Search Results (537)

With the implementation of the Western Development Strategy and the Belt and Road Initiative, engineering activities on the Loess Plateau have expanded substantially in both scale and depth. Consequently, the disintegration of Lishi loess, which has received relatively limited attention, has become an increasingly important concern in relation to geological hazards and engineering stability. This study investigated the disintegration behavior of remolded Lishi loess specimens with different initial water contents under controlled dry-density conditions and developed a mathematical model to characterize the disintegration process. In addition, three-dimensional particle flow code (PFC3D) simulations were performed to provide a particle-scale mechanical interpretation of the observed behavior. The experimental results showed that the disintegration curves of the specimens exhibited a typical asymmetric S shape at all tested initial water contents. The Gompertz model provided a compact empirical description of these curves, with coefficients of determination ranging from 0.993 to 0.999. In the model, α denotes the upper asymptote of the disintegration curve, λ characterizes the growth-rate behavior, and β represents the characteristic time associated with the inflection point. These parameters should be interpreted as empirical descriptors of the disintegration process rather than direct measures of the microscopic properties of loess. Although the model closely reproduced the experimental curves, further validation using independent datasets is required before it can be applied predictively to other specimens or test conditions. The PFC3D simulations provided an equivalent mesoscopic representation of contact-network weakening, bond breakage, and progressive particle detachment at different initial water contents. The simulated evolution qualitatively reproduced the progression from boundary-particle detachment to the gradual loss of specimen integrity and final particle accumulation. These findings characterize the water-content-dependent disintegration behavior of remolded Lishi loess and provide a preliminary basis for understanding the water sensitivity of disturbed or reworked Lishi loess in engineering applications. Full article

To improve the practicality of water-inrush hazard identification in underground metal mines under complex hydrogeological conditions, this study develops a multi-source information fusion evaluation framework. An index system is established that encompasses water-source conditions, water-conducting pathway characteristics, mining-induced disturbance, and goaf-related hazards. Subjective and objective information are integrated through combined weighting based on the intuitionistic fuzzy analytic hierarchy process (IFAHP) and the entropy weight method (EWM). To characterize uncertainty and support hazard classification, a normal cloud model is introduced. The proposed method is applied to three stopes, namely 150701, 200-6-1, and 400-27-3, in a copper–iron mine in Anhui Province. The evaluation results classify the three stopes as Level III, Level II, and Level IV, respectively, which are consistent with the observed water inflows of approximately 28 m³/h, 17 m³/h, and 35 m³/h. These results indicate that the proposed method shows applicability in stope-scale water-inrush hazard assessment in the case mine and can provide a quantitative reference for risk identification and prevention under complex hydrogeological conditions. Full article

The height of a water-conducting fractured zone (WCFZ) is directly related to the design of water-preserved coal mining and water-hazard risk assessment in ecologically fragile mining areas in western China. Existing empirical formulas have limited regional adaptability, and individual machine learning models may show insufficient stability under small-sample and nonlinear data conditions. To address this issue, a heterogeneous Stacking ensemble prediction framework was constructed based on measured data from the Yushen mining area. Mining thickness, working face length, mining method, burial depth, coal seam dip angle, and hard strata proportion coefficient were selected as input variables. The base layer consisted of support vector regression (SVR), classification and regression tree (CART), random forest (RF), extreme gradient boosting (XGBoost), and back-propagation neural network (BPNN), while Ridge regression was used as the meta-learner. Under the current data split, the test set R², RMSE, MAE, and MAPE of the Stacking model were 0.953, 10.99 m, 8.79 m, and 9.847%, respectively, indicating overall superiority over individual models and other ensemble configurations. The field validation results showed that the relative errors of the model for boreholes LD-1 and LD-2 in the fully mined area were 1.99% and 1.28%, respectively; however, an overestimation of 52.70% occurred for LD-3 in the coal-pillar-adjacent area. This indicates that the model is more suitable for the regional-scale screening of the maximum fractured-zone height and should not be directly used for fine-scale prediction in local boundary-affected zones. SHAP analysis showed that mining thickness, working face length, and hard strata proportion coefficient were the main influencing variables, and their response trends were generally consistent with key-strata control and the transition toward full-mining conditions. This study provides a reference for the rapid prediction of WCFZ height and preliminary evaluation of water-preserved coal mining in weakly cemented mining areas in western China. Full article

Understanding the dynamic evolution of pore and fracture structure (PFS) in coal under mining disturbance is essential for safe coal extraction. In this study, coal specimens collected from the Dongqu Mine, Taiyuan, Shanxi Province, China, were subjected to stepwise cyclic confining pressure loading–unloading tests using a triaxial in situ nuclear magnetic resonance (NMR) system. Based on T₂ spectrum measurements, the real-time evolution of PFS, stress–strain response, permeability-related behavior, average pore diameter, and fractal characteristics were systematically investigated. The results show that irreversible damage developed in the coal specimens during cyclic confining pressure loading–unloading. With increasing cycle number, the load-bearing capacity gradually decreased, internal damage intensified, and pore expansion and coalescence became more pronounced. Seepage pore porosity showed an overall increasing trend, indicating a gradual enhancement of inferred permeability. Therefore, seepage pore porosity can be used as an effective indicator for evaluating permeability-related evolution in coal. During both loading and unloading stages, the relative volumes of small pores (SP), medium pores (MP), and large pores and fractures (LPF) continued to increase, whereas their average pore diameters fluctuated. This indicates that pore volume growth was controlled not only by the enlargement or shrinkage of pre-existing pores but also by new PFS generation. Fractal analysis showed that the fractal dimensions of MP, LPF, and total pores exhibited clear scale-dependent evolution, whereas the calculated SP fractal dimensions were lower than 2 and were therefore not suitable for pore-surface fractal interpretation. Among the valid pore systems, LPF exhibited the highest fractal dimension, indicating that LPF dominate the structural complexity of coal. These findings provide new insight into the fractal evolution of unloading-induced PFS damage and offer theoretical support for mitigating gas outburst and water inrush hazards during coal mining. Full article

Less attention has been paid to soils with potentially toxic elements (PTEs) below agricultural land risk screening values, even though they continue to accumulate these elements. In this study, four typical areas in Ningxia were selected to determine the concentrations of cadmium (Cd) and arsenic (As) in 176 samples collected from 130 sampling sites across seven matrices. A refined mass balance model was developed by partitioning irrigation input into suspended-solid and supernatant phases and crop removal into grain and straw components. The model was used to analyze the contributions of various input and output factors and to predict future soil Cd/As concentrations and their related health risks via soil exposure. The input fluxes of Cd and As in the four regions ranged from 1.31 to 3.25 g·ha⁻¹·yr⁻¹ and 71.43 to 146.99 g·ha⁻¹·yr⁻¹, respectively, mainly contributed by irrigation water (40~64%), especially suspended solids in irrigation water, and atmospheric deposition (23~40%). The output fluxes of Cd and As were 0.89~1.43 g·ha⁻¹·yr⁻¹ and 13.81~33.86 g·ha⁻¹·yr⁻¹, respectively, dominated by crop harvesting (36~82%). The differences in input and output fluxes were mainly caused by the regional industrial structure and agricultural planting structure. The predicted results showed that soil Cd and As concentrations in all regions would not exceed regulatory limits after 100 years in the current scenario. A health risk assessment based on soil ingestion, dermal contact, and inhalation showed that the hazard indices for Cd and As were negligible, but their total carcinogenic risk reached notable levels. Over time, Cd-specific carcinogenic risk for children increased in several scenarios and transitioned from negligible to notable risk, with soil ingestion being the dominant exposure pathway. According to the results, targeted mitigation strategies, including the regulation of atmospheric deposition, optimization of irrigation water quality, and adoption of straw off-field practices, show potential to effectively limit the accumulation of potentially toxic elements in agricultural soils. Full article

Climate change is intensifying hydrological extremes, yet most frameworks assess drought and flood hazards independently, limiting integrated risk management. This study proposes a two-dimensional analytical framework to characterize the drought-flood continuum, moving beyond single-index approaches. We introduce the Hydro-Hazard Index (HHI) as a directionality metric (HHI = Flood Severity − Drought Severity) to classify the dominant hazard type, and the Total Severity Index (TSI = Flood Severity + Drought Severity) as a complementary metric to quantify overall hazard magnitude. Analyzing multi-temporal data from 115 hexagonal units (2018–2024), we employed dynamic features (trends, changes, volatility) and four machine learning models to classify areas as “flood-prone” based on validated flood records. Our results show HHI values ranging from −2.44 to 8.81, with 20.9% of areas classified as Flood-Dominated (mean HHI = 4.58) and 79.1% as Normal (mean HHI = 0.76). Crucially, the two-dimensional analysis revealed that areas with identical HHI values can have vastly different TSI values, under scoring the importance of our dual-index approach. Random Forest achieved the highest performance in predicting flood-prone status (Accuracy = 0.913, AUC = 0.967, Recall = 1.00), with flood_volatility as the most important predictor (24.2%). Spatial autocorrelation confirmed strong clustering of high-risk areas (Moran’s I = 0.716, p < 0.001). By analyzing flood and drought as distinct but interacting dimensions, this framework provides a more robust and nuanced tool for integrated risk assessment. While acknowledging limitations related to data availability and the need for further independent validation, the proposed framework supports sustainable water resource management and climate adaptation planning under increasing hydrological uncertainty. Full article

This research addresses the critical safety issue of harmful gas influx during tunnel excavation through unconventional gas-bearing structures. It focuses on six tunnels affected by shale gas influx along the Zhangnan Expressway of northwestern Hunan, China. The research reveals the geochemical characteristics, distribution patterns, and accumulation mechanisms of harmful gas in the shale formations of northwestern Hunan. The research adopts an integrated approach of “geological background analysis—multi-parameter testing—comprehensive evaluation”. It is based on geological and borehole data, field geological surveys, as well as laboratory and field tests. The research systematically analyzes the gas-bearing structural characteristics, geochemical parameters, and reservoir physical properties of the shale gas area in the Zhangnan Expressway. The geological regularities are summarized. The results show that the Longmaxi Formation of the Silurian system and the Qixia Formation of the Permian system serve as source rocks in the tunnel sites. The reservoirs are characterized by ultra-low porosity and permeability, with limited late-stage hydrocarbon generation potential. The gas-related hazard during tunnel construction and operation is primarily associated with the release of existing free and adsorbed gas. According to the calculation standards for absolute gas emission rates during construction, three tunnels are classified as micro-gas tunnels and three as non-gas tunnels. Two accumulation patterns are proposed: the self-sourcing composite accumulation pattern with micro-scale migration, and the accumulation pattern of self-generated and self-storage type of water pressure confinement. Enhanced monitoring, ventilation, and grouting sealing are recommended. This study develops an integrated “geology—testing—evaluation” assessment method for shale-gas-bearing tunnels. It provides important guidance for controlling harmful gas hazards in such tunnels and guaranteeing the sustainable development of tunnel construction. Full article

Background: Climate change is increasingly recognised not only as an environmental emergency but also as a structural determinant of health and health-system performance. Its clinical consequences will not be distributed evenly: high-income countries face rising heat mortality, infrastructure fragility, ageing-related vulnerability, and the need to decarbonise technologically intensive care; middle- and low-income countries face heterogeneous but often more compressed combinations of heat, infectious disease, food insecurity, water stress, displacement, conflict-related fragility, and limited fiscal capacity. Objective: This structured narrative review proposes a comparative framework for understanding how climate change will transform health care across high-, middle-, and low-income settings and identifies adaptation priorities that are resilient, equitable, and low-carbon. Methods: We synthesised major climate-health assessments, peer-reviewed epidemiological studies, modelling papers, systematic and scoping reviews, and health-system decarbonisation literature identified through targeted searches and reference chaining. Five climate-health pathways, specified a priori from established direct, indirect, and socially mediated pathway frameworks, were used to organise the review. Findings: Climate change will reshape health care through five interacting pathways: direct thermal injury and extreme-weather mortality; altered infectious disease ecology; food, water, and nutritional insecurity; mental, maternal-child, and occupational impacts; and damage to the infrastructure, workforce, supply chains, finances, and emissions profile of health systems. In high-income countries, climate stress exposes the limits of hospital-centred, carbon-intensive, just-in-time care. In middle-income countries, expanding coverage and technology coexist with uneven insurance, large informal workforces, and rapidly growing emissions. In low-income and fragile settings, the same hazards interact with undernutrition, weak surveillance, under-resourced primary care, and constrained finance to produce larger marginal health losses. Conclusions: The central contribution is the concept of the climate-health divide: the unequal conversion of shared climate hazards into clinical demand, service disruption, financial stress, and emissions-intensive responses. Climate resilience and healthcare decarbonisation should therefore be designed together rather than treated as separate agendas. Full article

Large deformation runout is a key factor in assessing the hazards posed by underwater landslides. However, conventional kinematic analyses often neglect both the progressive degradation of slope materials and the hydrodynamic response accompanying the interaction between the moving mass and the overlying water. Taking the well-documented St. Niklausen underwater landslide as a representative case, this study employs a coupled Eulerian–Lagrangian (CEL) model to investigate the earthquake-triggered initiation, large deformation movement, and hydrodynamic response of the landslide. A Python 2.7.15-based stress mapping method is developed to establish an accurate initial geostatic stress field for the irregular slope profile. The numerical model reproduces the principal stages of landslide initiation, runout, and deposition. The results reveal a progressive retrogressive failure mechanism in which successive sliding masses interact through a high-strength compression zone. The rear sliding mass continuously transfers compressive work to the frontal mass, thereby maintaining its downslope movement and indirectly promoting basal erosion to a maximum depth of approximately 6.2 m. In addition, rapid landslide motion generates pronounced vortical flow in the overlying water. These flow structures reflect the hydrodynamic response induced by landslide motion, although their net influence on basal resistance and final runout cannot be isolated from the present coupled simulation. These findings clarify the internal mechanical evolution of underwater landslide movement and characterize the accompanying hydrodynamic response, providing a methodological basis for assessing landslide mobility and related underwater hazards. Full article

Desertification is a serious environmental challenge in regions with desert landscapes, such as the Khorezm Oasis in the Republic of Uzbekistan. Low precipitation rates and shortages of irrigation water have driven dynamic changes in desert-related land use and land cover (LULC) classes, threatening environmental and food security. This study aims to assess desertification safety levels in the Khorezm oasis using geospatial technologies to better understand spatiotemporal dynamics and to support sustainable agricultural management. A multi-criteria decision-making (MCDM) approach was used for desertification assessment. Annual mean values of key indicators—land surface temperature, vegetation index, groundwater (GW) depth, wind speed, soil erodibility (K-factor), precipitation, normalized enhanced sand index, maximum air temperature, and LULC classes—were analyzed for the period 2000–2023. The results indicate that the normalized enhanced sand index and LULC classes exert the strongest influence on desertification processes. Areas classified as high to very high desertification hazard are predominantly concentrated in the Republic of Karakalpakstan, covering a total area of 2345.65 km². Ongoing water shortages in the Amu Darya River basin pose a significant risk of further expansion of desertified areas. The findings provide valuable insights for regional land management and desertification mitigation planning. Full article

Mediterranean islands face increasing climate risks from rising temperatures, prolonged droughts, extreme precipitation, and sea-level rise, while seasonal tourism intensifies water and energy demand during the most vulnerable periods of the year. This study examines whether incorporating tourism as an intrinsic component of the Water–Energy–Food nexus changes the assessment of climate risks in desalination-dependent island water systems. To address this question, the Water–Energy–Food (WEF) nexus is extended to Water–Energy–Food–Tourism (WEFT) and integrated into an EU-aligned Climate Risk and Vulnerability Assessment framework. The approach is applied to the Hermoupolis Water Supply System on Syros Island, Greece, where potable water supply depends largely on energy-intensive desalination. A technically bounded climate risk assessment is compared with a WEFT-adjusted assessment that accounts for tourism-driven demand amplification and water–energy interdependencies while keeping hazard exposure and likelihood climate-driven. The results show that heatwaves constitute the dominant near-term risk because they coincide with peak water demand and high electricity requirements for desalination. When tourism amplification is included, drought-related risks shift from medium to high already in the near future for key production and pumping components, indicating earlier emergence of critical risk conditions without changes in hazard probability. Coastal risks become more important toward the end of the century, especially under high-emission scenarios. The main contribution of the study is to show that tourism-driven amplification can be operationally incorporated into sensitivity and impact assessment while preserving comparability with a conventional CRVA. The proposed WEFT–KTM framework provides a transferable basis for assessing and prioritizing adaptation in desalination-dependent, tourism-driven Mediterranean island systems. Full article

Groundwater quality remains insufficiently characterized in the rural agriculture–residential interface of the Huaibei Plain, particularly with respect to nitrate (NO₃⁻) occurrence, hydrochemical controls, source contributions, and population-specific health risks. In this study, multivariate statistical analysis, source apportionment models, and health risk assessment models were applied to investigate the hydrochemical characteristics of groundwater and related non-carcinogenic risks to different populations. NO₃⁻ content exceeded the World Health Organization (WHO) guidelines for drinking water in 60.0% and 62.5% of wet- and dry-season groundwater, respectively. Groundwater NO₃⁻ was mainly influenced by agricultural non-point inputs and domestic sewage, whereas major-ion composition was primarily governed by water–rock interactions. Our deterministic health risk assessment model reveals that the hazard index (HI) exceeded the acceptable threshold of 1.0 in 76.25%, 65.00%, 66.25%, and 56.25% of groundwater samples for infants, children, adult females, and adult males, respectively. These results indicate that continuous monitoring, improved sewage collection, and more controlled nitrogen management are required in the rural agricultural–residential interface of the Huaibei Plain with regard to shallow domestic groundwater. Full article

Rainfall variability strongly influences both flood and drought hazards, especially in climatic transition zones where precipitation is highly seasonal and spatially heterogeneous. This study assessed long-term changes in rainfall patterns and compound flood–drought hazard in the Huaihe River Basin, China, using ERA5-Land-derived daily precipitation series at 174 spatial sampling locations during 1950–2025. Rainfall pattern indicators, flood-related rainfall extremes, and SPI-3-based drought indicators were calculated to characterize rainfall amount, frequency, intensity, dry–wet persistence, heavy rainfall events, and meteorological drought conditions. The Mann–Kendall test and Sen’s slope estimator were used to detect long-term trends, and a compound flood–drought hazard classification framework was developed based on a flood-related rainfall hazard index (FHI) and a drought-related hazard index (DHI). The results showed that annual total precipitation, wet days, and consecutive wet days decreased significantly, indicating reduced rainfall occurrence and wet spell persistence. Flood-related rainfall indicators generally showed decreasing tendencies, with more evident declines in persistent multi-day extremes than in single-day rainfall. In contrast, mean SPI-3 showed a significant drying tendency, although drought frequency, severe drought frequency, and drought intensity did not exhibit significant monotonic trends. Spatially, rainfall pattern, flood-related, and drought-related indicators showed clear heterogeneity across the basin. The compound hazard classification identified flood-dominated and drought-dominated areas as the two major hazard types, each accounting for 31.03% of the spatial sampling locations, while low compound hazard and compound flood–drought hazard areas each accounted for 18.97%. These findings indicate that flood- and drought-related hazards coexist but vary spatially across the Huaihe River Basin. The proposed framework provides preliminary rainfall-based information for differentiated flood–drought hazard assessment, climate-adaptive water resources planning, and the sustainable management of water resources in regions facing spatially heterogeneous hydroclimatic hazards. Full article

Evaluating grouting effectiveness in deep shafts remains difficult because water-control performance is jointly governed by hydraulic response, seepage-path sealing, grout-body quality, and surrounding rock stability under complex hydrogeological conditions. In this study, an integrated evaluation and seepage analysis framework was developed for the Lianhuashan Phosphate Mine shaft project in Zhongxiang City, Hubei Province, China. Multi-source engineering data from hydrogeological observations, geophysical detection, construction records, and laboratory tests were used to evaluate six representative working faces, and a two-dimensional Darcy flow model was established to interpret the seepage-control mechanism. The evaluation results show differences among the treated sections: the auxiliary shaft at the −29.8 m outlet achieved the highest comprehensive score of 74.79, whereas the main shaft at +13 m showed the weakest performance, with a score of 50.16. Overall, three sections were rated as good, two as moderate, and one as poor. The dominant controls on grouting effectiveness are total shaft inflow, surrounding rock integrity/stability, seepage point number, and sealing-related indices. Numerical simulations further show that grouting reduced total shaft inflow from 6.6080 to 2.0198 m³/h, corresponding to a reduction of 69.43%, and shifted the main hydraulic-gradient concentration from the shaft wall to the outer boundary of the grouted ring. Reducing grouting ring permeability from 5.10 × 10⁻¹³ to 1.00 × 10⁻¹⁴ m² further lowered shaft inflow to 0.2929 m³/h and increased water-control efficiency to 95.57%, whereas increasing ring thickness from 8 to 16 m reduced shaft inflow from 2.7063 to 1.7260 m³/h. In addition, moving the water-rich zone away from the shaft reduced total inflow from 2.5503 m³/h at X_f = 10 m to 2.0079 m³/h at X_f = 26 m. These results indicate that effective shaft grouting depends on the coordinated control of inflow suppression, conductive-path sealing, and structural stabilization. The proposed framework provides a practical basis for grouting evaluation and water hazard control in deep shafts under complex hydrogeological conditions. Full article