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Clean water is a fundamental need for communities, sourced from both surface water (e.g., rivers, streams, springs) and groundwater (surface and deep aquifers). Groundwater dynamics are influenced by natural factors, including geology and geomorphology, which determine aquifer characteristics such as type, depth, thickness, and permeability. Geological structures influence groundwater flow direction, while lithology affects aquifer ion concentration and water quality. Surface morphology impacts groundwater table depth and movement patterns, with morphogenesis influencing permeability, porosity, and infiltration rates. This research investigates groundwater potential in Yalimo Regency, Mountainous Papua Province. The research aims to evaluate aquifer characteristics using regional geological and geomorphological assessments complemented by advanced mapping technology. The methodology integrates field mapping with geospatial analysis to identify and delineate groundwater resources. Results provide a detailed understanding of aquifer distribution, capacity, and potential for sustainable utilization. Conclusions emphasize the importance of combining traditional and technological approaches for accurate groundwater resource assessment, offering insights for effective water management in the region. [ABSTRACT FROM AUTHOR]

Underground natural gas storage is an essential infrastructure for strategic reserves， emergency peak shaving， and national energy security. It is also one of the directions for optimizing the industrial layout of mature oilfields and promoting green and low-carbon transformation and development. The geological conditions of Shengli Oilfield are complex， with shallow gas reservoirs， small scale， scattered distribution， and abundant oil and water trap resources. However， it is difficult to evaluate the sealing property. In view of these characteristics， significant progress has been made in research related to gas storage since the “Thirteenth Five-Year Plan in 2016-2020” period. Different types of gas storage， such as loose sandstone gas reservoirs， gas cap oil reservoirs， and aquifers， have been studied and designed， and the first gas storage in abandoned water-flooded gas reservoirs in China， Y21 Gas Storage， has been built. Key technologies such as target screening and evaluation of gas storage in aquifers， injection and production operation optimization design of gas storage in aquifers， sealing evaluation of gas storage traps， and tracking evaluation of gas storage have been developed， which align with characteristics of Shengli Oilfield. At present， the construction of other types of gas storage still faces challenges such as limited data， small scale， poor efficiency， and difficulty in evaluating the dynamic sealing of traps. It is necessary to propose corresponding technical countermeasures and research directions in the site screening and evaluation of gas storage in oil reservoirs， the construction of gas storage in combination with scattered gas sand bodies， and the collaborative construction of gas storage in oil reservoirs with high water cut， to provide technical support for the large-scale construction and green development of gas storage in Shengli Oilfield.

Objective The analytical solution model is computationally efficient and widely used to estimate aquifer surges. Analytical solution models are computationally efficient but involving many assumptions, such as that the aquifer is homogeneous, the amount of water pumped is constant, while the head loss in the well is ignored; these models are often referred to as homogeneous models. In fact, these assumptions are often not met, resulting in nonnegligible errors in the results, especially for heterogeneous giant thick aquifers.Meanwhile, the homogeneous model cannot estimate the permeability coefficient and water inflow of the broken zone, which is not conducive to solve the water problem during tunnel construction. Methods In this study, two pumping tests were carried out on the Shengli Tunnel Project in Tianshan Mountain, Xinjiang. A geological model was established based on comprehensive logging data and borehole data; a heterogeneous numerical simulation method was used to quantitatively investigate the amount of groundwater inflow in bore holes. The parameters in the rate determination model of the observation data of the first pumping test were used, and the rationality of the model and the postrate parameters were verified by the observation data of the second pumping test. Results The permeability coefficients of the fracture zone, intact granite and relatively intact granite were inverted and were 0.000 93 m/d, 0.000 5 m/d and 0.000 3 m/d, respectively. The total water inflow and the water inflow of the fracture zone were predicted to be 14.80 m3/h and 10.46 m3/h, respectively, of which the water inflow of the broken zone accounted for 70.676% of the total water consumption. Conclusion Field observations revealed head loss in aan ultradeepbore hole during pumping test. The heterogeneous numerical simulation model can explain the ultradeep hole pumping test data better than the homogeneous model, and the total water inflow calculated by the homogeneous model is 18.67 m3/h, which overestimates the water inflow. During tunnel construction, the hydrodynamic parameters and water inflow obtained by the heterogeneous model are more reliable.

Determining the degree of an aquifer’s susceptibility to pollutants is an important tool for policy planning in subterranean water administration and conservation. In this work, subterranean water vulnerability was appraised with the use of DRASTIC methodology, which employs seven parameters: depth to groundwater (D); net groundwater recharge (R); aquifer media (A); soil media (S); topography (T); influence of vadose zone (I); and hydraulic conductivity (C). Different ratings were given to each parameter based on the hydro-geological and geo-electrical information obtained from the study area. Geo-electrostratigraphic data was acquired with vertical electrical soundings and electrical resistivity tomography surveys. The results demonstrated the existence of geoelectrical layers with variable resistivities ranging from high to low, with variable curve types. Longitudinal conductance measures indicated moderate subterranean water protective capacity. Analysis of DRASTIC vulnerability indices showed that the aquifer indicated moderate to high vulnerability to contamination. Vulnerability maps were generated to indicate locations of high vulnerability, the goal being to prevent indiscriminate haphazard and wildcat abstraction of groundwater in such locations. The quality category index (QCI) generated for the DRASTIC model indicated that underground water susceptivity is dependent on all 7 parameters employed in the model, with the most critical determinants being the depth to aquifer (D), net recharge (R), aquifer media (A), and impact of the vadose zone (I). The work recommends that anthropogenic activities that could contaminate groundwater resource be halted as the resource is indicated by DRASTIC models as being vulnerable.

It is indicated that surface water resources under the conditions of growing technogenesis and the consequences of military actions (military, geochemical pollution of catchment landscapes, destruction of treatment facilities, etc.) are classified as polluted and dirty (IV, V quality class). Underground water resources of Ukraine amount to 22.5 billion m3, of which up to 70% are protected or conditionally protected artesian waters of drinking quality, the transition to the use of which determines the relevance of the article. The purpose of the article is to analyze the potential factors of regional development of dangerous geofiltration processes of water use in underground water basins of Ukraine. The scientific novelty of the article lies in the assessment of the degree of influence of the complex of dangerous lithodynamic processes (HLDP), which have a hydrogeofiltration origin, on the qualitative characteristics of groundwater, the stability of the upper part of the rock massif, and the safe operation of water intake facilities. Practical significance. It is shown that with any scheme of depression funnel formation, the diffusion-convective movement of salts and microcomponents from the pore solutions of the poorly permeable (separating) layer is a stable spatio-temporal factor affecting the hydrogeochemical composition of water in operational aquifers. It has been proven that the hydrogeochemical evolution of the composition of water at most water intakes in Ukraine requires changes in approaches to the justification of well location schemes and the amount of allowable decreases in levels in operational horizons. It is estimated that engineering-geotechnically significant filtration compression of the aquifer occurs when the level drops by tens of meters or more. The results of spatio-temporal monitoring of filtration and compression subsidence of the earth's surface in the areas of depression funnels of water intakes and drainage and drainage systems of quarries and mines on the territory of Ukraine indicate that, in general, the amount of subsidence of the earth's surface is correlated with a decrease in the level in the operational aquifer, and in in most cases it is 1.0-2.5% of its value. It has been established that the subsidence of the earth's surface in the zones of depressions of underground water intakes is often accompanied by flooding and waterlogging of the territory, deformations of buildings and structures of engineering communications. It is stated that the active role in the development of the suffusion process during the operation of water intakes and drainage systems is played by the interlayering of fissured (crack-karst) sandy, multi-grained aquifers. This contributes to the formation of zones of increased hydraulic gradients and accelerated movement of hydrogeofiltration flow at the contacts of cracked and sand-dust layers and, as a result, activation of suffusion along the cracks. Calculations prove that the dangerous development of the suffusion process in the near-filter zone of the production well on the aquifer in multi-grained sands reaches 10-15 m. In the central zone of the depression funnel of a group or linear water intake, under the condition of the interaction of local well depressions, the distance of the development of suffusion deformations of the earth's surface increases significantly (up to 3-5 times) and worsens the engineering and geotechnical stability of production wells, pumping equipment, etc.

Kelurahan Sukarame di sebelah selatan kampus ITERA memiliki lahan kosong yang potensial untuk pembangunan perumahan, rumah kontrakan, dan industri. Namun, eksplorasi air tanah di daerah ini kurang banyak dilakukan, sehingga memerlukan perhatian khusus untuk dilakukan eksplorasi air tanah untuk kebutuhan pembangunan dan penduduk sekitar. Langkah penting dalam menghadapi masalah ini adalah mengetahui keberadaan akuifer untuk memperoleh sumber air tanah yang memadai. Identifikasi akuifer dilakukan menggunakan metode Vertical Electrical Sounding (VES). Dengan studi ini akan dapat menentukan jenis litologi bawah permukaan, mengetahui kedalaman lapisan akuifer dan dapat juga mengidentifikasi jenis akuifernya. Pengukuran dilakukan dengan 11 titik sounding menggunakan konfigurasi Schlumberger dengan AB/2 maksimal 100 meter. Berdasarkan nilai resistivitas, kawasan tersebut tersusun dari batu lempung tufan dengan nilai resistivitas 20 Ωm, batu pasir tufan dengan rentang nilai resistivitas antara 20-80 Ωm, dan batu tuf dengan nilai resistivitas 80 Ωm. Lapisan batu pasir tufan diduga merupakan lapisan dari akuifer. Pada daerah penelitian terdapat dua jenis akuifer yaitu akuifer bebas yang ditemukan pada kedalaman 3 meter dan akuifer semi-tertekan pada kedalaman 5 meter.

In the context of the current trend, today we are focused on low-carbon energy, so the question of carbon dioxide utilization is very important. Underground storage of carbon dioxide is an important part of carbon capture and storage (CCS) projects and a key technology to reduce emissions of carbon dioxide to the atmosphere. There are currently many carbon dioxide capture projects around the world, but each project has its own specifics. The article discusses the features of carbon dioxide capture in natural geological reservoirs and the principles of carbon dioxide retention in them. An example of some Carbon Capture in a natural geological reservoirs projects are given. The choice of a natural reservoir, the development of a technology for its identification and justification criteria are of key importance for the environmentally sustainable capture of carbon dioxide.

Streamflow generation in mountain watersheds is strongly influenced by snow accumulation and melt as well as groundwater connectivity. In mountainous regions with limestone and dolomite geology, bedrock formations can host karst aquifers, which play a significant role in snowmelt–discharge dynamics. However, mapping complex karst features and the resulting surface‐groundwater exchanges at large scales remains infeasible. In this study, timeseries analysis of continuous discharge and specific conductance measurements were combined with gridded snowmelt predictions to characterize seasonal streamflow response and evaluate dominant watershed controls across 12 monitoring sites in a karstified 554 km2 watershed in northern Utah, USA. Immense surface water hydrologic variability across subcatchments, years and seasons was linked to geologic controls on groundwater dynamics. Unlike many mountain watersheds, the variability between subcatchments could not be well described by typical watershed properties, including elevation or surficial geology. To fill this gap, a conceptual framework was proposed to characterize subsurface controls on snowmelt–discharge dynamics in karst mountain watersheds in terms of conduit flow direction, aquifer storage capacity and connectivity. This framework requires only readily measured surface water and climatic data from nested monitoring sites and was applied to the study watershed to demonstrate its applicability for evaluating dominant controls and climate sensitivity. [ABSTRACT FROM AUTHOR]

The results of the assessment of prospects for increasing the potential and capacity of water intakes in the city of Kropyvnytskyi, Kirovohrad region, are presented in article. The research was conducted in order to solve the problems of uninterrupted supply of drinking water to the population in the event of a reduction in the capacity of the Dnipro-Kirovohrad waterworks or a temporary suspension of its distribution water networks in the region as a result of russian aggression. The geological, structural and hydrogeological features of the territory of the Kirovohrad region are presented, and the characteristics of aquifers, their depth and the lithology of water-bearing rocks are given. The task and justification of setting up a complex of geophysical exploration methods, and the method of performing works are presented. The selected complex of geophysical methods and methods of interpretation of field materials allows us to identify with sufficient certainty the places of distribution of fractured groundwater. According to the analysis of available geological, geophysical and hydrogeological data near the city of Kropyvnytskyi, six promising areas are recommended for the search and exploration of underground water for drinking water supply. The results of geophysical studies conducted for the Suslovo area of the Kirovohrad region to determine the position of the optimal drilling points for additional exploratory and exploratory hydrogeological wells within the existing water intake are presented. The priority tasks for increasing the capacity of water intakes in the city of Kropyvnytskyi are substantiated. Geological, geophysical, and hydrogeological studies, as well as the study of hydrogeological conditions and sanitary protection zones for the further design of water intake structures from local water supply sources, have been substantiated for the selected prospective prospecting areas of the Kropyvnytskyi district for the search for groundwater.

The microbial denitrification process is the most important form of nitrate-nitrogen removal in groundwater. The reclaimed water reuse and livestock breeding caused antibiotic pollution usually co-occurs with nitrate. Therefore, it is necessary to conduct in-depth research on the effects of denitrification and the generation, accumulation, and dissemination of antibiotic resistance genes (ARGs) by antibiotics and their forms to comprehensively analyze the reasons for the increased concentration of nitrate in groundwater. Many studies in recent years have identified the dissociation/complexation, adsorption forms (interlayer adsorption/surface adsorption), and the products of hydrolysis and microbial degradation of antibiotics in groundwater systems; and have elucidated the inhibitory mechanism of antibiotics on the denitrification process from the perspectives of denitrifying microbial communities, the types and activities of functional enzymes, abundance of functional genes, as well as the production and transmission pathways of ARGs. The main conclusions are as follows: (1) In groundwater systems, antibiotics exist in various forms, and different forms of antibiotics exhibit significant differences in toxicity to microorganisms. (2) In the presence of antibiotics at levels ranging from nanograms to micrograms per liter, the denitrification process in groundwater is inhibited. Antibiotics alter the microbial community structure, suppress enzymatic activity, and increase the abundance of ARGs. Under the synergistic effects of these actions, the kinetics of nitrate degradation shift from zero-order to first-order. (3) During the antibiotic-induced inhibition of denitrification, there is also an increase in the emission of the greenhouse gas N2O. Antibiotics primarily affect the expression of the functional gene nosZ, and the concentration of N2O shows a negative exponential relationship with nosZ abundance. Based on the review of relevant literature, the prospects for future research are put forward: (1) quantitatively identifying the existence forms of typical antibiotics after entering groundwater systems; (2) elucidating the impact of antibiotics in different existence forms on denitrifying microbial communities, the types and activities of functional enzymes, and the abundance and diversity of functional genes; (3) exploring the dynamic process of denitrification functional genes under different existence forms and input modes of antibiotics, and establishing models for the production, enrichment, and transmission of ARGs; (4) combining field observations and laboratory experiments to study the denitrification process in groundwater systems under complex pollution from molecular biology, environmental chemistry, and hydrogeology perspectives. This research can provide a theoretical basis for addressing the increasingly complex groundwater pollution prevention and drinking water safety assurance.

This research is aimed at carrying out geophysical survey for groundwater in parts of Obio/Akpo Local Government Area of Rivers State, Nigeria, using the Schlumberger electrode configuration of vertical electrical sounding (VES) technique. The field data were obtained using ABEM terrameter SAS1000 which was applied on eight VES location, a maximum distance of 300m current electrode spacing was used in the eight vertical electrical sounding points. Data acquired were interpreted using IPIN2Win 2022 version and Surfer13 softwares. The results obtained showed a 4-layers type A curve for Rumuepirikom and Rumuolumini VES locations, 5-layers type A curve for Rumuosi VES location, 4 and 5-layers type H curve for Ozuoba and Eneka VES locations respectively, 5-layers type K curve for Egbelu VES location and 4-layers type HK curve for Rukpoku and Rumuola VES locations. The apparent resistivity values range from 29.3344 – 252898.2075Ωm for Egbelu, 22.6195 – 674.0601Ωm for Rukpoku, 1.0631 – 230.9071Ωm for Rumuepirikom, 29.5833 – 600.8296Ωm for Rumuosi, 32.9867 – 561.5283Ωm for Rumuola, 29.0597 – 458.4212Ωm for Ozuoba, 29.0597 – 134.0413Ωm for Rumuolumini and 71.2094 – 338.1611Ωm for Eneka VES locations, and shows that Rumuepirikom and Rumuolumini are the most groundwater potential zones, thus will yield sufficient groundwater to wells, while Egbelu and Rukpoku are the least groundwater potential zones, thus will not yield sufficient groundwater to wells. The knowledge of this study can be applied in groundwater resources management, hydrological studies and regional town planning programs.

Kebutuhan air di Aceh Besar terus mengalami peningkatan seiring dengan bertambahnya jumlah penduduk. Hal tersebut menjadikan eksplorasi air tanah penting dilakukan dalam rangka konservasi air tanah di wilayah tersebut. Pada penelitian ini dilakukan korelasi litologi dari empat sumur berdasarkan data electrical logging dan cutting untuk mengetahui persebaran lapisan akuifer serta kedalamannya di wilayah Aceh Besar. Data electrical logging memberikan informasi mengenai nilai resistivitas dan data cutting memberikan informasi mengenai sampel litologi dari masing-masing sumur. Data yang diperoleh dari keempat sumur diplotkan dengan software Logplot2003 sebagai validasi nilai resistivitas yang diperoleh dari electrical logging terhadap data cutting. Selanjutnya pengolahan data dilakukan dengan menggunakan software Rockwork16 untuk mengkorelasi litologi pada setiap sumur. Dari hasil pengolahan data diperoleh informasi berupa nilai resistivitas 2 – 172 Ωm dan litologi berupa lempung, lanau, lempung, pasir kasar, pasir lempungan, pasir, serpih, pasir lempung, pasir kasar, pasir sedang, pasir kasar, dan lempung di wilayah Aceh Besar. Melalui informasi tersebut dapat diketahui bahwa lapisan akuifer di wilayah aceh besar terletak pada kedalaman 82 m - 101 m dengan nilai resistivitas 37 – 147 Ωm dan 2 – 57 Ωm dengan masing-masing litologi berupa pasir kasar dan kerikil. Lapisan akuifer ini merupakan lapisan akuifer tertekan dan saling tersebar diantara ke empat sumur.

Relevance. The study focuses on assessing groundwater potentials and the effectiveness of the overburden protective layer in preventing contaminant intrusion into the groundwater aquifer within a municipality in the Western Niger Delta. Aim. Employing Vertical Electrical Sounding (VES), 2-D resistivity imaging, and Dar-zarrouk parameters, the research aims to investigate the geoelectric characteristics of the subsurface layers, delineate the aquiferous layer, and assess the protective capacity of the overburden. Methods. Nine VES were conducted using the Mini-Res Resistivity Meter with the Schlumberger array. Data processing utilized IPI2win software, revealing seven to eight geoelectric layers. The aquiferous layer, situated between the fifth and sixth layers, exhibited varying resistivity (924.9Ωm to 1629Ωm), thickness (34.52 m to 79.20 m), and depth (55.95 m to 106.00 m). Results. Dar-zarrouk hydraulic parameters (hydraulic conductivity, longitudinal conductance, transverse resistance, and transmissivity) were derived from aquifer resistivity and thickness. Hydraulic conductivity ranged from 6.55 m/day to 6.80m/day, transmissivity from 228.5 m²/day to 538.6 m²/day, longitudinal conductance from 0.031Ω– ¹ to 0.076Ω– ¹, and transverse resistance from 37385.1Ωm² to 129016.8Ωm². Zones with contrasting parameter values were identified. Conclusion. The overburden protective layer was rated as having poor capacity, rendering the aquifer highly vulnerable to contaminants. Conversely, the aquifer demonstrated potential for providing portable water, reflecting subsurface heterogeneity and ample hydraulic pressure. A recommended hydrochemical study will further assess water portability.

The Pacific Plate is one of the heaviest tectonic plates, hosting multiple Pacific Island countries. Geological research has long provided evidence of volcanic magmatic events, which have frequently caused subsurface activities. The formation of an active ring of fires across the Pacific Ocean is a geological signature of the intense volcanic events occurring over time. The study aims to verify the close correlation between groundwater features and volcanic magmatic events, which is evident in near-surface ground signatures and geothermal systems. Hot water springs and geysers emerge as manifestations of the active molten volcanic processes, releasing intense heat flux, gases, and pressure. Pacific Island countries exhibit common geological features, particularly in terms of parent rock materials, resulting in a unique combination of aquifer characteristics essential for long-term hydrological sustainability. The sustainability of groundwater resources is intricately linked with volcanic events and their associated signatures, which emerge abruptly over time. Furthermore, the study is to access the correlation of the pacific geological features within Fiji and various regions and its usages in terms of implementing water resources upon the identification of the active aquifers in the terrestrial and coastal plains. Fieldwork using various tomography methods from various regional countries executed by the Secretariat of the Pacific Community through the implementation of various programs has provided various supporting evidence that the magmatic activities featured by dikes, basins, and aquifers have water holding capacity which is hydrogeological connected to the main water aquifer. [ABSTRACT FROM AUTHOR]

Abstract The United Arab Emirates (UAE), located in an arid climate zone with low rainfall, relies on shallow aquifers for freshwater. Understanding the depth and extent of such aquifers is crucial for meeting water supply needs. The UAE's hydrogeology is influenced by neighboring mountains in Oman. The Al‐Jaww Plain in southeast of Al‐Ain city is an essential groundwater source, characterized by a large, flat area of gravel and sand deposits from the Oman Mountains. This study aims to map groundwater aquifers in the Al‐Jaww Plain by integrating the audio‐magnetotelluric (AMT) method, seismic reflection profiling, and borehole data. AMT data were collected along an 11‐km ENE–WSW profile and a 2D resistivity model was generated. The resulting model delineates three distinct geo‐electrical zones from the surface to a depth of 5 km. First, a shallow layer with low resistivity (0–15 Ωm) represents the Quaternary and Pliocene aquifers, in addition to the Upper Cretaceous Simsima and Tertiary groundwater aquifer zone, extending to a depth of 1.5 km. Second, a moderately resistive layer (15–250 Ωm) is recorded beneath the first layer, corresponding to the Upper Cretaceous Aruma foreland basin sequence. Finally, a high‐resistivity region (>250 Ωm) at depths exceeding 3 km is attributed to the allochthonous Hawasina thrust sheet, which is associated with Late Cretaceous obduction of the Semail ophiolite. These findings have practical implications for managing groundwater resources in Al‐Ain.

Groundwater resources are an ephemeral aspect of the ecosystem, especially in the university town of Ekpoma, where the issue of severe water shortages brought on by failed or unproductive boreholes has lingered over time. This study makes an effort to thoroughly define the groundwater-bearing zones and estimate their thicknesses and depths in order to identify the cause(s) of groundwater scarcity in Ekpoma and its peri-urban area. In order to accomplish the objectives of the work, fifteen (15) Vertical Electrical Soundings (VES) were conducted across the study location, leveraging Schlumberger electrode array, with current electrode spacing varying from 5.00 to 550.00 m. The results show there were five distinct geoelectrical strata identified: top soil, clayey sandstone, sand, consolidated sandstone, and unconsolidated sandstone. The unconsolidated sandstone layer constituted the aquifer units in the area, whose depth ranges between 103.00 m and 258.00 m. Besides, this study showed that there is strong indication/evidence of saturation of the aquifer identified in the Imo Shale Formation surrounding Irrua with highly porous and permeable materials atop it, justifying the region's highly productive wells and boreholes. The aquifers delineated in and around the Ekpoma community, on the other hand, have relatively high resistive values (3404.20–5303.00 ?m), indicating less saturation, and are equally overlain by less porous and permeable materials, establishing why Ekpoma (located within the Bende-Ameki and Ogwashi Asaba Formations) has a perennial groundwater shortage. The shallow aquifer units in the area of study were discovered to be rather thin, with the majority having a thickness of less than 30 m, making them less sustainable for long-term groundwater abstraction and resulting in failed boreholes in most portions of Ekpoma town. The study indicates that the groundwater prospects of Ekpoma and its environs are poor, and deep boreholes reaching a minimum depth of 250.00 m should be drilled since it is sustainable due to its significant thickness to serve the Ekpoma community and its environs. The present investigation findings can aid in improving knowledge of underlying geological conditions, evaluating the feasibility of the researched area for predicted urban and economic development, and sustaining water supply for connected activities.

Due to the unreasonable discharge of industrial waste, a large amount of heavy metal pollutant Cr(VI) enters the underground environment, which seriously threatens human health and ecological environment. The high mobility of Cr(VI) in groundwater environment makes it difficult to repair. A green, economic and effective interception method is urgently needed to improve the ability of groundwater Cr(VI) pollution control. In this paper, sodium metabisulfite is selected as a reducing agent, and Cr3+ generated from Cr(VI) in groundwater is used as an xanthan gum crosslinking agent to form a gel blocking barrier. The influences of various components on gel time and viscosity changes and the blocking effect of gel barrier on aquifer are studied. The results indicate that (1) in the system with Cr(VI) concentration up to 200 mg/L, xanthan gum solution with 0.4% mass concentration can form gel with certain mechanical strength within 1.5 h. (2) The gel has salt resistance and is suitable for common aquifers. Na+ and K+ of 2.5−5 g/L can promote the gel. (3) The injected gel blocking barrier can significantly reduce the coefficient of permeability of medium sand media to 1×10−7 cm/s, which can meet the demand of groundwater blocking. Injection-type gel barriers are formed without the introduction of harmful substances. After the interception, injection-type gel barriers can be naturally degraded by biological action without long-term changes under the aquifer hydraulic conditions. This study provides a theoretical basis for the construction of gel barrier in chromium contaminated groundwater.

The hydrogen and oxygen isotopes in precipitation have the altitude effect, and they participate in the groundwater circulation after the infiltration of precipitation. How does the altitude effect of hydrogen and oxygen isotopes in precipitation transform to the depth effect of hydrogen and oxygen isotopes in groundwater under the influence of groundwater flow systems? The existing research lacks quantification for this problem. In this study, the steady-state groundwater flow theoretical models represented by unidirectional inclined basin and bimodal wavy basin are constructed. The MODFLOW and MT3DMS programs are used to simulate the two-dimensional groundwater flow field in the profile and the convection-dispersion process of heavy isotope molecules to obtain the spatial distribution of D and 18O values in groundwater and discuss the mechanism of altitude effect of the hydrogen and oxygen isotopes transforming to depth effect in the groundwater flow systems. The results indicate that in the monoclinal basin, the altitude effect of D and 18O content in precipitation in the recharge area is transformed to the depth effect of δD and δ18O values in groundwater through the regional groundwater flow system which exponentially decreases with the increasing water table depth in the drainage area. In the bimodal wavy basin, when the permeability of the aquifer is relatively larger than the infiltration intensity (K0/w=1000), only one regional groundwater flow system develops, and the distribution of δD and δ18O presents a S-shaped curve with the increasing water table depth in the discharge area of regional groundwater. When the permeability of the aquifer is relatively smaller than the infiltration intensity (K0/w=250), multiple local groundwater flow systems develop in the bimodal wavy basin. The δD and δ18O indicate an S-shaped curve with the increasing water table depth in the discharge area of regional groundwater, while in the discharge area of local groundwater, they show a monotonic attenuation trend with the increasing water table depth. This study theoretically advances the understanding of the influence mechanism of groundwater flow systems on solute transport, and reveals the indicative role of hydrogen and oxygen isotopes in groundwater flow systems.

Abstract The Tatun Volcanic Group (TVG) is an active volcanic system that poses potential volcanic hazards to northern Taiwan. Groundwater migration can be sensitive to volcanic activities and can induce temporal gravity changes. Here we conducted four gravity measurement campaigns in 2012 with two CG5 relative gravimeters at a total of 31 gravity monitoring sites to probe the spatiotemporal groundwater variability in the TVG area. With careful adjustments to the gravity measurements, the standard point gravity error was approximately 8 μGal on average. The observed gravity changes were compared with the groundwater-induced gravity variations derived from two hydrological models: the continuous flow model that consisted of one permeable layer (Model A) and a dynamic groundwater flow model that used the hydrological solver MODFLOW (Model B). The results show that only gravity observations in the central TVG match the simulated gravity pattern, i.e., the hydrology in the central TVG follows free groundwater flows within the interconnected and porous strata. On the other hand, inconsistencies between simulated and observed gravity changes range from + 40 to – 80 μGal. The discrepancies were located at the eastern and western areas in the TVG and showed opposite variations over time. This pattern of temporal variability cannot be attributed to the use of shallow aquifer models that merely reflect the surface recharges and discharges. We infer that the pattern stems from deep flows, such as hydrothermal fluids alternately replenishing aquifers to the east and west of the TVG, i.e., deep fluid conduits may have developed to the east and west of the TVG and bypassed the central area.

Dental and skeletal fluorosis caused by consuming high-fluoride groundwater has been reported over several decades globally. Prediction maps to estimate the fluoride contaminated area rely on interpolation methods. This study presents a comparison of the accuracy of nine spatial interpolation methods in predicting the fluoride in groundwater. Leave-one-out cross-validation (LOOCV), hold-out validation and validation with an independent dataset were used to assess the precision of the interpolation methods. This is the first study on fluoride with a large dataset (N = 13,585) applied at the regional level in India. Our findings showed that the inverse distance weighted (IDW) algorithm outperformed other methods in terms of less discrepancy between measured and predicted fluoride. IDW and local polynomial interpolation (LPI) were the only methods to predict contaminated areas (fluoride > 1.5 mg/L). However, the area estimated by the typical assessment of the percentage of unsuitable samples was much higher (6.1%) compared to that estimated by IDW (0.2%) and LPI (0.2%). LOOCV provided viable results than the other two validation methods. Interpolation methods are accompanied with uncertainty which are regulated by the sample size, sample density, sample distribution, minimum and maximum measured concentrations, smoothing and border effects. Drawing a comparison among variegated interpolation methods capturing a wide range of prediction uncertainty is suggested rather than relying on one method exclusively. The high-fluoride areas identified in this study can be used by the Government in planning remediation actions. [ABSTRACT FROM AUTHOR]

A demonstration project for the geological storage of CO2 is currently being considered in the deep Precipice Sandstone formation of the Surat Basin, Queensland, Australia. Because of the presence of potential fresh water resources in this formation, a reservoir-scale two-dimensional reactive-transport model was developed to assess temporal and spatial changes in water quality imposed by co-injecting CO2 with SO2, NO2, and O2 at this location. The model shows that because the injection rate is relatively low (60,000 tons/year), flow is buoyancy-dominated and under these conditions the predicted CO2 flow pattern is quite sensitive to fine-scale heterogeneities and the resolution of the numerical mesh. The model also shows that SO2 and NO2 readily partition into the aqueous phase in close vicinity of their injection point, lowering pH somewhat beyond the acidification from CO2 dissolution. Only O2 under redox disequilibrium conditions is modeled to persist in the CO2 plume away from the injection point, however at sub-ppm levels. This modeling effort demonstrates acidification near the wellbore due to the preferential stripping of gas impurities, and accumulation of CO2 around a lithostratigraphic boundary above the target formation, where relatively rapid mineral dissolution (muscovite, chlorite and calcite) and precipitation (ankerite, kaolinite and chalcedony) occur.

The region of Chelghoum Laid - Tadjenanet is located in eastern Algeria, in the high plains. This area is characterized by a varied age (Mio-Plio-Quaternary) formations and the human demand is answered by the groundwater hosted into the superficial aquifer of the Mio-Plio-Quaternary formations. However, the overexploitation of this aquifer leads to a drop in the piezometric surface and an increase in salinity. of this aquifer leads to a drop in the piezometric surface and an increase in the salinity of the water. A hydrochemical study using characteristic ratios and statistical tools such as principal component analysis and hierarchical ascending classification, was performed using 28 water samples. Chemical analyzes show that the waters of this aquifer are of the calcium bicarbonate type on the limits of the study area, and calcium sulphate to sodium chloride in the centre. The spatial evolution of chemical water facies is explained by the phenomenon of dissolution and ion exchange between the alkali metals and alkaline earth metals coinciding with the West-East flow direction. The application of the various tools shows that the aquifer is recharged by precipitation at the plains border, where the water acquires its original mineralization from the carbonate formations, and becomes more mineralized in chlorides, sodium and sulphates concentrations in contact with the salt-bearing terrigenous formations of the Mio-Plio-Quaternary. The salinization of the waters seems to be mainly due to the dissolution of gypsum, halite and epsomite. The application of the ascending hierarchical classification and the principal component analysis shows the existence of two groups of water whose salinity increases from the borders towards the center of the plain following the main flow direction.

The coexistence of ammonium, arsenic and dissolved iron in groundwater is a common phenomenon in aquifer systems. They have a strong interaction and affect the nitrogen cycling and the migration and transformation of arsenic in groundwater systems. Based on the systematic survey of international and national literature on the process and influencing factors of groundwater nitrogen cycling, the functional microorganisms and their characteristics related to groundwater nitrogen cycling, and the hydrogeochemical process of arsenic enrichment in groundwater, this paper deciphers effects of nitrogen cycling (including nitrification, denitrification, Feammox, Anammox, and dissimilatory nitrate reduction to ammonium) on the migration and transformation of arsenic in groundwater. We proposed that the dynamic transformation of iron oxides and dissolved Fe (II) in aquifers is an important bridge for nitrogen cycling and the migration and transformation of arsenic in groundwater. The processes of nitrogen cycling in aquifers with different redox environments, the coupling mechanism between nitrogen cycling and arsenic migration and transformation, the interactions among Fe(III) - Fe(II) cycling, nitrogen cycling, and arsenic migration and transformation, nitrogen-iron-arsenic cycling in the surface water-groundwater interaction zone and its response to human activities are important scientific issues and research trend that need to be paid attention to in this field in the future. The solution of these scientific problems is not only conducive to identifying the source, migration and transformation of nitrogen in groundwater, but also beneficial to improving the systematical understanding of enrichment mechanism of groundwater arsenic.

Kota Tengah Subdistrict has the highest population density in Gorontalo City, with a population density of 6,755 people/km2. This high population density requires a large amount of water to meet the needs of the population, where one form of fulfillment is taken from groundwater. For this reason, it is necessary and important to know the characteristics of aquifers. This study aims to determine the characteristics of groundwater aquifers in the Kota Tengah Subdistrict. The method used is the resistivity geoelectric method to obtain aquifer characteristics in the form of material type (lithology), depth, and thickness of the aquifer. Based on the geoelectrical analysis in TS 01 there are 4 layers, namely topsoil, clay sand, sand, and clay; TS 02 contains topsoil, sand, and clay layers; TS 03 contains topsoil, sand, and clay. The study found that the lithology of the near-surface layer in the Kota Tengah subdistrict can be classified into aquifers and aquicludes. The aquifer layer is formed by sand-sized sedimentary deposits that have high permeability while the aquiclude is clay-sized which is impermeable. The aquifer layer was found starting from a depth of 0.57 m. The average thickness of the aquifer layer was 13.8 m which is interpreted as an unconfined aquifer. This study also found other deeper aquifer layers as confined aquifers that can not be further interpreted due to the limitations of the method used.

The article presents the physical and geographical characteristics of the Synychan water intake section of the Izium water intake, which is located 8 km southeast of the city of Izium, Kharkiv region. Hydrogeological features of aquifers operated by 4 wells are considered. Geomorphological features of the studied territory are analyzed. Aspects of the geological structure of the site are also reflected. The analysis of indicators of chemical composition of underground waters of the Synychan water intake site since 2003 is presented. Among the most relevant to the task of chemical compounds, the values of nitrates, chlorides and sulfates content, as well as data on total hardness and mineralization were selected. An increase in performance is observed in all wells. The intensity of the increase is different for each production well and the corresponding chemical compound. This indicates at least the heterogeneity of influencing factors and processes occurring in the aquifers of this water intake area. Among such factors and processes, taking into account the shallow depths of wells, we can consider the technogenesis. Since Synychan water intake is used to supply a significant number of residential areas of Izyum, a detailed analysis of the dynamics of the presented data is appropriate. The study of the dynamics of the distribution of chemical indicators of groundwater composition over different periods using mathematical and graphical methods will not only allow to inductively study the dynamics in previous years, but also quantitatively predict future trends in water composition of interstratal aquifers in the region. Considering the growing and growing shortage of quality water resources in Ukraine, the analysis of data from water intake areas of Izyum can give a representative picture of the real local situation in the field of water management, hydrogeology and hydrogeochemistry of Izyum district in general and town of Izyum in particular.

To prevent coal mine water disasters, the main objective of this study is to predict the water enrichment of the main aquifer in a coal mine of China that has been threatened by water inrush. The prediction is carried out using a geographic information system (GIS) and a coupled analytic hierarchy process (AHP) and entropy model. The flushing fluid consumption, burnt rock distribution, sand–shale ratio, and lithology structure index were determined as the main factors controlling the water enrichment of the aquifer. A thematic map of these main factors was constructed using the spatial data analysis functions of GIS and the data from a total of 146 drilling columns and field investigation. The weights of these controlling factors were calculated using the coupled model. A prediction map of the water enrichment of the aquifer was then developed by overlaying the thematic map with the weights of each controlling factor. The degree of water enrichment was finally divided into four levels for easy interpretation, where Level I denotes the highest water enrichment and poses the greatest threat of water disaster.

Assessment of groundwater potential of Iperindo area, Southwestern Nigeria was conducted by mapping spatial distribution of groundwater availability within the area and consequently locating areas of groundwater reserve to serve the community and its environs. This was achieved by integrating geophysical techniques involving landsat ETM-7 satellite data, aeromagnetic data, VLF-EM and electrical resistivity methods to delineate subsurface structures, understand the direction of groundwater flow, and detect the depth to groundwater aquifer. The result of landsat and aeromagnetic revealed some lineament intersection approximately NE-SW direction and interpreted to be potential sites for groundwater development. VLF-EM revealed geologic structures of significant hydrogeological importance at depths of 40 m to 200 m. Vertical electrical sounding (VES) confirmed high groundwater prospect in the areas with estimated depth to water table between 30 m and 100 m. The integrated results of the study revealed adequate groundwater spatial distribution for effective groundwater development in the area.

Many geophysical methods have been applied to locate groundwater in Nigeria’s rural and urban villages. Locating groundwater in low permeability formations like shales and siltstones is even more challenging due to the difficulty of mapping fracture zones within these formations. The fracture zones serve as potential aquifers in low permeability formations and have been the object of groundwater search in shales, siltstones and other low permeability formations. The electrical resistivity method has proven helpful in fracture mapping within low permeability formations due to the existing resistivity contrast usually observed between the fractured and non-fractured sections in the Shales and Siltstones. Three vertical electrical geosounding datasets (VES 1, VES 2 and VES 3) were acquired in the Schlumberger configuration, using a maximum current electrode spacing of 200m to delineate the fracture zones based on their electrical resistivities. The acquired datasets were processed and modelled using IP12 Win software, while the processed datasets were correlated with local geology to estimate the depths of the fractured shales in the area. Results show five modelled geo-electric layers with depths to the fractured shales ranging from 17-25m, while aquifer thicknesses range from 7 to 12m. Aquifer resistivities range from 58 - 115 ohm-m. The curves are primarily of the QH type. One of the Vertical Electrical Sounding Data points (VES 2) encountered an anomalously low resistivity zone at a depth range of 5 to 8m which was interpreted as a galena lode. The low resistivity zone has been confirmed through exploratory drilling to tie with Lead-Zinc lodes at a depth of 8m. [ABSTRACT FROM AUTHOR]

Arsenic contamination in groundwater affects tens of millions of people worldwide and is regarded as a major groundwater issue in New Zealand. This study was conducted to evaluate the connection between elevated groundwater arsenic concentrations and inferred redox state of aquifers across the Canterbury region. In total, 2,428 samples from 1,172 wells were analysed for arsenic concentrations, and groundwater redox state was inferred using geochemical indicators for each well. Most groundwater (~88% of wells; N = 1,031) had arsenic concentrations below laboratory detection limits, ~9.5% (N = 111 wells) had detectable arsenic concentrations below the New Zealand drinking-water Maximum Acceptable Value of 0.01 mg/L, and ~2.6% (N = 30 wells) had concentrations exceeding 0.01 mg/L. Arsenic concentrations were strongly associated with reducing groundwater; 47 (~43%) of 109 wells with reducing groundwater had detectable concentrations of arsenic, including 19 wells (~17%) with arsenic greater than 0.01 mg/L. Conversely, 840 wells had water classified as oxic, and only one of those wells exceeded the 0.01 mg/L Maximum Acceptable Value for arsenic in drinking-water. Arsenic concentrations were higher in coastal areas north of Christchurch, where confined aquifers are overlain and underlain by layers of peat and low-permeability sediment. Biogeochemical processes driving release are the same as those that cause arsenic contamination in groundwater elsewhere in the world. However, differences in regional geology and a relatively lesser availability of labile organic carbon appear to constrain the concentrations and spatial prevalence of groundwater arsenic in Canterbury compared to other arsenic-impacted regions (e.g., Southeast Asia). [ABSTRACT FROM AUTHOR]

Desa Gayau yang terletak di Kecamatan Padang Cermin, Kabupaten Pesawaran sering mengalami kekeringan air pada saat musim kemarau sehingga perlu dilakukannya pengukuran geolistrik untuk mengidentifikasi keberadaan lapisan akuifer air tanah. Pada penelitian ini konfigurasi yang digunakan adalah Schlumberger dengan panjang bentangan MN/2 sebesar 1, 5, 10, dan 20 meter. Sedangkan panjang bentangan AB/2 sebesar 6 hingga 300 meter. Pada tahapan inversi data VES, kami menggunakan algoritma Particle Swarm Optimization (PSO) untuk memperoleh nilai parameter resistivitas dan ketebalan lapisan. Algoritma ini dipilih karena cepat menuju konvergen dan relatif stabil. Hasil dari inversi ini diperoleh bahwa lapisan akuifer pertama berada pada kedalaman 21.4 - 52.1 meter dengan litologi batupasir berbutir halus dengan sisipan tufa Lapisan akuifer kedua berada pada kedalaman 52.1-70 meter dengan litologi breksi. Pada kedalaman 70 meter diinterpretasikan sebagai akuifer air tanah, namun memiliki debit yang kecil. Hal ini disebabkan karena litologi lapisan berupa breksi, dasit dan lava basal dari Formasi Hulusimpang. Sistem aliran air tanah pada lapisan ini merupakan sistem media pori yang berakibat pada debit rendah dan waktu pengisian kembali lapisan air tanah relatif lama.

This Technical Note, inspired by some recent international scientific contributions, focuses attention on the relationships existing between the diffusion of per- and polyfluoroalkyl substances and the drinking water environmental sector. Firstly, the analysis takes into consideration published data to highlight the ubiquity of PFAS in the aquifers of various nations. There are also some health implications resulting from the exposure of individuals to PFAS following the ingestion of contaminated water. The technical background is then compared with the current state of the regulatory framework, indicating the reasons, collateral initiatives and precautionary criteria that must guide an urgent and effective remodeling of the law.

Formulation of the problem. Water is one of the most important resources in the world. The Volyn region has significant reserves of surface and underground water, but irrational use of water resources leads to their depletion. Furthermore, today the anthropogenic loading on natural ecosystems is increasing, this factor leads to the deterioration of the ecological state of water resources. So that, research the peculiarities of the water using and ecological state of water bodies and underground aquifers is necessary for conservation and restoration water resources of the region. Review of previous publications and studies. The problem of water use in the Volyn region was being studied by many scientists. The information base of this article includes number scientific works, published by K. I. Herenchuk, F. V. Zuzuk, L. V. Ilin, Ya. O. Molchak, R. V. Migas, M. R. Zabokrytska, V. K. Khil-chevskyi, V. O. Fesiuk, S. V. Polianskyi, T. S. Pavlovska, O. V. Ilina, M. A. Khvesyk, I. V. Sanina, H. H. Liutyi, L. I. Shevchuk and others. Moreover, statistical information about water use and state of water resources was given in the ecological passports, yearbooks of the Volyn region and Ukraine. Also, systematic observations of aquatic ecosystems are carried out by Regional water resources office in the Volyn region. Methods. The methodological base of the study is theoretical foundations of the doctrine of nature management. The authors applied mathematical-statistical, graphic and cartographic methods. Besides, methods of induction, deduction, comparative analysis and synthesis were used during the research. Results. The article is devoted to the study of water resources in the Volyn region, peculiarities of their use by the population and economy. The authors pay attention to the all sources of water in the Volyn region and characterize their distribution. It is mentioned that the most important source of water is aquifers. The authors give information about the structure of water use by type of economic activity. It is clarified that the largest consumers of water are agricultural enterprises and communal services. Agriculture consumes water resources for irrigation and other purposes, however, much water in this branch of economy is used irrationally. Also, large amount of extracted water is exploited for water supply of settlements in the Volyn region. But, only 5,5 % of the used water is consumed by industry, in particular, by food and sugar branch. Besides, the peculiarities of water usage in the administrative districts of the Volyn region are analyzed. The authors investigated that the biggest consumers of water are population and economy of Lutsk, Gorokhiv, Ivanychi and Volodymyr-Volynskiy districts, the least water usage is inherent for Shatsk, Lyubeshiv and Lokachinsky districts. Moreover, it is mentioned, that the features of water usage in the Volyn region change in time. For example, the amount of water consumption during 2000-2014 was decreasing as a result of social-economic causes. The article considers the problem of the influence of different sources of pollution on the water resources in the Volyn region. It is noted, that the most vulnerable to the anthropogenic loading are surface water bodies, they are polluted generally by untreated sewage. For example, river waters consist many pollutants, concentration of which exceeds the maximum permissible concentration. Scientific novelty and practical significance. The structure and dynamics of water consumption in the Volyn region is characterized for the first time. Particular attention is paid to the research of modern ecological state of surface and underground water resources in connection with water use and other economic activities. The results of this exploring will help to optimize water use and to conserve water resources.

Abstract An electrical resistivity survey was carried out using the pole–pole configuration around the Sayanokami spring area in the northern part of Ito Campus (Kyushu University, Fukuoka, Japan) to study the groundwater aquifer and its electrical characteristics. A Code Division Multiple Transmission (CDMT) system was used. The CDMT system transmits 24 currents simultaneously and measures 24 potential responses with monitoring of actual current waveforms. The system can inject current from multiple electrodes into the underground environment simultaneously using different individual current waveforms. The two-dimensional (2-D) inversion results of the electrical resistivity data indicate three layers from top to bottom, as follows: (a) a thin layer with a thickness of 3 m and a low resistivity (

The Ougarta Mountains, located in southwestern Algeria, correspond to an imposing geological entity that corresponds to the center of interest in the geology of the Saharan platform. It is a vast area of elongated NW-SE reliefs, covering an area of 400 x 200 km². The Cambro-Ordovician represents the largest aquifer in the Ougarta region. The cracked type is still poorly known; it is located on a cracked base, and is composed of quartzite sandstone and shale forming a multilayer system, the details of which still remain to be sought and constitute a perennial aquifer for the supply of drinking water for the population. The present study is an attempt to better comprehend the structure and functioning of these basement aquifers. It mainly focuses on the description of soil profiles, structural investigations, and hydrogeological characterization improving knowledge on the hydrodynamic functioning of fractured base reservoirs (geometry of aquifers, hydrodynamic parameters, recharge, resource availability) with a view to the installation of catchment works to optimize, secure and sustain its exploitation in view of its strategic importance for the water supply of this region of Beni Abbes. This contribution is based on field observations and the use of several methods. Various joint approaches have been implemented to locate and characterize aquifers, zones favorable to hydraulic catchments. These are geology, hydrodynamics, piezometry and hydrochemistry. [ABSTRACT FROM AUTHOR]

Groundwater is an important source of recharge to the Yellow River in the area of the Maqu Plateau, but little is known about the groundwater hydrochemical characteristics and the formation mechanism. Phreatic water samples, surface water samples and sediment samples were collected from the study area to investigate their hydrochemical and isotopic characteristics and hydrogeochemical processes. The results show that river water and phreatic water samples have low salinity with Ca2+ and \begin{document}${\rm{HCO}}_3^- $\end{document} being the main constituents (TDS of 72−195 mg/L and 207−459 mg/L, respectively). Concentration of arsenic (As) in water samples range from 0.46 μg/L to 17.7 μg/L. The plot of hydrogen and oxygen isotopes shows that the phreatic water and surface water are mainly recharged from local meteoric water. The river water is relatively enriched in 18O and D relative to the phreatic water. The hydrochemistry of the river water are mainly influenced by evaporation, while the phreatic water is mainly influenced by rock weathering involving dissolution of carbonates. Saturation index of dolomite (SIdolomite) in 68% phreatic water samples is below zero, indicating that the phreatic water is unsaturated with respect to dolomite. As in the groundwater are possibly the result of reductive dissolution of iron-manganese oxide minerals in the unconfined aquifer sediments, which may be sourced from adsorbed As forms in the iron-manganese oxide minerals. This study is helpful in revealing the source of shallow groundwater and genesis mechanisms of groundwater chemicals in the upper stream of the Yellow River.

Sangon Hamlet is included in the mountains which are dominated by andesite rocks and volcanic breccias which cross each other and have a distribution of joints and faults forming a fracture. The fracture is a medium for draining water in the area. There is a difference in ground water level as seen from the well. To re-detail the groundwater flow that has been formed, a groundwater flow pattern modeling is carried out. The modeling is done by numerical method assisted by Modflow Flex Software. For building the model, it is necessary to prepare a concept model, calibration and validation. In this area there are 2 aquifer systems, namely unconfined aquifers and aquitards. Furthermore, the model was calibrated using the sensitivity analysis method. The calibration results are obtained, namely the RMS value of 8.74% with a standard error estimate of 1.27 m and a correlation coefficient of 0.98. From this model, it is known that the flow of water moves from the northwest-north area in the form of a plateau by heading to the east-southeast area which is a lower plain and towards the Plampang River.

The study area is located in the arid section of Punjab province, Pakistan. The accessibility of freshwater is the main problem in this area. The area is mainly flat and alluvial deposits are present down to 800 m. The groundwater is not fit for drinking because of its salinity. Hence, it is essential to mark the transition between fresh water and saltwater. Resistivity models were used to locate freshwater areas. The saltwater areas are between 10 and 30 m deep. Salt flats and clayrich deposits are visible on resistivity maps and were identified by low resistance values. After linking resistivity data and maps, it is determined that the south portion of the area has a freshwater aquifer, especially at a depth of 200 m. At this depth, the quality of water is very good, regardless of its mild salinity in some areas. The margin between salty and freshwater is set to no degree. This is dependent upon the recharge and usage of an aquifer. Groundwater pollution poses a severe threat to the city’s residents. Results from the physio-chemical analysis of the water samples confirm the presence of arsenic in excessive amounts in water samples and are outside the limits set by the WHO and NDWQS. Just two out of 10 samples are within the limits for safe drinking water. The results of this research are valued for groundwater management and the installation of tubular wells in freshwater areas for households and irrigation purposes.

Shallow riparian aquifers represent hotspots of biogeochemical activity in the arid western US. While these environments provide extensive ecosystem services, little is known of how natural environmental perturbations influence subsurface microbial communities and associated biogeochemical processes. Over a 6-month period we tracked the annual snowmelt-driven incursion of groundwater into the vadose zone of an aquifer adjacent to the Colorado River, leading to increased dissolved oxygen (DO) concentrations in the normally suboxic saturated zone. Strong biogeochemical heterogeneity was measured across the site, with abiotic reactions between DO and sulfide minerals driving rapid DO consumption and mobilization of redox active species in reduced aquifer regions. Conversely, extensive DO increases were detected in less reduced sediments. 16S rRNA gene surveys tracked microbial community composition within the aquifer, revealing strong correlations between increases in putative oxygen-utilizing chemolithoautotrophs and heterotrophs and rising DO concentrations. The gradual return to suboxic aquifer conditions favored increasing abundances of 16S rRNA sequences matching members of the Microgenomates (OP11) and Parcubacteria (OD1) that have been strongly implicated in fermentative processes. Microbial community stability measurements indicated that deeper aquifer locations were relatively less affected by geochemical perturbations, while communities in shallower locations exhibited the greatest change. Reactive transport modeling of the geochemical and microbiological results supported field observations, suggesting that a predictive framework can be applied to develop a greater understanding of such environments.

Shallow riparian aquifers represent hotspots of biogeochemical activity in the arid western US. While these environments provide extensive ecosystem services, little is known of how natural environmental perturbations influence subsurface microbial communities and associated biogeochemical processes. Over a 6-month period we tracked the annual snowmelt-driven incursion of groundwater into the vadose zone of an aquifer adjacent to the Colorado River, leading to increased dissolved oxygen (DO) concentrations in the normally suboxic saturated zone. Strong biogeochemical heterogeneity was measured across the site, with abiotic reactions between DO and sulfide minerals driving rapid DO consumption and mobilization of redox active species in reduced aquifer regions. Conversely, extensive DO increases were detected in less reduced sediments. 16S rRNA gene surveys tracked microbial community composition within the aquifer, revealing strong correlations between increases in putative oxygen-utilizing chemolithoautotrophs and heterotrophs and rising DO concentrations. The gradual return to suboxic aquifer conditions favored increasing abundances of 16S rRNA sequences matching members of the Microgenomates (OP11) and Parcubacteria (OD1) that have been strongly implicated in fermentative processes. Microbial community stability measurements indicated that deeper aquifer locations were relatively less affected by geochemical perturbations, while communities in shallower locations exhibited the greatest change. Reactive transport modeling of the geochemical and microbiological results supported field observations, suggesting that a predictive framework can be applied to develop a greater understanding of such environments.

A total of sixteen Vertical Electrical Sounding (VES) surveys and five physicochemical analyses were carried out in selected locations within the Yenagoa Metropolis, in Bayelsa State, Nigeria, to delineate the concentration of ferruginous minerals in freshwater aquifers in the area. For the geophysical survey, the Schlumberger electrode configuration was employed. The resulting data obtained was processed and interpreted using Excel suite, IPI2WIN resistivity, Surfer-11 and Rockworks software. The results revealed four to six geologic layers across the area, and were used to generate geoelectric maps which showed that in most part of the study area, there were uneven distributions of shallow aquifers (4 – 10m), and uneven layers of clay and sandy-silt at varying depths up to 20m. The physicochemical analysis of raw water samples collected from five boreholes located in close proximity to the VES sounding locations were analysed for physical and chemical parameters. Physical parameters tested include colour, conductivity, turbidity, and temperature. Chemical parameters analysed are pH, Dissolved Oxygen (DO), Total Dissolved Solids (TDS) Alkalinity, Total Iron, Carbonate, Chloride, Sulphate, and heavy metals such as copper, chromium, nickel, cadmium, manganese, zinc and lead. The pH was determined using a Mettler Toledo (GmbH 8603 Schwerzenbach) pH meter by direct measurement. An analogue mercury thermometer was used for temperature measurements and a Hach 2100A turbidimeter for turbidity determination. Also, the concentrations of Zinc, Lead, and Copper in the water samples were obtained using the flame atomic absorption spectrophotometer. It was observed that the values SO42- , Cl-, Na2+, Mg2+, Ca2+, F- have values below World Health Organization (WHO) standard in all boreholes tested while Mn2+, NH3, PO3−and Fe2+, K+, and Cu2+ have values above WHO standard in some boreholes. The pH values all showed that the water was slightly basic as the values all exceeded the neutral limit 7, with only station showing slightly elevated pH value 9, suggesting the presence of iron bacteria. F-, K+, Fe2+ and Mn2+ have values that exceeded the WHO standard. The results from Physicochemical and geophysical analysis suggest that at depths of 20 – 45m, the concentration of ferruginous minerals is high especially towards the north eastern section of the study area and so drilling should be made to approximate depths of 50 – 80m for minimal iron contamination in the aquifers.

The article considers an unprecedented case of intentional artificial pollution of the operational aquifer of local significance in the village of Tarasivka, located in Kyiv-Sviatoshynskyi district, Kyiv region by discharges of spent brine. The source of drinking ground-water pollution in the deposits of the Novopetrivska deposits of the Poltava Miocene sequence was established based on the results of express methods application and logical-apriori analysis. Based on hydrochemical tests, analysis of the results of water pumping from wells and calculations of salt migration rate, it has been proved that the source of contamination could only be a red caviar packing plant, which, according to the regulatory raw material washing technology, produces significant volumes of brine effluents. At the beginning of the study, several possible options for increasing water mineralization were considered, but all signs point to only one source. Firstly, the content of calcium, sodium and chlorine ions in the water is excessive, which rejects the possibility of its contamina-tion from the chemical storage site, which is also located in the area of possible impact; 2) the source of pollution is located higher above the groundwater flow, i.e. in the area of its supply; 3) mineralization (due to the presence of NaCl) in the water of the well, lo-cated 440 m downstream from the source of pollution, increases with increasing flow rate and duration of pumping and decreases after rains and infiltration of meltwater, which resembles seawater intrusion into coastal intakes, 4) mineralization increases along the aqui-fer from top to bottom, in accordance with the density and viscosity of the solution; 5) increased mineralization of this groundwater aquifer in this area is not an isolated phenomenon, salt water was found in wells only downstream from the above mentioned enter-prise, in addition, it appeared sequentially, first in a nearby well (365 m) – in about 5 years, then in another well (440 m) – in 6 years, which corresponds to the convective salt transfer rate in sand deposits at the appropriate flow gradients.

Electrical resistivity survey was conducted around Students’ Hostels in FUPRE to delineate prolific aquifer for potable water to serve the teeming population of staff and students. Five vertical electrical soundings (VES) using Schlumberger electrode configuration with a maximum current electrode spread of 300m were employed for data acquisition. WINRESIST software was employed to execute the iteration and inversion processes of computing resistivities, depths and thicknesses of the various layers and the curve types. Results indicate that the area is characterized by 4 distinct geoelectric layers inferred differently at the VES locations. Two potential groundwater aquifer zones are delineated. The unconfined shallow aquifer zones found at VES 1, 3, 4 and 5 locations have shallow overburden depth ranging between 3.7-19.3m and coarse-grained sand columns with thicknesses ranging between 2.8-17.7m while the confined deep aquifer zone found at VES 2 location coincides with deep overburden layer at a depth of 42.6m and coarse-grained sand column with appreciable thickness of 19.1m. These results suggest that boreholes for sustainable groundwater supply around the Students’ Hostels should be sited at VES 2 location and screened at a depth ≥40.0m. However, aquifers at VES 1, 3, 4 and 5 have potentials for groundwater but are vulnerable to contamination. It is recommenced that electrical resistivity and hydrogeological surveys should be conducted at different locations in FUPRE, before any borehole(s) are drilled, to delineate the appropriate aquifer for potable groundwater supply and to avoid possible contamination.

Securing and managing underground water resources requires a good knowledge of the structure, texture and connections of the reservoir, in order to develop realistic and reliable hydrogeological models. On the coastline of the Gulf of Lion Margin (S. France), the Balaruc-les-Bains deep karst reservoir is subjected to interactions between fresh, marine and deep thermal waters, respectively. Water resource usage for drinking, spa resort, and fish-farming raises important economic and social issues. These were addressed by an integrated research program, involving drilling of an exploratory borehole across the Jurassic carbonate reservoir. This contribution analyses the 750 m cores, in order to (i) characterise the architecture and evolution of the karst reservoir and (ii) investigate the paleo-fluids circulations, witnessed by calcite and dolomite mineralization in the fractures, karst cavities, and as cement of tectonic beccia. The structure of the reservoir is characterised by the superposition of several aquifers separated by marly intervals. At shallow level, the initial grainstone is incompletely dolomitized in metre-thick intervals, while limestone in the 210–340 m interval was completely dolomitized at an early stage. Dolomite has been subjected to penetrative extensional cataclastic deformation, while the preserved limestone is affected by normal faulting, resulting from NNE–SSW extension. Distinct types of karsts have been documented, from the top of the reservoir (paleo-lapiaz filled with Burdigalian marine marls), down to 500 m depth (paleo-endokarst filled with continental silts). The upper reservoir (75–150 m) is intensely karstified, and includes 0.1 to 1 m-wide cavities, where present day water fluxes are documented. Analyses of calcite and dolomite crystallisation under natural light and cathodoluminescence indicate precipitation from distinct fluids: formation water in chemical equilibrium with the host rock, water rich in oxides and hydroxides, ascending hydrothermal fluid and corrosive water of meteoric origin. Alternate dolomitization and calcitization observed in the upper reservoir suggests alternate flows of karstic freshwater and marine salt-water. Vertical, metre-long and centimetre wide open cracks are presently used for large water flows; several generations of syntaxial calcite growth provide evidence for varying chemistry of the circulating fluids. Structural cross cutting relationships allowed us to establish a relative chronology of events, which can be correlated with the regional geodynamic evolution. The study reveals that the present-day reservoir architecture results from the superimposition of structures formed during the Early Cretaceous extension, Maastrichtian-Eocene Pyrenean shortening, and Oligocene rifting of the Gulf of Lion. The reservoir was also shaped by successive karstification episodes and marine transgressions. Although the present-day hydrological system is controlled by, and reactivates structures inherited from a long-term evolution, it is characterised by frequent turn-overs of the water flow, tuned by high-frequency external forcings such as sea-level changes driven by Pleistocene glacio-eustasy, or varying precipitation rates.

Heterogeneity and insufficient site characterization limit our knowledge of the subsurface. Inversion techniques, which minimize the mismatch between observations and model predictions, have become an essential tool of subsurface characterization. Most optimization‐based approaches fail to incorporate various implicit priors and capture the geological complexity. We overcome these limitations by deploying the plug‐and‐play and consensus equilibrium (CE) strategies, which provide a flexible framework for image reconstruction. Our CE methodology for spatial delineation of geologic formations consists of an image denoiser and a variational auto‐encoder (deep learning‐based emulator). The former ameliorates the reconstruction noise, yielding well‐defined geological structures; its mathematical equivalence with the proximal operator allows the deployment of advanced denoisers (e.g., CNN‐based denoiser) that do not correspond to a regularization objective. The latter defines a geology prior that imposes a geological constraint, for example, continuity and shape of geological features, onto the reconstructed image. We conduct a series of numerical experiments dealing with transient two‐dimensional flow driven by a pumping well and natural hydraulic head gradient. They demonstrate the CE framework's ability to delineate, both probabilistically and deterministically, complex subsurface environments with sufficient quality. Key Points: We developed consensus equilibrium framework to reconstruct the subsurface from sparse dataOur framework integrates conventional optimization methods with machine learning‐based methodsThe method accurately reconstructs geologically complex models and efficiently reduces and quantifies the posterior uncertainty [ABSTRACT FROM AUTHOR]

Groundwater geochemistry and hydrogeochemical processeswere investigated from three different river basins in Bangladesh. The data were collected from BGS website. Total 113 groundwater water samples (10–274 m depth) from different locations of the Ganges-Brahmaputra-Meghna (GBM) river basins of Bangladesh were analyzed to know the diverse groundwater geochemistry and hydrogeochemical processes. GroundwaterCa2+, Mg2+, Na+, K+, Zn2+, Cl−, HCO3–, and SO42− concentrations were consideration for the investigations. The rank of major cations of The Ganges, Brahmaputra, and Meghna basins are Ca2+ > Mg2+ > Na+ > Zn2+ > K+, Ca2+ > Na+ > Mg2+ > K+, and K+ > Mg2+ > Zn2+ > Na+ > Ca2+, respectively. The rank of major anions of The Ganges, Brahmaputra, and Meghna basins are Cl− > SO42− > HCO3–, Cl− > HCO3– > SO42−HCO3– > Cl−>, respectively. The investigations were carried out usingbivariate plot interpretation and factor analysis. Silicate weathering, ion exchange, and seawater intrusion are the dominant processes except carbonate weathering in the Ganges basin. Carbonate weathering is dominant in the Brahmaputra and the Meghna basins. Silicate weathering and gypsum weathering are also present in the Brahmaputra and Meghnabasin’s aquifers to some extent. The Cl− over SO42− indicated anthropogenic influences into groundwater for all three basins.

Groundwater exploitation (borehole drilling) was carried out around Awka and environs in Anambra State, Southeastern Nigeria, to understand the underlying rock units encountered while drilling, differentiate boreholes with confined aquifers from those with unconfined aquifers, delineate the probable aquiferous zones from the borehole data, evaluate the challenges encountered while drilling (both geologic and technical), and identify mitigation measures employed to address these challenges. Detailed geologic log information of the boreholes was produced to illustrate the rock units encountered while drilling. Four rock units were identified, namely: shale, sandstone, clay, and gravel. These rock units were exposed within the Imo Formation and the Nanka Formation that underlie the study area. Results from the geologic log information of the boreholes indicate that the water table within the study area ranges from 11.2 m to 56.5 m from the soil surface, and the probable aquiferous zones vary from 6.8 m to 23.3 m in thickness. A detailed look at the lithologic logs of the boreholes show that 50% of the drilled boreholes possess confined aquifers while the remaining 50% have unconfined aquifers. A careful appraisal of the challenges encountered, which are mainly geologic, is strictly attributed to the geologic formation of the study area. Other technical challenges have been derived from mechanical faults developed during drilling.

Study region: In this study, we use stable isotopes of water to quantify the flow pathways delivering water to the tributaries, mainstem river and groundwater basin underlying urban San Diego. Information about sources of stormflow and recharge are necessary to maintain the health of waterways and aquifers, but studies of these processes are scarce in urban, semi-arid regions. Study focus: Isotopic methods have been used in experimental or natural watersheds, but also have potential to quantify urban water cycling behaviour and water sources. We sampled baseflow, precipitation, and hourly stormflow from eight events with a range of antecedent conditions, and used end member mixing analysis to determine stormflow and groundwater sources. New hydrological insights for the region: Our results show that hydrologic connectivity controls stormflow sources. After a dry summer, and early in storm events, connectivity of pre-event water with the channel is low, so only new precipitation reaches the river. In wetter conditions, connectivity is higher and pre-event surface water mixes with infiltration-origin groundwater. Deeper groundwater composition mimics stormflow, a mix of stagnated river water and infiltration-origin water. The close connection between streamflow and groundwater implies that improving groundwater quality requires improvements to surface water quality. Average uncertainty in source fractions was ±8.0 %, suggesting that despite complex water pathways in urban, semi-arid environments, isotopic sampling is valuable for quantifying water sources.