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An extensive database consisting of measurements of ground movements and pore pressures from 48 deep excavations is presented. The ground conditions for all cases are soft, normally consolidated clays, often underlain by a coarser layer of soil, i.e., confined aquifer, on top of bedrock. Traditionally wall and ground movements caused by deep excavations have been predicted without assessing effects of groundwater drainage or the influence of installation of tie-back anchors or foundation piles. This study clearly shows that the observed ground movements exceeded expected values based on induced shear movements and significant deformations occur at far distance from the excavation. The cause of the deformations is largely consolidation settlements due to pore pressure reduction, with a zone of influence recorded at up to 400 m distance from the excavation. The construction methods and opening of drainage paths to the confined aquifer is as important for pore pressure reduction, as exposing the confined aquifer itself. In addition, the groundwater drawdown is shown to be dependent on the ground conditions and mitigation measures. It is also shown that the pore pressure reduction and zone of influence may be very small if no drainage path is created, i.e., in case of strutted excavations and no piles or driven piles, or when the bedrock surface is not exposed. The drilling of tie-back anchors and piles are also seen to influence ground movements, especially at a distance of 2–4 times the excavation depth. Charts produced from the database enable estimation of expected groundwater drawdown including zone of influence. In addition, they can support decisions on construction methods, need for mitigating measures and extent of monitoring program in relation to deep excavations. [ABSTRACT FROM AUTHOR]

The vulnerability of oceanic islands in the face of climate change, vis-a-vis human development, is a serious issue at present. The island of Great Nicobar in the Nicobar archipelago in the Indian Ocean will face major challenges owing to its impending development activities. The eastern coastal part of the island was investigated through exploratory drilling, geophysical investigations, and water-table monitoring. Field investigations show that coralline sand is the major groundwater repository and is commonly developed through dug wells. Exploratory drilling down to 100 m depth revealed that the underlying Tertiary consolidated aquifer is of limited potential and showed increased salinity with depth. Water is also present along the contacts of shale–sandstone. The mean seasonal fluctuations in the depth to the water table was 0.18 m. Geoelectrical sections identified promising fresh groundwater zones along the east coast, with freshwater-bearing semi-weathered coralline limestone and coralline sand having a resistivity of 146–622 ohm m. Based on generated data, a 3D model of the aquifer system was constructed. The observed soil infiltration rate was 0.3–0.5 cm h−1. The specific capacity of the dug wells was c. 5 m2 min−1. The permeability of the phreatic aquifer was 5–11 m/day and the transmissivity was 0.11–0.2 m2 min−1. The optimum yield of the unconfined aquifer was 17–21 m3/day. The tidal influences on the aquifer system also added complexity to the island's hydrogeological dynamics. Despite the challenges of restricted access due to the presence of aboriginal tribes in the island, the present study provides the maiden set of hydrogeological data for the island, revealing the disposition of the aquifers, their properties and their spatio-temporal behaviour. [ABSTRACT FROM AUTHOR]

Because of its unique geographical properties, the Yaoquanshan area of Wudalianchi City, Heilongjiang Province, contains rich mineral water resources. We have carried out much research on the mineral water in the Yaoquanshan area of Wudalianchi City, which has also been supplemented by of previous studies. In this paper, through a controlled audio geoelectromagnetic method, geological drilling, groundwater level monitoring and water quality analysis, the structure, regional geology, hydrogeology and water geochemistry, as well as the characteristics of the distribution of metasilicate mineral water and natural soda water, the formation mechanism and the recharge, runoff and excretion of groundwater in the study area, are discussed. The results can provide a theoretical basis for the exploitation and utilization of mineral water resources in the southern region of the Wudalianchi Pharmaceutical Spring Mountain. [ABSTRACT FROM AUTHOR]

In this study, we visualize and analyze the literature on the Brahmaputra river using a spectral clustering algorithm, tracking research trends over time. We found that the focus of research on the Brahmaputra has changed over time in the last decade, with a shift from geology to hydrology and geochemistry and a rapid growth in climate change research in recent years. In the future, potential hot topics may be "water resource management" and other topics related to transboundary water resource management and cooperation. At the same time, this study also analyzes in detail the keywords and clusters "geohydrology" and "ecological risk and sustainable development", among other topics. We believe that future research should carefully consider the potential effects of transdisciplinary research trends. For instance, it is urgent that transborder governance and management regimes be renovated through joint efforts and cross-border effective actions carried out by multifaceted and multi-scalar agencies along this river. [ABSTRACT FROM AUTHOR]

The distribution of oxidation - reduction interfaces is of significance in mining production and exploration. By organizing geological exploration, mine geology, and production exploration data from Wandongshan ore section of Beiya gold polymetallic deposit, the factors influencing the distribution of the oxidation reduction interface were analyzed. Comparative analysis revealed that stratigraphy, intrusive rocks, tectonic structures, and hydrogeological conditions are the main factors affecting the distribution of the oxidation reduction interface while folding structures have no impact on its variation. Studying the 3D spatial distribution characteristics of the oxidation reduction interface and establishing a more accurate 3D spatial model are crucial for ensuring the accuracy of production planning and the determination of construction organization schemes. This allows for the efficient utilization of resources. [ABSTRACT FROM AUTHOR]

Karapınar region (Konya, Türkiye) is one of the important regions of the world in terms of sinkhole formations. The research aimed to map the sinkholes in detail, to determine their spatial distribution and geometrical parameters. For this purpose, the long axes, short axes, depths and the proximity to settlements of the sinkholes were measured and their circumferences and areas were calculated. During the studies, the relationship of the sinkholes with lithology, their cross sections, shapes and the related structures were determined and the sinkholes were divided into five main groups as following: Basement rock sinkholes, Obruk Plateau sinkholes, Seyithacı sinkholes, Siyeklik sinkholes and Basin sinkholes. The d/l ratios of each sinkhole group were separately determined and interpreted. Accordingly, most of the d/l ratios are smaller than 0.2. Namely, the long axes are higher than the depth and it indicates that the shallow and wide sinkholes are common in the region. It has been determined that the fracture systems in the region, as well as the lithology and groundwater factors, are quite effective in the formation and distribution of the sinkholes in the Karapınar region. Considering the distance of the sinkholes to the settlements, Seyithacı sinkholes are the most risky group in the region because they are deep and close to the settlements. [ABSTRACT FROM AUTHOR]

Population growth and expanding urbanization have caused persistent shortages and contamination of groundwater resources in Mali, Africa. The increase in groundwater salinity makes it more difficult for residents to obtain drinking water, it is necessary to clarify the causes and control factors of groundwater mineralization in Gao region, northern Mali. Based on the analysis of the hydrochemical composition of groundwater in 24 boreholes, Piper and Schöeller diagrams, principal component analysis (PCA) and hierarchical cluster analysis (HCA) are used to carry out multivariate statistical analysis on the main ions. The results show that the groundwater samples are weakly alkaline, with pH values ranging from 5.83 to 8.40, and the average values of boreholes are 7.50, respectively. The average electrical conductivity (EC) value is 354.4 (µS/cm), and the extreme value is between 124.0 and 1 247 (µS/cm). Water is usually mineralized and presents nine types of water phase. The three principal components explain 84.42% of the total variance for 13 parameters. The factor F1 (58.85%), the factor F2 (16.88%) and the factor F3 (8.69%) present for the majority of the total data set. In addition, multivariate statistical analysis confirmed the genetic relationship among aquifers and identified three main clusters. Clustering related to groundwater mineralization (F1), clustering related to oxide reduction and iron enrichment (F2), and clustering of groundwater pollution caused by nitrate and magnesium (F3). We found that agriculture, weathering activities and dissolution of geological materials promote the mineralization of groundwater. Groundwater quality in the Gao region is becoming less and less potable because of increasing salinity. [ABSTRACT FROM AUTHOR]

Lake level, area and volume are sensitive indicators of climate change. At present, many studies have focused on the interannual water balance of lakes, but lake level and area can change remarkably with seasons, especially for lakes with seasonal ice cover. Zhari Namco, a seasonal frozen lake, was selected as an example to investigate its seasonal water balance. Multi-source altimetry and Landsat data were used to obtain the seasonal lake level and area from 1992 to 2019, and seasonal lake volume variations were also estimated. The results indicated the average lake level, area and volume in autumn were the largest. The lake level, area, and volume experienced three turning points approximately in 2000, 2010, and 2016, and showed an overall increasing trend from 1992 to 2019, with slopes of 0.15 m/year, 2.17 km2/year, and 0.14 km3/year, respectively. The lake area expanded significantly in autumn, which was related to the abundant precipitation. Delay time of land surface runoff, increased temperature, and evaporation may be the reason for the low lake level and volume in summer. The precipitation was the dominant factor of water balance, which explained 62.09%, 62.43%, and 62.10% of the variations in lake level, area, and volume, respectively. [ABSTRACT FROM AUTHOR]

The Pilbara bioregion (Western Australia) has become a hotspot for subterranean fauna as a consequence of many surveys conducted to comply with Western Australian environmental regulation requirements. In this bioregion, mining developments can have major implications for subterranean fauna and their conservation. However the diversity and species distributions of most taxa are still poorly known, including the crustacean family Parabathynellidae. Recent studies on a widespread genus of this family (Atopobathynella) from the Pilbara highlighted several undescribed taxa with interesting patterns of distribution. In the Gudai Darri locality, the northern flank of the Hamersley Range occurs as a stepped escarpment intersected by dykes and gullies, with groundwater occurring within fractured rocks abutting the Fortescue River valley, where a separate regional aquifer occurs. This investigation aimed to observe whether stygofauna species distributions (1) reflected the separation between the two major aquifers within the Hamersley Range and the Fortescue Valley; and (2) were influenced by the presence of dykes. We examined the Atopobathynella species occurring in the study area using morphological and molecular data. The results reflected the hydrogeological complexity of the study area with six new lineages of Atopobathynella , recorded mainly in different gullies, that do not share a most recent common ancestor. Two species are described here A. pagetae sp. nov. and A. lythei sp. nov., and four additional species are delineated through preliminary morphological analyses and molecular data. This study will improve future environmental impact assessments and the understanding of Parabathynellidae taxa distribution in hydrogeological complex areas. [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]

Copyright of Afyon Kocatepe University Journal of Science & Engineering / Afyon Kocatepe Üniversitesi Fen Ve Mühendislik Bilimleri Dergisi is the property of Afyon Kocatepe University, Faculty of Science & Literature 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.)

First‐break picking is an essential step in seismic data processing. For reliable results, first arrivals should be picked by an expert. This is a time‐consuming procedure and subjective to a certain degree, leading to different results for different operators. In this study, we have used a U‐Net architecture with residual blocks to perform automatic first‐break picking based on deep learning. Focusing on the effects of weight initialization on first‐break picking, we conduct this research by using the weights of a pre‐trained network that is used for object detection on the ImageNet dataset. The efficiency of the proposed method is tested on two real datasets. For both datasets, we pick manually the first breaks for less than 10%$\%$ of the seismic shots. The pre‐trained network is fine‐tuned on the picked shots, and the rest of the shots are automatically picked by the neural network. It is shown that this strategy allows to reduce the size of the training set, requiring fine‐tuning with only a few picked shots per survey. Using random weights and more training epochs can lead to a lower training loss, but such a strategy leads to overfitting as the test error is higher than the one of the pre‐trained network. We also assess the possibility of using a general dataset by training a network with data from three different projects that are acquired with different equipment and at different locations. This study shows that if the general dataset is created carefully it can lead to more accurate first‐break picking; otherwise, the general dataset can decrease the accuracy. Focusing on near‐surface geophysics, we perform traveltime tomography and compare the inverted velocity models based on different first‐break picking methodologies. The results of the inversion show that the first breaks obtained by the pre‐trained network lead to a velocity model that is closer to the one obtained from the inversion of expert‐picked first breaks. [ABSTRACT FROM AUTHOR]

Many coastal and island communities depend on groundwater as the only source of freshwater, making it an invaluable resource. In the Mediterranean region, groundwater resources are highly vulnerable to natural and anthropogenic pressures, such as overexploitation, climate change, seasonal variations in precipitation, and seawater intrusion. Hence, an understanding of hydrogeological processes and groundwater chemistry is a basis for the sustainable management of coastal and island groundwater resources. Vis, a small and remote karst island in the Adriatic Sea, exhibits peculiar geological and hydrogeological settings, resulting in the island's autonomous water supply. The current pumping capacity (maximum of 42 l/s) meets most of the demand, but intensive summer tourism and climate change exert high stress on groundwater resources during the dry season. Consequently, in the last decade, occasional reductions for consumers occurred. Monitoring of in situ physicochemical parameters and groundwater sampling for chemical and isotopic analyses were conducted from 2020 to 2023 at deep borewells, shallow dug wells, and springs. Hydrochemical interpretation indicated that groundwater chemistry was affected primarily by carbonate and sulfate rock dissolution, mixing with seawater, reverse ion exchange, and dedolomitization. The majority of groundwater samples exhibit Ca–HCO3 hydrochemical facies, followed by Na–Cl and mixed facies. The low percentage of seawater in the mixture indicated that seawater intrusion is not too extensive even during prolonged dry periods, implying a favorable hydrostatic regime with relatively small but sufficient groundwater reserves of the island's aquifers, although the investigated period was characterized by significantly lower precipitation with respect to the 30-year average. [ABSTRACT FROM AUTHOR]

Highly permeable geological structures such as dissolution channels, open fractures, and faults create environmental challenges regard to hydrological and hydrogeological aspects of underground construction, often causing significant groundwater inflow during drilling due to the limitations of empirical and analytical methods. This study aims to identify the geological factors influencing water flow into the tunnel. High-flow zones' geological features have been identified and examined for this purpose. According to the geological complexity of the Nowsud tunnel, presence of different formations with different permeability and karstification have led to a high volume of underground inflow water (up to 4700 L/s) to the tunnel. The Nowsud tunnel faces significant geological and hydrogeological challenges due to its passage through the Ilam formation's LI2 unit, characterized by dissolution channels, faults, and fractures. The highest inflow rate (4700 L/s) occurred in the Hz-9 zone within the Zimkan anticline. The relationship between geological features and groundwater inflow indicates that anticlines are more susceptible to inflow than synclines. Additionally, different types of faults exhibit varying hydraulic effects, with strike-slip faults having the most significant impact on groundwater inflow, thrust faults conducting less water into the tunnel, and inflow through normal faults being negligible compared to the other two types of faults. The novelty of this paper lies in its detailed analysis of geological features influencing groundwater inflow into the Nowsud tunnel, providing empirical data on high-flow zones and differentiating the hydraulic effects of various fault types, which enhances the understanding and prediction of groundwater inflow in underground constructions. [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]

A hydrogeological study of the shallowest part of the halite nucleus of the Salar de Atacama is presented, focusing on the isotopic variability in δ18O and δ2H (SMOW) in the brine. It is observed that intensive brine extraction has induced upward vertical flows from the lower aquifer, which presents with a lighter isotopic composition (δ18O: −0.87‰ to −2.49‰; δ2H: −26.04‰ to −33.25‰), toward the upper aquifer, which has more variable and enriched isotopic values. Among the possible explanations for the lighter isotopic composition of the lower aquifer waters is the influence of paleolakes formed during the wetter periods of the Late Pleistocene and Holocene that recharged the underlying aquifers. The geological structure of the Salar, including faults and the distribution of low-permeability layers, has played a determining role in the system's hydrodynamics. This study emphasizes the need for continuous and detailed monitoring of the isotopic composition to assess the sustainability of the water resource in response to brine extraction and future climate changes. Additionally, it suggests applying this methodology to other salt flats in the region for a better understanding of hydrogeological processes in arid zones. The research provides an integrative view of the relationship between resource extraction, water management, and ecosystem conservation in one of the most important salars in the world. [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]

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design 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 Arabian Desert is characterised by very low rainfall and high evaporation, yet over 210 springs are on its northeastern edge in central Iraq along the Abu Jir lineament, which represents the western depositional margin of a foreland basin infilled by the floodplain sediments of the Tigris and Euphrates Rivers; there is little evidence of faulting. The springs discharge from gently east-dipping Paleocene–Eocene limestones, either where groundwater flowpaths intersect the ground surface or where groundwater flow is forced to the surface by confining aquitards. Calculated annual recharge to the aquifer system across the Arabian Desert plateau (130–500 million m3) is significant, largely due to rapid infiltration through karst dolines, such that karst porosity is the primary enabler of groundwater recharge. The recharge is enough to maintain flow at the Abu Jir springs, but active management of groundwater extraction for agriculture is required for their long-term sustainability. The hydrochemistry of the springs is determined by evaporation, rainfall composition (high SO4 concentrations are due to the dissolution of wind-blown gypsum in rainfall), and plant uptake of Ca and K (despite the sparse vegetation). Limestone dissolution has relatively little impact; many of the springs are undersaturated with respect to calcite and lack tufa/travertine deposits. The springs at Hit-Kubaysa contain tar and high levels of H2S that probably seeped upwards along subvertical faults from underlying oil reservoirs; this is the only location along the Abu Jir lineament where deep-seated faults penetrate to the surface. The presence of hydrocarbons reduces the Hit-Kubaysa spring water and converts the dissolved SO4 to H2S. [ABSTRACT FROM AUTHOR]

Mountains have a critical role in freshwater supply for downstream populations. As the climate changes, groundwater stored in mountains may help buffer the impacts to declining water resources caused by decreased snowpack and glacier recession. However, given the scarcity of groundwater observation wells in mountain regions, it remains unclear how mountain groundwater is being impacted by climate change across ecoregions. This study quantifies temporal trends in mountain groundwater levels and explores how various climatic, physiographic and anthropogenic factors affect these trends. We compiled data from 171 public groundwater observation wells within mountain regions across Canada and the United States, for which at least 20 years of monthly data is available. The Mann‐Kendall test for monotonic trend revealed that 54% of these wells have statistically significant temporal trends (p < 0.05) over the period of record, of which 69% were negative and therefore indicating overall declining groundwater storage. Wells in the western mountain ranges showed stronger trends (both positive and negative) than the eastern mountain ranges, and higher elevation wells showed fewer negative trends than the low elevation (<400 m asl) wells (p < 0.05). Correlation, Kruskal‐Wallis tests, stepwise multiple linear regression and random forest regression were used to identify factors controlling groundwater trends. Statistical analysis revealed that lower‐elevation mountain regions with higher average annual temperatures and lower average annual precipitation have the greatest declines in groundwater storage under climate change. Trends in temperature and precipitation, and ecoregion were also important predictors on groundwater level trends, highlighting geographic differences in how mountain wells are responding to climate change. Furthermore, sedimentary bedrock aquifers showed markedly more negative trends than crystalline bedrock aquifers. The findings demonstrate that the impact of climate change on mountain water resources extends to the subsurface, with important implications for global water resources. [ABSTRACT FROM AUTHOR]

North Florida's karst springs are among the largest and most abundant in the world. Despite relatively stable spring discharges, flow reversals can episodically occur in some springs when river waters backflow into the aquifer during flood events. Reversals are normal features of the springs along the Suwanee River, but the changing incidence of these reversals in response to anthropogenic activities or climate change remains unclear and the mechanisms responsible for these reversals remain poorly described. Here we develop a reduced‐complexity hydrogeological model of the Suwannee River catchment to explore conditions needed to induce spring flow reversals. Our model demonstrates that reversals require two conditions: (a) a hydrogeological setting that combines an upstream catchment with rapid hydrological responses to meteorological drivers, which freely drains to a downstream catchment containing the karst aquifer (i.e., the spring‐fed river segment); and (b) meteorological conditions that create sufficient temporal variability in recharge. Given both conditions, recharge events can propagate from the upstream catchment and fill the downstream river segment faster than it can drain, causing river stage to rise above the aquifer head, resulting in temporary spring flow reversal (or bank storage). Our model accurately predicts significant post‐flood increases in spring flow as bank storage recedes, and using measured electrical conductivity at a major river‐adjacent spring we also quantify the enhancement of limestone dissolution (cave enlargement) due to reversal events. A comprehensive assessment of the incidence and duration of reversal events shows a predominant influence of climate and vegetation changes over that of groundwater pumping. Plain Language Summary: North Florida's karst springs are among the largest and most abundant in the world. Spring flow is very stable and usually into the main river, but reversals of flow direction may occur temporarily, such that water from the river enters the subsurface through the springs. This is a natural feature, but its causes and future behavior under climate change and human activities are poorly understood. In this work, we develop a simple model of the Suwannee River catchment that describes spring flow and reversals, showing that reversals require both appropriate geological as well as meteorological conditions. We also show that spring flow reversals contribute significantly to the limestone cave enlargement near the river, and that the future characteristics of reversal events are most dependent on climate and vegetation changes. Key Points: A reduced‐complexity model explains flow reversals in Florida karst springs due to fast discharge response from upstream surficial aquiferThe occurrence of reversals requires a certain hydrogeological setting and sufficient temporal variability in aquifer rechargeThe model also quantifies enhanced limestone dissolution rates (cave enlargement) near the river due to flow reversals [ABSTRACT FROM AUTHOR]

Abstract Many coastal and island communities depend on groundwater as the only source of freshwater, making it an invaluable resource. In the Mediterranean region, groundwater resources are highly vulnerable to natural and anthropogenic pressures, such as overexploitation, climate change, seasonal variations in precipitation, and seawater intrusion. Hence, an understanding of hydrogeological processes and groundwater chemistry is a basis for the sustainable management of coastal and island groundwater resources. Vis, a small and remote karst island in the Adriatic Sea, exhibits peculiar geological and hydrogeological settings, resulting in the island’s autonomous water supply. The current pumping capacity (maximum of 42 l/s) meets most of the demand, but intensive summer tourism and climate change exert high stress on groundwater resources during the dry season. Consequently, in the last decade, occasional reductions for consumers occurred. Monitoring of in situ physicochemical parameters and groundwater sampling for chemical and isotopic analyses were conducted from 2020 to 2023 at deep borewells, shallow dug wells, and springs. Hydrochemical interpretation indicated that groundwater chemistry was affected primarily by carbonate and sulfate rock dissolution, mixing with seawater, reverse ion exchange, and dedolomitization. The majority of groundwater samples exhibit Ca–HCO3 hydrochemical facies, followed by Na–Cl and mixed facies. The low percentage of seawater in the mixture indicated that seawater intrusion is not too extensive even during prolonged dry periods, implying a favorable hydrostatic regime with relatively small but sufficient groundwater reserves of the island’s aquifers, although the investigated period was characterized by significantly lower precipitation with respect to the 30-year average.

Streamflow, dissolved oxygen, and water temperature underpin stream fish habitat suitability, so climate change could cause widespread habitat deterioration. Identifying stream characteristics that mediate habitat resilience to heatwaves will allow conservation effort prioritisation. Here, a set of readily applied metrics were used to assess hydrological and oxythermal responses of neighbouring salmonid streams, with distinctive geologies, soil‐types, and localised riparian shading, to periods of anomalously warm conditions. During heatwaves, low flows, warm‐water temperatures, and diel oxygen variability, associated with biogenic production and respiration, predominated. In a low‐shade stream lacking significant catchment water storage, high daytime (>22°C) and night‐time (>19°C) water temperatures and low early morning O2 concentrations (<5 mg L−1) accumulated oxythermal stress for salmonids throughout summer. A stream with localised shading and a higher proportion of underlying aquifers and permeable soils throughout its watershed experienced considerably less cumulative oxythermal stress (O2 > 6 mg L−1; temperatures <19°C), whilst slower release of subsurface water bolstered base flows during dry spells. Our findings support conservation of shaded streams with permeable watersheds characterised by higher soil infiltration rates and aquifer storage capacity as salmonid sanctuaries under a warmer, drier summer climate. Preventing water quality and hydromorphological deterioration are paramount for safeguarding their role as climate refugia. [ABSTRACT FROM AUTHOR]

When tunnel boring machines (TBMs) excavate through jointed rock masses, the cutting efficiency is strongly affected by the shear strength of joints, the mechanism of which, however, remains poorly understood. In this study, a series of disc-cutter indentation tests were conducted on granite rock mass specimens with different joint shear strengths. During the indentation, the cracking process was recorded by a digital image correlation (DIC) system. The deformation and strength of specimens, cracking behavior, rock breakage mode and cutting efficiency were quantitatively investigated. In addition, to investigate the combined effects of joint shear strength, orientation and spacing on the rock breakage mechanism, numerical rock mass models were established based on a particle flow code PFC2D. Experimental results reveal that the cracking of primary and secondary cracks changes from the mixed shear-tensile to tensile mode in the initial stage, while the joint shear strength does not affect the cracking mode in the subsequent propagation process. The rock breakage mode is classified to an internal block breakage mode, a cross-joint breakage mode and a cutters-dependent breakage mode. The cross-joint breakage mode is optimal for improving the cutting efficiency. Numerical simulation results reveal that the increase in the joint shear strength changes the internal block breakage mode to cross-joint breakage mode for rock masses of particular ranges of joint orientation and spacing. These findings provide basis for improving the TBM cutting efficiency through jointed rock masses. [ABSTRACT FROM AUTHOR]

Mechanical softening behaviors of shale in CO2-water--rock interaction are critical for shale gas exploitation and CO2 sequestration. This work investigated the cross-scale mechanical softening of shale triggered by CO2-water--rock interaction. Initially, the mechanical softening of shale following 30 d of exposure to CO2 and water was assessed at the rock-forming mineral scale using nanoindentation. The mechanical alterations of rock-forming minerals, including quartz, muscovite, chlorite, and kaolinite, were analyzed and compared. Subsequently, an accurate grain-based modeling (AGBM) was proposed to upscale the nanoindentation results. Numerical models were generated based on the real microstructure of shale derived from TESCAN integrated minerals analyzer (TIMA) digital images. Mechanical parameters of shale minerals determined by nanoindentation served as input material properties for AGBMs. Finally, numerical simulations of uniaxial compression tests were conducted to investigate the impact of mineral softening on the macroscopic Young's modulus and uniaxial compressive strength (UCS) of shale. The results present direct evidence of shale mineral softening during CO2-water--rock interaction and explore its influence on the upscale mechanical properties of shale. This paper offers a microscopic perspective for comprehending CO2-water-shale interactions and contributes to the development of a cross-scale mechanical model for shale. [ABSTRACT FROM AUTHOR]

The evaluation of urban underground space (UUS) suitability involves multiple indicators. Assigning weight to these indicators is crucial for accurate assessment. This paper presents a method for spatially variable weight assignment of indicators using the order relation analysis method (G1-method), the entropy weight method, an improved grey relational analysis (GRA) and a set of spatial weight adjustment coefficients. First, the subjective and objective weights of indicators for engineering geological and hydrogeological conditions were determined by the G1-method and entropy weight method, respectively, and their combined weights were then obtained using the principle of minimum discriminatory information. This study highlighted the impact of surface restrictions, such as buildings, on UUS, and the degree of the influence of these buildings gradually decreased with the increase in depth of the rock and soil mass in UUS, which resulted in changes in weights of indicators with depth. To address this issue, a coefficient was defined as the standardized value of the ratio of additional stress applied by restrictions to the self-weight stress of soil at the same depth to modify the combined weights so that all weights of indicators could vary in space. Finally, an improved GRA was used to determine the suitability level of each evaluation cell using the maximum correlation criterion. This method was applied to the 3D suitability evaluation of UUS in Sanlong Bay, Foshan City, Guangdong Province, China, including 16 evaluation indexes. This study comprehensively considered the influence of multiple factors, thereby providing reference for evaluating the suitability of UUS in big cities. [ABSTRACT FROM AUTHOR]

The northern slope of Mount Merbabu exhibits a volcanic landform with the possibility of spring formation, which can be analyzed using a hydrogeomorphological methodology. The objective of this study was to examine the hydrogeomorphological features of springs, including their physical attributes such as appearance, distribution, discharge, flow parameters, temperature, pH, total dissolved solids (TDS), and electrical conductivity. This research methodology involved the collection of primary data through the observation of specific geographical sites and the deliberate selection of sampling areas. The research findings indicated the presence of 30 spring locations on the northern slope of Mount Merbabu. These springs were found in various landform units, such as craters, cones, slopes, feet, plains, and volcanoes. The main numerical results indicated that the springs exhibited a wide range of discharge rates from 0.02 to 33.29 liters per second, temperature variations from 21.9 to 23.24 degrees Celsius, pH levels from 3.57 to 7.01, TDS values from 38 to 521 mg/L, and electrical conductivity from 40 to 814 µS/cm. The main conclusions were that these springs significantly contributed to the local water resources, with potential applications for agricultural and domestic use. However, the study was limited by the seasonal variations. The scientific novelty of this study lays in its comprehensive analysis of the hydrogeomorphological characteristics of these springs, which were previously undocumented. This research bridged a crucial gap in understanding the interactions between geological formations and spring water quality and quantity, offering valuable data for sustainable water resource management and conservation strategies. [ABSTRACT FROM AUTHOR]

Abstract Geological information is required to parameterize hydrogeological properties in groundwater flow models. Our aim was to provide a hydrogeological model for the island of Norderney, Northwest Germany and the surrounding Wadden Sea for this purpose. The model focuses on Holocene, Pleistocene and Pliocene deposits which are the most relevant to groundwater flow in and around the island's freshwater lens. For these geological units, borehole data was available that allowed us to distinguish between sediments acting as aquifers and aquitards. Conceptual units were derived that comprise the most common stratigraphic and petrographic features into discrete entities. The borehole data was supplemented by maps of the pre‐Holocene surface as well as data from an existing stratigraphic model for deeper geological units. The model was developed and created using the open‐source geological modelling software GemPy. The resulting model contains major hydrogeological units that can be assumed continuous over a larger extent of the model area based on the available data. From the deeper geology, a possible range of locations of the aquifer base below Norderney was extracted. By integrating borehole data, existing geological models and geological interpretations available in the literature, this dataset complements the so far mainly cross‐sectional and partial descriptions of the hydrogeology below Norderney.

This research aims at studying the intrinsic vulnerability of groundwater to diffuse environmental pollutants in the Muravera coastal agricultural area of Sardinia, Italy. The area faces contamination risks arising from agricultural practices, especially the use of fertilizers, pesticides, and various chemicals that can seep into the groundwater. The study examined the interplay among hydrological elements, including soil characteristics, groundwater depth, climate conditions, land use, and aquifer properties. To do that, the outcomes of FLOWS 1D physically-based agrohydrological model were analyzed in parallel with those of the overlay-and-index model SINTACS, in a sort of reciprocal benchmarking. By using FLOWS, water movement and solute transport in the unsaturated zone were simulated by, respectively, solving the Richard Equation (RE) and the Advection-Dispersion equation (ADE). As such, this model allowed to account for the role of soil hydraulic and hydrodispersive properties variability in determining the travel times of a conservative solute through the soil profile to the groundwater. For FLOWS simulations, a complete dataset was used as input, including soil horizons, soil physical and hydraulic properties of 36 soil profiles, average annual depth to groundwater table at each soil profile (ranging from 1 to 50 meters), and climatic temporal series data on rainfall and evapotranspiration. Detailed analyses of travel times for the movement of 25, 50, 75, and 100% of the solute mass to reach groundwater were conducted, revealing that the depth to groundwater predominantly influences vulnerability. This result was coherent with SINTACS vulnerability map due to the large impact of the depth to groundwater on SINTACS analysis. [ABSTRACT FROM AUTHOR]

Large samples of hydrometeorological time series and catchment attributes are critical for improving the understanding of complex hydrological processes, hydrological model development and performance benchmarking. CAMELS (Catchment Attributes and Meteorological time series for Large Samples) datasets have been developed in several countries and regions around the world, providing valuable data sources and testbeds for hydrological analysis and new frontiers in data-driven hydrological modelling. Regarding the lack of samples from low-land, groundwater-dominated, small-sized catchments, we develop an extensive repository of a CAMELS-style dataset for Denmark (CAMELS-DK). This CAMELS addition is the first containing both, gauged and ungauged catchments as well as detailed groundwater information. The dataset provides dynamic and static variables for 3330 catchments from various hydrogeological datasets, meteorological observations, and a well-established national-scale hydrological model. The dataset is enhanced with streamflow observations in 304 of those catchments. The spatially dense and full spatial coverage, supplying data for 3330 catchments, instead of only gauged catchments, together with the addition of simulation data from a distributed, process-based model enhance the applicability of such CAMELS data. This is especially relevant for the development of data-driven and hybrid physical informed modelling frameworks. We also provide quantities related to human impact on the hydrological system in Denmark, such as groundwater abstraction and irrigation. The CAMELS-DK dataset is freely available at https://doi.org/10.22008/FK2/AZXSYP (Koch et al., 2024). [ABSTRACT FROM AUTHOR]

The permeability of aquifers strongly influences groundwater flow characteristics. Worldwide, coastal groundwater is often the primary freshwater source for coastal communities and ecosystems but is also particularly vulnerable to abstraction since saltwater intrusion may threaten its quality. Thus, understanding coastal permeability is crucial to the sustainable use of coastal groundwater. Here, we present the first global dataset of coastal permeability (CoPerm 1.0), which provides data on coasts' landward, shoreline, and seaward permeability. CoPerm accounts for shoreline characteristics such as cliffs and beaches and contains information on four million segments representing more than two million kilometers of global coastline. Rocky Shores are the most abundant shoreline class, followed by mangroves, beaches, and muddy coasts. Permeability differs between the immediate shoreline (median permeability: 10−12.3 m2), the seaward (median: 10−13.3 m2), and the landward (median: 10−13 m2) sides of the coast. CoPerm provides input data for global coastal groundwater assessments and regional studies of submarine groundwater discharge or saltwater intrusion that can radiate into ecological and economic studies. [ABSTRACT FROM AUTHOR]

In the ruins of Hattuşa, the capital of the Hittite Empire more than 3,000 years ago, large, sedimented water storage ponds have been uncovered since 1998. An investigation based on time series of measured groundwater levels, showed that the ponds were supplied from layered aquifers which were opened at their source horizons directly at the uphill edge of the pond. When the groundwater level at the pond exceeds a threshold given by the geology at that edge, water pours into the pond. The principles and the path of filling become clear, but not the volumes and time distribution of the transfers. These results of the previous studies were amply published and are shortly summarized. The present investigation is also based on the time series of groundwater levels and of the discharge of a modern fountain as well as the local hydrogeological properties. The approach is simple but shows the effect of storage in the aquifer which delays the outflow into the pond, so that water from the rainy season was available in the dry season. Also, the annual outflow values are determined. Besides gaining knowledge it is an aim of the article to encourage interdisciplinary and process-oriented thinking. [ABSTRACT FROM AUTHOR]

The critical role of groundwater in meeting diverse needs, including drinking, industrial, and agricultural, highlights the urgency of effective resource management. Excessive groundwater extraction, especially in coastal regions including Urmia Plain in NW Iran, disrupts the equilibrium between freshwater and saline boundaries within aquifers. Influential parameters governing seawater intrusion—groundwater occurrence (G), aquifer hydraulic conductivity (A), the height of groundwater level above the mean sea level (L), distance from the shore (D), impact of the existing status of seawater intrusion (I), and thickness of the saturated aquifer (T)—merge to shape the GALDIT vulnerability index for coastal aquifers. This study enriches the GALDIT framework by incorporating two additional hydrogeological variables: hydraulic gradient (i) and pumping rate (P). This expansion produces seven distinct vulnerability maps (GALDIT, GAiDIT, GAiDIT-P, GALDIT-i, GALDIT-iP, GALDIT-P, GAPDIT). In the Urmia Plain, the traditional GALDIT index reveals vulnerability values ranging from 2 to 8.1, categorized into six classes from negligible to very high vulnerability. However, the modified indices, GAiDIT and GAiDIT-P, yield a three-class categorization, ranging from low to high vulnerability. The introduction of the "i" and "P" parameters in GALDIT-i and GALDIT-iP enhances the precision of vulnerability mapping, altering class distribution and intensifying vulnerability ratings. The eastern, central, and coastal areas of the Urmia Plain demonstrate high to very high vulnerability levels, in contrast to the lower vulnerability observed in the western regions. Both the GALDIT-P (r = 0.82) and GALDIT-iP (r = 0.81) indices show strong correlations with Cl concentration, thereby improving mapping accuracy over the traditional GALDIT index (r = 0.72). A sensitivity analysis highlights the critical influence of the "i" parameter, suggesting its weighting should be revised. Parameter recalibration serves to amplify the significance of "G," "L," "D," and "i" parameters, while diminishing others. The integration of multiple hydrogeological variables considerably enhances the precision of groundwater vulnerability assessments. [ABSTRACT FROM AUTHOR]

Abstract—In many aspects, the deep fluid regime plays a key role in seismicity, aseismic deformation of the lithosphere, and ore and oil genesis processes. An informative detailed analysis of the hydrogeology of shallow fault zones is presented in (Kocharyan and Shatunov, 2024), where it is noted that little is known about the character of the fluid dynamics of deep faults. This paper focuses mainly on the challenges of describing deep fault zones and highlights a number of inconsistencies that arise in this consideration. It is shown that the difficulties inherent in such a description are largely overcome by accounting for the processes of metamorphism and associated anomalies in the physical properties of the Earth's interior. Further refinement is given to the proposition that earthquakes occurring at different depths have different physical mechanisms. [ABSTRACT FROM AUTHOR]

The performance of reclamation cover systems could be affected by the colonization of plant roots, which may modify the hydrogeological properties of the construction materials. A four-year field investigation was conducted using six experimental cells with various soil layering designs over AMD-generating tailings reclaimed with an oxygen-barrier cover combined with an elevated water table. Both herbaceous and woody vegetation were installed on top of the cells to compare the influence on the properties of the cover material. Consecutive and undisturbed cores were collected from the cover's functional layer in 2020 and 2021, respectively. Root parameters, such as root length density, and hydrogeological properties were measured on the core samples to assess the possible relationships between the two categories of variables. Root observation trenches were also cut in each cell to better analyze the root density and occurrence profiles. Results showed that, within the four-year monitoring period of the study, both herbaceous and woody vegetation roots mostly colonized the top overburden layer of the cell (>86% visible roots) and barely occupied the functional layer of the reclamation cover (<10% visible roots). The observed maximum desorption rates for the functional layer were lower than the predicted values, which could be a short-term effect of the fine roots. No significant impact of roots on the main hydrogeological variables controlling the oxygen barrier efficiency were noted. At the end of the four-year study period, the hydrogeological behavior of the functional layer in all cells with/without vegetation/additional soil layers was found to be similar. [ABSTRACT FROM AUTHOR]

Groundwater level tidal analysis is a powerful technique to monitor aquifer's permeability and hence its change over time. Earthquakes are known to affect aquifer's properties, in their vicinity through static stress changes but also further away through dynamic stresses. Most often changes are in the form of permeability increases, but sometimes decreases; the changes can be either permanent or transient. These observations are relatively well documented but the physical processes behind these changes are not well understood. By combining solid‐earth and barometric tidal groundwater level responses in a borehole in a coherent poroelastic theoretical framework, and a bi‐layer hydrogeological model, we recover a 15 years‐long time series evolution of aquifer transmissivity and shear modulus. This study showcases the full potential of the tidal analysis method, coupling pore pressure diffusion and rock deformation, at the frontier of hydrogeology and rock physics. This unprecedented measurement of permeability and shear modulus evolution by tidal analysis reveals, during interseismic period, high sensitivity of this shallow aquifer to effective stress, and thus to pore pressure. Thanks to additional finite element simulation of seismic wave propagation, we explore the different mechanisms affecting permeability and shear modulus in the studied fractured andesite aquifer. This study confirms the predominant role of seismic dynamic stresses, and more precisely of dynamic shear stresses, in the change of permeability following an earthquake. Plain Language Summary: Tidal oscillations of groundwater level, observable in boreholes all around the world, are information‐rich signals for hydrogeologist to infer the properties of surrounding aquifers, and how they evolve over time. Most importantly, it allows to monitor aquifer permeability and how it evolves under the influence of earthquakes, especially through static stresses changes or seismic wave propagation. Here we push the limits of what tidal analysis can reveal by also retrieving the shear modulus of the studied aquifer. This new observable, combined with the computation of regional earthquakes stresses, allows us to understand better how aquifer properties are modified by earthquakes. The analysis reveals first that dynamic shear stresses are the most probable cause of permeability changes, and second that the sensitivity of our fractured aquifer permeability to pore pressure is high. Key Points: The 15‐years' time series of permeability and shear modulus of the aquifer is deduced from the analysis of solid earth and barometric tidesCo‐seismic irreversible changes of fractured aquifer permeability are induced by earthquakes dynamic shear stressesInterseismic permeability variations of the aquifer are controlled by pore pressure, that is, the hydraulic head [ABSTRACT FROM AUTHOR]

The Middle Western Cheliff plain hosts an important alluvial aquifer that is exploited for various uses including drinking water supply, irrigation and industry. This study aims to provide a hydrogeochemical characterisation of groundwater by using statistical methods and binary diagrams, as well as to evaluate the physico-chemical quality of groundwater by using the water quality index (WQI). Moreover, parametric indices such as SAR and %Na were used to evaluate the suitability of groundwater for irrigation. The hydrochemical approach based on results of 45 analyses of groundwater samples for the dry period 2019 enabled the determination of the most dominant chemical facies, which was chloride, sulphate, calcic and magnesium. The binary diagrams used indicated that the water-rock interaction and the evaporitic phenomenon are major geochemical processes that control the mineralisation of groundwater. The evaluation of groundwater quality for drinking water supply using WQI provided results with values ranging from 45.95 to 194.78, and above 60% of samples were classified into the category of excellent to good quality (WQI < 100), while the remaining 40% of water samples were classified in the category of poor quality for drinking (WQI > 100). However, the quality of groundwater is mostly acceptable for irrigation, mostly for plants with salinity-tolerant in drained soils. [ABSTRACT FROM AUTHOR]

Determining the type and properties of saturated groundwater for complex sedimentary facies, as well as the various properties of these sedimentary facies, requires extensive geological, hydrogeological, and geophysical studies. Therefore, identifying the different types of subsurface deposits and their physical properties as well as their geological, hydrogeological, and structural settings are the interesting features in this study which play an important role in achieving its objectives. To achieve these objectives, the Direct Current (DC) resistivity method and the Direct Current Time-Domain Induced Polarization (DC-TDIP) method were used. These two methods were applied because they are complementary methods, one of which is more accurate in sediments saturated with fresh water (the DC resistivity method) and the other in sediments saturated with salt water (DC-TDIP method). Also, the DC-TDIP method was applied to avoid ambiguity in the resistivity results, as well as their results were compared with the available geological and hydrogeological field data. Accordingly, 2D and 3D resistivity values were designed to describe the hydro-lithological environment of the recorded sediments, and their hydrogeoelectric properties and groundwater zones were also identified and divided. Also, 2D and 3D chargeability values were designed to distinguish between sediments, their depositional facies, and their saturated water properties. These values also succeeded in separating clay from non-clay layers, and clay layers from layers containing salt water. Therefore, it was found that the integration between the two methods helped in identifying and visualizing the characteristics of the sediments and determining their facies and their water content, which helped in understanding the complex sedimentary facies recorded in the study area as well as identifying the types and characteristics of groundwater contained in these facies. Therefore, it can be recommended to apply the previous methodology and include the two geophysical methods and their results to study complex facies deposits and determine their water content and type, especially in similar depositional environments that are located next to a source of salt water mixed with other types of water. [ABSTRACT FROM AUTHOR]

The Huayingshan coalfield is one of the most important coal districts in Southwest China. Coal mining may have an impact on the hydrochemical characteristics and regional evolution of karst groundwater. This study aims to analyze the hydrogeochemical characteristics, identify the evolution processes, and influencing factors that govern the hydrochemistry in multilayer karst aquifers in the coalfield. Statistical methods and conventional techniques were utilized to gain a thorough understanding of the origin and hydrogeochemical evolution of karst groundwater. The results revealed that the groundwater was fresh water and natural to mildly alkaline. It suggested that the relative abundance of main ions was proposed to be Ca2+ Mg2+ > K+ + Na+ for cations and > Cl– > for anions. A Piper diagram of the investigated water samples demonstrated that most groundwater was of the HCO3-Ca type. The results showed that dissolution of carbonate, gypsum, halite, and silicate minerals highly influenced the formation of , , Ca2+, Mg2+, and Na+. Cation exchange and/or absorption was another important regulatory process. concentrations were excessively high, proving that karst water was affected by agricultural activities in certain aquifers. Moreover, S2– concentrations were high in the borehole and mine tunnel samples, suggesting great acidification potential. Coal mining carries a risk of deteriorating the local water environment. This exposes sulfide minerals to oxygen and water, increases concentration, and reduces groundwater pH. Scientific research must focus on specific recharge area locations, runoff and drainage pathways, and hydrochemical evolution processes of karst water, and the contact of sulfide with water and oxygen must be controlled to protect groundwater quality and reduce pollution. The results suggest it may be helpful for investigation and treatment of water environment pollution, aid the protection of karst groundwater in the Huayingshan coalfield, and serve as a model for other comparable studies. [ABSTRACT FROM AUTHOR]

In arid climates, conventional water resources are severely limited and stressed in the face of rapid population growth and future climate change. So, it is necessary to find alternative non-conventional water resources for use in drought situations. Additionally, the non-conventional water resources in these areas are not sufficient to meet future water demand. Therefore, non-conventional water resources can be adopted as a strategic reserve to bridge the gap between water supply and demand in case of emergency and drought events. These resources might include rainwater harvesting, treated wastewater, and desalinated seawater. Managed aquifer recharge (MAR) can be applied to store these resources in the hydrogeological system using Geo information System—Multi Criteria Decision Analysis (GIS-MCDA) approach for determining the suitable MAR location for storage. North-west Kingdom of Saudi Arabia area was chosen for this study because it is extremely arid, has high potential for social and economic development, and it has newly constructed non-conventional water infrastructures distributed throughout the area including water desalination plants, Tertiary Sewage Effluent (TSE) waste water plants, and flash-flood storage dams. To identify the suitable MAR site location and structure, different data related to aquifer hydrogeology, surface hydrology, hydrometeorology, and water quality were applied. Then, GIS-MCDA holistic approach was applied with aid of ordered weighting average (OWA) technique. Finally, two maps were created to show the MAR location and structure type. Potential map indicates that ~ 18.85% of the area is suitable for MAR installations. About 0.17% of the total area exhibited very high potential, where infiltration ponds can be applied, 1.86% had high potential for construction of check dams with diversion channels, and 16.82% had moderate potential for installation of recharge wells. Additionally, 56 MAR structures were proposed and a map showing their locations has been created. Thus, results indicated that the study area is promising for MAR installation. These maps could aid the decision makers to propose a sustainable development plan for the future water resources of the area. [ABSTRACT FROM AUTHOR]

Inverse problems in hydrogeology pose a great challenge for modelers as they are ill-posed, resulting in a non-unique solution. High computational resources are needed for the calibration process, especially in the case of highly parameterized aquifers like karst limestone, characterized by significant heterogeneity. The nullspace Monte Carlo (NSMC) is a parameter-constrained Monte Carlo approach that can be used to quantify uncertainty, as it produces a set of solutions that calibrate the model. This method is used to assess uncertainty in the calibration of a karst aquifer in Qatar, which has high heterogeneity. Pilot points were used to reflect the geostatistics of the calibrated field, and the calibration results at these points were interpolated over the aquifer area using kriging. The NSMC was then used to produce 200 realizations of the null-space parameter field using the constrained random variable of hydraulic conductivity. The null-space realizations were then incorporated into the parameter space derived from the calibrated model. Statistical analysis of the calibrated hydraulic conductivity revealed a variation ranging from 0.1 to 350 m/d, indicating a considerable variability in the aquifer's hydraulic parameters. The areas with high hydraulic conductivity were concentrated in the central and eastern parts of the aquifer, and these same areas exhibited a high standard deviation. Based on the findings of this study, while the NSMC method is effective for uncertainty analysis in solving inverse problems, it is important to note that a considerable number of runs are necessary to reach the threshold of calibration error. This is because of the significant non-linearity inherent in the karst aquifer. [ABSTRACT FROM AUTHOR]

Groundwater numerical modeling is a crucial scientific tool for understanding groundwater circulation and supporting regional water resource planning and management. The effectiveness of these models depends largely on the accuracy of hydrogeological parameters within aquifers, which are often spatially heterogeneous and randomly distributed due to complex geological and tectonic factors. Traditional modeling approaches frequently overlook this randomness, compromising the precision and resolution of groundwater simulations. This study focuses on a section of the Qingshui River in the Huaihe River Basin. Using field and laboratory data, probability distribution functions for key parameters like hydraulic conductivity, specific yield, and specific storage were developed. These functions were integrated into the groundwater model to reflect the inherent stochastic nature of aquifer properties. This integration significantly enhanced model accuracy, reducing the root mean square error of simulated water levels from 0.47-1.43 m to 0.13-0.16 m and improving the Nash-Sutcliffe efficiency coefficients (NSE) from -2.96-0.73 to 0.94-0.98. Additionally, the model facilitated analysis of the interactions between river and groundwater, particularly in the hyporheic zone, under various scenarios. It identified spatial and temporal variations in groundwater recharge dynamics and delay effects at different distances from the river channel. For instance, recharge rates at 50 m and 150 m from the river were 0.295 m/day and 0.015 m/day, respectively, indicating stronger recharge closer to the river. The study also assessed the impact of varying river flows, riverbed permeability, and irrigation practices on water exchanges between the river and groundwater. These factors were found to significantly influence the intensity of water exchange, seepage, and groundwater reserves. This research provides valuable insights for managing river-groundwater interactions and analyzing the ecological environment of surrounding groundwater systems, underscoring the importance of incorporating stochastic characteristics into groundwater modeling. [ABSTRACT FROM AUTHOR]

In this work, electrical resistivity tomography was carried out together with physical hydrogeology techniques to evaluate the karst aquifer in the northwest region of the Yucatán Peninsula in a study area near the western edge of the Ring of Cenotes of the Chicxulub Crater. In addition, based on a systematic compilation of open-access data of water levels reported for the peninsular aquifer, maps of groundwater isolines and groundwater flows were generated using IDW interpolation, Empirical Bayesian Kriging, and the Flow Net method. From these results, a shallow aquifer is observed, with the presence of heterogeneities such as possible dissolution conduits and/or flooded caverns, approximately 20 m below ground level, formed by the dissolution processes of limestone rocks. On a regional scale, the geomorphological influence of the Ring of Cenotes on groundwater flows was observed. In general, the flow directions observed from these maps coincide with those conceptualized for this region of the peninsular aquifer. Nevertheless, some differences were observed depending on the interpolation method used. Our results contribute to hydrogeological studies carried out in the periphery of this ring, where the vulnerability of the aquifer to anthropogenic contamination has been highlighted due to the intrinsic features of the karst environment. [ABSTRACT FROM AUTHOR]

Information on the aquifer transmissivity and basement structure of Igarra, southwestern Nigeria, is scarce. Thus, this study aimed to apply electrical resistivity sounding and drilled borehole information to determine the underlying bedrock structure (basement structure) and the aquifer transmissivity of Igarra. Twenty vertical electrical soundings (VES) were carried out along 4 established E-W traverses intending to intercept the fracture systems. The resistivity data acquired were curved matched, and iterated using Schlumberger O' Neil software to obtain layer parameters. The layer parameters were evaluated to obtain the Dar-`Zarrouk parameters, which were used to determine the aquifer transmissivity. The resistivity-sounding result revealed four to six geoelectric layers that comprised topsoil, lateritic soil, weathered basement, fractured basement, partially fractured basement and fresh basement. The VES result revealed an undulating basement, with depths varying from 20.1 m to 53.8 m, suggesting evidence of fracturing and faulting within the basement. Correlation of the VES data and borehole log revealed that the weathered and the fractured basement constitute the aquifers, found between 2.4 - 53.8 m depths, and aquifer thickness ranged from 0.7 - 44.3 m. Analysis of the VES result showed an average computed transmissivity value of 18.48 m2 /day. These values indicate that the basement is undulating with adequate groundwater-yielding materials (aquifer), capable of promoting adequate recharge potentials from precipitation. [ABSTRACT FROM AUTHOR]

Random walk particle tracking (RWPT) is a discrete particle method that offers several advantages for simulating solute transport in heterogeneous geological systems. The formulation is a discrete solution to the advection‐dispersion equation, yielding results that are not influenced by grid‐related numerical dispersion. Numerical dispersion impacts the magnitude of concentrations and gradients obtained from classical grid‐based solvers in advection‐dominated problems with relatively large grid Péclet numbers. Accurate predictions of concentrations are crucial for reactive transport studies, and RWPT has been recognized for its potential benefits for this kind of application. This highlights the need for a solute transport program based on RWPT that can be seamlessly integrated with industry‐standard groundwater flow models. This article presents a solute transport code that implements the RWPT method by extension of the particle tracking model MODPATH, which provides the base infrastructure for interacting with several variants of MODFLOW groundwater flow models. The implementation is achieved by developing a method for determining the exact cell‐exit position of a particle undergoing simultaneous advection and dispersion, allowing for the sequential transfer of particles between flow model cells. The program is compatible with rectangular unstructured grids and integrates a module for the smoothed reconstruction of concentrations. In addition, the program incorporates parallel processing of particles using the OpenMP library, enabling faster simulations of solute transport in heterogeneous systems. Numerical test cases involving different applications in hydrogeology benchmark the RWPT model with well‐known transport codes. Article impact statement: Extension of MODPATH source code for modeling advection dispersion with random walk particle tracking. [ABSTRACT FROM AUTHOR]

In this study, we introduce a novel field‐based method to estimate specific yield (Sy) in fractured, low‐porosity granite aquifers using borehole nuclear magnetic resonance (bNMR). This method requires collecting a bNMR survey immediately following a pump test, which dewaters the near‐borehole fractures. The residual water content measured from bNMR is interpreted as "bound" and represents the specific retention (Sr) while the water drained by the pump is the Sy. The transverse relaxation cutoff time (T2C) is the length of time that partitions the total porosity measured by bNMR into Sr and Sy. When applying a calibrated T2C, Sy equals the bNMR total porosity minus Sr; thus, a calibrated T2C is required to determine Sy directly from NMR results. Based on laboratory experiments on sandstone cores, the default T2C is 33 ms; however, its applicability to fractured granite aquifers is uncertain. The optimal T2C based on our pumping test is 110 ± 25 ms. Applying this calibrated T2C on a saturated, A‐type granite at our field site, we estimate the Sy to be 0.012 ± 0.005 m3 m−3 which is significantly different from the Sy (0.021 ± 0.005 m3 m−3) estimate using the default T2C of 33 ms. This Sy estimate falls within a range determined using traditional hydraulic testing at the same site. Using the conventional T2C (33 ms) for fractured granite leads to an inaccurate Sy; therefore, it is essential to calibrate the bNMR T2C for the local site conditions prior to estimating Sy. Article impact statement: New method to determine specific yield in low, porosity fractured granite using borehole nuclear magnetic resonance. [ABSTRACT FROM AUTHOR]

This study examines the potential for aquifer storage and recovery (ASR) in the brackish portion of the Edwards aquifer in New Braunfels, Texas. Successful ASR relies on understanding hydraulic properties, aquifer heterogeneity, water geochemistry, and geochemical processes during operations. The research aims to investigate the chemistries of native groundwater and injectant during ASR operation, estimate the hydraulic properties of the aquifer layers, and assess the recovery rate for the recovered groundwater meeting the total dissolved solids (TDS) threshold. The study found that native groundwater is of Na‐Cl facies due to halite dissolution and a possible basinal brine migration associated with the zone of greatest fault displacement. High sulfate ions in background native groundwater result from sulfate‐bearing minerals' dissolution in the Kainer and Person Formations. The injectant water is of Ca‐Mg‐HCO3 facies due to the carbonate‐rich composition of the aquifer host matrix and interaction with the Guadalupe River riverbed. During ASR operations, mixing controlled the shift in hydrochemical facies from Na‐Cl to Ca‐Mg‐HCO3.The study also suggests a possible connection between Kainer and Person Formations and preferential pathways in the targeted storage zone aquifer. The estimated conductivity values also indicate dominant horizontal flow via possible fracture pathways in both the Person and Kainer Formation storage zones. Recovery of groundwater meeting the TDS of 1000 mg/L requires a recovery rate of 0.03 m3/s for 60 days after 40‐day storage. This research emphasizes that understanding the hydrogeological conditions and geochemical processes is critical to ASR feasibility in brackish carbonate multi‐aquifer fractured systems. [ABSTRACT FROM AUTHOR]

Geological information is required to parameterize hydrogeological properties in groundwater flow models. Our aim was to provide a hydrogeological model for the island of Norderney, Northwest Germany and the surrounding Wadden Sea for this purpose. The model focuses on Holocene, Pleistocene and Pliocene deposits which are the most relevant to groundwater flow in and around the island's freshwater lens. For these geological units, borehole data was available that allowed us to distinguish between sediments acting as aquifers and aquitards. Conceptual units were derived that comprise the most common stratigraphic and petrographic features into discrete entities. The borehole data was supplemented by maps of the pre‐Holocene surface as well as data from an existing stratigraphic model for deeper geological units. The model was developed and created using the open‐source geological modelling software GemPy. The resulting model contains major hydrogeological units that can be assumed continuous over a larger extent of the model area based on the available data. From the deeper geology, a possible range of locations of the aquifer base below Norderney was extracted. By integrating borehole data, existing geological models and geological interpretations available in the literature, this dataset complements the so far mainly cross‐sectional and partial descriptions of the hydrogeology below Norderney. [ABSTRACT FROM AUTHOR]

Groundwater, a fundamental asset, isn't effectively accessible in some parts of the world. The current research work pointed toward obtaining precise maps of potential groundwater zones. This study aimed for potential groundwater modeling and extracting the precise maps using four new advanced hybrid ML models (Dagging-HP, Bagging-HP, AdaBoost-HP, Decorate-HP) and one single model Hyperpipes (HP) in the Doji Watershed, situated in the eastern part of Golestan province, Iran. Among the selected models, the AdaBoost-HP model is the most efficient, with an AUC - ROC of 0.972, accuracy (0.922), sensitivity (0.906), and specificity (0.938), which gives the most promising values, when determining the collinearity between the 14 training factors, which are, in descending order of significance, LULC, Distance to stream (DtS), Topography wetness index (TWI), HAND, Distance to the road (DtR), Geomorphology, Topography position index (TPI), Lithology, Drainage density (DD), Elevation, Slope, Rainfall, and Clay (%). The AUC-ROC approach was employed to assess the model's performance along with Accuracy, Specificity, and Sensitivity. This model revealed that 7.37% has very high groundwater potential in the eastern and south-western parts of the study, whereas 36.8% has a very low groundwater potential in the north-western and south-eastern parts of the study. It can be said from this assessment that results obtained from this investigation are better and more reliable, which gives essential encouragement for further study put on this method for groundwater potential mapping of other areas of the world along with other areas of hydrogeological investigations. [ABSTRACT FROM AUTHOR]