Artykuły w czasopismach na temat „Aquifer”
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Salvador, N., J. P. Monteiro, R. Hugman, T. Y. Stigter i E. Reis. "Quantifying and modelling the contribution of streams that recharge the Querença-Silves aquifer in the south of Portugal". Natural Hazards and Earth System Sciences 12, nr 11 (6.11.2012): 3217–27. http://dx.doi.org/10.5194/nhess-12-3217-2012.
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Abstract. The water balance of the mesocenozoic aquifers of the Algarve, in the south of Portugal has traditionally been estimated considering only direct ("autogenic") recharge from rainfall occurring in the area of the aquifers. Little importance has been attributed to so-called allogenic recharge, originating from streambed infiltration from runoff generated outside the aquifers, particularly in the Palaeozoic rocks to the north where runoff is high. The Querença-Silves (QS) aquifer is the most important aquifer of the region both for irrigation and public water supply. Several important and sensitive surface/groundwater ecotones and associated groundwater dependent ecosystems exist at the springs of the natural discharge areas of the aquifer system. A numerical flow model has been in constant development over the last few years and currently is able to reproduce the aquifer's responses to estimated direct recharge and abstraction for the years 2001–2010. However, recharge calculations for the model do not take into account allogenic recharge infiltration along influent reaches of streams. The quantification of allogenic recharge may further improve the assessment of water availability and exploitation risks. In this paper an attempt is made to quantify the average annual contribution of allogenic recharge to the QS aquifer, based on monitoring data of the principal water courses that cross the aquifer system. Significant uncertainties related to surface runoff generated within the aquifer area, as well as areal recharge were identified and the consequences for the optimization of spatial distribution of transmissivity in the groundwater flow model are also addressed.
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Ducci, Daniela, i Mariangela Sellerino. "A Modified AVI Model for Groundwater Vulnerability Mapping: Case Studies in Southern Italy". Water 14, nr 2 (15.01.2022): 248. http://dx.doi.org/10.3390/w14020248.
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Many methods for evaluating the aquifer’s vulnerability to pollution have been developed in the past four decades by using geographic information system (GIS) tools. However, even if the aquifer vulnerability concept is well defined and the methods have been constantly tested and compared, the problem of the choice of the best “standard” method remains. To meet these objectives, aquifer vulnerability maps are of crucial importance. The choice of method depends on several factors, including the scale of the project, the hydrogeological characteristics of the area, and data availability. Among the many methods, the AVI (Aquifer Vulnerability Index) method has been widely used as it considers only two physical parameters. The AVI Index represents the hydraulic resistance of an aquifer to vertical flow, as a ratio between the thickness of each sedimentary unit above the uppermost aquifer (D, length), and the estimated hydraulic conductivity (K, length/time) of each of these layers. The AVI Index has a time dimension and is divided into five classes. In order to avoid a widespread presence of the higher vulnerability classes, especially in shallow aquifers, the AVI classification has been modified using statistical methods. The study reports the application of the modified AVI method for groundwater pollution vulnerability, in three different areas of southern Italy, highlighting the limitations of the method in alluvial aquifers and the differences with other methods.
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Strehlow, K., J. H. Gottsmann i A. C. Rust. "Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring". Solid Earth 6, nr 4 (10.11.2015): 1207–29. http://dx.doi.org/10.5194/se-6-1207-2015.
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Abstract. Well water level changes associated with magmatic unrest can be interpreted as a result of pore pressure changes in the aquifer due to crustal deformation, and so could provide constraints on the subsurface processes causing this strain. We use finite element analysis to demonstrate the response of aquifers to volumetric strain induced by pressurized magma reservoirs. Two different aquifers are invoked – an unconsolidated pyroclastic deposit and a vesicular lava flow – and embedded in an impermeable crust, overlying a magma chamber. The time-dependent, fully coupled models simulate crustal deformation accompanying chamber pressurization and the resulting hydraulic head changes as well as flow through the porous aquifer, i.e. porous flow. The simulated strain leads to centimetres (pyroclastic aquifer) to metres (lava flow aquifer) of hydraulic head changes; both strain and hydraulic head change with time due to substantial porous flow in the hydrological system. Well level changes are particularly sensitive to chamber volume, shape and pressurization strength, followed by aquifer permeability and the phase of the pore fluid. The depths of chamber and aquifer, as well as the aquifer's Young's modulus also have significant influence on the hydraulic head signal. While source characteristics, the distance between chamber and aquifer and the elastic stratigraphy determine the strain field and its partitioning, flow and coupling parameters define how the aquifer responds to this strain and how signals change with time. We find that generic analytical models can fail to capture the complex pre-eruptive subsurface mechanics leading to strain-induced well level changes, due to aquifer pressure changes being sensitive to chamber shape and lithological heterogeneities. In addition, the presence of a pore fluid and its flow have a significant influence on the strain signal in the aquifer and are commonly neglected in analytical models. These findings highlight the need for numerical models for the interpretation of observed well level signals. However, simulated water table changes do indeed mirror volumetric strain, and wells are therefore a valuable addition to monitoring systems that could provide important insights into pre-eruptive dynamics.
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Gan, Yiqun, i Quanrong Wang. "Technical note: A model of chemical transport in a wellbore–aquifer system". Hydrology and Earth System Sciences 28, nr 6 (22.03.2024): 1317–23. http://dx.doi.org/10.5194/hess-28-1317-2024.
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Abstract. Wellbore is proven to be the only effective way of delivering chemicals to a target aquifer during a tracer test or aquifer remediation. The volume of original water in the operational well is a critical parameter affecting the concentration of injected tracers or chemicals in the wellbore in the early stages. We found that the calculation of the wellbore water volume by previous numerical methods was correct when the wellbore penetrates an unconfined aquifer but incorrect when the wellbore penetrates a confined aquifer, further resulting in errors in describing the solute transport of injected chemicals in confined aquifers, such as MODFLOW/MT3DMS or FEFFLOW. Such errors caused by MODFLOW/MT3DMS and FEFFLOW increased with increasing wellbore water volume. This was because the groundwater in both the wellbore and aquifer was assumed to be confined where the water level was higher than the aquifer's top elevation and the groundwater thickness was assumed to be equal to the aquifer thickness. Actually, when the wellbore penetrated a confined aquifer, the groundwater was only confined in the aquifer, while it was unconfined in the wellbore. In this study, the solute transport model is revised based on the mass balance in a well–aquifer system, with special attention given to the wellbore water volume. The accuracy of the new model was tested against benchmark analytical solutions. The revised model could increase the accuracy of reactive transport modeling in aquifer remediation through the wellbore.
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Wu, Ming-Chang, i Ping-Cheng Hsieh. "Influence of nonuniform recharge on groundwater flow in heterogeneous aquifers". AIMS Mathematics 8, nr 12 (2023): 30120–41. http://dx.doi.org/10.3934/math.20231540.
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<abstract><p>The composition of soils in aquifers is typically not homogeneous, and soil layers may be cracked or displaced due to geological activities. This heterogeneity in soil distribution within aquifers affects groundwater flow and water level variations. In the present study, we established a two-dimensional (2D) mathematical model that considers the influence of surface recharge on groundwater flow in heterogeneous sloping aquifers. By considering temporal variations in surface recharge, slope angle and aquifer heterogeneity, the simulated results are expected to better reflect real conditions in natural aquifers. The effects of aquifer heterogeneity on groundwater flow and water levels are particularly significant in sloping aquifers. The study's findings indicate that even when the soil composition remains constant, variations in groundwater level and flow may be considerable, depending on factors such as soil alignment, slope angle of the aquifer's base layer and the direction of water flow.</p></abstract>
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Maulana, Fivry Wellda, i Arie Noor Rakhman. "Aplikasi Geofisika Terpadu Untuk Penelitian Potensi Air Tanah Aquifer Batu Pasir Di Alasombo, Indonesia". Jurnal Multidisiplin Madani 2, nr 1 (30.01.2022): 511–24. http://dx.doi.org/10.54259/mudima.v2i1.418.
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The purpose of this study was to determine the potential of groundwater in Alasombo, Weru District, Sukoharjo Regency, Indonesia. The investigation has been carried out using geophysical methods that are integrated with surface geological data to obtain an interpretation of the hydrogeological control of the aquifer. The lithology of the aquifer is dominated by sandstone which controls its role as 2 types of aquifers, namely unconfined aquifers or free aquifers and semi-confined aquifers or semi-free aquifers. The geoelectrical section shows that the groundwater-carrying layer that functions as an aquifer is the sandstone layer in the second layer and sandstone in the base layer. As an artesian aquifer or a confined aquifer, sandstone aquifers have a water volume between 31.5 to 260 m3/day, in a northwest-southeast direction. In terms of the quality of the conductivity value of water in the field, below 1500 µs/cm is freshwater type groundwater that can be recommended as a source of clean water.
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Zhang, Yi, i Dong Ming Guo. "Temperature Field of Single-Well Aquifer Thermal Energy Storage in Sanhejian Coal Mine". Advanced Materials Research 415-417 (grudzień 2011): 1028–31. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.1028.
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The technology of aquifer thermal energy storage(ATES) is an energy-saving technology which can provide a solution to energy shortages and resources expasion. The first key point of this technology is whether the aquifer can be use to store energy. In this paper, taking Sanhejian Coal Mine as an example, we choose Quaternary upper loose sandy porosity confined aquifer to bottom clayed glavel porosity confined aquifer as aquifers thermal energy storage, to discuss whether the aquifers can be used to store energy. The simulation results of aquifer temperature field show that the selected aquifers reach the goal of energy storage. And with the same irrigation flow, the lower the temperature, the more the cold water and the larger the low temperature region in aquifers thermal energy storage. With the same irrigation temperature, the lager the irrigation flow the more the cold water and the larger the low temperature region in aquifers thermal energy storage.
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Luo, Zhaoyang, Jun Kong, Chengji Shen, Pei Xin, Chunhui Lu, Ling Li i David Andrew Barry. "Effects of aquifer geometry on seawater intrusion in annulus segment island aquifers". Hydrology and Earth System Sciences 25, nr 12 (23.12.2021): 6591–602. http://dx.doi.org/10.5194/hess-25-6591-2021.
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Abstract. Seawater intrusion in island aquifers was considered analytically, specifically for annulus segment aquifers (ASAs), i.e., aquifers that (in plan) have the shape of an annulus segment. Based on the Ghijben–Herzberg and hillslope-storage Boussinesq equations, analytical solutions were derived for steady-state seawater intrusion in ASAs, with a focus on the freshwater–seawater interface and its corresponding watertable elevation. Predictions of the analytical solutions compared well with experimental data, and so they were employed to investigate the effects of aquifer geometry on seawater intrusion in island aquifers. Three different ASA geometries were compared: convergent (smaller side is facing the lagoon, larger side is the internal no-flow boundary and flow converges towards the lagoon), rectangular and divergent (smaller side is the internal no-flow boundary, larger side is facing the sea and flow diverges towards the sea). Depending on the aquifer geometry, seawater intrusion was found to vary greatly, such that the assumption of a rectangular aquifer to model an ASA can lead to poor estimates of seawater intrusion. Other factors being equal, compared with rectangular aquifers, seawater intrusion is more extensive, and watertable elevation is lower in divergent aquifers, with the opposite tendency in convergent aquifers. Sensitivity analysis further indicated that the effects of aquifer geometry on seawater intrusion and watertable elevation vary with aquifer width and distance from the circle center to the inner arc (the lagoon boundary for convergent aquifers or the internal no-flow boundary for divergent aquifers). A larger aquifer width and distance from the circle center to the inner arc weaken the effects of aquifer geometry, and hence differences in predictions for the three geometries become less pronounced.
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Tsepav, Matthew Tersoo, Aliyu Yahaya Badeggi, Obaje Nuhu George, Usman Yusuf Tanko i Ibrahim Samuel Ibbi. "On the Use of Electrical Resistivity Method in Mapping Potential Sources and Extent of Pollution of Groundwater Systems in Lapai Town, Niger State, Nigeria." Journal of Physics: Theories and Applications 5, nr 1 (30.03.2021): 18. http://dx.doi.org/10.20961/jphystheor-appl.v5i1.51563.
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<p>Electrical resistivity method employing the Schlumberger array was used to occupy forty four (44) vertical electrical sounding points in Lapai town with the aim of determining the depth to aquifers, aquifer thicknesses and aquifer protective capacity. The G41 Geotron resistivity meter was used in obtaining the apparent resistivity data which was processed using Interpex 1XD resistivity interpretation software. The results revealed four lithologic sections which include top lateritic soil, sandy clay, fractured basement and fresh basement. Both confined and unconfined aquifers were identified within the area, with four classes of aquifer proactive capacities as high, moderate, weak and poor. While the aquifer at VES 20 was highly protected, twenty other aquifers were moderately protected, eight others had weak protection and fifteen aquifers were poorly protected. The aquifers were generally of good thicknesses and at varying reasonable depths, making them good reservoirs of water in appreciable quantity. The average aquifer thickness was estimated to be 48.36m while the average depth to aquifers was estimated to be 56.68m.</p>
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Hera-Portillo, África de la, Julio López-Gutiérrez, Beatriz Mayor, Elena López-Gunn, Hans Jørgen Henriksen, Ryle Nørskov Gejl, Pedro Zorrilla-Miras i Pedro Martínez-Santos. "An Initial Framework for Understanding the Resilience of Aquifers to Groundwater Pumping". Water 13, nr 4 (17.02.2021): 519. http://dx.doi.org/10.3390/w13040519.
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Groundwater stored in aquifers experiences a wide variety of natural, induced and/or anthropogenic disturbances. Among them, groundwater extraction is the main disturbance that affects most of the aquifers in the world. Aquifer’s resilience, understood as the potential of the aquifer to sustain disturbances on the long term and to guarantee essential qualities and functions, provides a key tool when assessing sustainable groundwater management alternatives. The aim of this work is to illustrate an aquifer resilience framework that can support groundwater sustainable management. A theoretical framework is based on the identification of the key variables that parameterize the quantitative and qualitative responses of the groundwater flow system to pumping. An example from the literature based in Denmark is provided as an illustration of the proposed framework. The results show that long-term high quality data are essential to make a step further in aquifers dynamic responses. The quantitative understanding of the aquifer’s behavior before, during and after groundwater extraction provides a valuable source of information in order to identify thresholds of change (tipping points, transitions or regime shifts) which could permit pro-active groundwater management decisions. Moreover, a deeper understanding on the aquifer’s dynamics provides useful information in order to avert threats that may put the sustainability of the system at risk.
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Yuan, Hua. "Review on Aquifer Structure Theory in Aquifer Layered Distribution Area". Applied Mechanics and Materials 470 (grudzień 2013): 907–10. http://dx.doi.org/10.4028/www.scientific.net/amm.470.907.
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In the nature, most phreatic or confined aquifers are of layered distribution. Based on the actual distribution of aquifer and whether there exists transfluence contact between each aquifer, the layered distribution aquifer basically is simplified as multi-aquifer or double aquifer structure. In this paper, all of the aquifer structure models proposed by domestic and foreign scholars are summarized. Furthermore, the mathematical model of each aquifer structure is detailed illustrated.
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Domingo-Pinillos, Juan, Javier Senent-Aparicio, José García-Aróstegui i Paul Baudron. "Long Term Hydrodynamic Effects in a Semi-Arid Mediterranean Multilayer Aquifer: Campo de Cartagena in South-Eastern Spain". Water 10, nr 10 (24.09.2018): 1320. http://dx.doi.org/10.3390/w10101320.
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The Mediterranean basin contains many semi-arid environments where aquifers are subject to intensive exploitation, generally to meet irrigation demands. The Campo de Cartagena aquifer is a clear example from such a semi-arid environment, and its hydrodynamic effects have aroused great scientific interest. The main objective of this study is to evaluate the hydrodynamic effects that have occurred in the last century of anthropogenic activity in this aquifer system. This aquifer is subject to intensive exploitation and shows clear deficits in times of drought, with recharge by irrigation playing an important role. This study’s methodology includes groundwater modelling to reconstruct the transient evolution of the aquifer system during the last century, to generate water balances and to illustrate how the evolution of irrigation has, in many ways, changed the aquifer’s groundwater flow pattern. The results delineate the hydraulic communication of the aquifer stratums through specific geological structures, as well as the flow transfer from the Quaternary layer to the Mar Menor and the Mediterranean Sea. The reconstruction of the entire system’s temporal evolution shows a fragile water balance that is supported by surface-water contributions.
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Medihala, P. G., J. R. Lawrence, G. D. W. Swerhone i D. R. Korber. "Spatial variation in microbial community structure, richness, and diversity in an alluvial aquifer". Canadian Journal of Microbiology 58, nr 9 (wrzesień 2012): 1135–51. http://dx.doi.org/10.1139/w2012-087.
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Relatively little is known regarding the spatial variability of microbial communities in aquifers where well fouling is an issue. In this study 2 water wells were installed in an alluvial aquifer located adjacent to the North Saskatchewan River and an associated piezometer network developed to facilitate the study of microbial community structure, richness, and diversity. Carbon utilization data analysis revealed reduced microbial activity in waters collected close to the wells. Functional PCR and quantitative PCR analysis indicated spatial variability in the potential for iron-, sulphate-, and nitrate-reducing activity at all locations in the aquifer. Denaturing gradient gel electrophoresis analysis of aquifer water samples using principal components analyses indicated that the microbial community composition was spatially variable, and denaturing gradient gel electrophoresis sequence analysis revealed that bacteria belonging to the genera Acidovorax , Rhodobacter , and Sulfuricurvum were common throughout the aquifer. Shannon’s richness (H′) and Pielou’s evenness (J′) indices revealed a varied microbial diversity (H′ = 1.488–2.274) and an even distribution of microbial communities within the aquifer (J′ = 0.811–0.917). Overall, these analyses revealed that the aquifer’s microbial community varied spatially in terms of composition, richness, and metabolic activity. Such information may facilitate the diagnosis, prevention, and management of fouling.
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Jaka Yuwana, Ngudi Aji, Nora Herdiana Pandjaitan i Roh Santoso Budi Waspodo. "Prediksi cadangan air tanah berdasarkan hasil pendugaan geolistrik di Kabupaten Grobogan, Jawa Tengah". JURNAL SUMBER DAYA AIR 13, nr 1 (27.12.2017): 23–36. http://dx.doi.org/10.32679/jsda.v13i1.139.
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One of the solutions for water shortage in Grobogan District is groundwater utilization. Excessive groundwater pumping will decrease groundwater level and trigger a landsubsidence. It is necessary to conduct hydrogeological study to determine the groundwater storage in this area. The purpose of this research were to determine the hydrogeological conditions, aquifer characteristics and potential of groundwater storage in Grobogan district. This research used geoelectrical method to identify rock characteristics. The results showed that the geological formation in Grobogan district consisted of Qa, Tmpk, Tmpl, Tps, Tmw and Qp. Grobogan district had 5 aquifers system, there are: poorly productive aquifers, moderately productive aquifers, locally productive aquifers, extensive productive aquifers and region without exploitable groundwater. The aquifer layer consisted of sand, marl sandy, silty sand and calcareous sand. The unconfined aquifer was located at 1,2 - 58 m from soil surface with average thickness of 13,54 m and the hydraulic conductivity of 3,54 m/day. The confined aquifer depth can be estimated between 29 - 174 m from soil surface with average thickness of 37,4 m and the hydraulic conductivity of 3,87 m/day.The predicted groundwater storage in Grobogan district of unconfined aquifer was 401,33 l/sec and confined aquifer was 1.804,95 l/sec.
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Singh, K. P. "Nonlinear estimation of aquifer parameters from surficial resistivity measurements". Hydrology and Earth System Sciences Discussions 2, nr 3 (10.06.2005): 917–38. http://dx.doi.org/10.5194/hessd-2-917-2005.
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Abstract. The present study is focused on an examination of the correlation relationships for hydraulic permeability and transmissivity with electrical resistivity in a range of fractured and alluvial aquifers. The observed permeability data for fractured rock aquifers at some locations is correlated nonlinearly with electrical resistivity of the aquifers estimated from resistivity sounding data and it is found that the permeability of the aquifer in this region exponentially decreases with increase in resistivity. Permeability of the hard rock aquifer within the weathered zone and alluvium aquifers increases exponentially with increase in resistivity, and transmissivity decreases exponentially. However, in case of fracture rock and sandwiched aquifers, transmissivity increases exponentially with increase in resistivity. An attempt has been made to find general functional relationship between hydraulic parameters and resistivity of the aquifer, and therefore, published and observed data from India and other parts of the world has been taken under consideration. It is found that for fracture rock and alluvium aquifers, permeability and the transmissivity are best defined as the exponential functions of aquifer resistivity. The application of electrical parameters obtained from resistivity data for evaluation of hydraulic parameters has been demonstrated in detail within the Osmania University Campus, Hyderabad (India). The empirical relations between aquifer parameters and resistivity are established for transforming resistivity distribution into permeability and transmissivity of the aquifer. The information thus obtained from resistivity data on permeability of the aquifer and transmissivity distribution in the study area can be used for optimal use and assessment of water resources.
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Lei, Kunchao, Fengshan Ma, Jiurong Liu, Yong Luo, Wenjun Cui, Yi Zhou, He Liu, Xinghui Wang, Miaozhuang Tian i Long Zhao. "Leaking recharge mechanism in the multi-layer aquifer system of a typical land subsidence area in Beijing". Proceedings of the International Association of Hydrological Sciences 382 (22.04.2020): 309–14. http://dx.doi.org/10.5194/piahs-382-309-2020.
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Abstract. It is of great significance to reveal the mechanism of land subsidence to further find out the mechanism of leakage flow in multi-layer aquifer systems and the water-release compression of weak aquifers. In this paper, conditions of groundwater leakage flow are expounded, and the initial hydraulic gradient calculation formula in the aquitards are deduced. The data of Tianzhu Land Subsidence Monitoring Station are selected to preliminarily discuss the leakage flow mechanism of the multi-layer groundwater system and water-release compression of weak aquifers. The results show that, firstly the weak aquifer layers in the shallow strata above 91.32 m in Tianzhu Land Subsidence Station are all in the state of unidirectional drainage consolidation, and the water heads in the upper strata are higher than those in the lower strata. However, the hydraulic gradient between the two adjacent aquifers is smaller than the initial hydraulic gradient in the weak aquifer layer, so no leakage recharge effect is generated. Secondly, the water level of the two adjacent aquifers in the deep formation below 91.32 m shows a continuous downward trend, among which the weak aquifer is drained and consolidated on both sides, and the pore water head in the middle of the weak aquifer is the lowest. Although the strata has a large amount of compression, no leakage recharge phenomenon occurs. Thirdly, in a multi-layer aquifer system, when the head difference between adjacent aquifers is small and there is a thick viscous layer between them, it is difficult for the upper aquifer to overcome the shear strength of the bound water in the weak aquifer below, leaking recharge barely occurs.
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Jamali, Muhammad Afzal, Muhammad Hassan Agheem, Akhtar Hussain Markhand, Shahid Ali Shaikh, Asfand Yar Wali Arain, Mujeeb Ur Rehman Khaskhely, Ali Ghulam Sahito, Kashif Ahmed Memon i Waqarullah Hassan Mujtaba. "Exploration of Shallow Geothermal Energy Aquifers by Using Electrical Resistivity Survey in Laki Range Jamshoro district Sindh, Pakistan". International Journal of Economic and Environmental Geology 12, nr 1 (8.06.2021): 46–52. http://dx.doi.org/10.46660/ijeeg.vol12.iss1.2021.561.
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Geothermal water is increasingly used around the world for its exploitation. Bulk electrical resistivity differences can bring significant information on variation of subsurface geothermal aquifer characteristics. The electrical resistivity survey was carried out in Laki range in lower Indus basin in the study area to explore the subsurface geothermal aquifers. The Schlumberger electrode configuration with range from 2 m to 220 m depth was applied. Three prominent locations of hot springs were selected including Laki Shah Saddar, Lalbagh and Kai hot spring near Sehwan city. After processing resistivity image data, two hot water geothermal aquifers were delineated at Laki Shah Sadder hot springs. The depth of first aquifer was 56 m and its thickness 38 m in the limestones. The depth of second aquifer of 190 m and with thickness of 96 m hosted in limestone. In Lalbagh hot springs two geothermal aquifers were delineated on the basis of apparent resistivity contrast, the depth of first aquifer zone in sandstone was in sandstone 15 m and thickness 12 m, while the depth of second aquifer was 61m and thickness was 35m. In Kai hot springs two hot water geothermal aquifers were delineated. The depth of first geothermal aquifer was 21m and thickness was 18 m and the depth of second aquifer was 105 m and thickness was 61m present in sandstone lithology. Present work demonstrates the capability of electrical resistivity images to study the potential of geothermal energy in shallow aquifers. These outcomes could potentially lead to a number of practical applications, such as the monitoring or the design of shallow geothermal systems.
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Ju, Qiding, Youbiao Hu, Kai Chen i Qimeng Liu. "Hydrogeochemical Processes and Connection of Multi-Layer Groundwater System in Sunan Mining Area, Eastern China". International Journal of Environmental Research and Public Health 19, nr 19 (29.09.2022): 12392. http://dx.doi.org/10.3390/ijerph191912392.
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Groundwater is an important freshwater resource in the world and serves as the main source of water for mining areas in Northern China. Coal mining may cause changes in water quality. As such, to identify ways to prevent water contamination, this study investigates the hydrogeochemical processes and transport paths of a complex aquifer system in the Sunan mining area in Northern China. Using the APFS-MLR model, a geographic information system (GIS) spatial analysis, and a hydrochemical correlation analysis method, this study identifies the potential mineral phases in groundwater, the spatial distribution of mineral reactions, and the contribution rate of these reactions to hydrochemical variables. Inverse modeling is used to verify hydrogeochemical process. The study reveals the relationship between multiple aquifers and four hydrological transport paths. Here, Path 1 and Path 2 show that the Quaternary aquifer, Carboniferous aquifer, and Ordovician aquifer are recharging the Permian aquifer through mineral dissolution and precipitation, cation exchange, and sulfate reduction. On the other hand, Path 3 and Path 4 show that tthe connections of Carboniferous and Ordovician limestone aquifers are dominated by the dissolution and precipitation of minerals and cation exchange, and that they are mainly recharged by the Quaternary aquifer. In the future, the water level of the Permian aquifer may rise somewhat after mining ends, and the mixing of water from the Permian aquifer, Quaternary aquifer, Carboniferous aquifer, and Ordovician aquifer could cause cross-pollution. In addition, sewage produced by human activities may recharge the deep water through the shallow water, polluting the deep karst water. As such, measures should be taken to reduce the hydraulic connection between Permian mine water and karst aquifers. The results of this study may benefit water quality predictions and treatment approaches in other complex multi-layer aquifer areas in the world.
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Willems, Cees J. L., Andrea Vondrak, Dirk K. Munsterman, Marinus E. Donselaar i Harmen F. Mijnlieff. "Regional geothermal aquifer architecture of the fluvial Lower Cretaceous Nieuwerkerk Formation – a palynological analysis". Netherlands Journal of Geosciences 96, nr 4 (grudzień 2017): 319–30. http://dx.doi.org/10.1017/njg.2017.23.
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AbstractThe primary challenge for efficient geothermal doublet design and deployment is the adequate prediction of the size, shape, lateral extent and thickness (or aquifer architecture) of aquifers. In the West Netherlands Basin, fluvial Lower Cretaceous sandstone-rich successions form the main aquifers for geothermal heat exploitation. Large variations in the thickness of these successions are recognised in currently active doublet systems that cannot be explained. This creates an uncertainty in aquifer thickness prediction, which increases the uncertainty in doublet lifetime prediction as it has an impact on net aquifer volume. The goal of this study was to improve our understanding of the thickness variations and regional aquifer architecture of the Nieuwerkerk Formation geothermal aquifers. For this purpose, new palynological data were evaluated to correlate aquifers in currently active doublet systems based on their chronostratigraphic position and regional Maximum Flooding Surfaces. Based on the palynological cuttings analysis, the fluvial interval of the Nieuwerkerk Formation was subdivided into two successions: a Late Ryazanian to Early Valanginian succession and a Valanginian succession. Within these successions trends were identified in sandstone content. In combination with seismic interpretation, maps were constructed that predict aquifer thickness and their lateral extent in the basin. The study emphasises the value of palynological analyses to reduce the uncertainty of fluvial hot sedimentary aquifer exploitation.
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Mazi, K., A. D. Koussis i G. Destouni. "Intensively exploited Mediterranean aquifers: resilience and proximity to critical points of seawater intrusion". Hydrology and Earth System Sciences Discussions 10, nr 11 (14.11.2013): 13817–54. http://dx.doi.org/10.5194/hessd-10-13817-2013.
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Abstract. We investigate here seawater intrusion in three prominent Mediterranean aquifers that are subject to intensive exploitation and modified hydrologic regimes by human activities: the Nile Delta Aquifer, the Israel Coastal Aquifer and the Cyprus Akrotiri Aquifer. Using a generalized analytical sharp-interface model, we review the salinization history and current status of these aquifers, and quantify their resilience/vulnerability to current and future sea intrusion forcings. We identify two different critical limits of sea intrusion under groundwater exploitation and/or climatic stress: a limit of well intrusion, at which intruded seawater reaches key locations of groundwater pumping, and a tipping point of complete sea intrusion upto the prevailing groundwater divide of a coastal aquifer. Either limit can be reached, and ultimately crossed, under intensive aquifer exploitation and/or climate-driven change. We show that sea intrusion vulnerability for different aquifer cases can be directly compared in terms of normalized intrusion performance curves. The site-specific assessments show that the advance of seawater currently seriously threatens the Nile Delta Aquifer and the Israel Coastal Aquifer. The Cyprus Akrotiri Aquifer is currently somewhat less threatened by increased seawater intrusion.
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Wumu, Rizky Hizrah, Ahmad Zainuri i Noviar Akase. "Karakteristik Akuifer Menggunakan Metode Geolistrik Resistivity Di Kecamatan Kota Tengah Kota Gorontalo". Jambura Geoscience Review 4, nr 1 (24.01.2022): 60–68. http://dx.doi.org/10.34312/jgeosrev.v4i1.12752.
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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.
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Babagana, Saleh Mustapha, i Satendra Sharma. "GEOPHYSICAL CHARACTERIZATION OF AQUIFER SYSTEMS USING VERTICAL ELECTRICAL SOUNDING METHOD IN DEMSA, NORTHEAST NIGERIA". International Journal of Research -GRANTHAALAYAH 8, nr 11 (4.12.2020): 175–84. http://dx.doi.org/10.29121/granthaalayah.v8.i11.2020.2379.
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Electrical resistivity method using vertical electrical sounding (VES) technique and Schlumberger array was employed with the aim of delineating limits and types of aquifer system(s), and stratigraphic composition of the Demsa area, a confluence of Benue River in Northeast Nigeria. The result revealed that the hydrogeology of the area may be controlled by fractures (secondary porosity) developed in sedimentary units. Two aquifers, namely the upper alluvial aquifer and the confined deeper aquifer systems exist in the study area. The two aquifers occur at depths of 20.5 – 41 m, and 43.8 – 78.9 m respectively, and are separated by a thin layer of poorly permeable clays and silts, ranged between 1.1 – 5.3 m in thickness. The lateral extent of the aquifer systems extend almost evenly across the area. The aquifers’ thickness tends to decrease with increase in distance of VES station from the Benue River which suggested that the aquifer systems are probably recharged by direct escapement of the Benue River.
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Mazi, K., A. D. Koussis i G. Destouni. "Intensively exploited Mediterranean aquifers: resilience to seawater intrusion and proximity to critical thresholds". Hydrology and Earth System Sciences 18, nr 5 (8.05.2014): 1663–77. http://dx.doi.org/10.5194/hess-18-1663-2014.
Pełny tekst źródłaStreszczenie:
Abstract. We investigate seawater intrusion in three prominent Mediterranean aquifers that are subject to intensive exploitation and modified hydrologic regimes by human activities: the Nile Delta, Israel Coastal and Cyprus Akrotiri aquifers. Using a generalized analytical sharp interface model, we review the salinization history and current status of these aquifers, and quantify their resilience/vulnerability to current and future seawater intrusion forcings. We identify two different critical limits of seawater intrusion under groundwater exploitation and/or climatic stress: a limit of well intrusion, at which intruded seawater reaches key locations of groundwater pumping, and a tipping point of complete seawater intrusion up to the prevailing groundwater divide of a coastal aquifer. Either limit can be reached, and ultimately crossed, under intensive aquifer exploitation and/or climate-driven change. We show that seawater intrusion vulnerability for different aquifer cases can be directly compared in terms of normalized intrusion performance curves. The site-specific assessments show that (a) the intruding seawater currently seriously threatens the Nile Delta aquifer, (b) in the Israel Coastal aquifer the sharp interface toe approaches the well location and (c) the Cyprus Akrotiri aquifer is currently somewhat less threatened by increased seawater intrusion.
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SA, Sonloye. "Formulation of Generalized Hillslope Leakage-Dependent Model for Groundwater Flow in N-Aquifer System within a Sedimentary Basin". Arid-zone Journal of Basic and Applied Research 4, nr 1 (8.04.2024): 1–16. http://dx.doi.org/10.55639/607.494847.
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In this study, the recently derived Hillslope Leakage-dependent (HL-D) models for groundwater flow in leaky three-aquifer system have been generalized to obtain Generalized Hillslope Leakage-dependent, GHL-D equation that model groundwater flow in leaky n-aquifer system. This generalization extends the capability of Hillslope Leakage-dependent (HL-D) equations to modeling groundwater flow in any number of aquifers (n-aquifer system) of all configurations within a sedimentary basin. The formulated GHL-D Model was tested on some aquifer types and the results have shown that it can be used to obtain groundwater flow models for both hillslope (sloping) and horizontal single aquifer (unconfined and confined) as well as for multi-aquifer system containing any number of aquifers within a sedimentary basin. This unique feature of GHL-D equation to model most aquifers types and configurations makes it a more elegant groundwater flow modeling tool with potentials for wider applications than most of the existing groundwater flow models. The GHL-D Model, when use for simulations of groundwater flow in single or multi-aquifer system, will have the capability of giving better understanding of the groundwater flow dynamics in such systems. This is important because most of the sedimentary basins of the world are multi-aquifer in nature and accurate knowledge of groundwater flow within them is important to geoscientists in determining long time yield and water sustainability in such geological structures
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Sindico, Francesco. "The Guarani Aquifer System and the International Law of Transboundary Aquifers". International Community Law Review 13, nr 3 (2011): 255–72. http://dx.doi.org/10.1163/187197311x585338.
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AbstractArgentina, Brazil, Paraguay and Uruguay signed the Guarani Aquifer Agreement on 2 August 2010. This is the first international treaty regarding the management of a specific transboundary aquifer to have been adopted after the UN International Law Commission (UNILC) adopted the Draft Articles on the Law of Transboundary Aquifers, which have been annexed to UN General Assembly Resolution 63/124. The latter encourages States to take into account the Draft Articles when devising arrangements for the management of specific transboundary aquifers. The Guarani Aquifer Agreement, therefore, is a first response to this call from the international community. In this article the background to the Guarani Aquifer Agreement is explored, including an overview of the key characteristics of the Guarani Aquifer System and the steps that have led to the adoption of the Guarani Aquifer Agreement. Sovereignty, the obligation to cooperate and the incipient institutional framework are discussed as key elements arising from the Guarani Aquifer Agreement. Finally, the article argues that a link between the latter and the UNILC Draft Articles can be appreciated. This link has important practical implications especially in relation to the applicability of the UNILC Draft Articles for interpretation purposes of the Guarani Aquifer Agreement.
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Afazal Jamali, Muhammad, Muhammad Hassan Agheem, Akhtar Hussain Markhand, Shahid Ali Shaikh, Asfand Yar Wali Arain, Mujeeb ur Rehman Khashkheli, Ali Ghulam Sahito, Kashif Ahmed Memon i Waqar Ullah Hassan Mujtaba. "Exploration of Shallow Geothermal Energy Aquifers by Using Electrical Resistivity Survey in Laki Range Jamshoro district Sindh, Pakistan". International Journal of Economic and Environmental Geology 12, nr 1 (13.02.2024): 46–52. http://dx.doi.org/10.46660/ijeeg.v12i1.146.
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Geothermal water is increasingly used around the world for its exploitation. Bulk electrical resistivitydifferences can bring significant information on variation of subsurface geothermal aquifer characteristics. Theelectrical resistivity survey was carried out in Laki range in lower Indus basin in the study area to explore thesubsurface geothermal aquifers. The Schlumberger electrode configuration with range from 2 m to 220 m depth wasapplied. Three prominent locations of hot springs were selected including Laki Shah Saddar, Lalbagh and Kai hotspring near Sehwan city. After processing resistivity image data, two hot water geothermal aquifers were delineated atLaki Shah Sadder hot springs. The depth of first aquifer was 56 m and its thickness 38 m in the limestones. The depthof second aquifer of 190 m and with thickness of 96 m hosted in limestone. In Lalbagh hot springs two geothermalaquifers were delineated on the basis of apparent resistivity contrast, the depth of first aquifer zone in sandstone was insandstone 15 m and thickness 12 m, while the depth of second aquifer was 61m and thickness was 35m. In Kai hotsprings two hot water geothermal aquifers were delineated. The depth of first geothermal aquifer was 21m andthickness was 18 m and the depth of second aquifer was 105 m and thickness was 61m present in sandstone lithology.Present work demonstrates the capability of electrical resistivity images to study the potential of geothermal energy inshallow aquifers. These outcomes could potentially lead to a number of practical applications, such as the monitoring orthe design of shallow geothermal systems.
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Setyaningsih, D. L., K. D. Setyawan, D. P. E. Putra i Salahuddin. "Hydrogeological Conceptual Model in the Middle of Randublatung Groundwater Basin". IOP Conference Series: Earth and Environmental Science 926, nr 1 (1.11.2021): 012078. http://dx.doi.org/10.1088/1755-1315/926/1/012078.
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Abstract Randublatung groundwater basin is one of the groundwaters basins with massive utilization of groundwater pumping. However, the knowledge of the comprehensive hydrogeological system in this groundwater basin is limited, so this research aims to determine a comprehensive hydrogeological conceptual model of the Randublatung groundwater basin. The methodology was conducted by collecting secondary and primary data of deep and shallow wells to evaluate boundaries of pattern and direction of groundwater flow and develop the aquifer system’s geometry. The result shows that the groundwater flow boundaries are Grogol River in the west, Wado River in the East, Bengawan Solo river in the South as a river boundary, and Rembang Mountains in the North as a constant head boundary. Therefore, groundwater flows from the hills area to the Bengawan Solo River and the north as the river’s flow. Based on the log bor evaluation, the aquifer system of the study area consist of an unconfined aquifer with a maximum thickness of 20 m and three layers of confined aquifers with thickness vary between 8 to 60 m. the hydraulic conductivity of the aquifers depends on the aquifer’s lithology range from sand, gravel, limestone, and sandstone. This hydrogeological conceptual model provides essential information for numerical groundwater models in the middle of the Randublatung groundwater basin.
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Sehah, Sehah, Hartono Hartono, Zaroh Irayani i Urip Nurwijayanto Prabowo. "Designing Aquifer Model for the Banks of the Serayu River, Sokawera, Somagede, Banyumas, Indonesia by Means of 1D-Electrical Resistivity Data". Journal of Mathematical and Fundamental Sciences 53, nr 3 (3.12.2021): 344–57. http://dx.doi.org/10.5614/j.math.fund.sci.2021.53.3.1.
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A geoelectric survey using the 1D-electrical resistivity method was applied to design a groundwater aquifer model for the banks of the Serayu River in Sokawera Village, Somagede District, Banyumas Regency, Indonesia. The aim of this research was to identify the characteristics of aquifers in the research area based on resistivity log data. Acquisition, modeling, and interpretation of resistivity data were carried out and the results were lithological logs at seven sounding points. Correlation between the lithological logs resulted in a hydrostratigraphic model. This model is composed of several hydrological units, i.e. shallow aquifer, aquitard, and deep aquifer. The shallow aquifers are composed of sandy clay (10.81-18.21 Wm) and clayey sand (3.04-7.43 Wm) with a depth of groundwater from the water table to 27.51 m. The deep aquifers are composed of sandstone with variation of porosity (2.24-12.04 Wm) at a depth of more than 54.98 m. Based on this model, potential shallow aquifers were estimated to be at sounding points Sch-5, Sch-6, and Sch-7. This hydrostratigraphic model shows that the two types of aquifers are separated by an aquitard layer, allowing groundwater infiltration from the shallow aquifer to the deep aquifer and vice versa. Moreover, the Serayu riverbanks in this research area are estimated to be a groundwater discharge area.
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Zahid, Anwar, Farhana Islam, M. Rashidul Hassan, Kamrul Islam i Nur Ahmed. "Analysis of Aquifer Pumping Test Data to Determine Deep Groundwater Security in Southeastern Bangladesh". Journal of Natural Resources and Development 8 (1.12.2018): 125–43. http://dx.doi.org/10.5027/jnrd.v8i0.12.
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In southeastern Bangladesh, where water quality in the upper aquifers is a serious constraint, future development will likely be confined to deep fresh groundwater. Owing to the importance and pervasive use of deep groundwater, the sustainability of water use has received extensive attention. However, excessive extraction from deep aquifers may pose a threat to the storage as well as the quality of water due to the high susceptibility to salinization and arsenic contamination from upper aquifers. Hence, determining the extension of aquifer units and the characterizing aquifer sediments are very important to ensure sustainable development and management of limited fresh groundwater resources. The study area extends over six districts of the southeastern coastal region of Bangladesh. In order to assess and monitor deep fresh groundwater potential in the study area, aquifer pumping tests were performed at six locations with up to 72 h of constant-discharge prior to recovery. Different methods were used to analyze the drawdown and recovery data considering aquifers as confined or leaky-confined. Based on transmissivity values it was found that the studied deep aquifers have moderate to high potential for potable water supply. However, this deep fresh groundwater may not be safe for a longer period where upper aquifer units contain saline groundwater and where there is no significant aquitard encountered above or below the deep aquifer. Irrigation extraction of the deep groundwater is not recommended.
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De Paoli, Caroline, Thierry Duren, Estelle Petitclerc, Mathieu Agniel i Alain Dassargues. "Modelling Interactions between Three Aquifer Thermal Energy Storage (ATES) Systems in Brussels (Belgium)". Applied Sciences 13, nr 5 (24.02.2023): 2934. http://dx.doi.org/10.3390/app13052934.
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Shallow open-loop geothermal systems function by creating heat and cold reserves in an aquifer, via doublets of pumping and reinjection wells. Three adjacent buildings in the center of Brussels have adopted this type of aquifer thermal energy storage (ATES) system. Two of them exploit the same aquifer consisting of Cenozoic sands, and started operation in 2014 and 2017, respectively. A previous hydrogeological model developed by Bulté et al. (2021) has shown how the thermal imbalance of one of the systems jeopardizes the thermal state of this upper aquifer. Here, the interactions with a more recent third ATES system located in the deep aquifer of the Palaeozoic bedrock are studied and modelled. After being calibrated on groundwater flow conditions in both aquifers, a 3D hydrogeological model was used to simulate the cumulative effect of the three geothermal installations in the two exploited aquifers. The results of the simulations showed that although the hydraulic interactions between the two aquifers are very weak (as shown by the different observed potentiometric heads), heat exchanges occur between the two aquifers through the aquitard. Fortunately, these heat exchanges are not sufficient to have a significant impact on the efficiency of the individual geothermal systems. Additionally, this study shows clearly that adding a third system in the lower aquifer with a mean power of 286 kW for heating between October and March and an equivalent mean cooling power between April and September is efficient.
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Kronfeld, Joel, Israel Carmi i Dror Avisar. "The Yarkon-Taninim Aquifer (Judea Group Israel): What Radiocarbon Can Tell". Radiocarbon 61, nr 5 (20.06.2019): 1377–85. http://dx.doi.org/10.1017/rdc.2019.51.
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ABSTRACTRadiocarbon (14C) conclusively demonstrates that the very important Yarkon-Tanininm aquifer, named after the two springs where the drainage presumably occurs, is in actuality two distinct aquifers—Upper and Lower. The springs have higher 14C activities than the exploitation wells that surround them (all drilled into the Upper aquifer). The springs are situated at faults that allow the Lower aquifer water to rise due to its higher pieziometric head and drain along with the Upper aquifer. The Lower aquifer water flows rapidly along a path that includes a karstic system. The Upper aquifer flows more slowly, primarily through a system of cracks in the carbonate aquifer. The Upper aquifer groundwater in the Beer-Sheba extension flows northwards at approximately ~4–7 m/yr.
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Shirazi, Sharif Moniruzzaman, Md Ibrahim Adham, Noorul Hassan Zardari, Zubaidah Ismail, Hosen Md Imran i Munir Ahmed Mangrio. "Groundwater quality and hydrogeological characteristics of Malacca state in Malaysia". Journal of Water and Land Development 24, nr 1 (1.03.2015): 11–19. http://dx.doi.org/10.1515/jwld-2015-0002.
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Abstract Groundwater quality and aquifer productivity of Malacca catchment in Peninsular Malaysia are presented in this article. Pumping test data were collected from 210 shallow and 17 deep boreholes to get well inventory information. Data analysis confirmed that the aquifers consisting of schist, sand, limestone and volcanic rocks were the most productive aquifers for groundwater in Malacca state. GIS-based aquifer productivity map was generated based on bedrock and discharge capacity of the aquifers. Aquifer productivity map is classified into three classes, namely high, moderate and low based on discharge capacity. Groundwater potential of the study area is 35, 57 and 8% of low, moderate and high class respectively. Fifty two shallow and 14 deep aquifer groundwater samples were analyzed for water quality. In some cases, groundwater quality analysis indicated that the turbidity, total dissolved solids, iron, chloride and cadmium concentrations exceeded the limit of drinking water quality standards.
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Trieu, Duc Huy, Ngoc Thanh Tong, Van Lam Nguyen, Ba Quyen Pham, Dai Phuc Hoang i Hoai Thu Trinh. "Classification of hydrogeological structure along the Red River in the Hanoi area". Tạp chí Khoa học và Công nghệ Biển 21, nr 3 (30.09.2021): 299–310. http://dx.doi.org/10.15625/1859-3097/16431.
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Hanoi city has abundant groundwater, supplemented by the surface water (mainly Red River) all year round, and the extensive shallow aquifers, which are easily exploited by large-diameter wells. There always exists some open hydrogeological windows in the Red River area with an open structure; therefore, the groundwater has a strained hydraulic relationship with the Red River water system Along the Red River from Ba Vi to the end of Phu Xuyen district, there are nine regions with three types and four sub-types of different hydrogeological structures. In particular, the sub-type I-A of the groundwater has a tight hydraulic correlation with the Red River since the hydrogeological structure of the Red River bottom includes three aquifers: Holocene (qh), upper Pleistocene (qp2), and lower Pleistocene (qp1) that constructs a hydraulic system. The sub-type I-B is characterized by the hydrogeological structure at the Red River bottom, including the aquitard in Vinh Phuc and two aquifers qp2 and qp1, which form a hydraulic system. The sub-type II-A is distinguished by the fact that the Red River crosses the aquifer qh; there are no aquitards between the aquifer qh and qp2 to form a hydraulic system; the aquitard separates the aquifer qp1. The sub-type II-B is identified by the fact that the Red River crossing the aquifer qh; there is an aquitard between the aquifer qh and qp2; there are no aquitards between the aquifer qp2 and qp1 so that can create a hydraulic system. Type III has a solid existence of both aquifers and aquitards; thus, the hydraulic relationship between the Red River and the aquifers qp2 versus qp1 is inferior.
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Akanbi, Olanrewaju Akinfemiwa, i Moshood ‘Niyi Tijani. "Sustainability and Conceptual Groundwater Hydraulic Models of Basement Aquifers". Materials and Geoenvironment 66, nr 2 (1.06.2019): 87–98. http://dx.doi.org/10.2478/rmzmag-2019-0016.
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AbstractGroundwater flow of the basement terrains of the Ibarapa region was studied by carrying out pumping test and measurement of borehole inventory. The view was to identify the associated aquifer systems from the time-drawdown curves, quantify the estimable hydraulic properties and develop hypothetical models for the understanding of the groundwater flow in the area underlain by diverse crystalline bedrocks. Three aquifer types were identified namely, dual, leaky and regolith. The yield of groundwater in dual and leaky aquifers that dominated terrains underlain by amphibolite and gneisses was sustainable, but the discharge of regolith aquifers mainly associated with migmatite and granite terrains declined at late pumping stage. The transmissivities of the dual and leaky aquifers were between 2.02 and 11.65 m2/day, while those of regolith aquifers were mostly less than 1.00 m2/day. The average aquifer transmissivities in m2/day by bedrocks were: 6.85, 2.57, 0.76 and 1.72, correspondingly. The inter-relationships between transmissivities and groundwater discharge showed diverse aquifer representations, from sustainable high-yielding to unsustainable low-yielding types. Conscientious effort is, therefore, required for well construction in the area.
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Sun, Lin Hua. "Application of Rare Earth Elements for Water Source Discrimination in Renlou Coal Mine, Northern Anhui Province, China". Applied Mechanics and Materials 99-100 (wrzesień 2011): 1195–98. http://dx.doi.org/10.4028/www.scientific.net/amm.99-100.1195.
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Rare earth element (REEs) concentrations were measured for groundwater and wall rock samples from two aquifers (sandstone and limestone aquifers) in Renlou coal mine, northern Anhui Province, China. The results indicate that groundwater from these two aquifers are rich in REEs as expressed by their Nd concentrations (0.012 and 0.008 μg/L). They all show heavy REEs enrichment with low NdRN/YbRN ratios (0.35 and 0.40) when normalized to their aquifer rocks. Y- Ho fractionation are only observed for groundwater from limestone aquifer with high Y/Ho ratio (97 in average), whereas groundwater from sandstone aquifer have low Y/Ho ratios (24 in average). The former is considered to be related to the release of Y and Ho from calcite with different partition coefficient. The similarity of some REEs between groundwater and aquifer rock, as well as the different rock composition of aquifers, provide possibility for discrimination of water sources by using REEs, and Y/Ho ratios and Eu anomalies are expected to be useful in Renlou coal mine.
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Maghsoudi, Rahimeh, Saman Javadi, Mojtaba Shourian i Golmar Golmohammadi. "Determining the Optimal Aquifer Exploitation under Artificial Recharge using the Combination of Numerical Models and Particle Swarm Optimization". Hydrology 10, nr 5 (25.04.2023): 100. http://dx.doi.org/10.3390/hydrology10050100.
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Determining optimal exploitation from aquifers is always a major challenge, especially for aquifers facing a drop in their groundwater level. In aquifers with artificial recharge, more complex algorithms are required to determine the optimal exploitation amount. Therefore, in this study, the optimal amount of harvest from the exploitation wells has been determined using a combined simulation–optimization model considering the artificial recharge in Yasouj aquifer in Iran. The model is based on a combination of MODFLOW code and gene expression programming (GEP) simulator tool to simulate the aquifer and particle swarm optimization (PSO) to maximize the total exploitation from the aquifer. The simulation results showed that the artificial recharge was ineffective in maximum exploitation from the aquifer. As a result, considering several constraints, including the maximum pumping rate from the aquifer and the permissible drop in the groundwater level, the maximum exploitation from the aquifer was defined as the objective function. The optimization results showed that the optimal exploitation rate is equal to 8.84 million cubic meters (MCM) per year, and only 74% of the water from artificial recharge can be used based on this amount. Additionally, the most appropriate locations to exploit this amount of water are the northwest and east of the aquifer. According to the findings, it is suggested to ban exploitation from the central and southern parts of the aquifer due to the low groundwater level. The results of the sensitivity analysis show that the reduction in the maximum exploitation rate along with a 50% drop in the groundwater level play an effective role in decreasing the optimal exploitation amount.
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Lei, Jun Qin, Xiu Qing Zheng i Hong Fei Zang. "The Effect of Coal Mining on the Multi-Aquifer System". Advanced Materials Research 919-921 (kwiecień 2014): 1252–56. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.1252.
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Based on the analysis of the regional geological and hydrogeologic conditions of a coal mine in Xishan Coalfield, Shanxi Province in China, the groundwater aquifer system is generalized as a three layers structure in vertical direction and a three-dimensional unsteady flow model in confined aquifer is established. The regime of karst groundwater levels under the coal mining conditions for both Carboniferous and Ordovician limestone aquifers are predicted by using Visual Modflow. The results show that the groundwater levels of the two aquifers are all in decline as a result of coal mining. After 2373 days of mining, the maximum drawdown is 137m in Carboniferous limestone aquifer with the unwatering area in southeast, while the water level in Ordovician limestone aquifer dropped by 8.1m. The dropped rates of groundwater levels in the two aquifers trend to decrease with the coal mining. The results play an important role in the reasonable protection of water resources.
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Zhai, Wen, Wei Li, Yanli Huang, Shenyang Ouyang, Kun Ma, Junmeng Li, Huadong Gao i Peng Zhang. "A Case Study of the Water Abundance Evaluation of Roof Aquifer Based on the Development Height of Water-Conducting Fracture Zone". Energies 13, nr 16 (7.08.2020): 4095. http://dx.doi.org/10.3390/en13164095.
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In the eastern mining area of Ningxia, China, multi-layered sandstone aquifers are widely distributed in the underground. However, the water abundance of these aquifers is not clear, which brings great challenges to the prevention and control of mine water disaster. In this paper, five mining areas in eastern Ningxia were taken as the study area, and the distribution characteristics of aquifer and the mine water filling source were analyzed through the analysis of geological data and numerical simulation. Finally, the lithology influencing index (LII) was constructed, and the water abundance of the aquifer was evaluated. The results show that the sandstone aquifer III in the lower part of the Jurassic Zhiluo formation is the main water-source aquifer of the #2 coal seam in the study area, while the middle aquifer II and the upper aquifer I are indirect water-source aquifers; the areas with extremely strong and strong water abundance are Maiduoshan, Hongliu, the south of Shicaocun, southeast and southwest of Meihuajing, and the central and southern areas of Shuangma mining areas; when the depth of water drainage boreholes in the roof reaches the development height of the water-conducting fracture zone, the pre-drainage measures can effectively control the mining inrush water of the working face and ensure the safety production. This research is of great significance to the prevention and control of mine water disaster.
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Kovács, Attila. "Quantitative classification of carbonate aquifers based on hydrodynamic behaviour". Hydrogeology Journal 29, nr 1 (27.01.2021): 33–52. http://dx.doi.org/10.1007/s10040-020-02285-w.
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AbstractA quantitative classification of carbonate aquifers based on hydrodynamic behaviour is introduced. This type of classification is necessary to understand the physical functioning of carbonate hydrogeological systems and to provide a realistic interpretation of field data. Carbonate aquifers are generally considered as karst systems; however, geomorphology and aquifer geology alone are insufficient for determining hydrodynamic behaviour. Analysis of spring and well hydrographs based on analytical solutions is applied to establishing a quantitative classification. A base-flow recession coefficient is used as an indicator of hydrodynamic behaviour. Detailed numerical analyses suggest that carbonate systems can be classified into two distinct groups based on hydrodynamic behaviour. The physical processes depend on a combination of hydraulic and geometric parameters, and their functional relationships can be quantitatively determined. The proposed classification methodology involves making an assumption about aquifer type, estimating aquifer properties from hydrograph data, and comparing the results with field observations. The proposed classification methodology was applied to aquifers representing the two groups of carbonate systems. In both cases, the applied methods revealed crucial information about hydrodynamic functioning of the investigated systems. While the studied limestone aquifer showed karstic hydrodynamic behaviour, the investigation of a dolomite aquifer disproves a priori assumptions on karstic flow conditions. Dolomite aquifers represent an ambiguous group of carbonates and require caution in the selection of investigation tools and interpretation of hydrogeological data. The introduced methodology provides a reliable means of determining the hydrodynamic functioning of an aquifer and supports the quantitative classification of carbonate hydrogeological systems.
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Islam, Mazeda, Khairul Bashar, Nasir Ahmed, Md Golam Rasul, Sahadat Hossain i Md Mizanur Rahman Sarker. "Hydrogeologic Characteristics and Groundwater Potentiality of Lower Aquifer of Singair Upazila, Manikganj District, Bangladesh". Journal of Bangladesh Academy of Sciences 42, nr 1 (12.08.2018): 25–40. http://dx.doi.org/10.3329/jbas.v42i1.37830.
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The study area is located in the central part of Bangladesh. The aims of this study were to explain the hydrogeological characteristics of aquifers and evaluate the groundwater potentiality. The borehole logs revealed three types of zones: upper aquitard (low permeability clays, silty clays & silts), upper aquifer (very fine sand to fine sand) and lower aquifer (medium to coarse sands and gravels). Both aquifer waters are mainly Ca-Mg-HCO3 type. Except arsenic (As), most of the ions of both aquifer waters are within the limit of drinking standard of WHO (2004) and Bangladesh (DoE, 1997). Arsenic concentrations of upper aquifer exceed both the WHO (10 μg/l) and Bangladesh standard (50 μg/l) and for lower aquifer exceed only WHO standard. Waters of both aquifers in north western and central part of the study area show high arsenic concentration due to lack of continuous impermeable layer between them as revealed from borelog data. Water quality index map also indicates that north western and central part is not suitable for groundwater development because of inferior quality. The average δ18O values for upper and lower aquifer waters are isotopically enriched compared to river water (~10.08‰). Similar isotopic composition of upper (~4.77‰) and lower aquifer waters (~5.50‰) indicates both waters were mixed in the past and mixing may be continued in the future. The mixing may be preferentially from the upper aquifer to lower aquifer because of water abstraction, lack of impermeable layer and high permeability of the upper aquifer etc. Therefore, the potentiality of the lower aquifer may not be suitable for large-scale groundwater development project without any mitigation measure.Journal of Bangladesh Academy of Sciences, Vol. 42, No. 1, 25-40, 2018
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Zhang, Yi, i Dong Ming Guo. "Temperature Field of Doublet-Wells Aquifer Thermal Energy Storage in Sanhejian Coal Mine". Advanced Materials Research 430-432 (styczeń 2012): 746–49. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.746.
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Utilizating of tube-well irrigation, the technology of aquifer thermal energy storage (ATES) store rich cold energy in winter and cheap warm energy in summar into aquifers seasonally. In this paper, taking Sanhejian Coal Mine as an example, we discuss that with the same pumping and irrigation flow in doublet wells, distribution and change of temperature field in aquifers both at the end of energy storage and after the period of no pumping and no irrigation. The simulation results of aquifer temperature field show that 2~10°C water body of aquifers is decreasing in the period of no pumping and no irrigation, but it is only a small reduction with a stable trend. And after the period of no pumping and no irrigation, about 11°C water body of aquifers stores steadily in the aquifer, so the selected aquifers is suitable and its effect of energy storage is good.
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Anwar, Samsul, Sri Cahyo Wahyono i Fahruddin Fahruddin. "Identifikasi Lapisan Akuifer Tertekan Dengan Metode Geolistrik di Desa Lok Rawa Kecamatan Mandastana Kabupaten Barito Kuala Kalimantan Selatan". Jurnal Teori dan Aplikasi Fisika 8, nr 2 (31.07.2020): 151–58. http://dx.doi.org/10.23960/jtaf.v8i2.2447.
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One way to be able to identify rocks below the surface, depth, including groundwater aquifer layers is to do geophysical measurements using the schlumberger geoelectric method. This study aims to determine thickness and depth of aquifers in Lok Rawa Village, Mandastana District, Barito Kuala Regency. The results of the schlumberger configuration geoelectric study showed rock layers in Lok Rawa Village at the measurement points GL1, GL2 and GL3 consisting of weathered, sand, and fine clay (silt) layers. Lapiasan aquifers in Lok Rawa Village at the measurement points GL1, GL2 and GL3 consisting of free aquifer layers are estimated to occur at a depth of 3─5 m with a resistivity value of 7─15 Ωm. Depressed aquifer layer is estimated to be at a depth of 25─75 m and ≥ 110 m with resistivity values of 7─15 Ωm. Of the 2 types of aquifer layers, the most confined aquifer layer has the potential to contain ground water.
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Bhutia, Namgyal Tshewang, i Malavika Sinha. "Geo-physical attributes of Shushunia’s aquifer, Chhatna block, Bankura district, West Bengal, India". Landscape & Environment 17, nr 2 (30.12.2023): 1–11. http://dx.doi.org/10.21120/le/17/2/1.
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Shushunia hill lies in a transitional zone of the South Singbhum Mobile Craton and northern Gondwana formation. The Shushunia hill appears like a porcupine peak and it has structural similarity to the Eastern Ghat. The Shushunia hill zone is an example of a contact spring. In the foothill zone, two perennial springs are observed. The study purely deals with its aquifer and water quality. Based on the present rock strata and the nature of the contact aquifer, its early condition has been assumed. The discharge of the confined aquifers occurs by leakage. The water temperature depicts the springs are not of geothermal origin. Shushunia's aquifer is the shallow flow system water table and it is the subdued replica of surface topography. The comparatively high discharge rate during post-monsoon indicates the fractured conduit-water seepage towards the aquifer. Moreover, twin-contact aquifers do not yield water uniformly. The perennial aquifer may act as a municipal water supply source for drinking purposes in the future.
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Hafid, Feyrouz, Aziez Zeddouri, Hichem Zerrouki, Badreddine Saadali, Lassaad Ghrieb i Asma Sid. "Use of Hydro-chemical Tools to Improve Definitions of the North-Western Sahara Aquifer System, Case of Ouargla Groundwater, Algeria". Environmental Research, Engineering and Management 79, nr 1 (11.04.2023): 133–47. http://dx.doi.org/10.5755/j01.erem.79.1.33057.
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The North-Western Sahara Aquifer System (NWSAS) is a complex multi-layered aquifer system with extraordinary continental groundwater reserves. This largest aquifer in the world straddles three countries: Algeria, Libya, and Tunisia. It contains more than 50,000 billion cubic meters of water; of which, 70% is in Algerian territory in the southeast of the country. This water is the result of accumulation over 1 million years. In the Wadi Mya basin (Algeria), this system is characterized by two overlaid aquifer systems: the complex terminal (CT), a shallow aquifer housed in the Senonian-Eocene and Mio-Pliocene formations, and the continental intercalary (CI), a deep aquifer hosted in the Albian, Aptian and Barremian formations. The main purpose of this study is to carry out a correlation between the geochemical composition of the water and the facies of the aquifer formation. The adopted approach will allow deciphering the hydro-chemical relationships between the different levels of the two aquifer systems in the Wadi Mya basin. To acquire the chemical composition of water, the study method goes through a targeted sampling and physicochemical analysis of water followed by a statistical analysis as well as correlation and geochemical modelling: the interpretation of specific diagrams (Piper), correlations between chemical elements in binary graphs, and principal component analysis (PCA). The performed geochemical modelling by examining the saturation index and chemical balance of water helps to better understand the origin of mineralization, elucidate the mixing of waters originating from different aquifers, as well as highlight the relationship between deep and shallow aquifers in the Wadi Mya Basin hydrodynamic conversion. The obtained results indicate that the overall mineralization occurring within the study area is dominated by sodium chloride and calcium chloride-sulfate facies. This can be explained by the dissolution of halite, gypsum, and anhydrite evaporitic rocks, intercalated in the aquifer matrix besides the effects of the extended stay of fossil waters with low recharging and cation exchange reactions resulting from water-rock interactions. The interference recorded between the geochemical signatures of the two aquifers favors the hypothesis of interconnection between aquifers through fractures. Through the implementation of such academic research, this invaluable source of life will stay sustainable for future generations.
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Benaafi, Mohammed, i Abdulaziz Al-Shaibani. "Hydrochemical and Isotopic Investigation of the Groundwater from Wajid Aquifer in Wadi Al-Dawasir, Southern Saudi Arabia". Water 13, nr 13 (3.07.2021): 1855. http://dx.doi.org/10.3390/w13131855.
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The Wajid aquifer is considered the main source of water for drinking and irrigation in Wadi Al-Dawasir and Najran, the southern region of Saudi Arabia. This aquifer has been used since the 1960s, and due to the expansion in agricultural activities, the aquifer has been overexploited. The study aims to understand the origin, hydrochemical processes of the groundwater in the shallow unconfined, deep unconfined, and confined parts of the Wajid aquifer in the Wadi Al-Dawasir area. In-situ hydrochemical parameters (pH, temperature, EC, and TDS) were measured in the field, and groundwater samples were collected for major ions and stable isotopes (2H and 18O) measurements in the laboratory. The results show that the groundwater in shallow unconfined, and confined aquifers are of two types; Cl.SO4-Ca. Na and Cl.SO4-Na. Ca; however, groundwater in deep, unconfined aquifers is characterized as HCO3-Ca. Na, and Cl. HCO3-Ca. Na; types of groundwater. The isotopic analysis results reveal that all groundwater samples have values of δ18Oand δ2Hclose to the local and global meteoric water lines, indicating the meteoric origin of Wajid groundwater. Three major hydrochemical processes, including rock weathering, ion exchange, and evaporation, have been identified as key controls on the chemical composition of water in the studied aquifer. The evaporation and ion exchange processes have more influence on the chemical composition of groundwater in the shallow unconfined and confined aquifers. On the contrary, weathering of carbonate minerals affected more the chemistry of groundwater in a deep unconfined aquifer. The unconfined section of the Wajid aquifer shows a reverse pattern of salinity with higher salinity in the recharge area, which is most probably related to the return irrigation water and leaching of salty soil. The open fractures in the upper part of Wajid sandstone most likely act as conduits to percolated saline water to the Wajid aquifer.
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Han, Tao, Yong Xue, Weikui Lv, Yu Zhang i Tingting Luo. "Prediction and Analysis of Vertical Additional Force of Shaft Wall in Topsoil Containing Multiple Aquifers during Drainage". Sustainability 15, nr 4 (5.02.2023): 2877. http://dx.doi.org/10.3390/su15042877.
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Studying the additional force in topsoil containing multiple aquifers can have a significant impact on predicting shaft wall fracture and guaranteeing shaft safety, as the aquifer number increases as drainage occurs. In this study, a numerical model calculating the effect of drainage on additional force in topsoil, containing multiple aquifers, was established on the basis of several practical engineering cases. The changes in the stress displacement of the shaft wall was analyzed during three different stages of shaft construction using typical parameters, and the effects of the various factors on the additional force variation under different water level gap conditions, depending on whether the drainage was synchronized or unsynchronized, were studied. The results indicate that the increment in the additional force, with an increasing water level gap in the central aquifer, is obviously larger than that in the bottom aquifer, and the difference in the maximum additional force between these two aquifers is approximately 0.6 MPa. The increasing number of central aquifers results in a higher increment in this force, which reaches 12 MPa with an increasing number of central aquifers. Meanwhile, a threshold value (about 0.6~0.7 H) exists for the depth of a central aquifer in terms of its effect on the additional force.
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Cerar, Sonja, i Janko Urbanc. "Carbonate Chemistry and Isotope Characteristics of Groundwater of Ljubljansko Polje and Ljubljansko Barje Aquifers in Slovenia". Scientific World Journal 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/948394.
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Ljubljansko polje and Ljubljansko Barje aquifers are the main groundwater resources for the needs of Ljubljana, the capital of Slovenia. Carbonate chemistry and isotope analysis of the groundwater were performed to acquire new hydrogeological data, which should serve as a base for improvement of hydrogeological conceptual models of both aquifers. A total of 138 groundwater samples were collected at 69 sampling locations from both aquifers. Major carbonate ions and the stable isotope of oxygen were used to identify differences in the recharging areas of aquifers. Four groups of groundwater were identified: (1) Ljubljansko polje aquifer, with higher Ca2+values, as limestone predominates in its recharge area, (2) northern part of Ljubljansko Barje aquifer, with prevailing dolomite in its recharge area, (3) central part of Ljubljansko Barje aquifer, which lies below surface cover of impermeable clay and is poor in carbonate, and (4) Brest and Iški vršaj aquifer in the southern part of Ljubljansko Barje with higher Mg2+in groundwater and dolomite prevailing in its recharge area. The radioactive isotope tritium was also used to estimate the age of groundwater. Sampled groundwater is recent with tritium activity between 4 and 8 TU and residence time of up to 10 years.
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Zuurbier, Koen Gerardus, i Pieter Jan Stuyfzand. "Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery in a coastal subsurface". Hydrology and Earth System Sciences 21, nr 2 (27.02.2017): 1173–88. http://dx.doi.org/10.5194/hess-21-1173-2017.
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Abstract. Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater recovery efficiency (RE) during aquifer storage and recovery (ASR) in coastal aquifers. ASR was applied in a shallow saltwater aquifer overlying a deeper, confined saltwater aquifer, which was targeted for seasonal aquifer thermal energy storage (ATES). Although both aquifers were considered properly separated (i.e., a continuous clay layer prevented rapid groundwater flow between both aquifers), intrusion of deeper saltwater into the shallower aquifer quickly terminated the freshwater recovery. The presumable pathway was a nearby ATES borehole. This finding was supported by field measurements, hydrochemical analyses, and variable-density solute transport modeling (SEAWAT version 4; Langevin et al., 2007). The potentially rapid short-circuiting during storage and recovery can reduce the RE of ASR to null. When limited mixing with ambient groundwater is allowed, a linear RE decrease by short-circuiting with increasing distance from the ASR well within the radius of the injected ASR bubble was observed. Interception of deep short-circuiting water can mitigate the observed RE decrease, although complete compensation of the RE decrease will generally be unattainable. Brackish water upconing from the underlying aquitard towards the shallow recovery wells of the ASR system with multiple partially penetrating wells (MPPW-ASR) was observed. This leakage may lead to a lower recovery efficiency than based on current ASR performance estimations.
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Neupane, Sharmila, Ananta Prasad Gajurel, Nir Shakya, Maartin Lupker i Rabina Hada. "Assessment on connection between shallow and deep aquifers using isotope analysis of surface water and groundwater in Sunsari and Morang Districts". Journal of Nepal Geological Society 59 (25.07.2019): 73–78. http://dx.doi.org/10.3126/jngs.v59i0.24991.
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The Sunsari and the Morang Districts confine the eastern region of the Koshi River and are considered as a huge potential of groundwater zones. The study mainly focuses on the concept of delineation of recharge source of groundwater and connection between aquifer system through isotopic analysis. Altogether 33 samples are collected from surface and groundwater for the isotopic analysis. Majority of the samples of flowing artesian wells are encountered under the range of -7.03‰ to -6.53‰. The shallow aquifers fall under the range of -5.94‰. to -5.34‰ and deep aquifers fall over a wide range of -7.13 ‰. to -6.53‰ for δ18O. Clustering of samples from isotopic analysis gives idea of surface water and groundwater interconnection along with the recharge source identification. Isotopic variation of majority of samples ranges from -7.34‰ to -4.74‰ while depleted value for δ18O is -10.16‰ in shallow aquifer of Jamungachhi, which indicates that the recharge source is precipitation at higher elevation. The d excess (greater than 10‰) concluded that the aquifer system in the study area is complex and recharged from various sources. The range of enrichment is measured as 2.6‰< 1.96‰<1.87‰<1.55‰ for shallow aquifers, rivers, deep aquifers and flowing artesian well. The significant increase in coarse particle towards the northern part reveals the good aquifer sequence in the northern zone and proves the best recharge area. The overall aquifer system in the study area is complex and recharged from various sources. Most of the aquifers are recharged from the river sand precipitation at higher altitude.
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Vargas-García, María del Carmen, Fernando Sola i Ángela Vallejos. "Comparative Study of Microbial Diversity in Different Coastal Aquifers: Determining Factors". Water 15, nr 7 (28.03.2023): 1337. http://dx.doi.org/10.3390/w15071337.
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Coastal aquifers have been extensively studied from the hydrodynamic and geochemical points of view, but there is still a significant gap in the knowledge of their microbial diversity. The bacterial communities of four coastal aquifers at different depths and salinities were studied in order to infer the anthropogenic and physico-chemical influences on groundwater microbiota. At the physico-chemical level, samples from different aquifers, but with similar salinities, are more similar than those taken within the same aquifer. The microbial community at the phylum level shows the dominance of Proteobacteria, Firmicutes, and Actinobacteria. Samples from the same aquifer, although having very different salinities, are more similar than samples with similar physico-chemical characteristics. Therefore, the taxa present in these media are resilient to environmental variations. The aquifer preserving the most pristine conditions harbors the lowest values of biodiversity, compared to those affected by anthropic activities. The incorporation of pollutants into the aquifer favors the development of a so-called “rare biosphere”, consisting of a high number of taxa which represent a low percentage (<1%) of the total microbial community. The analysis of microbial biodiversity in a coastal aquifer could be used as an indicator of the degree of anthropic alteration.