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The reactivation mechanism of multi-slide landslides entails high complexity, and the shear mechanical properties of high groundwater-level landslides are crucial for analyzing the formation mechanism of reactivated landslides. Taking the K39 landslide of Wenma Expressway in Yunnan Province as the research object, we identified the geological and hydrogeological conditions of the landslide, the physical and mechanical properties of the slip zone soil, and the landslide deformation law using geological mapping, geotechnical engineering, indoor testing, and in situ monitoring. The results show the landslide exhibited alternating acceleration and deceleration movements under seasonal heavy rainfall and high groundwater levels. The shear strength of the soil in the deep sliding zone was greater than that of the soil in the shallow sliding zone. The deep and shallow sliding zone soils showed a decrease in shear strength with increased water content. Moreover, the residual strength of the deep sliding zone soil displayed a negative rate with an increased shear rate. In contrast, the residual strength of the shallow sliding zone soil exhibited a positive rate. Furthermore, under different shear rates, the residual internal friction angle and cohesion of the deep sliding zone soil decreased with increased water content, whereas only the residual internal friction angle of the shallow sliding zone soil followed this pattern. Finally, we performed a sensitivity analysis using the GA-BP neural network for the ring shear test parameters of the deep and shallow sliding zone soils, which included consolidation pressure, water content, and shear rate. Our analysis revealed that the residual strength of deep sliding zone soils is most affected by water content, whereas the residual strength of shallow sliding zone soils is most affected by consolidation pressure. Furthermore, it was found that the effect of water content on residual strength is much greater than the effect of shear rate on residual strength for both deep and shallow sliding zone soils. The study results contribute to a unified understanding of how shear rate affects residual strength mechanisms, support research on shear mechanical properties for multiple landslide revivals, and inform engineering practices and policies in landslide-prone areas. [ABSTRACT FROM AUTHOR]

The potential for static liquefaction of tailings is a major focus in the design and operation of tailings storage facilities. This research models the behaviour of unsaturated tailings, with a variety of degrees of saturation, addressing the propensity for static liquefaction during monotonic loading. Unsaturated triaxial tests, including constant suction conditions and constant water–air mass conditions, were performed. A bounding surface plasticity model was used to simulate the results. The constant mass condition is relevant to undrained closed-system loading, which may prevail during fast deformation after the tailings becomes unstable, when the air and water in the pore space remain locked inside the tailings. Boyle's law and hydraulic hysteresis were accounted for to model the changes of pore air and water pressures, and suction, with the change in tailings volume. Good agreement was achieved between test results and model simulations. Additional simulations to mimic rising water tables under constant total stress states in the field, situations that may trigger instabilities, are also shown. Results are added to charts which relate peak and post-liquefaction strengths, as well as collapse lines, to measures of initial state, for unsaturated conditions, which may be of use in practice. [ABSTRACT FROM AUTHOR]

The aim of the study was to analyse precipitation, subsurface runoff and concentrations of nutrients in water (NH4 +- -N, NO3 --N and PO4 3- ions). The study was conducted at the lysimetric station in Jaworki (Małe Pieniny, Nowy Targ district, Malopolska province, 600 m a.m.s.l.). Measurements were carried out during vegetation periods, from April to September. The paper consists of an analysis of data in two periods - 2001-2018 and 2019-2022. Data in the historical years (2001-2018) showed that water quality as well as its quantitative variability was low, mainly until 2015. The year 2018 indicated slow changes in this regard. Analysis of the years 2019-2022 indicated that the outflow was almost identical. The years 2019 and 2022 were characterized by significantly higher leachate concentrations. Ammonium ion contents were similar. Analysis of nitrate ions in leachate showed an increasing trend over the years. Phosphates, on the other hand, showed a similar trend to nitrate ions. The study showed which types of land use have the greatest impact on both subsurface runoff volume and leachate water quality. In mountainous conditions, the type of use, as well as the climate and soil, have an extremely significant impact on the volume and quality of runoff, which affect the quality of groundwater and surface water. [ABSTRACT FROM AUTHOR]

Organic compounds pose significant environmental concerns, including groundwater contamination. Clays are commonly used as liners to prevent contaminant permeation into the groundwater tables, necessitating an understanding of clay's behavior in the presence of organic compounds. The presence of organic contaminants results in changes in the dielectric constant of pore fluid, which influences the interparticle energies and double layer thickness in the soil-pore fluid system. This study aims to elucidate the mechanisms of these changes by examining the response of smectite and kaolinite to variations in the dielectric constant. Experimental tests, including Atterberg limits, unconfined compression strength, water adsorption, sedimentation, pH, and XRD, were performed on clay samples at different concentrations of water-isopropyl alcohol mixtures. Results indicate that smectite exhibits higher Atterberg limits and water adsorption capacity compared to kaolinite. Smectite also shows more pronounced changes in response to decreasing dielectric constant. Conversely, changes in kaolinite's behavior were attributed to variations in pore fluid viscosity and dipole moment. These findings emphasize the importance of considering viscosity and dipole moment alongside dielectric constant in predicting kaolinite behavior. Overall, this study enhances the understanding of how variations in pore fluid dielectric constant affect the geotechnical and geo-environmental behavior of smectite and kaolinite. [ABSTRACT FROM AUTHOR]

Coal mining in arid and semiarid regions often leads to numerous ecological and environmental problems, such as aquifer depletion, lake shrinkage, vegetation degradation, and surface desertification. The drainage from coal mining activities is a major driving force in the evolution of the groundwater-soil-vegetation system. In order to explore the effect of groundwater level fluctuation on soil properties and the response mechanism of surface vegetation in coal mining areas, this study is based on hydrogeological and ecological vegetation investigations in the Bojianghaizi Basin, and soil and vegetation samples are collected in the areas with different groundwater levels, and soil and vegetation indexes are analyzed with the aid of methods such as numerical statistics, linear regression, and correlation analysis with the aid of the Origin software. The results show that there is a significant negative correlation between groundwater table (GWT) and soil water content (SWC), soil conductivity, soil organic matter (SOM), soil available nitrogen (SAN), and soil available potassium (SAK). Mining activities have led to the destruction of the soil structure, greatly reducing its ability to retain water and fertilizer. The contents of SWC, SOM, and SAN in the mining area are significantly reduced, which are at least 49.73%, 47.56% and 59.90% lower than those around the mining area. On the northern and southern sides of the lake, serious soil salinization exists in the lakeshore zone where the depth to the water table is <0.5 m, and the water required for the growth of vegetation here mainly comes from the groundwater, so there are only a few water-loving and saline-resistant plants; when the depth to the water table is 0.5–7 m, the growth of surface vegetation is influenced by the double impacts of the water table and atmospheric precipitation with a high degree of species richness; when the depth to the water table is >7 m, the surface vegetation is only dependent on the limited atmospheric precipitation for water. When the depth of groundwater is >7 m, the surface vegetation only relies on limited atmospheric precipitation for water, and drought-tolerant plants mainly grow in these areas. This study not only provides a scientific basis for the sustainable development and environmental protection of similar mines in the world, but also has important significance in guiding the ecological management and rational utilization of water resources in coal mine areas. What is more, This study provides valuable insights into sustainable water resource management in arid and semi-arid regions, crucial for mitigating the ecological impacts of coal mining activities. [ABSTRACT FROM AUTHOR]

With climate change, population growth and the resulting escalating water shortage, humanity is increasingly turning to non-renewable and even fossil groundwater resources, which poses a major challenge to sustainable water management. In this study, 2D basin-scale numerical simulations were carried out on the COMSOL Multiphysics® finite element numerical platform to identify non-renewable water resources in the Central Pannonian Basin (Central Europe, Hungary) based on the lack of hydraulic connection to recharge areas. The concept and boundary conditions (fixed water table configuration at the top, pressure-elevation profiles on the lateral sides, and constant pressure on the bottom) were derived from a previous basin-scale hydraulic data evaluation study, while the hydrostratigraphic subdivision was based on seismic and well log interpretations. As a result, topography-driven groundwater flow systems fed by meteoric water infiltration were separated from a transition zone, which contains non-renewable groundwater resources and covers 85% area of the simulated 110 km long and roughly 1600 m deep cross-section what was previously thought to be fully renewable. Such complex flow pattern and re-interpretation of the renewable and non-renewable groundwater resources can be expected in any terrestrial sedimentary basin with over-pressured flow domains. [ABSTRACT FROM AUTHOR]

This paper introduces a novel application of spatial-temporal graph neural networks (ST-GNNs) to predict groundwater levels. Groundwater level prediction is inherently complex, influenced by various hydrological, meteorological, and anthropogenic factors. Traditional prediction models often struggle with the nonlinearity and non-stationary characteristics of groundwater data. Our study leverages the capabilities of ST-GNNs to address these challenges in the Overbetuwe area, Netherlands. We utilize a comprehensive dataset encompassing 395 groundwater level time series and auxiliary data such as precipitation, evaporation, river stages, and pumping well data. The graph-based framework of our ST-GNN model facilitates the integration of spatial interconnectivity and temporal dynamics, capturing the complex interactions within the groundwater system. Our modified Multivariate Time Graph Neural Network model shows significant improvements over traditional methods, particularly in handling missing data and forecasting future groundwater levels with minimal bias. The model's performance is rigorously evaluated when trained and applied with both synthetic and measured data, demonstrating superior accuracy and robustness in comparison to traditional numerical models in long-term forecasting. The study's findings highlight the potential of ST-GNNs in environmental modeling, offering a significant step forward in predictive modeling of groundwater levels. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The persistent trend of rising temperatures and shifting weather patterns caused by climate change has prompted significant concern around the world. This research aims to evaluate the instability of slopes in Almaty, Kazakhstan, under various rainfall patterns, groundwater tables, and slope geometries by incorporating the principles of unsaturated soil mechanics. However, there have been a limited number of studies incorporating the principle of unsaturated soil mechanics with constant rainfall patterns in Central Asia, particularly in Kazakhstan, on the impact of rainfall-causing landslides. Hence, in this research, GeoStudio software (SEEP/W and SLOPE/W) was used to simulate the factor of safety (FoS) and pore water pressure for the investigated slopes under different rainfall patterns. Results from Hyprop and statistical method show that the saturated volumetric water content is 0.502, whereas the residual one is 0.147 and for the permeability function the conductivity coefficient started to sharply decrease at the suction value of 2 kPa when the air-entry value was 24 kPa. Findings from numerical analysis show the change in FoS for the slope of 10mheight and 27-degree slope angle was 6%, 7%, 7%, and 8% for cyclic, delayed, advanced, and normal distributions, respectively. For the slope with 20 m height and the same 27-degree angle, the change in FoS was 8%, 10%, 8%, and 11% for the cyclic, delayed, advanced, and normal distributions, respectively. These same patterns were shown in slopes with 35-degree and 45-degree angles, having the same 10 m and 20 m heights. Comparatively, this shows that slopes under cyclic rainfall patterns (240mmof rain within 12 days) are less prone to failure compared to slopes under continuous, delayed, or regularly distributed rainfall patterns. Moreover, an increase in slope height and angle also affect the FoS negatively. It should be noted that the results obtained are only applicable to clayey-loam soil. [ABSTRACT FROM AUTHOR]

Dwindling groundwater supplies threaten food security and livelihoods. Output subsidies for farmers are a ubiquitous agricultural policy tool, yet their contribution to growing groundwater stress remains poorly quantified. We show how output subsidies guaranteeing the purchase of crops at higher than market prices may have contributed substantially to declining water tables in India. Our analysis suggests that these policies may have led to a 30% over-production of water intensive crops. In the northwestern state of Punjab, rice procurement can potentially account for at least 50% of the groundwater table decline over 34 years. In the central state of Madhya Pradesh, wheat procurement adopted in the late 2000s appears to have driven a 5.3 percentage point increase in dry wells and a consequent 3.4 percentage point increase in deep tubewells. These results suggest that well-intentioned but poorly designed subsidies can impose harmful externalities on the environment and undermine long-term sustainable development. The study shows that India's agricultural subsidies have driven significant groundwater depletion by incentivizing overproduction of water-intensive crops like rice and wheat. This impact is evident in both Punjab's alluvial aquifers and Madhya Pradesh's hard rock aquifers. [ABSTRACT FROM AUTHOR]

Driven by the need for integrated management of groundwater (GW) and surface water (SW), quantification of GW–SW interactions and associated contaminant transport has become increasingly important. This is due to their substantial impact on water quantity and quality. In this review, we provide an overview of the methods developed over the past several decades to investigate GW–SW interactions. These methods include geophysical, hydrometric, and tracer techniques, as well as various modeling approaches. Different methods reveal valuable information on GW–SW interactions at different scales with their respective advantages and limitations. Interpreting data from these techniques can be challenging due to factors like scale effects, heterogeneous hydrogeological conditions, sediment variability, and complex spatiotemporal connections between GW and SW. To facilitate the selection of appropriate methods for specific sites, we discuss the strengths, weaknesses, and challenges of each technique, and we offer perspectives on knowledge gaps in the current science. [ABSTRACT FROM AUTHOR]

The observed climate changes and increasing groundwater levels in the forest-steppe region should be reflected in the water regime of meadow-chernozemic soils (Gleyic Chernozems). This article analyzes the seasonal dynamics of volumetric moisture content in a fallow Gleyic Chernozem (Siltic, Hyperhumic, Pachic) and two arable Gleyic Chernozems (Siltic, Aric, Hyperhumic, Pachic), as well as the level of groundwater in the Tokarevskii district of Tambov oblast during the period from fall 2022 to summer 2023. The obtained data are compared with regime observations of volumetric moisture content and groundwater levels in these soils performed in 1969–1971. The use of automated monitoring systems for the soil moisture content and groundwater levels has allowed continuous data collection on soil moistureand detailed tracking of seasonal changes. The fallow meadow-chernozemic soils is characterized by higher moisture levels compared to arable soils; the upper horizons of cultivated soils are characterized by a higher frequency of wetting–drying periods and a shorter continuous duration of these periods, which is confirmed both by moisture monitoring data and by the morphological features of the soils, such as the form of carbonate pedofeatures and the depth of their detection. During the observation period in 2022–2023, the meadow-chernozemic soils were relatively dry, despite the higher than normal annual precipitation. Wilting point moisture in the top 20-cm layer of cultivated soils was established from March 2023, and in the fallow soil, from the end of April 2023. Periods with the moisture content exceeding the field capacity within the 60-cm-thick upper soil layer were not observed during the entire observation period. The soils were drier than in the dry year of 1972, when the moisture content was less than the wilting point in the upper part of the profile from June to September. In the wet years of 1969–1970, the moisture content did not drop below the wilting point in the upper 20-cm layer throughout the observation period. The main reason for this difference in the moisture content is the change in the groundwater level: in 2022–2023, the groundwater level was more than 4 m deep, whereas in 1969 it did not go deeper than 2 m, and in 1971, deeper than 4 m. As a result, the soil's uptake of moisture through capillary rise did not occur in 2022–2023, and the water regime of the meadow-chernozemic soils more closely resembled the water regime of typical chernozems (Haplic Chernozems). [ABSTRACT FROM AUTHOR]

Groundwater level (GWL) forecasting with machine learning has been widely studied due to its generally accurate results and low input data requirements. Furthermore, machine learning models for this purpose can be set up and trained quickly compared to the effort required for process-based numerical models. Despite demonstrating high performance at specific locations, applying the same model architecture to multiple sites across a regional area can lead to varying accuracies. The reasons behind this discrepancy in model performance have been scarcely examined in previous studies. Here, we explore the relationship between model performance and the geospatial and time series features of the sites. Using precipitation (P) and temperature (T) as predictors, we model monthly groundwater levels at approximately 500 observation wells in Lower Saxony, Germany, applying a 1-D convolutional neural network (CNN) with a fixed architecture and hyperparameters tuned for each time series individually. The GWL observations range from 21 to 71 years, resulting in variable test and training dataset time ranges. The performances are evaluated against selected geospatial characteristics (e.g. land cover, distance to waterworks, and leaf area index) and time series features (e.g. autocorrelation, flat spots, and number of peaks) using Pearson correlation coefficients. Results indicate that model performance is negatively influenced at sites near waterworks and densely vegetated areas. Longer subsequences of GWL measurements above or below the mean negatively impact the model accuracy. Besides, GWL time series containing more irregular patterns and with a higher number of peaks might lead to higher model performances, possibly due to a closer link with precipitation dynamics. As deep learning models are known to be black-box models missing the understanding of physical processes, our work provides new insights into how geospatial and time series features link to the input–output relationship of a GWL forecasting model. [ABSTRACT FROM AUTHOR]

Irrigation is crucial for sustainable agriculture and improving farm yields, but a significant gap exists between the irrigation potential created and its actual utilization. This gap is due to losses in canal conveyance and the inefficiency of conventional irrigation methods within canal command areas. Most modernization efforts in India focus on implementing micro-irrigation for tube well systems, addressing the problem of water table decline experienced in many districts. With this context, the present study examines the command area of Gadarjudda minor of the Upper Ganga Canal in Haridwar district, Uttarakhand, India, to assess the present state of the canal by conducting on-site surveys and feasibility of micro-irrigation by evaluating the viability of replacing minor canals with a gravity flow piped irrigation network. The evaluation involves assessing the current canal status, designing the gravity flow piped irrigation network, and conducting a social survey to determine farmers' willingness, awareness, and purchasing capacity toward adoptin of micro-irrigation systems on their farms. The study identifies high conveyance loss and poor maintenance in conventional irrigation methods, highlighting the importance of micro-irrigation in the study area. The profile of the minor canal is adequate to support gravity flow in the pipe network, with velocity and pressure head within permissible limits. A social survey revealed that 85% of farmers are willing to adopt micro-irrigation, but low purchasing capacity (36%) hampers its adoption. The study concludes that micro-irrigation is viable in the Gadarjudda minor canal command area as long as a piped irrigation network is implemented and farmers receive government subsidies and proper training. [ABSTRACT FROM AUTHOR]

The face stability analysis of a longitudinally inclined shield tunnel using an analytical approach in water‐rich areas is still a research gap. To solve this face stability problem, a numerical simulation based on the FLAC3D is first conducted to calculate the seepage field behind the inclined tunnel face. An improved rotational failure mechanism is developed to make it possible to investigate the face stability of inclined tunnels using analytical approaches. In the framework of the kinematic approach of limit analysis, the limit support pressures and corresponding failure surfaces of the inclined tunnel face are determined to analyze the face stability issue. The interpolation tool (griddata) in MATLAB is adopted to involve the obtained numerical values of pore water pressures into the analysis of the stability issue. The analytical solutions obtained from the proposed method are validated by comparisons with existing results from published literatures and numerical results. For a quick estimation of the inclined tunnel face stability in water‐rich areas, a series of design charts are then presented for various soil strength parameters, water tables, and inclined angles. Finally, an application of the proposed method to a practical tunneling case is provided, which further illustrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Due to a heavy reliance on groundwater, Bangladesh is experiencing a severe decline in groundwater storage, with some areas even facing land subsidence. This study aims to investigate the relationship between groundwater storage changes and land subsidence in Bangladesh, utilizing a combination of GRACE and InSAR technologies. To clarify this relationship from a macro perspective, the study employs GRACE data merged with GLDAS to analyze changes in groundwater storage and SBAS-InSAR technology to assess land subsidence. The Dynamic Time Warping (DTW) method calculates the similarity between groundwater storage and land subsidence time series, incorporating precipitation and land cover types into the data analysis. The findings reveal the following: (1) Groundwater storage in Bangladesh is declining at an average rate of −5.55 mm/year, with the most significant declines occurring in Rangpur, Mymensingh, and Rajshahi. Notably, subsidence areas closely match regions with deeper groundwater levels; (2) The similarity coefficient between the time series of groundwater storage and land subsidence changes exceeds 0.85. Additionally, land subsidence in different regions shows an average lagged response of 2 to 6 months to changes in groundwater storage. This study confirms a connection between groundwater dynamics and land subsidence in Bangladesh, providing essential knowledge and theoretical support for further research. [ABSTRACT FROM AUTHOR]

This study evaluates the use of remote sensing data to improve the understanding of groundwater resources in climate-sensitive regions with limited data availability and increasing agricultural water demands. The research focuses on estimating groundwater reserve dynamics in two major river basins in Morocco, characterized by significant local variability. The study employs data from Gravity Recovery and Climate Experiment satellite (GRACE) and ERA5-Land reanalysis. Two GRACE terrestrial water storage (TWS) products, CSR Mascon and JPL Mascon (RL06), were analyzed, along with auxiliary datasets generated from ERA5-Land, including precipitation, evapotranspiration, and surface runoff. The results show that both GRACE TWS products exhibit strong correlations with groundwater reserves, with correlation coefficients reaching up to 0.96 in the Oum Er-rbia River Basin and 0.95 in the Tensift River Basin (TRB). The root mean square errors (RMSE) were 0.99 cm and 0.88 cm, respectively. GRACE-derived groundwater storage (GWS) demonstrated a moderate correlation with observed groundwater levels in OERRB (R = 0.59, RMSE = 0.82), but a weaker correlation in TRB (R = 0.30, RMSE = 1.01). On the other hand, ERA5-Land-derived GWS showed a stronger correlation with groundwater levels in OERRB (R = 0.72, RMSE = 0.51) and a moderate correlation in TRB (R = 0.63, RMSE = 0.59). The findings suggest that ERA5-Land may provide more accurate assessments of groundwater storage anomalies, particularly in regions with significant local-scale variability in land and water use. High-resolution datasets like ERA5-land are, therefore, more recommended for addressing local-scale heterogeneity in regions with contrasted complexities in groundwater storage characteristics. [ABSTRACT FROM AUTHOR]

From a value-added trade perspective, this study utilizes the world input–output tables and the water footprint data of each industry in each country in the Eora database to explore the virtual water resources of 19 countries (the G20 countries excluding the European Union) in 2016. We calculated nine value chain decompositions and the pattern of virtual water flows and then explored the implied virtual water use due to the trade of intermediate goods and final goods, and we also analyzed the unequal trade of virtual water and added value among countries. The results indicate the following. Firstly, in most countries, the largest portion of virtual water is attributed to exports of intermediate inputs that are produced in the source country and fully utilized by the direct import countries, followed by the foreign value-added component of intermediate goods, while the smallest share of virtual water is returned to the country. Secondly, in value-added trade, excluding the rest of the world (ROW), China, France, Italy, Japan, Mexico, South Korea, South Africa, Saudi Arabia, and Germany are net importers in the virtual water trade between G20 countries, and the USA is the largest net exporter of virtual water. Thirdly, intermediate product trade is the dominant form of implied virtual water trade among countries, which leads to a net flow ratio of implied virtual water of about 80% to 90%. Lastly, the Virtual Water Inequality Index shows that thirteen country combinations, including Brazil and Argentina, exhibit significant inequality, and most countries are in a relatively equal state. In addition, the virtual water and added value of the relatively economically developed regions benefit more from the virtual water trade. Therefore, it is crucial for countries to reduce their consumption of virtual water when trading intermediate products to develop high-value-added and low-water-consumption industries and to choose appropriate virtual water trade targets. [ABSTRACT FROM AUTHOR]

Given the vulnerability of surface water to the direct impacts of climate change, the accurate prediction of groundwater levels has become increasingly important, particularly for dry regions, offering significant resource management benefits. This study presents the first statewide groundwater level anomaly (GWLA) prediction for Arizona across its two distinct aquifer types—unconsolidated sand and gravel aquifers and rock aquifers. Machine learning (ML) models were combined with empirical Bayesian kriging (EBK) geostatistical interpolation models to predict monthly GWLAs between January 2010 and December 2019. Model evaluations were based on the Nash–Sutcliffe efficiency (NSE) and coefficient of determination (R2) metrics. With average NSE/R2 values of 0.62/0.63 and 0.72/0.76 during the validation and test phases, respectively, our multi-model approach demonstrated satisfactory performance, and the predictive accuracy was much higher for the unconsolidated sand and gravel aquifers. By employing a remote sensing-based approach, our proposed model design can be replicated for similar climates globally, and hydrologically data-sparse and remote areas of the world are not left out. [ABSTRACT FROM AUTHOR]

The spread of sargassum on beaches in Africa, Brazil, Central America, and the Caribbean has increased to become a social, environmental, and economic problem. In recent years, the presence of biomass on the coasts of the Mexican Caribbean has been recorded as ≈2360 m3 Km−1, reaching up to 200 m wide in the northern part of the coasts. Its removal from the coast and, later, the continent is one of the strategies implemented to mitigate its impact on land. Several studies have reported the seasonality of and geographic variation in sorbed metals in sargasso. However, it is unknown whether these metals can mobilize or remain in sargassum tissue once they reach accumulation sites. This study included seawater, sargassum tissue as a consortium, and S. natans and S. fluitans, as well as the leachate generated in the process of degradation per se and percolated by rain. Of the 10 metals evaluated (As, B, Fe, Zn, Mn, Cd, Al, Ni, Cu, and Pb for water, tissue, and leachate), only B is recurrent in water from the north of the Mexican Caribbean, in addition to traces of Al and Fe. Meanwhile, in tissue, the results coincide with those of previous studies, where As is recurrent, although its concentration varies with the mentioned variability. The leachate showed that four to eight metals of those present in the tissue were detected, including As, Fe, and Al, which represent a potential impact on coastal systems and infiltration into shallow water table areas. [ABSTRACT FROM AUTHOR]

Oases in arid regions consist of river–lake–groundwater systems characterized by complex hydrological cycles and fragile ecosystems. Sustainable water resource management, aimed at multi-source ecological restoration, is crucial for oasis ecological protection and represents a current research challenge. This study focuses on the Bohu irrigation area, using ecological water levels, the MIKE-SHE hydrological model, and the water balance equation to propose a multi-objective groundwater and surface water regulation scheme that meets both the ecological safety requirements of the irrigation area and the ecological water demands of the Small Lake. Key findings include the following: (1) The regional ecological water level ranges from 1.69 m to 4 m, with about 74% of the area exceeding this range, threatening local ecology. (2) The proposed regulation method adjusts 91.25% of areas exceeding the ecological water level to within the acceptable range. (3) Under various planting scenarios, the minimum water distribution from the west branch of the BLSM water diversion hub should be 824.632 ×   10 6   m 3 / a to meet Small Lake ecological demands. When this volume exceeds 831.902 ×   10 6   m 3 / a , both groundwater regulation and Small Lake ecological demands are satisfied. This paper quantifies the water cycle mechanisms in complex hydrological interaction areas, providing specific solutions to regional ecological problems, which holds significant practical relevance. [ABSTRACT FROM AUTHOR]

The conjunctive use of surface water and groundwater is practiced worldwide as a measure to address water supply uncertainty. This paper focuses on a scenario in which an aquifer is open to multiple users and examines the impact of such an open-access environment on the stabilization function of conjunctive management. We construct a non-cooperative stochastic dynamic game model where multiple users utilize groundwater intake from a common aquifer as a complement to fluctuating surface water. We also propose a simpler baseline applicable to dynamic environments to compute the benefits of the stabilization function when users are unable to adjust groundwater intake to surface water uncertainties. We then apply the model to the real-world case of the water supply environment of the Cao'e River in China. Simulation results show that open access leads to diminishing stabilization values as higher pumping costs due to declining stocks lead to a weakening of users' incentive to utilize groundwater flexibly. Furthermore, the stabilization function itself is destabilized as the number of users increases. This is because greater groundwater intake and a decline in stocks amplify variations in pumping costs caused by different patterns of surface-water fluctuation. [ABSTRACT FROM AUTHOR]

The scarcity of groundwater monitoring in Kosovo, particularly in Lipjan, underscores the urgency to assess and safeguard this vital resource amidst escalating water demands and mounting pollution. This study addresses the critical gap in groundwater data by proposing the establishment of a comprehensive monitoring system. The primary goal was to develop a system capable of providing real-time data on groundwater quality and quantity within the capture area. Specific research objectives include the daily real-time monitoring of groundwater quality, identification, and quantification of contaminants in the aquifer, as a basis for further work on delineation of contaminant sources impacting the capture area, and monitoring and quantifying water extraction rates from individual wells, therefore establishing the necessary protection zones. Seven divers have been installed in 7 monitoring wells in Lipjan to measure the water level and pressure, as well as a multiparameter sensor for water quality monitoring for pH, temperature, specific conductivity, total dissolved solids, and dissolved oxygen. The digital monitoring system has been set up to input and log the incoming data. The aim was to gather this data, analyze it and use it to create a model and calibrate it to match the observed data. Concurrently, a sensitivity analysis was performed to prioritize data collection and establish which parameters have the most significant impact on the model outcomes. This ensures the establishment of a model which will, in the future, be used to predict and forecast groundwater levels and quality and determine protection zones. [ABSTRACT FROM AUTHOR]

The Coln is an ecologically sensitive river in a limestone dominated catchment with no major tributaries. Three in‐line turbidity sensors were installed to monitor changes in the dynamics of suspended sediment transport from headwaters to the confluence. The aims were to (i) provide estimates of yield (t km−2 year−1) and likely drivers of suspended sediment over ~3 years and (ii) assess turbidity dynamics during storm events in different parts of the catchment. In addition, the sensor installation allowed a novel wavelet analysis based on identifying groups of turbidity peaks to estimate transport times of suspended sediment through the catchment. Yearly suspended sediment yields calculated for the upper catchment were typically less than 4 t ha−1 year−1 being similar to other UK limestone or chalk‐based rivers. Time series autoregressive integrated moving average models including explanatory variable regression modelling indicated that river discharge, groundwater level and water temperature were all significant predictors of turbidity levels throughout the year. However, high model residuals demonstrate that the models failed to capture random turbidity events. Five parts of the time series data were used to examine sediment dynamics. Plots of scaled discharge verses turbidity demonstrated that in the upper catchment, after initial suspended sediment generation, sediment quickly became limited. In the lower catchment, hysteresis analysis suggested that sediment dilution occurred, due to increasing base flow. The novel wavelet analysis demonstrated that during winter 'sediment events' identified as groups of turbidity peaks, took ~18 h to pass from the first sensor in the upper catchment to the second sensor (10.3 km downstream of sensor 1) and 24 h to the third sensor (23.3 km from sensor 1). The work demonstrates the potential for using multiple turbidity sensors and time series statistical techniques in developing greater understanding of suspended sediment dynamics and associated poor water quality in ecologically sensitive rivers. [ABSTRACT FROM AUTHOR]

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Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Context: Process-based crop growth models can explain soil and crop dynamics that influence the optimal N rate for crop production. Currently, there is a lack of understanding regarding the accuracy of process-based models for site-specific zones within fields, as well as the key factors that need to be considered when calibrating these models for zone-specific economic optimum N rate (EONR). Objective: We calibrated the Agricultural Production Systems sIMulator (APSIM) model in contrasting zones within fields, quantified the model performance, and used the calibrated model to develop long-term corn yield response to N to assess the temporal variability between zones and sites to assist decision making. Methods: We conducted four N rate experiments (2 fields × 2 zones within a field) over two years in southeast Nebraska. Experimental data were used to calibrate and test the APSIM model. APSIM simulated corn yield response to N for each zone and site was obtained by running numerous iterations of the calibrated model at different N rates. Observed and simulated corn yield response to N rate were analyzed with statistical models to estimate the EONR. Results and conclusions: The APSIM model predicted corn yield over 11 historical years with a relative root mean square error (RRMSE) of 12% and yield at EONR in the N studies with RRMSE of 8.8%. The simulated EONR was lower than the observed EONR across sites, years, and zones with greater error than yield. The simulated yield increase with N fertilization was under-estimated in fine textured soils and over-estimated in medium textured soils. Long-term corn yield response to N showed that temporal variation in simulated EONR was greater than spatial variation. Long-term EONR and yield at EONR increased with increasing rainfall, while yield at zero N was greatest in normal years. Temporal variation was driven primarily by year-to-year variation in N loss (CV of 67% ± 9.5). Soil texture, hydrological properties, water table, and tile drainage were key variables for accurate site-specific model calibration. Improvements in simulating site-specific EONR may be realized by including in-situ or remotely sensed data for better estimation of N dynamics. We concluded that APSIM can provide valuable insights into systems dynamics in this region, but it can't provide precise N-rate estimates. Our study contributes to understanding of the within-field variability using simulation modeling. [ABSTRACT FROM AUTHOR]

Usually, the term 'rising damp' refers to capillary water rising from the ground which may damage architectural heritage. In this work, the essence of rising damp in extremely arid regions and its driving force are revealed based on experiments monitoring the relative humidity (RH) and atmospheric pressure (AP) in the Dunhuang Mogao Grottoes. The air in the vadose zone, the unsaturated region between ground level and the top of the water table, is here referred to as 'earth-air'. When the AP rises, the earth-air is compressed, and atmospheric air enters into the soil. Then, when the AP drops, moist earth-air expands and rises into the structure. The RH in the soil is thus negatively correlated with the AP, yielding a correlation coefficient of up to –0.94. Under the action of this long-term dry–wet alternation, the salt present in the building near ground undergoes repeated cycles of crystallization and dissolution, resulting in efflorescence and a deterioration zone. Therefore, the deterioration due to rising damp in extremely arid regions is caused by the rising of moist earth-air rather than capillarity. The height to which it rises is directly proportional to the amplitude of the daily AP fluctuation and thickness of the vadose zone, exhibiting a bimodal fluctuation pattern on a daily scale. The discovery of this mechanism of rising damp provides a scientific basis for preventive conservation interventions. [ABSTRACT FROM AUTHOR]

Groundwater resources in water-stressed regions, such as the Middle East, face significant challenges due to low precipitation, high temperatures, and elevated evaporation rates, which are compounded by anthropogenic stresses. In this context, Saudi Aramco (the national petroleum and natural gas company of Saudi Arabia) has contributed in the search for potential groundwater sources to ensure an adequate supply of potable water for the country's citizens, agricultural needs, and industrial usage. In this study, we combined geographic information system (GIS), remote sensing (RS) and analytic hierarchy process (AHP) techniques to evaluate the vulnerability of groundwater potential (taking Hail as a case study). With a total of 7 thematic layers (i.e., geology, slope, lineament density, land use/land cover, annual rainfall, drainage density, and soil texture), we found that groundwater potential zones with moderate to high coverage account for 91.9%, which is notably close to the borehole data, with a groundwater potential validation accuracy of 90.0%. The obtained results offer a crucial tool for decision-makers and managers, enabling them to develop timely protection and monitoring measures for groundwater resources. Highlights: This study used RS-GIS + AHP modeling to evaluate groundwater potential. The groundwater potential zones in the Hail region can be classified into three categories. RS-GIS + AHP is a useful tool for analyzing groundwater resource levels. Potential recharge areas were delineated for the Hail region. [ABSTRACT FROM AUTHOR]

The performance of gravity recovery and climate experiment (GRACE) and GRACE-Follow On (GRACE-FO) satellites in estimating groundwater level (GWL) changes on a local scale is a challenging issue. Then, this study aims to investigate the performance of GRACE and GRACE-FO in monitoring GWL changes on a local scale compared to observations at groundwater wells and the results of groundwater modeling. The study utilized hundreds of groundwater observational data points and 180 satellite data from 2002 to 2020 in five Iranian provinces. The data from satellites GRACE and GRACE-FO were modified by subtracting hydrological parameters outputs of the global land data assimilation system (GLDAS) from the satellites' estimations. The significant trends in GWL changes were studied by Sen's slope and Mann–Kendall, which represented a significant declining trend in GWL in all studied provinces. Applying 1–2 month time lags to the observational data improved the correlation coefficients between satellite estimations and the observations at groundwater wells. The best correlation coefficients between observational GWL changes and GRACE estimations in Fars, Khorasan Razavi, Sistan and Baluchistan, East Azerbaijan, and Golestan provinces were calculated as 0.53, 0.42, 0.4, 0.51, and 0.36. Those values for GRACE-FO were calculated as 0.95, 0.67, 0.72, 0.78, and 0.3, respectively, which proved the better performance of GRACE-FO compared to GRACE. Meanwhile, the GWL changes estimated from GRACE-FO were compared to the results of groundwater modeling, which was performed by using MODFLOW via the GMS10.4 interface in Azarshahr aquifer located at East Azarbaijan revealed a satisfactory agreement. [ABSTRACT FROM AUTHOR]

The analysis of the influence of human activities and climate change on groundwater is an important basis for formulating groundwater management policies. However, the relationship between climate change, human activities and groundwater system is complex, and the research on the response of groundwater to changing environment is in the initial stage. In this paper, the interactions between groundwater water cycle and climate change and human activities are analyzed, based on climate change data and hydrogeological information from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). The MODFLOW model was used to develop a numerical model of shallow groundwater movement in Zhongmu County, Henan province, and to predict the response of groundwater levels to climate change and human activities in three cases from 2016 to 2050. The results show that under the current scenario, the groundwater level will decrease at an average annual rate of 4.24 cm/A from 2016 to 2050. Under the climate change scenario, the precipitation increased by an average of 5.01%, the annual evaporation increased by an average of 17.84% and the annual temperature increased by an average of 1.29 °C from 2016 to 2050 under the three emission cases of RCP2.6, RCP4.5 and RCP8.5, under the climate change–autonomous human activities scenario, when water conservation and South–North Water Transfer Project water supply are implemented simultaneously, the water table will decrease by an average of 5.58 CMA per year under the direct impact scenario and by an average of 4.44 CMA per year under the indirect impact scenario, the water table dropped by 3.21 cm/A. The changing environment will have an important effect on groundwater circulation, and appropriate measures must be taken to deal with the continuous decline of groundwater level. [ABSTRACT FROM AUTHOR]

In M'bahiakro, nitrate contamination of drinking well water is becoming a cause for concern and continues despite the efforts made in the town. To help monitor these waters, this study aims to predict nitrate concentrations in the M'bahiakro water table based on physico-chemical parameters measured in situ. To this end, a gradient error back-propagation (BPNN) artificial neural network (ANN) was developed to simulate nitrate concentrations using temperature (T), electrical conductivity (EC), dissolved oxygen (O2), redox potential (Eh) and well water depth as input data. The resulting dataset was divided into two parts to form the artificial neural network, where 70% of the dataset was used for training, and the remaining 30% was also divided into two equal parts: one for testing and the other for model validation. The models were configured using a constructive approach, which consists of testing each input variable individually in a reference network and combining the variables until the best intelligent model is obtained according to the chosen performance criteria. The intelligent models obtained were evaluated on the basis of the coefficient of determination (R2) closest to 1 and the lowest mean square error (MSE). The results obtained showed that the BPNN models developed using four input variables in the dry and rainy seasons provided the best results. The MSE and R2 values were around 0.01 mg/L and 95%, respectively. They are obviously more accurate since the mean square errors are low with coefficients of determination close to unity. The BPNN models thus obtained were able to reproduce satisfactorily the nitrate concentrations obtained experimentally in 19 wells in the town of M'bahiakro. However, it is essential to continue this study in order to define the time interval during which the BPNN models obtained can remain valid in terms of performance in the M'bahiakro area. [ABSTRACT FROM AUTHOR]

Over-exploitation of groundwater in arid and semi-arid regions requires an understanding of dynamics for effective management strategies. This study uses an artificial neural network (ANN) to predict groundwater levels using initial water level, pumping, and hydrological and meteorological input variables. A sensitivity analysis assessed predictors' impact on accurate groundwater level prediction. The accuracy of predictions by the ANN model was examined through different performance evaluation criteria and the result achieved is satisfactory as compared to reasonable statistical indicator values. A comparison of results simulated by the ANN model and numerical groundwater flow model (MODFLOW) was carried out and it was found that the prediction of the ANN model was consistently superior to that of the numerical model. Therefore, data-driven models such as ANN can provide better predictions of groundwater level that will aid in groundwater resource management. [ABSTRACT FROM AUTHOR]

This study takes a nearby foundation pit project of a high-speed railway in Yancheng City, Jiangsu Province as an example to investigate the impact of deep foundation pit projects on groundwater and the surrounding environment. Through on-site monitoring, in-situ testing, and numerical simulation, we conducted a comprehensive study of the impact of foundation pit projects on groundwater and the surrounding environment. The evolution of groundwater levels and surface displacement during the excavation of foundation pits was analyzed, and a method for measuring the permeability of target soil layers in situ was studied. The simulation of recharge under various soil conditions was performed, and the outcomes demonstrated the effective isolation of hydraulic connections between the interior and exterior of the foundation pit by the water-resistant curtain. Precipitation head and constant head recharging tests were employed to ascertain the actual permeability. The characteristic time method calculation exhibited remarkable efficiency and accuracy in determining the permeability coefficient of the recharging soil layer. Recharging phreatic and confined water layers has differing degrees of influence on surface deformation, with the impact of confined water layers requiring more time to stabilize. These findings contribute significantly to a more comprehensive understanding of the environmental repercussions associated with deep excavation projects, thereby enhancing safety and environmental protection measures in excavation construction practices. [ABSTRACT FROM AUTHOR]

Nitrate contamination in drinking water is now gaining global attention because of its potential effect on human health. In this study, nitrate concentrations and their potential sources in groundwater and surface water were investigated using hydrochemical and isotopic methods. The physical parameters were measured in-situ using multi parameter meters; major ions, stable isotopes (δ2H and δ18O of H2O) and δ15N and δ18O of NO3− were measured using the Ion Chromatography, laser spectrometry and titanium (III) reduction method respectively. The results indicate that the dominant water type is Ca-Mg-HCO3, followed by the Ca–Mg–Cl hydrogeochemical facies. The plot of NO3−/Cl− against Cl− revealed that the dominant sources of NO3− in the groundwater are manure/sewage with few traces from soil inputs. Meanwhile the plot of δ2H-H2O against δ18O-H2O showed that rainfall is the main source of groundwater recharge with few groundwater samples showing evidence of recharge from an enriched source (Black Volta River). The plot of δ18O – NO3− against δ15N – NO3− suggests that a significant percentage of nitrate is from manure and sewage, followed by the soil zone, hence leading to nitrification and denitrification being important biological processes affecting NO3− concentrations in groundwater in the study area. The stable isotope mixing model suggests manure contributed a mean proportional contribution of about 74% of NO3− to groundwater in the study area, while soil nitrogen contributed 10%. The Nitrate Pollution Index (NPI) suggests that about 80.2% of water samples were pollution free, while anthropogenic activities resulted in about 8.3% of the pollution index. Since most samples with lower nitrate pollution indices were observed around recharged areas and increased toward the discharge points, our study suggests the possibility that recharge areas of the water was free or lowest in nitrate contamination. [ABSTRACT FROM AUTHOR]

Due to over exploitation of groundwater, there is a drastic decrease in groundwater level and its quality. The groundwater samples have been analysed to estimate its aptness for domestic and agricultural in Sivakasi Taluk industrial areas. In the course of post monsoon and summer of 2020, twenty two samples have been collected from the research area. The groundwater samples were examined for various parameters like pH, EC, TDS, TA, TH, Ca2+, Mg2+, K+, Na+, Cl−, SO4−, HCO3−, F−, DO and samples were compared with BIS, WHO and ICMR standards. It is inferred through results that EC and TDS values were spiked up due to excess presence of Cl−, Na+, Ca2+, Mg2+, F− and NO3− present in water samples near the industrial areas and natural rock formation. The water samples were evaluated for their suitability for irrigation and were assessed by SAR, % Na, Kelly's ratio and MH, USSL diagram shows majority of the samples are apt for agricultural. Piper plot indicates that majority of the collected samples fall under the Na–Cl category thereafter by Mg- HCO3- Cl, Ca–Mg–Cl and Na + K –Cl types and this infers anthropogenic influences. Gibb's plot shows that the collected samples fall under evaporation dominion field followed by rock-water dominion field of the two seasons. It is recommended to provide Artificial Recharge structures, recharge ponds in the area of research to increase the under-groundwater level and its standard. [ABSTRACT FROM AUTHOR]

This study aimed to estimate radon concentrations in groundwater and surface water to evaluate radon (222Rn) contamination in drinking water within the Amreli region of Saurashtra, Gujarat, India. Water samples from 84 sites, covering about 3000 km2, were analyzed using the RAD7 device from Durridge Instruments. Samples were collected in 250 ml radon-tight bottles. Radon concentrations ranged from 0.1 to 13.6 Bq/L, averaging 4.52 Bq/L. At three sites (P9, P29, P35), radon levels exceeded the USEPA limit of 11.1 Bq/L. P9 and P29 are near the Tulsishyam geothermal area, while P35 is close to the Savarkundla fault. Geothermal fluids in Tulsishyam may facilitate radon migration, and swarm-type earthquakes near Savarkundla could also contribute to radon migration. Concurrently, physicochemical parameters like Potential of Hydrogen (pH) and Total Dissolved Solid (TDS) were measured, with no significant correlation found between radon levels and these parameters. Samples were taken from tube wells with depths ranging from 105 to 750 feet, averaging 359 feet. A strong and significant correlation (0.83) was observed between radon concentration and water depth. Health risks from radon exposure were assessed by estimating annual effective dose rates for different age groups through ingestion and inhalation. In some instances, the annual effective dose rate surpassed the WHO-recommended value of 100 µSv/year. However, in most instances, the presence of radon in the water does not indicate a significant radiological risk. [ABSTRACT FROM AUTHOR]

Infrastructure development in mountainous regions is vital due to rapid population growth and increased tourism. Most of these regions are vulnerable to landslides under rainfall events due to changes in the shear strength of the soil slopes under wetting cycles. Thus, the stability of foundations on slopes must be evaluated under variably saturated conditions. Models for evaluating the bearing capacity of foundations on slopes by accounting for variably saturated and transient conditions are scarce. A comprehensive semi-analytical model in the slip-line framework was developed in this study to investigate the bearing capacity of foundations on slopes under various controlling factors. The proposed model integrated the slip-line theory using a one-dimensional unsaturated transient-flow equation––the Richards equation––to evaluate the stability of foundations on soil slopes under unsaturated transient-flow conditions. Suction stress profiles were estimated using different soil hydraulic models for partly saturated soils to incorporate into the slip-line theory for estimating the bearing capacity of foundations under different field conditions. The developed framework was successfully validated using the existing limited cases under unsaturated steady-state and transient conditions. A parametric study was undertaken to study the influence of soil type, slope angle, rainfall infiltration, and depth of water table. The influence of different unsaturated hydraulic characteristics on the bearing capacity was clearly brought out, for the first time, using the measured soil hydraulic characteristics data. The model performance was satisfactory and is useful for evaluating the bearing capacity of footings resting on slopes under different natural conditions. [ABSTRACT FROM AUTHOR]

In light of the pressing need for optimizing the cost and efforts involved in geotechnical investigations, this study presents a spatial analysis and interpretation of geological and geotechnical database of Riyadh City. By consolidating available data from geotechnical investigation reports of the study area, spatial maps have been developed focusing on subsoil types and rock quality designation. The application of the geostatistical analyst extension in ArcMap highlights significant spatial variation in subsoil characteristics, leading to a more accurate zonation of geotechnical profile. It is emphasized that among several interpolation methods, the inverse distance weighting emerges as a better approach for representing these variations, enabling the creation of detailed geotechnical zonation maps. Considering its importance, the data on groundwater table depths at various locations were also retrieved and visualized illustrating the frequency of presence of groundwater in bedrock (limestones) or in the surface soils. This insight can be instrumental in strategizing groundwater pumping for water supply as well as designing dewatering systems for potential excavations in the study area. The findings of this study indicate that a GIS-based overview of subsoil profiles allows the construction engineers to plan and execute projects more effectively, resulting in considerable savings in time and financial resources associated with site investigations as well as contributing the sustainable development of infrastructure projects in the region. [ABSTRACT FROM AUTHOR]

The objectives of this research were to create a topographic model using Mathematica and hydrologic model using ArcGIS for water management aimed at preventing forest fires in the Khuan Kreng peat swamp forest. Pan basin area in Kreng Sub-district, characterized by low mountains, where the Cha-Uat canal intersects the krajood forest, was revealed by the hydrographic model. Kreng Sub-district was traversed by three main streams: Khuan canal, Hua Pluak Chang canal, and Laem canal. Additionally, several tributary canals that interconnect, ultimately converging into the Cha-Uat Phraek Muang canal were identified. During the dry period, the water from these canals flowed into the Cha-Uat Phraek Muang canal. To mitigate the risk of fires, it was essential to install water table measuring devices and underground barrier gates at the drain points. This ensured the return of water from the Cha-Uat Phraek Muang canal to the Khuan Kreng peat swamp forest. Maintaining sufficient water table level was crucial, as the occurrence of fires was more likely when the water table dropped below the soil surface. When the swamp forest was adequately hydrated, wildfires were confined to a narrow area since they could only burn on the forest surface, which was easier to extinguish. [ABSTRACT FROM AUTHOR]

Nitrate pollution of surface and groundwater could be a worldwide issue resulting in the threat to the environment and public health. The removal of nitrate from water was carried out using gamma aluminum oxide (γ-Al2O3) nano powder. The nano powder was synthesized from aluminum oxide powder using the aqueous-based reflux method and applied for nitrate removal. The surface properties of the activated γ-Al2O3 were characterized using FTIR, XRD, and BET surface area analysis. Analysis of variance (ANOVA) was used to analyze nitrate removal to determine the appropriate regression model, which was found to be the quadratic model with a coefficient of determination (R2 = 0.99). The adsorption process was observed to be dependent on initial nitrate concentration, adsorbent dose, and time. The optimized nitrate removal efficiencies were 97.01% using a dose of 2.26 gL−1, an initial nitrate concentration of 10 mgL−1, and a contact time of 45 min. Additionally, the kinetics of nitrate ion adsorption was discussed based on pseudo-first order and pseudo-second order kinetic models. The experimental data fitted well with the pseudo-second order kinetic model, indicating that the adsorption mechanism is chemisorption. The equilibrium adsorption of nitrate experimental data followed the both Freundlich and Langmuir isotherm (R2 = 0.95), implying a homogeneous nature of the γ-Al2O3 surface sites. These results suggest further consideration of the practical application of γ-Al2O3 for nitrate treatment for domestic purposes. [ABSTRACT FROM AUTHOR]

Global warming has prompted globally widespread permafrost thawing, resulting in enhanced greenhouse gas release into the atmosphere. Studies conducted in the Northern Hemisphere reveal an alarming increase in permafrost thawing. However, similar data from Antarctica are scarce. We conducted a 2‐D Deep Electrical Resistivity Tomography (DERT) survey in Taylor Valley, Antarctica, to image the distribution of permafrost, its thicknesses, lower boundaries, and hydrogeology. Results show resistive, discontinuous domains that we suggest represent permafrost units. We also find highly conductive layers (5–10 Ω·m), between 300–350 m and 600–650 m below ground level and a shallower (∼50–100 m depth) conductive layer. The combined data set reveals a broad brine system in Taylor Valley, implying multi‐tiered groundwater circulation: a shallow, localized system linked with surface water bodies and a separate deeper, regional circulation system. The arrangement of these brines across different levels, coupled with the uneven permafrost distribution, underscores potential interplay between the two systems. Plain Language Summary: Permafrost (perennially frozen ground) and its increasing thaw is a key indicator of climate change. The gradual increase of global temperature accelerates permafrost thawing at high latitudes, resulting in enhanced carbon release into the atmosphere, ultimately exacerbating global warming. During the austral summer of 2020, we conducted an electrical resistivity survey in Taylor Valley, McMurdo Dry Valleys, Antarctica, to map the thickness of permafrost, determine its lower boundaries and identify the presence and connectivity of saline groundwater at depth. The ice‐free Dry Valleys are the only place in Antarctica where it is possible to study the permafrost directly. Results show a complex distribution of permafrost, with layers of saline groundwater at different levels. We recognized two distinct zones: one of low resistivity around Lake Fryxell, related to the presence of two systems of brines at different depths, and the other displaying typical ice‐rich frozen ground resistivity values near Coral Ridge. These findings reveal variations in permafrost thickness and brine depth along the valley, both horizontally and vertically. Our research identifies a multi‐level groundwater circulation system: a shallow, local network, connected to surface water bodies like Lake Fryxell, above a deeper, regional system. Key Points: Resistivity data show a complex hydrogeological scenario, with uneven permafrost distribution and different levels of brinesResults show a multi‐tiered system of groundwater circulation of brines: a shallow system connected to the surface and a deeper regional systemObservations are consistent with a model of upwelling of over pressured deep brines enhancing permafrost thawing from beneath [ABSTRACT FROM AUTHOR]

Ambient noise interferometry has become a common technique for monitoring slight changes in seismic velocity in a variety of contexts. However, the physical origin of the resolved small velocity fluctuations is not well established for long‐term seasonal effects. Here we propose a physical forward model of scattered waves in a deformable medium that includes acousto‐elastic effect, which refers to non‐linear elasticity with third‐order elastic constants. The model shows that small pressure perturbations of a few kPa due to seasonal variations in the water table can induce seismic velocity changes compatible with those measured at the surface by ambient noise interferometry. The results are consistent with field observations near the deep geothermal site of Rittershoffen (France). They illustrate the capability in modeling the diffuse wavefield from scattering synthetic waves to reproduce ambient noise signals for monitoring environmental and/or deep reservoir signals. Plain Language Summary: Monitoring the fine evolution of the Earth's crust either prior to catastrophic events such as earthquakes or landslides, or georesource exploitation, is an important objective for risk management. Ambient noise interferometry is one of the emerging tools for assessing the minute evolution of seismic velocities in the subsurface. However, the physical origin of the observed small velocity changes is not well established. Here we propose a physical model of scattered waves in a deformable medium that includes non‐linear elastic effects, which are not conventionally considered. The model shows that small pressure perturbations of a few kPa due to seasonal variations in the water table can induce seismic velocity changes compatible with those measured at the surface by ambient noise interferometry. The results are consistent with field observations near the deep geothermal site of Rittershoffen (France). They illustrate the capability in modeling scattered synthetic waves to reproduce ambient noise signals. Key Points: We develop an acousto‐elastic model for seismic wave scattering in a deforming layered subsurfaceStress fluctuations induced by seasonal water table variations are shown to be responsible for significant changes in seismic velocitiesThe model is providing an interpretation tool for environmental monitoring signals obtained from ambient seismic noise [ABSTRACT FROM AUTHOR]

It is unknown how antibiotics would behave after entering the hyporheic zone (HZ), which is an area where groundwater and surface water alternate continuously. In this study, the hydrolysis process in the HZ was investigated based on the intermediates identified by HPLC-Q-TOF-MS and FTIR, and the active sites of sulfamethoxazole (SMX) were predicted by density functional theory (DFT). The results showed that the hydrolysis rate of SMX during surface water recharged groundwater reached 38.94%, and the contribution rate of hydroxyl radicals reached 48.35%. In neutral and alkaline environments, SMX hydrolysed more quickly. This is due to the fact that ·OH, as the main precursor of OH-, is much higher in quantity under alkaline conditions. Inorganic anions such as NO3-, HCO3- and ${\rm CO}_3^{2-}$ CO 3 2 − may inhibit the hydrolysis of SMX by eliminating the reactive oxygen species generated in the HZ. In the process of groundwater recharging to surface water, the concentration of dissolved oxygen (DO) and the rate of SMX hydrolysis gradually reduced. Nitrification, hydroxylation and polymerisation are the main hydrolysis pathways of SMX. The hydrolysis products of SMX in the HZ are more plentiful and have a higher hydrolysis rate compared to the single oxygen environment. The study on the hydrolysis mechanism of SMX in this paper will provide a theoretical basis for the treatment of antibiotic pollution. The degradation pathways and influencing factors of sulfamethoxazole in the hyporheic zone. [ABSTRACT FROM AUTHOR]

Hydrological changes in groundwater coupled with earthquakes had been documented in previous studies by global researchers. Although few reports investigate multiple geochemical parameters that respond to earthquakes, trace elements received less attention, whereas they were suggested to be more sensitive to small earthquakes than the commonly used geochemical parameters. Beijing is located in the Zhangjiakou-Bohai(Zhang-Bo) seismic belt of North China, and although the occurrence of small earthquakes is frequent, the great historic earthquake in the Sanhe-Pinggu area M8 in 1679 in the adjoining southeast of Beijing gained widespread public attention. To find effective precursors that are significant for operational earthquake forecasting of the Beijing area, we carried out a one year test research project through weekly collection of groundwater samples during June 2021 to June 2022 from the seismic monitoring well of Wuliying in northwest Beijing. The 41 trace elements chemical compositions were analyzed for each sample. During the project ongoing period, the biggest earthquake with a magnitude of ML3.3 occurred in the Chaoyang District of Beijing on 3 February 2022. The content changes in these trace elements were systematically monitored before and after the earthquake. Through retrospective research, it was found that a few sensitive trace elements were anomalous to be coupled to the earthquake, including Li,Sc, Rb, Mo, Cs, Ba, W, U, Sr, Mn, Ni,andZn. In addition to trace elements, we examined stable isotopes of hydrogen and oxygen and the existing hydrological data on groundwater level, temperature, major ions, and gases to assess the validity of geochemistry as a monitoring and predictive tool. We only found that F(fluorine) ions and He (helium) gas had apparent shifts related to the earthquakes, while no shifts in the groundwater level were observed. Such characteristics of multiple geochemical parameters indicate that trace elements are likely to be more sensitive to crustalstrain than the groundwater level and major ions. We assumed a most likely mechanism of the combination of mixing and water-rock interactions to explain the phenomenon. The probable scenario was that minor stresses caused by the earthquakes might create microcracks in bedrocks, thereby leading to a small volume of chemically distinct water mixing with the original water of the aquifer, and finally, the earthquakeinduced rock fractures enhance the water-rock interactions, resulting in the post-seismic recovery of trace elements and δ180 value migration to the GWML. More testing works to find other sensitive sites to investigate multiple geochemical characteristics aiming at long-term to short-term earthquake prediction in the Beijing area and Zhang-Bo seismic belt are in progress. [ABSTRACT FROM AUTHOR]

Groundwater pollution from subsurface leaching of eroded soil, pesticides and fertilizers under agricultural fields are deteriorating the quality of groundwater. In this connection, this study aimed to prepare a groundwater vulnerability map using the DRASTIC (Depth to water table, net Recharge, Aquifer media, Soil media, Topography, Impact of vadose zone media and hydraulic Conductivity) model to evaluate the soil erosion and groundwater quality relationship under soil erosion prone areas of the Panjkora river basin in the northern Pakistan. In this model, relative weights between 1 and 5 are assigned (5 being the most important) to D-R-A-S-T-I-C variables that may affect groundwater quality. According to the results, 72161.64 Hectares (ha) of the study area is low vulnerable to contamination, 144828.70 ha area is slightly moderate vulnerable, 239582.22 ha area is moderate vulnerable, 121769.37 ha area is high vulnerable, and 944.61 ha area is very high vulnerable to groundwater contamination. Groundwater samples from soil erosion hotspots were examined to establish a correlation between soil erosion and groundwater contamination. Total dissolved solids (TDS) and NO2 concentration in some areas were found to be higher than the World Health Organization (WHO) permissible limits. Soil erosion exhibited a positive correlation with groundwater contamination with correlation coefficient (r) of 0.89, root mean square difference (RMSD) of 2.24 and bias of 0.094. The DRASTIC model was validated through ROC AUC curve (score = 0.62). This study is a first attempt to evaluate the inherent groundwater vulnerability and sensitivity to pollution in this region with severely declining groundwater quality due to several unexplored reasons. [ABSTRACT FROM AUTHOR]

The high groundwater level coal mining areas have a long history of mining and are mainly located in east-central region of China. Subsidence caused by coal mining occur in several different periods. However, the subsidence change regularity in each periods remains unclear. This study aimed to reveal the subsidence change regularity in high groundwater level coal mining areas during different periods. The Juye coal mine, located in Heze City, Shandong Province, China, was selected for the study. Firstly, 55 Sentinel-1A radar satellite images from August 2018 to July 2020 were acquired for this research. The "two-track method" of D-InSAR technology was employed to process the images. Secondly, based on subsidence velocity of 1.7 mm/day, the subsidence process was divided into three periods: initial, active and weakening. Thirdly, elevation data of ground levelling points were used to check the accuracy of subsidence monitoring using Sentinel-1A data. At last, the subsidence change process in different periods was analyzed and the change regularity was summarized. The results are shown as follows: (1) the monitoring accuracy of different periods is high, and R2range from 0.961 to 0.983. (2) The subsidence characteristics are not obvious in initial period. The subsidence funnel begin to form and the mean maximum subsidence in center is greater than 1400 mm in active period. The subsidence velocity gradually decrease and eventually stabilize in weakening period. (3) Appearance of subsidence, development of subsidence funnels and formation of subsidence basins are spatial period characteristics of coal mining-induced subsidence. The results can provide an important basis for land conservation in mining areas. [ABSTRACT FROM AUTHOR]

Karst areas exhibit intricate geological attributes, and the geological and environmental issues caused by urban development cannot be ignored, especially the issue of karst surface collapses. In this study, we developed two analytical methods and analyzed the stability of the overburden stratum of 3D spherical karst caves with surface load, vacuum absorption erosion force, and groundwater table considerations. The first analytical method is based on the improved Terzaghi theory, while the second analytical method is based on the upper limit analysis. A case study was conducted in Wuhan, China. The results from both analytical methods indicated a potential susceptibility to collapse, suggesting the excellent accuracy of these two methods. The results were also compared with the numerical solutions from previous studies. Notably, the accuracy of the upper limit analysis was inversely proportional to the depth ratio, while the results obtained through the improved Terzaghi theory were consistent with those of the numerical solutions, particularly under conditions of relatively high depth ratios. This study examined various facets, including the development of karst caves, soil shear strength, groundwater table fluctuations, and boundary failure angles. Furthermore, we explored the effects of geometric and geotechnical parameters on the stability of karst caves. [ABSTRACT FROM AUTHOR]

Worldwide, the drainage of peatlands has turned these systems from CO2 sinks into sources. In the Netherlands, where ∼7 % of the land surface consists of peatlands, drained peat soils contribute >90 % and ∼3 % to the country's soil-derived and total CO2 emissions, respectively. Hence, the Dutch National Climate Agreement has set targets to cut these emissions. One potential mitigation measure is the application of subsurface water infiltration systems (WISs) consisting of subsurface pipes connected to ditchwater. WISs aim to raise the water table depth (WTD) in dry periods to limit peat oxidation while maintaining current land-use practices. Here, we used automated transparent chambers in 12 peat pasture plots across the Netherlands to measure CO2 fluxes at high frequency and assess (1) the relationship between WTD and CO2 emissions for Dutch peatlands and (2) the effectiveness of WISs in mitigating emissions. Net ecosystem carbon balances (NECBs) (up to 4 years per site, 2020–2023) averaged 3.77 and 2.66 tCO2-Cha-1yr-1 for control and WIS sites, respectively. The magnitude of NECBs and the slope of the WTD–NECB relationship fall within the range of observations of earlier studies in Europe, though they were notably lower than those based on campaign-wise, closed-chamber measurements. The relationship between annual exposed carbon (C; defined as the total amount of carbon within the soil above the average annual WTD) and NECB explained more variance than the WTD–NECB relationship. The magnitude of the NECB represented 1.0 % of the annual exposed C on average, with a maximum of 2.4 %. We found strong evidence for a reducing effect of WISs on CO2 emissions, reducing emissions by 2.1 (95 % confidence interval 1.2–3.0) tCO2-Cha-1yr-1 , and no evidence for an effect of WISs on the WTD–NECB and annual exposed carbon–NECB relationships. This means that relationships between either WTD or exposed carbon and NECB can be used to estimate the emission reduction for a given WIS-induced increase in WTD or exposed carbon. High year-to-year variation in NECBs calls for multi-year measurements and sufficient representative measurement years per site as demonstrated in this study with 35 site-year observations. [ABSTRACT FROM AUTHOR]

The application of hydrogeophysical techniques to delineating aquifers was conducted in De Aar, the eastern part of the Karoo region, Northern Cape, South Africa. Previously, recharge estimations in this region assumed a uniform aquifer type, overlooking the presence of diverse aquifer systems. This study identified both unconfined and confined aquifers to improve recharge potential assessments. Vertical electrical resistivity sounding (VES) and ground telluric methods were applied. Six VES stations and eleven profiles were measured using a 1D Wenner array configuration. The VES data, processed with IPI2win software, generated a 2D subsurface model. In contrast, the telluric data were analyzed using an automated algorithm to create a 2D profile. The electric potential difference curve was interpreted in comparison with lithological cross-sections. The VES results revealed three to four distinct layers of low-resistivity (0.9–8.1 Ωm), moderate-resistivity (22.4–125 Ωm), and high-resistivity (68–177 Ωm) values, indicating three lithological formations. The telluric data suggested that shallow groundwater boreholes were located in areas with groundwater levels above 50 m. These findings, which matched the lithological data, pointed to a double-layer aquifer system, suggesting that recharge estimates should be carried out to different aquifer layers. The study demonstrated how hydrogeophysical methods can effectively delineate aquifer systems and enhance the identification of recharge areas. [ABSTRACT FROM AUTHOR]