction in arid inland basins is driven by complex meteorological–hydrological conditions, water supply, pumping, and irrigation demand. Using data from the Zhangye Basin (2018–2025), this study selected 10 representative wells from 51 candidates to build a one-day-ahead framework with a 60-day input window. Dempster–Shafer evidence theory fused five criteria (Pearson, Spearman, lagged correlation, mutual information, and tree-model importance) to screen external variables. Long short-term memory network (LSTM), temporal convolutional network (TCN), and Transformer served as first-level sequence models; extreme gradient boosting (XGBoost) as the second-level stacking learner; and SHapley Additive exPlanations (SHAP) to quantify feature contributions. Dempster–Shafer evidence theory (D-S evidence theory) results indicated that groundwater pumping proxy variable (GPV), irrigation water-demand intensity proxy variable (IWD), surface-water supply proxy variable (SWS), canal-diversion proxy variable (CDV), air temperature (AT), runoff, vapor pressure deficit (VPD), and canal irrigation supply–demand coupling intensity (CISDCI) exhibited high process-representation relevance. During the 90-day test period, Stacking achieved the lowest RMSE for six of 10 wells. Regional average RMSE, MAE, and NSE values were 0.1596 m, 0.0772 m, and 0.9326 for the Zhangye group, and 0.0185 m, 0.0133 m, and 0.9177 for the Gaotai group. SHAP showed historical groundwater-level data dominated contributions, accounting for 64.17% and 43.96% in the Zhangye and Gaotai groups, respectively, and indicating model dependence rather than direct hydrological causality. This framework provides a cautious reference for short-term groundwater forecasting and input selection under the given data conditions. Full article

Groundwater is a vital resource for drinking water supply, agriculture, and industrial activities. However, contamination by organic pollutants may pose significant threats to both ecosystem integrity and human health. This study assessed the environmental and human health risks associated with polycyclic aromatic hydrocarbons (PAHs) in groundwater collected from 27 localities in the central–northeastern Romanian Plain. The concentrations of naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, and indeno [1,2,3-cd]pyrene were determined using high-performance liquid chromatography coupled with fluorescence detection. Benzo[a]pyrene concentrations ranged from <LOD to 0.08 ng/L, while total concentrations varied between 2.56 to 11.2 ng/L. The environmental risk associated with groundwater contamination was classified as low to moderate, with total risk coefficients ranged from 0.2 to 2.3. Potential contamination sources were identified using the diagnostic ratio method, complemented by multivariate statistical analysis, indicating predominantly pyrogenic and mixed pyrogenic–petrogenic sources. Human health risk assessment indicated that groundwater ingestion posed neither non-carcinogenic risks (Hazard Index, HI < 1) nor unacceptable carcinogenic risks. The Incremental Lifetime Cancer Risk (ILCR) values ranged from 5.7 × 10⁻⁹ to 2.2 × 10⁻⁸ for infants, 2.7 × 10⁻⁹ to 1.0 × 10⁻⁸ for children, and 1.5 × 10⁻⁹ to 6.1 × 10⁻⁹ for adults. Full article

Unsafe water sources contaminated with fecal bacteria and antibiotic-resistant pathogens represent a critical public health challenge in rapidly urbanizing regions. This study investigates the occurrence, distribution, and antimicrobial resistance (AMR) patterns of Escherichia coli across interconnected water sources in Guwahati, India, including river water, wells, municipal supply, and groundwater. A total of 87 samples were analyzed using membrane filtration, biochemical identification, and automated confirmation, followed by antibiotic susceptibility testing and phenotypic detection of β-lactamase production. Total coliforms were detected in 64.4% of samples, while E. coli was confirmed in 51.7%. According to World Health Organization risk thresholds, 93.3% of river water samples and 50% of groundwater samples fell within the very-high-risk category (>1000 CFU/100 mL), indicating widespread fecal contamination in sources used for domestic purposes. Antibiotic-resistant E. coli was identified across all water types, with 14.1% of isolates exhibiting multidrug resistance (MAR index > 0.2). Notably, 20.6% of isolates produced β-lactamases, including one extended-spectrum β-lactamase (ESBL) producer, while no carbapenemase-producing strains were detected. The co-occurrence of multidrug-resistant E. coli across surface and groundwater systems is consistent with the interconnected nature of urban water contamination and suggests the potential for widespread exposure through drinking water pathways, though direct transfer between water systems was not experimentally confirmed in this study. These findings underscore the urgent need for improved wastewater management, protection of groundwater resources, and strengthened antibiotic stewardship within a One Health framework to mitigate the environmental dissemination of AMR. Full article

Pumped-storage hydropower (PSH) remains the main grid-scale energy storage technology in Europe, yet much of the fleet is ageing and requires periodic verification against current geotechnical standards. The Dychów plant (88 MW, western Poland), in service since the 1930s and classified as national critical energy infrastructure, has a documented history of surface mass movements, including a 1997 landslide on the frontal dam. To reassess its condition, two earthen sections were analysed: lateral section of the frontal dam of the upper reservoir and the embankment of the derivation channel. Electrical resistivity tomography (ERT) profiles, measured using a gradient array in 2023 and further detailed in 2024 along the same GNSS-fixed lines, imaged the internal structure of both sections. The resistivity cross-sections, verified against shallow control boreholes and archival geological data, supplied the geometry of the finite-element (FEM) models in ZSoil: the confirmed layer boundaries became the material zones, and piezometric observations set the groundwater boundary conditions. The safety factor SF was then computed with the shear-strength reduction technique for four calculation variants and two groundwater scenarios per section. The resulting SF equals 1.75 for the side section of the frontal dam area and ranges from 1.80 to 2.10 for the channel embankment. A parametric reduction in the friction angle of saturated medium sand gives limit values of φ = 12.3° (dam) and φ = 20.3° (embankment), which are clearly below realistic in situ values. Overall, both structures meet the SF ≥ 1.50 requirement for Class I hydraulic structures. The ERT-to-FEM workflow offers a non-invasive and repeatable tool for the periodic reassessment of ageing PSH infrastructure, which continues to balance variable renewable generation. Full article

Sustainable management of hydrogeological systems that supply water and exhibit high hydrologic complexity can be studied through pragmatic numerical modeling supported by field-constrained conceptualization. This study develops a local-scale three-dimensional groundwater flow numerical model using FEFLOW for the Barranca Lebrija settlement in Aguachica town, where the Lebrija River, the Musanda floodplain lake, and groundwater system converge. The numerical model incorporates: (i) the three-dimensional distribution of geological units and lithology; (ii) water level observations from the Musanda floodplain lake; (iii) stage records from the Lebrija River; (iv) boundary conditions and flux estimates inherited from a previous regional groundwater model; and (v) hydraulic heads from two monitoring wells and five community wells. Steady-state and transient conditions were calibrated, and a sensitivity analysis was performed to identify the parameters that most strongly control surface water–groundwater exchange. The simulations reproduce seasonal groundwater level trends and demonstrate the exchange pathways among the river, floodplain lake, and groundwater system. Results indicate dual behavior: during wet periods, flooding of the Musanda floodplain lake driven by high river levels seeps into the underlying aquifer, whereas in dry periods the floodplain lake reverses its role and becomes a principal discharge boundary. This local-scale, boundary-driven approach provides a computationally tractable framework to quantify SW–GW exchange in data-scarce tropical floodplains and supports monitoring design and water-supply management. Full article

Geothermal energy is a locally available, low-carbon resource that may support heat supply, building decarbonisation and regional energy diversification in non-volcanic crystalline settings. This study proposes an exploratory GIS-based approach for geothermal favourability mapping in the Guarda District, Central Portugal, where Hercynian granites, major fault systems and thermal and mineral water occurrences define a structurally controlled hydrogeothermal framework. Hydrogeochemical data from 54 groundwater abstraction points were integrated through silica-derived apparent geothermometric indicators, classical hydrothermal-parameter estimation and Empirical Bayesian Kriging Regression Prediction (EBKRP). Apparent silica-derived temperature indicators, circulation depth, geothermal gradient and theoretical thermal power were estimated, with log₁₀ transformed thermal power used as the dependent variable and distance to major mapped faults as the structural covariate. Apparent silica-derived temperature indicators range from 21.3 °C to 121.2 °C, with a mean of 64.6 °C, while estimated geothermal gradients range from 20.3 °C/km to 92.1 °C/km. Higher estimated values occur preferentially near NE–SW and NNW–SSE fault systems, suggesting that structural permeability may influence deep groundwater circulation. The interpretation explicitly acknowledges that, in low-temperature systems, dissolved silica may be influenced by chalcedony or amorphous silica control, as well as by cooling, mixing and incomplete re-equilibration during fluid ascent. The resulting map is interpreted as a screening-level favourability product, not as a definitive assessment of exploitable geothermal resources, and supports the prioritisation of future structural mapping, geophysical surveys, exploratory drilling, borehole temperature logging and applied geothermal assessment in fractured granitic terrains. Full article

Groundwater quality in arid and semi-arid regions is increasingly affected by salinization, evaporation, abstraction, and agricultural return flow. This study evaluates the hydrochemical evolution, isotopic characteristics, ²²²Rn activity, and water-use suitability of groundwater and associated waters in Karbala Governorate, central Iraq. Seventeen groundwater, lake water, and municipal supply water samples were analyzed for physicochemical parameters, major ions, δ¹⁸O, δ²H, and ²²²Rn. Hydrochemical, isotopic, and water-quality assessment methods were applied to evaluate groundwater evolution, salinization, and suitability for drinking and irrigation. The waters are near-neutral, with pH values of 6.18–7.35, but are strongly mineralized. Electrical conductivity ranges from 1440 to 16,305 µS/cm, and total dissolved solids (TDS) range from 592 to 10,191 mg/L. Most samples belong to a Ca–Mg–SO₄–Cl facies, indicating sulfate- and chloride-rich hard water evolution. The highest mineralization occurs near Karbala proper and lake-influenced sites. Ion ratios and chloro-alkaline indices indicate that evaporite dissolution, gypsum/anhydrite dissolution, carbonate interaction, evaporation, and local ion exchange jointly control groundwater chemistry. Stable isotopes indicate meteoric origin with variable evaporative enrichment; however, highly saline but isotopically depleted water, particularly W8, shows that evaporation alone cannot explain salinization. ²²²Rn activities range from below detection to 11.28 Bq/L and mainly reflect local aquifer contact and degassing. High TDS, sulfate, chloride, and very high hardness limit suitability for drinking-water use. For irrigation, the sodium hazard is low, but salinity, hardness, magnesium hazard, and permeability constraints make most samples unsuitable or restricted. Management should prioritize salinity and hardness control, treatment or blending before domestic use, restricted irrigation of the least saline wells under drainage and soil-salinity monitoring, protection of less mineralized recharge zones, and long-term monitoring of lake-adjacent and agriculturally influenced wells. Full article

We propose a quantitative, spatially explicit framework for assessing local self-sufficiency and resilience within the Water–Energy–Food (WEF) Nexus. The methodology introduces normalized, per capita indicators that quantify the degree of dependence on local versus external resources, explicitly incorporating physical availability, renewability, energy requirements, infrastructure, and land-use constraints. In contrast to conventional composite indices, the proposed framework adopts a non-compensatory structure, whereby deficiencies in one sector cannot be offset by surpluses in another, reflecting the physical constraints of the nexus. Indicator values range from 0 (complete dependence on external resources) to 1 (full local self-sufficiency) and are formulated dynamically, enabling comparison across existing conditions and alternative infrastructural or policy scenarios. The framework is applied as a proof of concept to a small rural settlement in North Euboea, Greece. The results indicate substantial potential for food and renewable energy self-sufficiency under optimized infrastructure configurations, while also revealing critical vulnerabilities associated with groundwater-dependent water supply and seasonal energy imbalances. The analysis further demonstrates how spatial proximity, energy–water coupling, and land-use competition jointly constrain achievable self-sufficiency levels, highlighting trade-offs that are often overlooked in sectoral or purely volumetric assessments. By explicitly linking resource flows with spatial proximity and infrastructural choices, the proposed indicators provide a robust and transparent tool for resilience-oriented planning under conditions of climatic, environmental, and systemic uncertainty. Full article

Urban water insecurity is an increasingly critical challenge in rapidly urbanizing regions of the Global South, driven by population growth, environmental degradation, infrastructure limitations, and institutional constraints. Kathmandu Valley, Nepal, exemplifies these interconnected pressures. This study presents a systematic review of 45 peer-reviewed and selected grey literature sources published between 2000 and 2025, conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were included if they examined drinking water contamination, public health risks, household coping practices, wastewater-related exposure, or governance dynamics in Kathmandu Valley, Nepal. Findings were synthesized using a narrative thematic approach. The review identifies widespread contamination across municipal supply systems, groundwater, tanker water, traditional water sources, and household-stored water. Microbial contamination, particularly total coliforms, fecal coliforms, and Escherichia coli, emerged as the most consistently reported and immediate public health concern. Chemical and physicochemical contaminants, including ammonia, iron, arsenic, nitrate, and turbidity, were also widely reported, especially in shallow and deep groundwater systems. Seasonal dynamics further influenced exposure risks, with increased microbial contamination during monsoon periods and greater dependence on alternative and less regulated water sources during dry seasons. The findings further indicate that unsafe water exposure is associated with a substantial burden of waterborne diseases and emerging risks such as antimicrobial resistance. Although household water treatment practices reduced contamination in some cases, risks often persisted due to recontamination during storage and handling. These burdens disproportionately affected marginalized and peri-urban populations with limited access to safe and reliable water infrastructure. The review also highlights persistent governance challenges, including institutional fragmentation, weak regulatory enforcement, inadequate infrastructure investment, and growing dependence on informal water supply systems. Together, these conditions contribute to a hybrid urban water system in which formal and informal sources coexist without consistent quality control. Overall, the evidence demonstrates that water insecurity in Kathmandu Valley is a systemic condition shaped by the interaction of environmental contamination, unequal exposure, household coping limitations, and fragmented governance. By integrating environmental, public health, and governance evidence, this review advances understanding of urban water insecurity in rapidly urbanizing contexts and highlights the need for integrated, equity-oriented, and governance-informed interventions. These findings have broader relevance for cities across the Global South experiencing similar environmental and infrastructural pressures. Full article

Groundwater resources are essential to global freshwater supply, and accurate groundwater level prediction is critical for sustainable water resource management. To overcome the limitations of traditional deep learning models in long-sequence groundwater forecasting, including weak generalization, reduced long-term prediction accuracy, and limited interpretability, this study proposes a dual-path Informer-p model integrated with residual theory. The main path captures nonlinear temporal dependencies and long-term hydrological patterns, while the residual path provides a stable linear prediction baseline to enhance local fluctuation representation and robustness to extreme events. The model was validated using long-term groundwater observations from 34 monitoring stations across five major ecosystems in China. Results from representative stations, including Ailao Mountain, showed that Informer-p achieved excellent predictive performance with RMSE = 0.05 m, MAPE = 1.2%, R² = 0.95, and KGE = 0.95, reducing RMSE and MAPE by 37.5% and 52%, respectively, compared with the original Informer. Across all stations, Informer-p outperformed the original Informer at 22 stations, with the greatest improvement observed in forest ecosystems. SHAP analysis identified window maximum, original groundwater level, and window minimum as the dominant predictive features. The proposed model provides an effective tool for national-scale groundwater level prediction and sustainable groundwater management. Full article

Small decentralized water supply systems are often sensitive to local pollution and require a clear understanding of recharge conditions and the hydrodynamics within the water resource catchment. This study develops a conceptual hydrogeological model for the Šmarna Gora area based on geological mapping, long-term monitoring of chemical parameters, and stable isotope analyses (δ¹⁸O, δ²H) of precipitation and groundwater. The study was initiated in response to rising pollutant concentrations in the drinking water. Estimates of transit time (TT) and mean residence time (MRT) were used to characterize recharge, mixing processes, and differences between the SG and ZAVRH wells, the existing and alternative water supply wells. Isotope data show that the aquifer is predominantly recharged during colder periods and that Mediterranean air masses have become an increasingly important source of precipitation, suggesting a shift in precipitation patterns. The results indicate that SG has longer TT (6–8 months) and MRT (up to 1–2 years). In contrast, ZAVRH shows shorter TT and MRT (4–6 months), and lower pollutant concentrations. The hydrogeological regime in the catchment of the ZAVRH well is characterized by a dynamic, fast-flowing system with limited storage and more intensive dilution of contaminants by infiltrating water, whereas the catchment of the SG well functions as a deeper and more buffered aquifer with prolonged groundwater residence and a more direct hydraulic linkage to the contaminant source. The findings distinguish two hydrogeological regimes and provide a basis for planning water supply solutions and protection measures. Full article

Disinfection of drinking water prevents waterborne diseases but can lead to the formation of trihalomethanes (THMs), which are linked to an increased risk of cancer. This study examined the association between water source allocation and THM levels in Israel. A retrospective analysis of water quality reports, published by the Israeli Ministry of Health, was conducted, including only samples collected from the water distribution system between 2015 and 2024. To assess temporal and geographic variability, monthly and annual averages were calculated. Trends were evaluated using interrupted time series regression. Overall, 16,268 samples were included, with a study-wide mean THM level of 30.41 µg/L, mainly due to Bromoform. Elevated THM levels were observed in northern districts, particularly before 2020, with seasonal peaks in the summer months. After 2020, as surface water utilization increased, THM levels also rose in central Israel, with no discernible seasonal pattern. Southern regions, supplied mainly by desalinated water, showed consistently low levels. This analysis indicates that the water source influences THM formation, as increased surface-water use is associated with higher THM concentrations. Mixing surface and groundwater with desalinated water may reduce exposure in areas with high THM levels, highlighting the need for informed water management policies. Full article

Reliable surveillance of dissolved ²²²Rn in arid-region aquifers is challenged by very low natural activity and method-dependent biases, especially humidity sensitivity in electrostatic detectors and air–water partitioning during closed-loop aeration, which can obscure true concentrations needed for defensible drinking-water baselines under preventive frameworks. This study aimed to optimize and field-validate a low-background RAD7 Big-Bottle (RAD H₂O) closed-loop protocol tailored for arid conditions and apply it in a regional survey of groundwater used for potable supply in northeastern Saudi Arabia. Groundwater from wells across the region (shallow and deep completions) was collected and analyzed using isotope-resolved alpha spectroscopy (Po-218 and Po-214 windows) with strict chamber humidity control (≤7% RH), background checks, systematic blanks, duplicates, drift control (±10%), and uncertainty propagation. Air-phase chamber counts were mandatorily converted to water-phase activity using the CAPTURE parameterized by measured loop volumes, temperature, salinity, and humidity, and agreement was evaluated using regression diagnostics and Bland–Altman analysis. The optimized method achieved sub-Bq·L⁻¹ performance, with MDL improving from ~0.1645 Bq·L⁻¹ (30 min) to ~0.0233 Bq·L⁻¹ (1500 min) and ~0.0165 Bq·L⁻¹ (3000 min), and LOQ decreasing from ~0.50 to ~0.0707 and ~0.050 Bq·L⁻¹, respectively. Raw air-phase readings systematically overestimated dissolved radon by ~26% (slope ≈ 1.26), a bias removed by the validated air → water conversion. Surveyed ²²²Rn concentrations were uniformly low (0.03–3.20 Bq·L⁻¹), far below commonly used reference values (e.g., ~11.1 and ~100 Bq·L⁻¹), with no persistent spatial hotspots and broadly overlapping shallow/deep distributions, indicating variability dominated by local lithology and fracture-controlled flow rather than depth. A tiered monitoring scheme is recommended: short screening, routine baselining at ~900–1500 min total counting, and ~3000 min for ultralow verification, providing a transferable template for sustainable baseline programs in arid aquifers. Full article