Search

Vugs are usually distributed in carbonate reservoirs, which have an important contribution to oil reserves. The number, size, distribution mode, and distance from the well of vugs are important factors affecting the transient pressure response, which cannot be fully described by continuum mode. Therefore, a discontinuum single-phase oil model which treat the vug as an aquifer is proposed to study the effect of vugs on transient pressure response. Four oilfield cases are used to calibrate and validate the proposed model and code. After verifying the model, a vertical well model is established to conduct the sensitivity study. We found that the larger the vug, the greater the number of vugs and the closer the distance between the vug and the well, the greater the effect. When multiple vugs are symmetrically distributed around the well and the formation is isotropic, it can be equivalent to a large vugs which means that the derivative curve of pressure can only reflect the characteristics of one vug but not all vugs. The findings of this study can help for better understanding of effect of vugs on the transient pressure response and have great significance for further exploration and development of carbonate reservoir. [ABSTRACT FROM AUTHOR]

In semi-arid northeastern Brazil, where water is scarce, rainforest refugia can be seen along the coastal relief, where the trade winds bring in humidity from the Atlantic Ocean, or further inland, at the Araripe plateau where water comes from aquifer resurgence. In order to reconstruct past changes in water resurgence and in their associated vegetation types, we analyzed pollen, charcoal, and trace elements from sediment cores collected in the permanent swamps created by the resurgences. Our high temporal resolution analyses show that the vegetation was more sparse and drier than today until 2700 cal yr BP. Between 2700 and 2000 cal yr BP, palm swamp and evergreen forest tree taxa started to expand, suggesting an increase in water resurgence. At 2000 cal yr BP, the moist forest with Mauritia expanded and fire activity changed from mixed to woody fuel particles. During the last 200 cal yr BP, a decrease in the palm tree Mauritia flexuosa, an expansion of Poaceae and an increase in macrocharcoal particles are attributed to an increase in anthropogenic activities in the Araripe Basin. The Late-Holocene climatic trend seen at Araripe mirrors that of eastern Brazil and has controlled the aquifer activity, including during the major droughts that affected the region. This is highly relevant for the application of public policies that rely on the aquifers of Araripe for the 21st century. [ABSTRACT FROM AUTHOR]

Arsenic contamination in groundwater of Bengal basin was first reported in early 80s. Even after two decades of extensive research, our ability to pinpoint the arsenic-free sources, with precision, is limited. Proxies as indicator of arsenic concentration in groundwater are also lacking. It is imperative to formulate some cost-effective, user-friendly screening tool for the detection of arsenic safe wells. The present study utilises validation tests, colourimetry and statistics, to validate the platform colour hypothesis. Results show that red-stained platforms can identify arsenic-contaminated wells with 83% certainty; while black-stained platforms identify arsenic safe wells with 62% certainty, 78% sensitivity and 69% specificity. Black-coloured well platforms identify manganese-contaminated wells with 96% certainty; while red-stained well platforms mark manganese safe wells with 36% certainty and 93% specificity. The performances of such tests improve with increasing prevalence. A comprehensive colour chart thus prepared can be used as handy tool for identification of arsenic-contaminated wells. [ABSTRACT FROM AUTHOR]

This study enhances the understanding of riverbank filtration and improves management of the Mississippi River valley alluvial (MRVA) aquifer during a managed aquifer recharge (MAR) pilot project at Shellmound, MS. Using high‐resolution electrical resistivity tomography (ERT) and self‐potential (SP) geophysical methods, we characterized the heterogeneous MRVA aquifer and monitored groundwater flow near a pumping well. ERT was used to provide detailed spatial characterization, filling gaps left by airborne electromagnetic (AEM) data and soil boring logs, while SP techniques were used to monitor groundwater flow, predict drawdown trends, and investigate surface‐groundwater interactions. Results showed that SP signals were influenced by groundwater flow, river infiltration, and water mixing due to pumping disturbance of natural geochemical stratification, with significant river interaction observed after 1 h of pumping. The integration of ERT and SP methods revealed lithologic heterogeneity, explaining greater drawdowns on the northern side of the well and increased flow from the riverside. This comprehensive approach offers valuable insights into aquifer management and sustainability. [ABSTRACT FROM AUTHOR]

Water inrush from underlying aquifers under the synergistic action of complex faults and mining activities seriously threatens the mining of coal seams in North China. The failure characteristics of the coal seam floor under complex fault conditions are the keys to understanding the water inrush mechanism during mining. To investigate floor failure characteristics and water inrush mechanisms influenced by complex fault structures, theoretical analysis and numerical simulation were carried out. An improved theoretical model is first proposed, including complex fault structures such as horst, graben, and step fault structures. The calculation formula for waterproof coal pillars under complex fault conditions is established based on the improved theoretical model. The failure and displacement characteristics of the coal floor under complex faults are analyzed via numerical simulation. Compared with those under normal mining conditions, the theoretical and numerical simulation results reveal the following: (1) Under the horst structure, the floor failure characteristics show an increase in the compression failure area on both sides, and shear failure occurs on the large-dip fault side. The simulation results reveal that the failure width on the large-dip fault side increases by 25%, indicating a failure trend toward the large-dip fault side. The width of waterproof coal pillars needs to be increased by 20% to ensure mining safety. (2) Under the graben structure, the floor failure characteristics show an increase in the compression failure area on both sides, and shear failure occurs on the small-dip fault side. The simulation results reveal that the failure width on the small-dip fault side increases by 25%, indicating a failure trend toward the small-dip fault side. The width of waterproof coal pillars needs to be increased by 40% to ensure mining safety. (3) Under the step fault structure, the floor failure characteristics show compression failure on both sides, increasing the floor compression failure area on the large-dip fault side. The simulation results show that the failure width on the small-dip fault side increases by 15%, the large-dip fault side increases by 50%, and the floor failure depth increases by 20%. The width of waterproof coal pillars needs to be increased by 50% to ensure mining safety. [ABSTRACT FROM AUTHOR]

ABSTRACT Groundwater quality assessment is crucial for ensuring safe drinking water, protecting public health, and maintaining sustainable water resources for agricultural and industrial uses. The Awash River basin faces significant groundwater quality challenges due to rapid population growth, high urbanization, large‐scale irrigation, and industrial pollution. The main objective of this study is to evaluate the intrinsic vulnerability of aquifers to pollution in the Awash Basin and identify hotspots requiring urgent intervention using a modified DRASTIC overlay analysis method. In addition to the seven parameters considered in the generic DRASTIC overlay analysis (depth to the water table, recharge, aquifer media, slope, soil media, vadose zone, and hydraulic conductivity), we incorporated land use/land‐cover (LULC) and lineament density (LD) distributions (DRASTIC‐LU‐LD). This modification allowed us to produce more realistic groundwater vulnerability maps for the basin. To identify the most influential parameters in the overlay, sensitivity analysis was conducted using Map Removal Sensitivity Analysis (MRSA) and Single Parameter Sensitivity Analysis (SPSA). Initially, the generic DRASTIC index in the area ranges from 69 to 181, categorizing the area into four vulnerability zones: very low (21%), low (51%), medium (27%), and high (1%). After incorporating LU and LD, the index values ranged from 90 to 240. Based on the percentage of the total area studied, the inclusion of LU decreased the very low and low vulnerability zones from 72% to 44% and the inclusion of LD increased the high‐ and very‐high‐vulnerability zones from 14% to 27%. The areas most vulnerable to groundwater pollution are in the western (upper Awash), middle Awash, and northwestern regions, particularly in city centers where groundwater abstraction is significant. These high‐vulnerability zones coincide with municipal, industrial, and agricultural pollution sources. The vadose zone parameter has the highest impact in both MRSA and SPSA, with a variation index value of 3.08% and a mean effective weight of 27.93%, respectively. By identifying areas vulnerable to groundwater pollution, this study provides a valuable basis for informed decision‐making and the development of effective strategies for protecting groundwater from urban, industrial, and agricultural pollution sources. [ABSTRACT FROM AUTHOR]

In this work, conceptual approximations of the Boussinesq equation were introduced and analyzed, resulting into a very accurate and well-applicable model for horizontal unconfined aquifers during the pure drainage phase, without any recharge and zero-inflow conditions. The model was constructed by employing a variety of methods that included wave solution, variable separation, and series expansion, and its analysis and performance against the Boussinesq equation, at early and later times, providing fruitful insights enlightening the main mechanisms and physical characteristics of the drainage phase. The modeled non-linear forms were finally linearized, concluding with explicit analytical expressions that accurately incorporated most of the basic characteristics regarding the evolution of the water table and the outflow from the exact Boussinesq equation under different initial conditions. The endeavors of this work can be utilized for theoretical and modeling purposes related to this problem. [ABSTRACT FROM AUTHOR]

Manganese (Mn) is one of the most abundant metals naturally present in the environment, but currently, it also represents an important factor of environmental contamination due to intense human activity. To investigate the nature of the presence of concentrations above the limits (CSC) established by Legislative Decree 152/06 for manganese in the groundwater underlying a non-hazardous solid waste plant, a study was carried out on the geochemical characteristics of the aquifers present in the study area. The study aimed to determine the natural background value (NBV) of Mn in the groundwater underlying the study area, according to the "Guidelines for Determining the Background Values of Soils and Groundwater" of ISPRA. Indeed, NBV assessment and site-specific considerations can help identify any specific sources of contamination in an area. In the study area, the chemical–physical and geochemical parameters of the water of 11 piezometers were analyzed. Subsequently, statistical tests were applied to detect an NBV identified as 192.3 µg/L, therefore much higher than the CSC, due to possible ongoing local phenomena linked to the geogenic conditions of the soil, which could determine high manganese values. In fact, in the study area, some lithologies favor establishing anaerobic environments and releasing manganese in the groundwater as hydroxides. Consequently, this process can lead to high manganese concentrations, even exceeding legal limits. [ABSTRACT FROM AUTHOR]

Coal-bearing strata belong to sedimentary strata, and there are multiple aquifers. The accurate detection of deep aquifers is helpful to the safe mining of the working face. In order to provide guidance for the interpretation of the surface-to-underground transient electromagnetic method (SUTEM) that can be used to detect deep aquifers, we used theoretical analysis and numerical simulation methods in this study. Taking uniform half-spaces, single aquifers, and double aquifers as examples, we systematically studied the data characteristics and degree of influence of SUTEM under the influence of shallow aquifers. The results indicate the following: Under the influence of the primary field distribution, the x or y component of the induced electromotive force received by the underground receiving point has a positive and negative inflection point, which increases the difficulty of data interpretation, and the z component is easier to use for data interpretation. The influence of the aquifer on the early data of the underground receiving point is much greater than that of the ground receiving point, and the late influence is closer to the ground receiving point. The change in resistivity of the shallow aquifer has the greatest influence on the ability of each measuring point to detect the data of the deep aquifer; this influence is followed by change in thickness, and change in depth has the least influence on the detection capability of each measuring point. [ABSTRACT FROM AUTHOR]

The purpose of this study is to locate groundwater-saturated aquifers in the Vindhyan fringe belt in the Mirzapur district of Uttar Pradesh, India, and evaluate their protection using geoelectrical indices. The Schlumberger electrode layout, with a maximum half-current distance between electrodes of 300 m, was used to perform three gradient profilings and six geoelectrical soundings. The inversion IPI2win program and the traditional partial curve matching approach were used for geoelectrical sounding data interpretation. Four to five geologic units are identified in the research region based on the interpretation of the geoelectrical sounding data. These are the top-surface soil, clay, kankar/laterite and sand, weathered sandstone, and compact sandstone. The research region is characterized by HA-type sounding curves, and the obtained findings suggest the presence of groundwater-saturated zones and cracks in the area. The weathered sandstone saturated with water shows resistivity ranges between 375.4 and 407.1 Ω-m and depth ranges from 96.8 to 97.6 m. Thematic maps were prepared for total longitudinal conductance, transverse resistance, overburden thickness, and electrical anisotropy. The protective capacity of the aquifer is measured using the transverse resistance (Tr) and longitudinal conductance (Lc) of the Dar Zarrouk parameters. Based on the longitudinal conductance of the aquifers, the results obtained indicate that the research region is dominated by a good aquifer protective capacity rating. [ABSTRACT FROM AUTHOR]

The Main Karoo Basin in South Africa is a typical example of an expanding arid region dependent on groundwater resources. Dolerite dikes in the region, analogous to dolerite dikes worldwide, are known to influence subsurface groundwater flow and spatially relate to high-yielding boreholes. Here, the effect of dolerite dikes on groundwater flow is remotely assessed using the Modified Soil Adjusted Vegetation Index derived from high-resolution multi-spectral satellite imagery. From imagery collected during the wet and dry seasons of 2018 and 2021, two aquifer models relating to 505 dikes were identified; (1) barrier-controlled aquifers are induced by ~ 56% of dikes, (2) fractured aquifers are induced by ~ 35% of dikes. Surficial areas overlying aquifers are also shown to sustain vegetation growth through dry seasons. This research demonstrates the efficacy of vegetation indices to rapidly characterise dike-related aquifer models and their seasonal sustainability, critical for effective groundwater exploration and management. [ABSTRACT FROM AUTHOR]

Research into land subsidence caused by groundwater withdrawal is hindered by the availability of measured heads, subsidence, and forcings. In this paper, a parsimonious, linked data‐driven and physics‐based approach is introduced to simulate pumping‐induced subsidence; the approach is intended to be applied at observation well nests. Time series analysis using response functions is applied to simulate heads in aquifers. The heads in the clay layers are simulated with a one‐dimensional diffusion model, using the heads in the aquifers as boundary conditions. Finally, simulated heads in the layers are used to model land subsidence. The developed approach is applied to the city of Bangkok, Thailand, where relatively short time series of head and subsidence measurements are available at or near 23 well nests; an estimate of basin‐wide pumping is available for a longer period. Despite the data scarcity, data‐driven time series models at observation wells successfully simulate groundwater dynamics in aquifers with an average root mean square error (RMSE) of 2.8 m, relative to an average total range of 21 m. Simulated subsidence matches sparse (and sometimes very noisy) land subsidence measurements reasonably well with an average RMSE of 1.6 cm/year, relative to an average total range of 5.4 cm/year. Performance is not good at eight out of 23 locations, most likely because basin‐wide pumping is not representative of localized pumping. Overall, this study demonstrates the potential of a parsimonious, linked data‐driven, and physics‐based approach to model pumping‐induced subsidence in areas with limited data. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to the spatiotemporal design of groundwater quality monitoring networks for coastal aquifers. A fusion model combines the outputs of several developed simulation models to make estimates more accurate. A modified GALDIT method is used to incorporate the aquifer vulnerability to saltwater intrusion. The value of information (VOI) theory is applied to determine sufficient monitoring wells. The groundwater quality monitoring network is designed by employing a robust decision-making (RDM) approach under different management strategies and economic considerations. This approach incorporates the deep uncertainties of some critical variables, including water level and total dissolved solids (TDS) concentration at the coastline and pumping flow rates of agricultural wells. The new methodology is implemented in the coastal Qom-Kahak aquifer, Iran. The results illustrate that the combination model has significantly improved evaluation criteria compared to individual prediction models. The fusion model results indicate that thirty monitoring wells would be ideal. The RDM-based analyses in the Qom-Kahak aquifer showed that an optimal network with 30 monitoring wells outperforms the current network regarding various criteria, such as VOI and variance of estimation error. The new well configuration also demonstrates a suitable spatial distribution. Given that the current sampling frequencies are unsuitable for areas with varying vulnerabilities, we recommend sampling every 3 months in areas with moderate vulnerabilities and once every three seasons in areas with low vulnerabilities, based on the information transfer index. Finally, a management strategy in which the pumping rate should be less than 60% of the current rate is suggested to prevent saltwater intrusion into the aquifer. [ABSTRACT FROM AUTHOR]

Basin aquifers are important groundwater sources in the Western United States that are increasingly stressed due to growing populations, increased resource use, and the impacts of climate change. These aquifers are mainly recharged through melting snowpack in the surrounding mountains that infiltrates to the water table and flows directly into the basin (Mountain Front Recharge), or through deeper groundwater pathways that flow from the mountains directly into the basin aquifer (Mountain Block Recharge). However, the dominant system of recharge remains uncharacterized in many mountain basin aquifers. To address this challenge, near‐surface geophysical methods are being implemented to efficiently measure properties that govern groundwater storage and movement. This study infers groundwater storage and recharge to the Casper Aquifer around Laramie, WY, building off past studies that relied solely on sparse monitoring well data and observation of rainfall events. In this study, we use a clustering analysis on airborne electromagnetic data to define hydrogeophysical layers within the Casper Aquifer. These layers, which represent significant changes in bulk subsurface electrical resistivity, are integrated with existing hydrologic, lithologic, and smaller scale geophysical datasets to build a more representative hydrogeophysical model. Through this analysis, we define two sub‐aquifers within the larger Casper Aquifer system that are connected through structurally induced fractures and faults. This research highlights the importance of integrating geophysical data at multiple scales for defining hydrogeophysical layers that provide both a more complete understanding of basin aquifer recharge dynamics and constrain more detailed hydrologic models. Plain Language Summary: Growing populations, increased resource use, and climate change all lead to rising stress on groundwater resources in the Western United States. Groundwater in the western mountain region is generally stored in sedimentary basin aquifers that are understood to be recharged through precipitation that either: (1) infiltrates the water table and then flows directly into the basin, or (2) through deeper groundwater paths that flow from the crystalline cores of the mountains into the basin aquifers. However, relevant recharge systems are uncharacterized in many mountainous aquifers of the Western US. To address this challenge, near‐surface geophysical methods are being used to efficiently measure properties that govern groundwater storage and movement into these basin aquifers. This study uses hydrologic and multiple scale near surface geophysical data (airborne, surface and borehole) as inputs to constrain the storage and recharge dynamics on the Casper Aquifer near Laramie, WY. Integrating lithologic, hydrologic, and geophysical data at fine to large scale, highlights that the Casper Aquifer recharges primarily through snowmelt infiltration atop the nearby Laramie Range, where it flows downslope into the basin until it intersects fracture zone permeability pathways that facilitate movement of groundwater to shallower levels from a deeper primary subsurface aquifer layer. Key Points: Hydrogeophysical layers, distinct by their geophysical properties, are defined through the integration of multi‐scale geophysical dataNew mountain basin, front slope flow recharge regime defined for basin aquifers that outcrop from valley basin to summit of front slopeIntegrating multiscale geophysical data generates more complete understanding of groundwater storage and movement than traditional hydrologic studies [ABSTRACT FROM AUTHOR]

Most studies on solute transport in coastal aquifers affected by tides focus on the transport of instantaneous released solute, and there are few studies on continuously released solute affected by tides. In this study, the image monitoring method is used to establish the quantitative relationship between the concentration of the colored tracer and the hue value of the image, and the digital image is used to determine the tracer concentration distribution. Using image monitoring method laboratory experiments, quantitative analysis of the characteristics of continuously released solute transport in coastal unconfined aquifers under the tidal influence. Experiments show that the high tide inhibits the increase in the concentration of each point in the aquifer. Under the influence of tides, the solute plume retreats towards the land. During the low tide period, the solute plume migrates toward the sea again. And the solute plume will maintain a relatively stable shape after entering the aquifer for a long enough time. Ignoring the tidal effect seems to have little effect on the estimation of the position of the solute plume, but ignoring the tidal effect has a certain influence on the estimation of the dispersion range of the solute plume. No matter whether considering the tidal action, the final dispersion range of the solute plume is almost the same. But before the solute plume reaches a stable state, ignoring the tidal effect will lead to a smaller dispersion range of the solute plume. [ABSTRACT FROM AUTHOR]

In the past decades, most of the efforts have often been invested in the joint identification of contamination and hydraulic conductivity field in inland subsurface aquifers. However, the booming economy and dense population around the coast have brought a new challenge to the forefront: the serious pollution of coastal aquifers. Coastal aquifers are highly vulnerable ecological areas, which are affected by inland pollutants carried by groundwater during its entry into the sea and are also influenced by seawater intrusion. This article addresses the inverse problem of coastal aquifer pollution, which is subject to tidal effects, using the Iterative Local Updating Ensemble Smoother (ILUES) algorithm. The adopted ILUES algorithm is leveraged to efficiently extract pollutant concentration and salinity data for the identification of the source release history and characterization of the hydraulic conductivity field of a site with multiple pollutant sources. This study is based on a variant of the traditional benchmark problem, analyzing the influence of algorithm parameters, tidal effects, and heterogeneity on data assimilation. The article further demonstrates the great potential of ILUES to address new challenges. In addition, the significance of multi-level monitoring wells for the estimation of hydraulic conductivity in coastal multi-layered heterogeneous aquifers is explained. [ABSTRACT FROM AUTHOR]

This study focuses on detecting and mitigating soil salinization in four coastal areas of the Mekong Delta (Vietnam). Salinity patterns in the soils of the Mekong River Delta are not random but linked to land use practices and distance to the sea. We examine two quick yet reliable remote sensing-based techniques to detect the coastal aquaculture area and separate it from the inland freshwater farmland. These techniques can eventually be used to identify locations with an elevated risk of salinization in other coastal regions. Finally, we investigate a salinization mitigation solution based on creating a managed aquifer recharge system along the buffer zone that separates the coastal aquaculture area from the inland freshwater agriculture area. The implementation of an infiltration pond system is technically feasible in the Mekong Delta provided that hydrogeological characteristics, the fresh-saline interface position, and freshwater demands are considered. The transitional zone between freshwater agriculture and brackish water aquaculture in Bac Lieu, Soc Trang, Tra Vinh and Ben Tre provinces is optimal for implementing an aquifer recharge/freshwater barrier scheme. [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]

We present a new analytical solution to study the mechanical coupling on tidal‐induced head fluctuations in a coastal aquifer system. The conceptual model consists of two overlying confined units that extend infinitely under the sea. The proposed model assumes that the tidal fluctuations in the overlying aquifer are described by the classical equation derived by van der Kamp. For the underlying aquifer, a closed form analytical expression is derived by solving a boundary value problem that considers the loading effect produced by the overlying unit. The amplitude and phase lag of the underlying aquifer depend on both the specific storage and the thickness of the overlying unit. A parametric study shows that the mechanical coupling effect can be important for both large values of specific storage and thickness of the overlying aquifer. [ABSTRACT FROM AUTHOR]

Distributed, coupled surface‐groundwater hydrologic models are high‐dimensional, given the necessity to reflect the spatially diverse nature of complex hydrologic processes. Furthermore, inverse/inference problems involving these high‐dimensional models are naturally ill‐posed, given the limited information content of state observations that are typically assimilated. Many inversion/inference algorithms do not cope well with high dimensionality, leaving the practitioner to make subjective choices related to uncertain model inputs. The objective of this study is to evaluate the impact of these subjective calibration choices within a formal sensitivity analysis, uncertainty analysis, and parameters estimation (SA‐UA‐PE) framework on model testing for a surface‐subsurface hydrologic model. In doing so, we address the concepts of 'over‐parameterisation' and 'under‐parameterisation'. We completed a series of numerical experiments, testing several otherwise subjective aspects of the calibration process: (1) the number (5, 10, 15, 20) and type (soil, aquifer, land surface, channel) of calibration parameters selected); (2) the type of state observations assimilated (streamflow, groundwater head); and (3) the length of testing period (1 to 14 years), using monthly streamflow and groundwater head as testing data. The experiments were completed for models of the Winnebago River watershed (Minnesota, Iowa), (significant tile drainage) and the Nanticoke River watershed (Delaware, Maryland (significant groundwater‐channel interactions). The selected hydrologic model is SWAT+, using the gwflow module for physically based groundwater storage and flow modelling, and simulations are run for the 2000–2015 period. Through this process, we found that increasing the number of parameters from 5 to 15 improves the representation of streamflow, principally through an improvement of groundwater storage representation and baseflow generation, but minimal improvement when increasing to 20 parameters. Therefore, the SA‐UA‐PE process can be optimised based on an ideal number of parameters that yield adequate results while maintaining a lower computational burden. The method presented here can be used for any watershed, using integrated surface‐subsurface hydrologic models. [ABSTRACT FROM AUTHOR]

The saline aquifer CCS is a crucial site for carbon storage. Safety monitoring is a key technology for saline aquifer CCS. Current CO2 leakage detection methods include microseismic, electromagnetic, and well-logging techniques. However, these methods face challenges, such as difficulties in determining CO2 migration fronts and predicting potential leakage events; as a result, the formulation of test timing and methods for these safety monitoring techniques are somewhat arbitrary. This study establishes a gas–water two-phase seepage model and solves it using a semi-analytical method to obtain the injection pressure and the derivative curve characteristics of the injection well. The pressure derivative curve can reflect the physical properties of the reservoir through which CO2 flows underground, and it can also be used to determine whether CO2 leakage has occurred, as well as the timing and amount of leakage, based on boundary responses. This study conducted sensitivity analyses on eight parameters to determine the impact of each parameter on the bottom-hole pressure and its derivatives, thereby obtaining the influence of its parameters on different flow stages. The research indicates that, when a steady-state flow characteristic appears at the outer boundary, CO2 leakage will occur. Additionally, the leakage location can be determined by calculating the distance from the injection well. This can guide the placement and measurement of safety monitoring methods for saline aquifer CCS. The method proposed in this paper can effectively monitor the timing, location, and amount of leakage, providing a technical safeguard for promoting CCS technology. [ABSTRACT FROM AUTHOR]

The geological storage of carbon dioxide (CO2) in offshore saline aquifers stands as a primary option for reducing CO2 emissions in coastal regions. China's coastal regions, particularly Shandong and Jiangsu provinces, face significant challenges in CO2 reduction. Therefore, evaluating the feasibility of CO2 geological storage in the adjacent seas is critical. To assess the suitability of a CO2 storage site, understanding its structural and reservoir characteristics is essential to mitigate injection and storage risks. In this study, we analyzed the structural characteristics and potential traps of the Yantai Depression in the South Yellow Sea Basin based on seismic data interpretation. We further conducted well logging analysis and post-stack seismic inversion to obtain lithological data, including acoustic impedance and sandstone content percentages from the Cenozoic Funing Formation, Dainan–Sanduo Formation, and Yancheng Formation. Our findings highlight that the Yantai Depression in the South Yellow Sea Basin exhibits diverse structural traps and favorable reservoir–caprock combinations, suggesting promising geological conditions for CO2 storage. This area emerges as a suitable candidate for implementing CO2 geological storage initiatives. [ABSTRACT FROM AUTHOR]

This study investigates the hydrological dynamics of the Pativilca Basin in the Southern Hemisphere using the SWAT (Soil and Water Assessment Tool) model. Seventy-seven watersheds across a mountainous region were analyzed using elevation data, land cover, soil type, and gridded meteorological products (RAIN4PE and PISCO) for hydrological simulations. Watershed delineation, aided by a Digital Elevation Model, enabled the identification of critical drainage points and the definition of Hydrological Response Units (HRUs). The model calibration and validation, performed using the SWAT-CUP with the SUFI-2 algorithm, achieved Nash–Sutcliffe Efficiency (NSE) values of 0.69 and 0.72, respectively. Cluster analysis categorized the watersheds into six distinct groups with unique hydrological and climatic characteristics. The results showed significant spatial variability in the precipitation and temperature, with pronounced seasonality influencing the daily flow patterns. The higher-altitude watersheds exhibited greater soil water storage and more effective aquifer recharge, whereas the lower-altitude watersheds, despite receiving less precipitation, displayed higher flows due to runoff from the upstream areas. These findings emphasize the importance of incorporating seasonality and spatial variability into water resource planning in mountainous regions and demonstrate the SWAT model's effectiveness in predicting hydrological responses in the Pativilca Basin, laying the groundwork for future research in mountain hydrology. [ABSTRACT FROM AUTHOR]

Groundwater exploitation is an important cause of land subsidence. A reasonable evaluation of the impact of land subsidence in groundwater exploitation area on railway engineering is of great significance for railway construction and operation. Taking the subsidence area of Heze-Lankao section of the Lunan high-speed railway as an example, and based on field surveys, a three-dimensional seepage-stress coupling land subsidence model was established using InSAR data and ground-level measurement data from May 2016 to July 2020 for model calibration. The model predicted and analyzed groundwater changes and land subsidence patterns in the next 15 years under different mining conditions. The results showed that the land subsidence along the railway was mainly caused by groundwater exploitation within a 200 m range on both sides of the line. Under current exploitation conditions, the influence radius of the subsidence funnel along the railway will continue to increase in the next 15 years. By 2035, the cumulative subsidence at the center of the subsidence area will reach about 200 mm, posing a severe threat to the normal operation of the high-speed railway. Closing the pumping wells within 200 m along the line can significantly mitigate the land subsidence risk, reducing annual subsidence by about 20 mm by 2035. [ABSTRACT FROM AUTHOR]

The southern Gabès aquifer in southeastern Tunisia faces significant stress due to unsustainable groundwater extraction. This study employs a SEAWAT model to evaluate groundwater losses, salinization mechanisms, and the interaction between the confined aquifer and the Mediterranean Sea. The model, incorporating well pumping rates, regional freshwater inflows from the Matmata Mountain Range, and the Mediterranean Sea boundary, demonstrated high accuracy in simulating hydraulic heads. Findings reveal that regional inflow is only half of the current pumping rate, indicating unsustainable groundwater use. The study also assessed salinity dynamics by modeling the Mediterranean Sea as a constant head and salinity boundary. Results suggest limited exchange between the aquifer and the sea, challenging previous assumptions. While the immediate risks of salinization are low, continued over-extraction could compromise the aquifer's long-term sustainability. This research highlights the need for stricter local groundwater management, offers insights into regional coastal aquifer interactions, and contributes to global discussions on managing stressed aquifer systems. [ABSTRACT FROM AUTHOR]

A new solution is presented for the steady-state shape factor of a partially penetrating well in an unconfined aquifer. The problem is solved by taking into account mixed boundary conditions at the well, i.e., zero flux at the well casing and constant head at the well screen equal to the head in the well so that the flow through the well screen is non-uniform. The new method is compared with established methods, such as those of Bouwer and Rice and Zlotnik et al., demonstrating that the new approach provides more accurate results under certain conditions. The comparison highlights that the new method is particularly effective in scenarios where the assumptions of uniform flow through the well screen do not hold. This study assumes idealized conditions, such as homogeneity, isotropy, and negligible storativity in the aquifer, which may limit the method's applicability in more complex environments. The computational demands of the iterative solution process may pose challenges for practical use, especially in resource-constrained settings. [ABSTRACT FROM AUTHOR]

The Sierra Seca aquifer system is located in the northeast (NE) of the province of Granada, in the Prebetic Domain (Betic Cordillera). It is composed of different aquifer units hosted in the Lower Cretaceous and Upper Cretaceous limestones. The two aquifers are separated by a low permeability marl layer, which effectively acts as a barrier between them. To outline the behavior of the hydrogeological system, 407 samples of precipitation and 67 samples of groundwater were obtained from May 2020 to Oct. 2022 and isotopically ( δ 18 O and δ 2 H ) analyzed. For the estimation of the recharge elevation, a new methodology has been applied to estimate the isotopic content of recharge as a function of precipitation. This allowed the evaluation of the vertical gradient of both precipitation ( ∇ Z δ 18 O P = − 2.9   ‰ / k m ) and aquifer recharge ( − 4.4   ‰ / k m ≤ ∇ Z δ 18 O R ≤ − 2.9   ‰ / k m ). Therefore, estimating (1) the recharge zone elevation associated with the aquifer system, which is comprised between 1500 and 1700 m a.s.l., and (2) the transit time of recharge to reach the outflow point of the aquifer system, which varies between 4 and 5 months, is possible. Additionally, three tracer tests were conducted to outline the hydrologic connection between the recharge and discharge zones of the aquifer system. The results show that the Fuente Alta spring drains the limestones of the Lower Cretaceous, while La Natividad spring does the same with the limestones of the Upper Cretaceous. In the case of the Enmedio spring, groundwater discharge is related to infiltration through the streambed of the watercourse fed by the Fuente Alta spring. [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]

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.)

The safety of aquifer gas storage (AGS) depends on the mechanical stability of the caprock to a great extent. The injection and production operation of AGS will cause the disturbance of the in-situ stress due to the change of pore pressure in the reservoir and caprock, which may lead to the failure of caprock. The con AGS is established based on geological structure and hydrogeological information. By using the finite element method, the factors such as boundary condition, properties of reservoir and caprock, and in-situ stress coefficient are considered, respectively, and the variation of formation pressure and disturbed stress in the process of injection and production are analyzed. The results show that the boundary conditions are of significant influence on the stress field. The shear failure risk of reservoir–caprock interface under closed boundary is the greatest. The in-situ stress coefficient has the greatest influence on the failure risk of the caprock, followed by the permeability of the reservoir and caprock. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) emerges as a pivotal player in the transition to renewable energy sources. To address the seasonal fluctuations in energy dynamics, underground storage emerges as the most efficient approach, and saline aquifers within sedimentary basins as promising repositories for substantial H 2 volumes. However, this potential storage solution remains relatively unexplored. Conducting a comprehensive health, safety, and environment (HSE) risk assessment is vital for the technological advancement and public acceptance of geological H 2 storage sites. This study introduces a methodology designed to select and classify potential formations based on their HSE risks, offering a safety-oriented approach to identifying suitable storage sites. The proposed methodology underwent testing in two deep saline aquifers located in distinct geological contexts within the Iberian Peninsula. The aim of this study is to establish a foundation for further investigations and implementation of geological H 2 storage sites while ensuring safety and adhering to environmental and health standards. [Display omitted] • The proposed methodology is a useful risk assessment tool for site selection. • The tool addresses the early stages of the decision process. • The risk assessment of a site is carried out through a qualitative evaluation. • Uncertainties associated with the state of knowledge are incorporated. [ABSTRACT FROM AUTHOR]

The depletion of oil and gas reservoirs leaves many deep and expensive wells with no option but to be abandoned. However, these wells could have a second chance to extend their life as a source of geothermal energy, especially if they are located next to urban or industrial areas in need of heating. This article shows a technical analysis of the well recirculation or geothermal doublet in a single well approach as a strategy to reuse wells that cross aquifers. Different aspects of this strategy are highlighted, including the technical conditions required for the application, the well completion, and the geothermal performance. The latest is assessed via numerical reservoir simulations using geological data from an existing well. The results show that vertical petrophysical heterogeneities play an important role in the performance and feasibility of this approach. [ABSTRACT FROM AUTHOR]

Introduction: Groundwater demand has been considerably heightened due to rapid urban growth, specifically in arid areas that rely primarily on groundwater. This study aims to utilize remote sensing and aeromagnetic data, combined with the Analytic Hierarchy Process (AHP) based GIS, to evaluate potential groundwater zones in the Sohag area, Egypt. Methods: Nine thematic layers, including soil moisture, rainfall, lithology, normalized difference vegetation index (NDVI), drainage density, lineament density, slope, and land use/land cover, were developed using various remote sensing datasets. Besides the remote sensing-derived thematic layers, a geophysics-derived thematic layer represented by the RTP aeromagnetic map was included. The aeromagnetic data were analyzed and interpreted to outline the subsurface structure affecting groundwater storage and flow. Also, the aeromagnetic data analysis helps estimate the basement depth that constitutes the Nubian Aquifer's base and identifies regions with considerable thick sedimentary deposits and significant water reserves. Results and discussion: The groundwater potentiality map was consistent with production wells in the area, and sites for drilling new wells were predicted, especially in the Nile Valley around the Tahta, El-Hamimia, and west Sohag cities. The most promising sites are clustered along the Nile Valley, and the study area's northwestern and northeastern parts. The results indicate that the predominant magnetic structural trends are NW-SE, NE-SW, N-S, and E-W, which contribute to the formation of a series of subsurface horsts (H) and grabens (G). Three main basins (A, B, and C) were identified as the most profound areas. These basins represent the most promising areas for groundwater accumulation, making them attractive for future hydrogeological exploration. This integrated approach strongly offers a powerful and effective tool to assist in developing an appropriate plan to manage groundwater in arid regions. [ABSTRACT FROM AUTHOR]

Numerical modeling offers a valuable alternative to analytical solutions for pumping test analysis. However, little is known about how discretization impacts results accuracy and runtime. This study presents a systematic method for defining the spatiotemporal discretization of pumping test numerical models based on dimensionless parameters. Two types of analysis are considered: one where observations are made in the pumping well, and another one where observations are made in different wells. The influence of the discretization parameters on results accuracy and runtime is investigated and an optimal set of parameters is determined that minimizes runtime while maintaining the maximum error under 1% for an “average” aquifer. Lower runtimes are achieved when the analysis focuses on the pumping well, which is attributed to the steady‐state analytical solution approximating drawdown in the well in the numerical scheme employed. Additional tests demonstrate the robustness of the derived set of parameters in different configurations. [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]

Carbonate and karst aquifers are of great importance for human water supplies, for supporting aquatic habitats and providing ecosystem services. Optimizing the groundwater withdrawals is therefore essential for obtaining the maximum flow rate for human purposes while minimizing the negative effects on the environment. In particular, when the abstraction of groundwater occurs through wells, the problem of defining the sustainable yield arises. This study analyzes pumping tests conducted in carbonate and karst aquifers in southern Italy to derive indications for defining the sustainable yield of yields. The four examined cases concern the Mesozoic–Cenozoic platform and transition pelagic carbonate rocks characterized by different degree of fracturing and karstification and hosting a carbonate aquifer with variable average groundwater yields. The analysis compared drawdown–time trends and their derivatives for 35 pumping tests with theoretical curves to identify the flow dimension. Parameters useful for examining the well yields were then determined. The results show that the response to the pumping of the investigated aquifers is very variable, both among the different sites and within the same site. Well yields are very different due to aquifer heterogeneity, local hydrostratigraphy and structural setting, and position of the pumping center within the groundwater flow system. To determine the operational pumping rate for a well in this environment, this study emphasizes the importance of analyzing drawdown trends over time to correctly predict the well's long-term response to pumping. Specifically, when pumping induces a steady-state drawdown response, the focus for defining the sustainable abstraction shifts to the basin or aquifer scale. Conversely, when a transient drawdown response to pumping results, the well's capacity to capture groundwater becomes the primary factor for well yield and its sustainability. [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]

The detection of concealed water-conducting structures is essential for preventing water inrush disasters. Aiming to mitigate the limitations inherent in using any single technique, a comprehensive approach that combines integrated mining geophysical exploration, hydrogeological drilling, and hydrochemical exploration (GDH) is proposed for the exploration of concealed water-conducting structures. By conducting a thorough analysis of the background geological data obtained through surface exploration, potentially concealed water-conducting structures can be predicted. Then, a combination of the seismic reflection method (SRM) and mine transient electromagnetic method (MTEM) can be used to detect the location and water-bearing properties of the target structures. Afterwards, the target drilling areas are defined by the anomalies detected by the integrated mine geophysical technique, and the drilling method can directly acquire the hydrogeological information of water-conducting structures and verify the results of the geophysical methods. By means of hydrochemical analysis, inrush water sources and their runoff conditions can be identified, and the spatial relationship betweenof the source aquifers and mining space can be determined; hence, the properties, scale, and configuration of the water-conducting structures can finally be evaluated. Employing a water-conducting fault in a mine as a case study, we verified that the integrated method overcomes the limitations and possible biases of each method, providing a multiple-method solution that can accurately detect concealed water-conducting structures to help prevent water inrush disasters. [ABSTRACT FROM AUTHOR]

It is an effective measure to prevent water damage in coal mines in order to construct drainage boreholes in water-filled aquifers of a working face roof. The hydrogeological parameters of the roof water-filled aquifer and the parameters of the drainage borehole are closely related to the underground drainage effect. Taking the 3085 working face of the Donghuantuo Mine in Kailuan as an example, the influence degree of hydrogeological parameters and hydrophobic borehole parameters on the amount of drainage water was analyzed using the generalized gray correlation degree. Based on Visual Modflow, the 3D groundwater visualization model was established and the dredging borehole was generalized into the pumping borehole. By changing the main influencing factors, the design optimization of the advanced hydrophobic borehole was discussed. The results showed that the aquifer thickness had a great influence on the amount of water discharged, and the influence degree of the sharp angle between the formation and the direction of drilling, the depth of the final hole, the azimuth angle of drilling, the dip angle of drilling, the elevation of the final hole and the elevation of the borehole on the amount of water discharged decreased successively. Based on the simulation calculation, it could be observed that the hydrophobic borehole should be placed in a position with a larger accumulated thickness of the aquifer to have a better effect of hydrophobic depressurization. [ABSTRACT FROM AUTHOR]

Accurately gauging the risk of water inrush from underlying aquifers is paramount for ensuring safety in coal mine production. This paper presents an Improved Vulnerability Index Model for water-inrush (IVIM), a risk evaluation system built upon eight factors influencing coal-floor water inrush events. Firstly, the Combined Weight Method (CWM) was utilized to establish static comprehensive weights. Then, the Dynamic Weight Theory (DWT) facilitated the construction of a zoning variable weight model to determine the dynamic weights of controlling factors. Finally, the Uncertainty Analysis Model (UAM) was employed to create a linear uncertainty measure function for determining risk levels. The model was applied to the Qipanjing Mine in Inner Mongolia and compared against the Traditional Vulnerability Index Model (TVIM). Results indicated higher inrush risks in the southern and western parts of the study area compared to the eastern and northern sections, with geological structural regions exhibiting significantly greater risks. Monitoring water pressure and detecting fracture structures represent critical priorities. Compared to TVIM, IVIM yielded a 28% proportion of relative danger and danger zones, surpassing the 19% identified by TVIM. The model's effectiveness was validated utilizing the Fitting Rate of Water-inrush Points (FRWP), with IVIM achieving a 100% FRWP—significantly exceeding TVIM's 66.67%. IVIM effectively addresses the issue of localized weight variation in the study area and risk area outline under uncertain working conditions, aspects overlooked by TVIM. This method demonstrates a significant advantage in assessing the risk of water inrush from aquifers. [ABSTRACT FROM AUTHOR]

Groundwater is one of the most important sources of freshwater, contributing significantly for drinking and other domestic activities around the world. However, its quality is deteriorating over time due to overexploitation and anthropogenic activities. Rib watershed is located in the Tana basin (Ethiopia), is intensively cultivated and urbanizing area. Therefore, this study attempted to assess groundwater vulnerability to pollution using the GIS-based Modified DRASTIC Model. The modified DRASTIC model was selected due to it incorporates both hydrogeological parameters and anthropogenic factors for assessment. The necessary data were collected from the field, and downloaded from websites and laboratory experiments (No3-). The results showed that more than 73.24% of the watershed is under medium to high vulnerability. Highly vulnerable areas of the watershed (22.48%) was confined to the Southern parts of the watershed (under built-up and cultivated areas). Based on single parameter sensitivity analysis, its vulnerability was highly influenced by aquifer media (24.1%), net recharge (21.75%), land use/land cover (15.1%), and depth of groundwater table (13.6%). The Modified drastic model was validated based on the observed data of nitrate concentration in groundwater. Based on the observed data of nitrate concentration, high-vulnerable areas were more contaminated than medium and low-vulnerable areas. The modified drastic index has a strong correlation with nitrate concentration with (r = 0.76) and (P < 0.043). Therefore, the result indicated that the area is vulnerable to contamination calling for appropriate groundwater management. Hence, this finding helps to plan and minimize future contamination of groundwater by considering its vulnerability before high-risk activities are allowed. [ABSTRACT FROM AUTHOR]

The hydrogeological conditions of the Qianbei coalfield are complex, and karst water in the roof rock frequently disrupts mining operations, leading to frequent water inrush incidents. Taking the representative Longfeng Coal Mine as a case study, research was conducted on the development pattern of the water-conducting fracture zone and the water inrush mechanisms beneath karst aquifers. On the basis of key stratum theory and calculations of the stratum stretching rate, the karst aquifer in the Changxing Formation was identified as the primary key stratum. It was deduced that the water-conducting fracture zone would develop into the karst aquifer, indicating a risk of roof water inrush at the working face. Numerical simulations were used to study the stress field, displacement field, and plastic zone distribution patterns in the overlying roof strata. Combined with similar simulation tests and digital speckle experiments, the spatiotemporal evolution characteristics of the water-conducting fracture zone were investigated. During the coal mining process, the water-conducting fracture zone will exhibit a "step-type" development characteristic, with the fracture morphology evolving from vertical to horizontal. Near the goaf boundary, the strain gradually decreases, and the instability of the primary key stratum significantly impacts the mining space below, leading to the closure of interlayer voids or the redistribution of water-conducting fissure patterns. Field measurements of the water-conducting fracture zone reveal that postmining roof fractures can be classified into tensile-shear, throughgoing, and discrete types, with decreasing water-conducting capacity in that order, the measured development height of the water-conducting fracture zone (51 m) aligns closely with the theoretical height (51.37 m) and the numerical simulation height (49.17 m). Finally, from the perspective of key stratum instability, the disaster mechanisms of dynamic water inrush and hydrostatic pressure water inrush beneath the karst aquifers in the northern Guizhou coalfield were revealed. The findings provide valuable insights for water prevention and control efforts in the Qianbei coalfield mining area. [ABSTRACT FROM AUTHOR]

Since the mid-1970s, groundwater resources in Bermuda have been explored to supplement growing potable water demand on the island. Much of this work has focused on modeling the shape and size of freshwater lenses beneath the island's surface, mainly the Devonshire Lens. Less attention has been paid to how these freshwater lenses interact with surrounding coastal seawater, a process that may grow in importance as sea levels rise. Due to isotopic differences between aquifer water and seawater, these interactions can be tracked using the oxygen isotopic composition of water (δ18Ow) samples collected from coastal and subterranean areas. A pilot study found more temporal variation in coastal seawater δ18Ow along Bermuda's South Shore (the section of the coast closest to the Devonshire Lens) compared to elsewhere around the island and suggested that freshwater was discharging into coastal seawater fromthe Devonshire Lens in significant quantities. However, this study was limited by its small dataset so could not quantify the full spatial and temporal variability of δ18Ow in this area. Here, we present salinity and δ18Ow measurements from seawater samples collected around Bermuda and in wells tapping the Devonshire Lens on timescales ranging from hourly to monthly to better visualize the dynamic interaction between coastal seawater and aquifersourced freshwater. We find tight correlation between salinity and δ18Ow in well waters, indicating a simple linear mixing relationship between seawater and aquifer water in the subsurface. We confirm previous findings of larger variability in δ18Ow along the South Shore compared to elsewhere and relate observed changes to tidal height on hourly to monthly timescales. Surprisingly, South Shore seawater salinity does not vary in accordance with δ18Ow, implying additional mechanisms, such as the addition of salt spray, must be acting to mute salinity changes. These findings also demonstrate the potential in using δ18Ow to study submarine groundwater discharge, as salinity measurements alone did not detect as much variability. As sea levels rise and interactions between ocean and aquifer waters change, coastal and well water δ18Ow measurements may be helpful in tracking these processes, and in particular, changes in aquifer size. [ABSTRACT FROM AUTHOR]

Background: Chlorophenoxy compounds represent a group of selective herbicides widely used around the world. Chlorophenoxy herbicides are toxic, chemically stable, and can migrate into groundwater through soil leaching, posing a significant threat to drinking water safety and human health. Chlorophenoxy herbicides in groundwater aquifers are subject to anaerobic processes; however, the pathway and microbiology involved in the attenuation of chlorophenoxy herbicides under anaerobic condition are largely unknown. Here, the anaerobic degradation process of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), a typical chlorophenoxy herbicide, was investigated. Results: The initial 52.5 ± 2.3 μM 2,4,5-T was completely degraded by a sediment-derived microbial consortium, with 3,4-dichlorophenol, 2,5-dichlorophenol, 3-chlorophenol (3-CP) and phenol being identified as the intermediate products. Reductive dechlorination of 3-CP to phenol and the subsequent elimination of phenol were the key transformation steps in the overall degradation process of 2,4,5-T. Amplicon sequencing suggested that Dehalobacter, Sulfuricurvum, Bacteroides, Acetobacterium, and Clostridium sensu stricto 7 might contribute to the transformation of 2,4,5-T to phenol, and Smithella, Syntrophorhabdus, Methanofollis and Methanosaeta likely cooperated to accomplish the complete mineralization of phenol. Conclusions: This study reported the anaerobic degradation of 2,4,5-T via reductive dechlorination and the subsequent syntrophic metabolization of phenol, an intermediate product transformed from 2,4,5-T. Dehalobacter was identified as the organohalide-respiring population catalyzing the reductive dechlorination reaction. Syntrophorhabdus and methanogenic populations were likely involved in anaerobic phenol oxidation and facilitated the complete mineralization of 2,4,5-T. [ABSTRACT FROM AUTHOR]

Brazilian mining ventures aged 30 years or older were studied, revealing historical oversights in environmental planning that have caused substantial environmental liabilities during active mining and decommissioning. Electrical resistivity tomography surveys were conducted in a decommissioning uranium mine in southeast Brazil. The results provided valuable insights into local hydrogeological dynamics, revealing the flow of acid mine drainage in two distinct systems: the porous waste rock pile and the fractured underlying crystalline basement. Geo-electrical sections displayed conductive anomalies indicating hydraulic connectivity between the waste rock pile and the underlying fractured aquifer through crystalline basement fractures. This connection was substantiated by sub-vertical zones of low electrical resistivity interpreted as groundwater influx from the porous system to the fractured aquifer. Consequently, the waste rock pile acted as a localized recharge zone for the regional aquifer, facilitating chemical exchanges between the two systems. Furthermore, the study successfully differentiated less impacted saturated zones (resistivity ≈80 Ω·m) from those associated with acid mine drainage (< 40 Ω·m). Preliminary investigations identified a complex fracture network in the study area, comprising two main fault systems with preferential NE and NW orientations, nearly orthogonal to each other. This fracture network demonstrated continuity, playing a fundamental role in sustaining flow within the local and regional drainage network. [ABSTRACT FROM AUTHOR]

The global transition to renewable energy sources such as wind and solar has created a critical need for effective energy storage solutions to manage their intermittency. This review focuses on compressed air energy storage (CAES) in porous media, particularly aquifers, evaluating its benefits, challenges, and technological advancements. Porous media-based CAES (PM-CAES) offers advantages, including lower costs and broader geographical availability compared to traditional methods. This review synthesizes recent advancements in numerical modeling, simulation, and experimental studies, which have enhanced the understanding of air–water–heat flow interactions and improved efficiency in these systems. Field studies demonstrate that using existing idle and abandoned wells can minimize infrastructure costs and environmental impact. This review underscores the potential of CAES in porous media to support the growing demand for sustainable and reliable energy storage solutions. [ABSTRACT FROM AUTHOR]

Mountainous zones are often characterized by complex orography and contacts between different aquifers that usually complicate the use of isotope hydrology techniques. The Apennine chain (Italy) and 10 mountain and mid‐mountain areas belonging to it are the objective of this study. An original isotopic data treatment, able to identify the most probable recharge area for several springs/springs' groups/wells, has been developed. The method consists of a two‐step approach: (1) the determination of the spring/wells computed isotope recharge elevation; (2) an advanced δ18O precipitation distribution model over the study area supported by statistical and GIS‐based procedures implemented by two processes: first, the clipping of precipitation δ18O values (depicted from the δ18O–elevation relationships obtained for each study area) over a most probable recharge area for each analyzed spring or well and, second, the calculation of the overlapping distribution between the spring/well mean δ18O values ± σ and the precipitation δ18O content for each outcropping aquifer. A new regional δ18O gradient covering 150 km latitudinal length of central Italy has been defined. Seven LMWL and δ18O–elevation relationships able to represent the local precipitation isotopic composition have been obtained. The mean elevation of the springs and wells recharge areas have been assessed by a comparison between the obtained gradient with nine δ18O gradients available in the literature and those obtained at a local scale. The new isotopic modeling approach can stress whether the mere isotope modeling based on the stable isotope of oxygen agrees with the hydrogeological setting of the study areas. [ABSTRACT FROM AUTHOR]

The issues associated with long‐screened wells (LSWs) (and open boreholes) at contaminated sites are well documented in the groundwater literature but are still not fully appreciated in practice. As established in seminal and review papers going back over three decades, the interpretation of sampling results from LSWs is challenging in the presence of vertical hydraulic gradients and borehole flow; furthermore, LSWs allow for vertical redistribution of contamination between aquifer layers. Acknowledgment of these issues has led to the development of new technologies and well designs to enable discrete‐zone monitoring (DZM), yet LSWs remain common for many reasons, for example, as multipurpose wells, for geophysical logging, and (or) as legacy installations. Despite the literature on LSWs and despite the adoption of DZM at many sites, the use of LSWs persists and the challenges of interpreting sampling results from LSWs remain. In this issue paper, we provide a conceptual overview of the problems posed by LSWs and review existing literature and past work to improve the interpretation of sampling in LSWs. We draw on experience from previous studies at the Hanford Site in eastern WA, USA, and use synthetic examples to illustrate key concepts and challenges for interpretation. A recently published analytical modeling framework is used to develop illustrative synthetic examples and demonstrate a workflow for building scientific intuition to understand issues around interpreting samples from LSWs, which is critical to effective characterization and groundwater remediation at sites with LSWs. [ABSTRACT FROM AUTHOR]

Tianjin, a coastal metropolis in north China, has grappled with land subsidence for nearly a century. Yet, emerging evidence suggests a notable decrease in subsidence rates across Tianjin since 2019. This trend is primarily attributed to the importation of surface water from the Yangtze River system via the South‐to‐North Water Diversion Project, initiated in December 2014. Utilizing Sentinel‐1A Interferometric Synthetic Aperture Radar (InSAR) data (2014–2023), this study reveals that one‐third of the Tianjin plain has either halted subsidence or experienced land rebound. As a result, the deep aquifer system (~−200 to −450 m) beneath one third of the Tianjin plain has completed a consolidation cycle, leading to the establishment of new, locally specific preconsolidation heads. The identification of the newly established preconsolidation head seeks to answer a crucial question: How can we prevent the reoccurrence of subsidence in areas where it has already ceased? In essence, subsidence will stop when the local hydraulic head elevates to the new preconsolidation head (NPCH), and permanent subsidence will not be reinitiated as long as hydraulic head remains above the NPCH. The difference of the depth between current hydraulic head and the NPCH defines the safe pumping buffer (SPB). This study outlines detailed methods for identifying the NPCHs in the deep aquifer system from long‐term InSAR and groundwater‐level datasets. Determining NPCHs and ascertaining SPBs are crucial for estimating how much groundwater can be safely extracted without inducing permanent subsidence, and for developing sustainable strategies for long‐term groundwater management and conservation. [ABSTRACT FROM AUTHOR]

Pump‐and‐treat technologies are widely used in groundwater remediation and site cleanup. Such technologies involve pumping contaminated groundwater to the surface for treatment. Following treatment, the water is often reinjected back into the aquifer (referred to as pump‐treat‐inject or PTI) for potential reuse. The treatment system is often designed to remove dissolved‐phase contaminants in groundwater such that water meets applicable cleanup standards (herein referred to as "full treatment"). However, in some cases, the treatment system may not effectively reduce the dissolved‐phase concentrations (herein referred to as "partial treatment") for some of the contaminants present in groundwater. Modeling PTI under partial treatment conditions is challenging because contaminant concentrations in injected water depend on the pumped water concentrations and the system treatment efficiency. Essentially, the injected water concentration (a transport model input) is unknown prior to transport simulation. This study presents a novel iterative approach to modeling PTI under partial treatment scenarios, where the injected water concentration is linked to the modeled pumped water concentration. The method was developed for a complicated three‐dimensional (3D) flow and transport modeling study conducted for a confidential remediation site where PTI with partial treatment was applied. However, due to the complexity of the 3D model and the confidential information of the site, a simple two‐dimensional (2D) numerical model is presented to demonstrate the iterative method. The 2D model test runs and the 3D model application in a remediation site showed that the iterative simulation results quickly converged to a viable final solution. [ABSTRACT FROM AUTHOR]