Articles de revues : « Groundwater circulation »

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Olichwer, Tomasz, Robert Tarka et Magdalena Modelska. « Chemical composition of groundwaters in the Hornsund region, southern Spitsbergen ». Hydrology Research 44, n^o 1 (11 juillet 2012) : 117–30. http://dx.doi.org/10.2166/nh.2012.075.

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Chemical composition of groundwaters was investigated in the region of the Hornsund fjord (southern Spitsbergen). The investigations were conducted during polar expeditions organized by the University of Wroclaw in two summer seasons of 2003 and 2006. Three zones of groundwater circulation: suprapermafrost, intrapermafrost and subpermafrost, were identified in areas of perennial permafrost in the region of Hornsund. The zone of shallow circulation occurs in non-glaciated (suprapermafrost) and subglacial areas. In this zone, the chemical composition of groundwater originates from initial chemical composition of precipitation, mineralogical composition of bedrock, oxidation of sulphides and dissolution of carbonates. The intermediate system of circulation is connected with water flow inside and below perennial permafrost (intrapermafrost and subpermafrost). In this zone, the chemical composition of groundwater is mainly controlled by dissolution of carbonates, ion exchange processes involving Ca2+ substitution by Na+, and oxidation of sulphides under oxygen-depleted conditions. The subpermafrost zone (deep groundwater circulation) occurs in deep-tectonic fractures, which are likely conduits for the descent of shallow groundwater to deeper depths. In this zone, the groundwater shows lower mineralization comparing to intrapermafrost zone and has a multi-ion nature Cl–HCO3–Na-Ca–Mg.

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Long, Xiting, Keneng Zhang, Ruiqiang Yuan, Liang Zhang et Zhenling Liu. « Hydrogeochemical and Isotopic Constraints on the Pattern of a Deep Circulation Groundwater Flow System ». Energies 12, n^o 3 (28 janvier 2019) : 404. http://dx.doi.org/10.3390/en12030404.

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Characterization of a deep circulation groundwater flow system is a big challenge, because the flow field and aqueous chemistry of deep circulation groundwater is significantly influenced by the geothermal reservoir. In this field study, we employed a geochemical approach to recognize a deep circulation groundwater pattern by combined the geochemistry analysis with isotopic measurements. The water samples were collected from the outlet of the Reshui River Basin which has a hot spring with a temperature of 88 °C. Experimental results reveal a fault-controlled deep circulation geothermal groundwater flow system. The weathering crust of the granitic mountains on the south of the basin collects precipitation infiltration, which is the recharge area of the deep circulation groundwater system. Water infiltrates from the land surface to a depth of about 3.8–4.3 km where the groundwater is heated up to around 170 °C in the geothermal reservoir. A regional active normal fault acts as a pathway of groundwater. The geothermal groundwater is then obstructed by a thrust fault and recharged by the hot spring, which is forced by the water pressure of convection derived from the 800 m altitude difference between the recharge and the discharge areas. Some part of groundwater flow within a geothermal reservoir is mixed with cold shallow groundwater. The isotopic fraction is positively correlated with the seasonal water table depth of shallow groundwater. Basic mineral dissolutions at thermoneutral conditions, hydrolysis with the aid of carbonic acid produced by the reaction of carbon dioxide with the water, and hydrothermal alteration in the geothermal reservoir add some extra chemical components into the geothermal water. The alkaline deep circulation groundwater is chemically featured by high contents of sodium, sulfate, chloride, fluorine, silicate, and some trace elements, such as lithium, strontium, cesium, and rubidium. Our results suggest that groundwater deep circulation convection exists in mountain regions where water-conducting fault and water-blocking fault combined properly. A significant elevation difference of topography is the other key.

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Elmore, Andrew Curtis, et Jason B. Hellman. « Model-Predicted Groundwater Circulation Well Performance ». Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management 5, n^o 4 (octobre 2001) : 203–10. http://dx.doi.org/10.1061/(asce)1090-025x(2001)5:4(203).

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Rybach, L. « Deep groundwater circulation in Hercynian basement ». Environmental Geology 32, n^o 2 (15 septembre 1997) : 137–41. http://dx.doi.org/10.1007/s002540050202.

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MATUSIAK, Magdalena, Stanisław DĄBROWSKI et Witold RYNARZEWSKI. « COMPARISON OF LOCAL AND REGIONAL GROUNDWATER FLOW MODELING APPROACHES OF THE MULTILAYER GROUNDWATER SYSTEM IN THE VICINITY OF THE LIS GROUNDWATER INTAKE ». Biuletyn Państwowego Instytutu Geologicznego 471 (1 octobre 2018) : 97–108. http://dx.doi.org/10.5604/01.3001.0012.5051.

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We analyzed 27 km2 of the Prosna valley aquifer near Kalisz. The region was previously a subject of four model-based studies of local and regional range. Furthermore, additional modelling researches were conducted that aimed at evaluation of Upper Jurassic aquifer exploitation, which seems to be a separate groundwater circulation system. The models used in the analyses differed in terms of grid size (100, 125, 250 and 500 m), groundwater circulation scheme (two-, three- or seven-layered), and the software used (Hydrylib or Modflow). The results of groundwater steady-state flow indicate the essential influence of the groundwater circulation scheme and the mesh size on groundwater flow balance. It also emphasizes the importance of deep aquifers in the detailed model-based study in the case of groundwater intakes located within the river valleys of regional drainage range.

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Dendys, Marta, Andrzej Szczepański et Barbara Tomaszewska. « Groundwater circulation in the Miechów Trough and the central part of the Carpathian Foredeep (Poland) : a hydrogeological conceptual model ». Geologos 24, n^o 3 (1 décembre 2018) : 177–87. http://dx.doi.org/10.2478/logos-2018-0019.

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Abstract The Miechów Trough and the central part of the Carpathian Foredeep in southern Poland have a highly complex geological structure and numerous fault zones. These features play a significant role in hydrogeological conditions of the area. In this area drinking water, medicinal groundwater or thermal groundwater occur, so recognition of their circulations is basic for reasonable groundwater management. In this note, a hydrogeological conceptual model, created for the purpose of regional scale mathematical modelling, is presented. This conceptual model illustrates the geology of the hydrogeological system modelled, as well as hydrogeological conditions and characteristics of groundwater circulation, as determined by tectonics. Typical of the research area is the wide diversity of geological and hydrogeological conditions. The Busko-Zdrój area, a region with a long history of exploitation of medicinal groundwater, presents the best example.

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He, Min, Juan Juan Jin et Peng Liu. « Application Research on Groundwater Circulation Exploration Based on Fluent Simulation ». Applied Mechanics and Materials 556-562 (mai 2014) : 940–44. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.940.

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It is very important to study the groundwater circulation and water chemistry evolution in the management and protection of water pollution. We use the Fluent simulation technology and the isotope tracer method to do simulation on the flow and distribution of groundwater. In the simulation process we set the model of Fluent isotope labeling group, and enter the groundwater flow parameters in the boundary condition, including water viscosity, osmotic pressure, and the average flow velocity. We use isotope tracer method to simulate the water flow. Finally, according to the law of groundwater flow, we predict the evolution rules of groundwater chemical by using the inverse geochemical simulation technology. It provides a theoretical basis for the management and protection of groundwater pollution.

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Zhao, Yuqing, You-Kuan Zhang, Yonglin Yang, Feifei Li et Sa Xiao. « Groundwater Circulation in the Xianshui River Fault Region : A Hydrogeochemical Study ». Water 12, n^o 12 (25 novembre 2020) : 3310. http://dx.doi.org/10.3390/w12123310.

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Water samples from rainfall, river, springs, and wells in the Xianshui River fault region near Xialatuo, China were collected during two sampling campaigns to investigate the complex groundwater circulation in the region. The major ions, stable isotopes, and four natural radium isotopes of the water samples were analyzed, and the results were utilized to identify different groundwater circulation depths. Most water samples excluding the one at a hot spring and the one at a borehole possess similar hydrochemical compositions and lower total dissolved solids (TDS), implying that their circulation depth is relatively shallow or that residence time is short. The sample at the hot spring has high TDS and high temperature as well as the high F concentration, inferring that it may circulate at a deeper depth. The sample at the borehole contains mixed hydrochemical characteristics of other samples. Three groundwater flow systems may exist in the study area: the shallow groundwater system recharged by precipitations and local groundwater flow, the deep groundwater system recharged by the regional groundwater flow, and the intermediate one between the above two systems. The finding of the three flow systems is supported by the δ2H and δ18O as well as the apparent radium ages of the samples. The δ2H and δ18O values at the intercept of the line formed by the shallow groundwater samples and the local meteoric water line (LMWL) are similar to those of modern precipitations. The δ2H and δ18O values at the intercept of the line formed by the deep groundwater samples and the LMWL show that it is probably recharged by relatively older precipitations. The 2H and 18O values of the borehole samples are between the above two intercept points. The deep-circulated groundwater with high temperature has longer apparent radium age than other water samples. The apparent radium ages of the shallow groundwater are similar but less than that of the deep groundwater. Groundwater at the borehole may circulate at a depth between the above two. The results of this study improve our understanding of the complex groundwater circulation and enable us to better protect and manage the groundwater resources in the region.

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Xia, Yubo, Haitao Li, Bing Wang, Zhen Ma, Xu Guo, Kai Zhao et Changrong Zhao. « Characterization of Shallow Groundwater Circulation Based on Chemical Kinetics : A Case Study of Xiong’an New Area, China ». Water 14, n^o 12 (11 juin 2022) : 1880. http://dx.doi.org/10.3390/w14121880.

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Xiong’an New Area, located in the middle of the North China Plain, will have been built as a “city of the future.” Urban planning and construction need to comprehensively consider the constraints of hydrogeological conditions such as aquifer structure and parameters. As the main aquifer in this area, the paleo-channel is heterogeneous and anisotropic, and the two-dimensional hydraulic conductivity in each horizontal direction cannot be obtained from aquifer tests. Therefore, this study adopts a chemical kinetics method to calculate the ionic activity and mineral saturation indices of shallow groundwater, determine the groundwater chemical potential field, and construct a horizontal two-dimensional groundwater chemical kinetics model. This model is used to calculate the hydraulic conductivity, flow rate and retention time of groundwater in areas of different chemical kinetics, as well as evaluate horizontal heterogeneity of the Quaternary paleo-channel aquifer. The results indicate that the groundwater chemical potential field can reflect the characteristics of the groundwater seepage field in each horizontal direction. The paleo-channel is the main channel of groundwater circulation, which shows the statistical difference of its permeability. Alluvial and lacustrine strata affect groundwater circulation due to their different hydrogeological structures and permeability. The groundwater chemical kinetics results of hydraulic conductivity along the paleo-channel are approximately consistent with traditional hydrogeological calculation results derived from aquifer test data. Hydraulic conductivity is higher in the extension direction of the paleo-channel, and lower if the path crosscuts multiple paleo-channels. This feature can be used to build a hydrogeological structure model combined with drilling data. Furthermore, excessive groundwater exploitation will change the actual flow rate and retention time of groundwater, thereby affecting the groundwater circulation conditions. This study of groundwater circulation in Xiong’an New Area by means of chemical kinetics makes up for the deficiency in the study of the unconsolidated sedimentary aquifer anisotropy within the paleo-channel.

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Dinkel, Eva, Burga Braun, Josephin Schröder, Moritz Muhrbeck, Winfried Reul, Alexander Meeder, Ulrich Szewzyk et Traugott Scheytt. « Groundwater circulation wells for geothermal use and their impact on groundwater quality ». Geothermics 86 (juillet 2020) : 101812. http://dx.doi.org/10.1016/j.geothermics.2020.101812.

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Johnson, Richard L., et Michelle A. Simon. « Evaluation of groundwater flow patterns around a dual-screened groundwater circulation well ». Journal of Contaminant Hydrology 93, n^o 1-4 (août 2007) : 188–202. http://dx.doi.org/10.1016/j.jconhyd.2007.02.003.

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Idrissi, Bouhsine El Fellah, Said Hinaje, Bouamama Cherai et Khalid Mehdi. « Rôle De La Fracturation Dans La Circulation Des Eaux Souterraines Et La Répartition Des Sources : Cas Du Bassin Hydrogéologique De Sefrou (Moyen Atlas Septentrional, Maroc) ». European Scientific Journal, ESJ 12, n^o 24 (30 août 2016) : 277. http://dx.doi.org/10.19044/esj.2016.v12n24p277.

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The formation of the basin of Sefrou is related to the normal successive movements of the faults N130, N80, N30 and N170 which follow one another since the upper Miocene until the recent medium-Quaternary. Seeing the dynamic of groundwater in the carbonated lands (Liasic dolomites) is primarily guided by the fractures and the cracks; we propose to study the influence of brittle tectonics on the spatial organization of the flows and the relation of the groundwater circulation with the fracturing. The analysis of the fracturing (affecting the Flavio-lake and travertines deposits of plio-quaternary age and their Miocene and Jurassic substratum) and the structural cuts as well as the correlation of the piezometric map established from the piezometric reports with that of the fracturing, allowed us to note that the fractures play a very important part in the geometry of the Liasic aquifer and the mode of the circulation of groundwater. This circulation is dependent on the zones of weaknesses along the faults and fractures. Water emergences are very variable and controlled by the paramount influence of the nature of the lithological formations and the tectonic structure on underground circulations. Indeed, the sources of water located in the basin of Sefrou are indexed, according to their origin, inside two types: sources of emergence and sources of discharge.

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Ta, Mingming, Xun Zhou, Yanqiu Xu, Yuan Wang, Juan Guo et Xinyun Wang. « Occurrence and flow systems of the anticline-controlled thermal groundwater near Chongqing in eastern Sichuan Basin of China ». Hydrology Research 51, n^o 4 (25 juin 2020) : 739–49. http://dx.doi.org/10.2166/nh.2020.169.

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Abstract A review and assessment of earlier studies shows that the thermal groundwater near Chongqing in the eastern Sichuan Basin of China has a unique occurrence called the ‘basin-anticline outcropping’ type. Its occurrence and emergence are strongly controlled by the nearly north–south trending anticlines. The basin-anticline outcropping type groundwater is similar to that of the basin type but also has the characteristics of the outcropping type because of the anticlines. The natural hot springs in the study area exist mainly in the outcropping areas of the carbonates, in the middle and the plunging ends of the anticlines where the topography was cut by rivers. They can also rise through the overlying sandstones and form up-flow springs. Geothermal wells tapping the carbonate reservoirs on the flanks of the anticlines also produce thermal groundwater. The groundwater flow can be divided into three levels: (1) shallow circulation system with groundwater of HCO3-Ca type and low TDS discharging through normal temperature springs, (2) middle circulation system with groundwater of SO4-Ca type and TDS of 2–3 g/L discharging through hot springs and (3) deep circulation system with groundwater of Cl-Na type and high TDS discharging through hot springs or wells.

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Przylibski, T. A. « Shallow circulation groundwater – the main type of water containing hazardous radon concentration ». Natural Hazards and Earth System Sciences 11, n^o 6 (15 juin 2011) : 1695–703. http://dx.doi.org/10.5194/nhess-11-1695-2011.

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Abstract. The main factors affecting the value of 222Rn activity concentration in groundwater are the emanation coefficient of reservoir rocks (Kem), the content of parent 226Ra in these rocks (q), changes in the volume and flow velocity as well as the mixing of various groundwater components in the circulation system. The highest values of 222Rn activity concentration are recorded in groundwaters flowing towards an intake through strongly cracked reservoir rocks undergoing weathering processes. Because of these facts, waters with hazardous radon concentration levels, i.e. containing more than 100 Bq dm−3 222Rn, could be characterised in the way that follows. They are classified as radon waters, high-radon waters and extreme-radon waters. They belong to shallow circulation systems (at less than a few dozen metres below ground level) and are contemporary infiltration waters, i.e. their underground flow time ranges from several fortnights to a few decades. Because of this, these are usually poorly mineralised waters (often below 0.2–0.5 g dm−3). Their resources are renewable, but also vulnerable to contamination. Waters of this type are usually drawn from private intakes, supplying water to one or at most a few households. Due to an increased risk of developing lung tumours, radon should be removed from such waters when still in the intake. To achieve this aim, appropriate legislation should be introduced in many countries.

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Li, Xiaojie, Jianwei Zhang et Zhuojing Yang. « Simulation of Migration Law of Organic Pollutants in Circulating Wells ». Advances in Civil Engineering 2022 (20 juillet 2022) : 1–12. http://dx.doi.org/10.1155/2022/7342604.

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Groundwater resources are one of the most important freshwater resources for human beings. The protection of groundwater resources is an important measure for human survival. Therefore, it is extremely important to discuss the treatment of pollutants in groundwater. The purpose of this paper is to simulate and analyze the migration law of organic pollutants using the experimental circulating well. In the analysis, this paper uses the gas-liquid-solid three-state model to simulate the pollutants for organic pollutants. It independently analyzes pollutants in different states. For the movement law, this paper not only simulates the vertical transition circulation well in the laboratory but also simulates the transport law of pollutants in the well. The experimental results show that in the laboratory environment, the simulated value of the circulation well designed in this paper is not far from the actual value, and the accuracy rate is more than 90%. And according to the movement law of organic pollutants, it is found that the variable flow rate and the dispersion, porosity, and thickness of the skin have a great influence on the migration of pollutants.

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Hernández-Antonio, A., J. Mahlknecht, C. Tamez-Meléndez, J. Ramos-Leal, A. Ramírez-Orozco, R. Parra, N. Ornelas-Soto et C. J. Eastoe. « Groundwater flow processes and mixing in active volcanic systems : the case of Guadalajara (Mexico) ». Hydrology and Earth System Sciences Discussions 12, n^o 2 (3 février 2015) : 1599–631. http://dx.doi.org/10.5194/hessd-12-1599-2015.

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Abstract. Groundwater chemistry and isotopic data from 40 production wells in the Atemajac and Toluquilla Valleys, located in and around the Guadalajara metropolitan area, were determined to develop a conceptual model of groundwater flow processes and mixing. Multivariate analysis including cluster analysis and principal component analysis were used to elucidate distribution patterns of constituents and factors controlling groundwater chemistry. Based on this analysis, groundwater was classified into four groups: cold groundwater, hydrothermal water, polluted groundwater and mixed groundwater. Cold groundwater is characterized by low temperature, salinity, and Cl and Na concentrations and is predominantly of Na-HCO3 type. It originates as recharge at Primavera caldera and is found predominantly in wells in the upper Atemajac Valley. Hydrothermal water is characterized by high salinity, temperature, Cl, Na, HCO3, and the presence of minor elements such as Li, Mn and F. It is a mixed HCO3 type found in wells from Toluquilla Valley and represents regional flow circulation through basaltic and andesitic rocks. Polluted groundwater is characterized by elevated nitrate and sulfate concentrations and is usually derived from urban water cycling and subordinately from agricultural practices. Mixed groundwaters between cold and hydrothermal components are predominantly found in the lower Atemajac Valley. Tritium method elucidated that practically all of the sampled groundwater contains at least a small fraction of modern water. The multivariate mixing model M3 indicates that the proportion of hydrothermal fluids in sampled well water is between 13 (local groundwater) and 87% (hydrothermal water), and the proportion of polluted water in wells ranges from 0 to 63%. This study may help local water authorities to identify and quantify groundwater contamination and act accordingly.

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Hernández-Antonio, A., J. Mahlknecht, C. Tamez-Meléndez, J. Ramos-Leal, A. Ramírez-Orozco, R. Parra, N. Ornelas-Soto et C. J. Eastoe. « Groundwater flow processes and mixing in active volcanic systems : the case of Guadalajara (Mexico) ». Hydrology and Earth System Sciences 19, n^o 9 (24 septembre 2015) : 3937–50. http://dx.doi.org/10.5194/hess-19-3937-2015.

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Abstract. Groundwater chemistry and isotopic data from 40 production wells in the Atemajac and Toluquilla valleys, located in and around the Guadalajara metropolitan area, were determined to develop a conceptual model of groundwater flow processes and mixing. Stable water isotopes (δ2H, δ18O) were used to trace hydrological processes and tritium (3H) to evaluate the relative contribution of modern water in samples. Multivariate analysis including cluster analysis and principal component analysis were used to elucidate distribution patterns of constituents and factors controlling groundwater chemistry. Based on this analysis, groundwater was classified into four groups: cold groundwater, hydrothermal groundwater, polluted groundwater and mixed groundwater. Cold groundwater is characterized by low temperature, salinity, and Cl and Na concentrations and is predominantly of Na-HCO3-type. It originates as recharge at "La Primavera" caldera and is found predominantly in wells in the upper Atemajac Valley. Hydrothermal groundwater is characterized by high salinity, temperature, Cl, Na and HCO3, and the presence of minor elements such as Li, Mn and F. It is a mixed-HCO3 type found in wells from Toluquilla Valley and represents regional flow circulation through basaltic and andesitic rocks. Polluted groundwater is characterized by elevated nitrate and sulfate concentrations and is usually derived from urban water cycling and subordinately from agricultural return flow. Mixed groundwaters between cold and hydrothermal components are predominantly found in the lower Atemajac Valley. Twenty-seven groundwater samples contain at least a small fraction of modern water. The application of a multivariate mixing model allowed the mixing proportions of hydrothermal fluids, polluted waters and cold groundwater in sampled water to be evaluated. This study will help local water authorities to identify and dimension groundwater contamination, and act accordingly. It may be broadly applicable to other active volcanic systems on Earth.

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Cangemi, Marianna, Maria Grazia Di Figlia, Rocco Favara et Marcello Liotta. « CO2 Degassing in Sicily (Central Mediterranean) as Inferred from Groundwater Composition ». Water 12, n^o 7 (10 juillet 2020) : 1959. http://dx.doi.org/10.3390/w12071959.

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The circulation of groundwater is influenced by several factors, including permeability changes due to the dynamics of the stress field acting along tectonic discontinuities. Open faults can act as preferential pathways for the escape of crustal and subcrustal gases, such as CO2, towards the surface, allowing their chemical interaction with meteoric fluids. Here, we present the first map of dissolved CO2 partial pressure in the groundwater of Sicily, Italy. Based on the chemical analysis of 557 samples of groundwater, which were collected in wells and springs, we calculated the related CO2 partial pressure (PCO2) using PHREEQC software. The spatial distribution of the calculated PCO2 values highlights a general homogeneity at the regional scale, interrupted by positive anomalies linked to the main seismogenic or volcanic areas. Faults work as preferential escape pathways for deep CO2. The subsequent CO2–water–rock interaction determines the chemical composition of circulating water. As a consequence, groundwater composition can be successfully used to identify anomalous degassing areas.

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R.A., T. Listyani, Nana Sulaksana, Boy Yoseph C.S.S.S.A. et Adjat Sudradjat. « Groundwater Flow Model In The Center Of West Progo Dome, Kaligesing, Purworejo, Central Java And Its Surrounding Area, Based On Hydrochemical And Isotopic Characteristics ». Bulletin of the Geological Society of Malaysia 71 (31 mai 2021) : 227–41. http://dx.doi.org/10.7186/bgsm71202118.

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Groundwater studies were carried out in the center of the West Progo Dome, at Kaligesing, Purworejo District, Central Java, and its surrounding area, with an emphasis on hydrochemical problems. As a water-scarce area, groundwater studies are urgently needed in this area. This research is intended as a hydrogeological study with the aim of knowing the conceptual groundwater flow model in the study area. The method used is a field hydrogeological survey as well as hydrochemical and natural isotope analysis supported by chemical and groundwater isotope data. Less clear hydrochemical evolution indicates that the process of groundwater flow is dominant in the local flow system. Groundwater facies is dominated by bicarbonate type, neutral pH, relatively low total dissolved solid (TDS), and electric conductivity (EC), and influenced by season or rainfall. The dominant hydrochemical processes in the groundwater system are leaching, ion exchange, sulfate reduction, and dilution. Groundwater facies is determined by the rock minerals marked by differences in hardness and TDS. Whereas, stable isotope contents of groundwater vary from light to heavy. Springs with light isotopes show the circulation of deep groundwater flow or from a relatively high recharge zone, either locally or from other places around it. Isotopic enrichment in all seasons can occur due to evaporation or mixing with surface water that has undergone previous evapotranspiration, indicated by increasing of heavy isotopes or δD-excess (d) of groundwater. There are two types of groundwater flow patterns, namely shallow and deep groundwater flow patterns. Shallow groundwater is characterized by heavy isotopes, shifted with relatively small d. Deep groundwater circulation pattern is characterized by a consistent, light δD value and appreciable d.

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Yuan, Haowei, Zhihui Qu, Chaoyu Zhang, Yutong Jiang et Ying Zhang. « Study on radius of influence of groundwater circulation well in the field experiment ». E3S Web of Conferences 352 (2022) : 01012. http://dx.doi.org/10.1051/e3sconf/202235201012.

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In recent years, groundwater circulation wells (GCW) have gradually become a research hotspot as an In-situ remediation technology. This technology reduces the construction of gas phase extraction wells and saves underground space compared to the traditional Air sparging (AS) remediation technology, the remediation process involves both volatile removal and microbial degradation. This study fully combines the background conditions of an organic contamination site and designs a positive circulation airflow lift circulation well. By analyzing the diffusion law of chloride tracer with aeration time and the changes of water level and water pressure of the monitoring well, it is known that the influence radius of the circulation well can be stabilized at 5.00 m when the aeration volume is 10 L/min. It not only has an essential demonstration significance for the development of groundwater circulation well remediation technology, but also provides reference process parameters for subsequent applications in type site remediation engineering applications.

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Liu, Chengjing, Yuanmei Jiao, Dongmei Zhao, Yinping Ding, Zhilin Liu et Qiue Xu. « Effects of Farming Activities on the Temporal and Spatial Changes of Hydrogen and Oxygen Isotopes Present in Groundwater in the Hani Rice Terraces, Southwest China ». Water 12, n^o 1 (17 janvier 2020) : 265. http://dx.doi.org/10.3390/w12010265.

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Landform changes caused by human activities can directly affect the recharge of groundwater, and are reflected in the temporal and spatial changes in groundwater stable isotope composition. These changes are particularly evident in high-intensity farming areas. In this study, we tested and analyzed groundwater stable isotope samples at different elevations of rice terraces in a typical agricultural watershed of the Hani Terraces, a World Heritage Cultural Landscape in southwest China. Thus, we determined the characteristic variations and factors that influence the temporal and spatial effects on groundwater stable isotopes in the Hani Terraces, which are under the influence of high-intensity farming activities. The elevation gradients of δ18O and δ2H in groundwater are significantly increased due to farming activities. The values were 0.88‰ (100 m)−1 and −4.5‰ (100 m)−1, respectively, and they changed with time. The groundwater circulation cycle is approximately three months. We also used the special temporal and spatial variation characteristics of the groundwater isotopes as a way to evaluate the source and periodic changes of groundwater recharge. In addition, high-intensity rice farming activities, such as ploughing every year from October to January can increase the supply of terraced water to groundwater, thus ensuring the sustainability of rice cultivation in the terraces during the dry season. This demonstrates the role of human wisdom in the sustainable and benign transformation of surface cover and the regulation of groundwater circulation.

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Serianz, Luka, Nina Rman et Mihael Brenčič. « Hydrogeochemical Characterization of a Warm Spring System in a Carbonate Mountain Range of the Eastern Julian Alps, Slovenia ». Water 12, n^o 5 (17 mai 2020) : 1427. http://dx.doi.org/10.3390/w12051427.

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The Alps represent an area where many deep groundwater circulations occur as thermal springs. In the Bled case study, the thermal water temperature, at it is discharged to the surface, is between 19–23 °C. In order to determine the extent (e.g., geometry) and the origin of the pronounced deep circulation system in the Bled area, chemical and isotopic measurements of waters from different hydrogeological systems were performed (e.g., surface water, thermal water, fresh groundwater). Hydrogeochemical methods were used to tie together the above-mentioned parameters. The results have shown that thermal outflow in Bled is determined by the presence of a deep-water circulation system, where the dissolution of carbonates minerals is the main hydrogeochemical process affecting chemical components of natural water flow. The correlation of the major ions suggests that the recharge area is represented by both limestone and dolomite rocks. Moreover, the results of δ18O and δ2H of all samples indicate that the recharge is mainly meteoric precipitation. The recharge altitude was estimated for two sampled fresh groundwater springs. The isotopic compositions of those two springs suggest the range from δ18O = −8.68‰, δ2H = −57.4‰ at an elevation of 629 m to δ18O = −9.30‰, δ2H = −60.1‰ at an elevation of 1216 m. The isotopic analysis has confirmed that the thermal water recharges from altitudes of 1282–1620 m a.s.l.

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Wang, Dong, Xiao Si Su, Guang Cai Hou, Zhen Hong Zhao et Hong Yun Ma. « The Geochemical and Isotopic Evidences of Groundwater Circulation in Ordos Plateau Cretaceous Basin, P.R of China ». Advanced Materials Research 518-523 (mai 2012) : 4293–98. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.4293.

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The hydrological cycling of groundwater in Ordos Cretaceous Basin show obvious stratification, the cycle can be divided into three layers by cycling depth, the shallow, the intermediate and the deep. In this paper, a classification standard formed with geochemical and isotopic information is described. The standard is based on a large number of borehole investigation and stratified sampling. In the shallow layer, the groundwater mostly is fresh water with lower amount of total dissolved solids, the dominated anion is HCO3,tritium and14C features show a high or rich properties; in the intermediate layer, the geochemical type of groundwater are SO4or SO4-Cl, the age of groundwater calculated by14C is less than 5000a; in the deep groundwater cycling, dominated anion show a complete evolution processes along the flow direction (HCO3-SO4-Cl) from recharge to discharge area, the groundwater age is commonly bigger than 5000a and even bigger than 10000a in the discharge area.

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Miller, Gretchen R., et Andrew Curtis Elmore. « Modeling of a Groundwater Circulation Well Removal Action Alternative ». Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management 9, n^o 2 (avril 2005) : 122–29. http://dx.doi.org/10.1061/(asce)1090-025x(2005)9:2(122).

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Grasby, Stephen, Grant Ferguson, Alyson Brady, Christine Sharp, Peter Dunfield et Margot McMechan. « Deep Groundwater Circulation through Gas Shales in Mountain Belts ». Procedia Earth and Planetary Science 17 (2017) : 532–33. http://dx.doi.org/10.1016/j.proeps.2016.12.134.

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Lagerstedt, E., G. Jacks et F. Sefe. « Nitrate in groundwater and N circulation in eastern Botswana ». Environmental Geology 23, n^o 1 (février 1994) : 60–64. http://dx.doi.org/10.1007/bf00773140.

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Li, Hailong, Michel C. Boufadel et James W. Weaver. « Tide-induced seawater–groundwater circulation in shallow beach aquifers ». Journal of Hydrology 352, n^o 1-2 (avril 2008) : 211–24. http://dx.doi.org/10.1016/j.jhydrol.2008.01.013.

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Elmore, Andrew Curtis, et Thomas Graff. « Best Available Treatment Technologies Applied to Groundwater Circulation Wells ». Remediation Journal 12, n^o 3 (juin 2002) : 63–80. http://dx.doi.org/10.1002/rem.10034.

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Gallagher, Ron, et Andrew Curtis Elmore. « Groundwater circulation well operation using wind turbine–generated energy ». Remediation Journal 18, n^o 3 (mars 2008) : 31–39. http://dx.doi.org/10.1002/rem.20169.

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Schäffer, Rafael, Kristian Bär, Sebastian Fischer, Johann-Gerhard Fritsche et Ingo Sass. « Mineral, thermal and deep groundwater of Hesse, Germany ». Earth System Science Data 13, n^o 10 (25 octobre 2021) : 4847–60. http://dx.doi.org/10.5194/essd-13-4847-2021.

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Abstract. The composition of mineral, thermal or deep groundwaters is of interest for several geotechnical applications, such as drinking-water supply, spas or geothermal energy. Verified and reliable knowledge of temperature, pH, hydrochemical composition and other parameters is crucial to extract fluids with as few technical problems as possible and exploit groundwater reservoirs economically and environmentally sustainably. However, at sites where empirical data are lacking, the correct prediction of fluid properties is often difficult, resulting in considerable economic risks. Here we present the first comprehensive and publicly available database of mineral, thermal and deep groundwaters of Hesse compiled from published and our own data. Presently, it contains 1035 datasets from 560 different springs or wells sampled since 1810. A dataset consists of metadata like location; altitude; depth; rock type or stratigraphic unit; information on the water type; references; physical–chemical parameters; concentrations of major, minor and trace elements; and content of dissolved and free gases as well as isotope data. The dataset allows the evaluation of time series and distribution of groundwater properties both laterally and vertically. We show a simple statistical evaluation based on the five major hydrogeological regions of Hesse. Our database can be used to re-evaluate genesis and circulation of deep groundwaters, to estimate reservoir temperatures with a solution geothermometer, or to assess groundwater ages by means of isotope data. It can also be useful for a first conception of deep geothermal utilization. In the future, an update and extension of the database is intended. The database of mineral, thermal and deep groundwaters of Hesse has been made available by Schäffer et al. (2020) in xlsx and csv file format at TUdatalib, https://doi.org/10.25534/tudatalib-340. The second updated version of the database can be accessed directly at https://tudatalib.ulb.tu-darmstadt.de/handle/tudatalib/2508.2 (last access: 20 October 2021).

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Durrance, E. M., et M. J. Heath. « Thermal groundwater movement and radionuclide transport in SW England ». Mineralogical Magazine 49, n^o 351 (avril 1985) : 289–99. http://dx.doi.org/10.1180/minmag.1985.049.351.16.

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AbstractHeat flow in SW England is well above average for the UK as a whole, but northwards towards Bath and Bristol the values decrease rapidly. However, hot springs occur both in the Bath-Bristol area and in mines in Cornwall. The development of hydrothermal circulation systems is thus not controlled entirely by geothermal gradient: the presence of a suitable fracture permeability is the main requirement. The thermal ‘head’ produced, which nevertheless depends upon the temperature and volume of water in the system, theoretically can exceed local topographic heads even in areas of low geothermal gradient.Thermal groundwaters usually carry above average quantities of radioelements in solution because of the long residence times involved. 222Rn values are often particularly high. High concentrations of 222Rn in surface waters arise from the discharge of groundwater. The results of a survey of 222Rn in streams in SW England have established areas of high values which are interpreted as rising limbs of convection cells with dimensions in the order of 5–10 km.In SE Devon γ-ray spectrometry of soils shows two E.-W. belts of high activity. The northern is coincident with the faulted southern margin of the Crediton Trough, while the southern is coincident with the westerly extension of the Abbotsbury fault system. Groundwater movement along deep-seated fracture systems is considered to be the explanation of these features. The horizontal scale of the area involved suggests that a thermal rather than local topographic head is the driving force. Groundwater circulation within fractures, driven by a thermal head, may therefore occur even in areas of low geothermal gradient and should be considered when selecting waste disposal sites.

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Kuo, Chih-Ping, et Hung-Jiun Liao. « Challenge of Using Groundwater for Buildings Air Conditioning in Subtropical Areas ». Sustainability 14, n^o 1 (30 décembre 2021) : 364. http://dx.doi.org/10.3390/su14010364.

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Using circulating groundwater to cool air-conditioning is not new in high latitude regions but difficult in subtropical areas. Different from only using fans to remove the heat from indoor air for drier air in the high latitude region, the latent heat inside the humid air in subtropical areas makes the operation more difficult. Latent heat inside the humid air must remove away by air-conditioning including compressor and fan for cooling indoor air, which means more electrical power is required for the operation. To save total electrical power for the air-conditioning system is the main goal of this study. To use the advantage of groundwater with lower temperature to lower down the work of compressor, this research compared two ways, close/open types of water/groundwater circulation, both using groundwater to remove the heat generated by a 15RT (45 kW) air-conditioning. Full-scale tests and simulations were performed in this study to evaluate the efficiency of transferring the heat produced by air-conditioning systems to stably flowing groundwater in a grave stratum under Taipei Basin. With a closed circulating cooling water system, this study found that a 15RT air conditioner could only operate continuously for 4 h before it had to be shut down due to overheating. Additionally, groundwater must carry the heat away within the following 20 h. In changing the closed circulating water system to an open one, a system that uses a circulatory method to extract groundwater upwards and conduct heat exchange with an air conditioning system can enable the continuous operation of such a system with the same heat production condition. Numerical simulations for the heat dissipation behavior of two circulatory systems were performed herein. The results verified the aforementioned phenomena observed from both tests. The result showed both systems can provide air-conditioning working well. The total electrical power for a 15RT air-conditioning in sub-tropical areas can be reduced by 22% using circulating groundwater. Considering the system optimization, the total power consumption can be reduced by about 28%.

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Hassan Aden, Abdek, Jasmin Raymond, Bernard Giroux et Bernard Sanjuan. « New Insights into Hydrothermal Fluid Circulation Affected by Regional Groundwater Flow in the Asal Rift, Republic of Djibouti ». Energies 14, n^o 4 (22 février 2021) : 1166. http://dx.doi.org/10.3390/en14041166.

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The Asal Rift hosts a lake located in a depression at 150 m below sea level, where recharge is influenced by regional groundwater flow interacting with the Ghoubbet Sea along the coast of Djibouti. This regional groundwater flow is believed to influence hydrothermal fluid circulation, which we aim to better understand in this study, having the objective of developing concepts for geothermal exploration in the area. To this end, magnetotelluric data acquired in the Asal Rift were processed and analyzed. 1D inversion models of electrical conductivity were interpolated for interpretation. These data were then used to build a 2D hydrogeological model, allowing multiphase flow and heat transfer simulations to be performed, considering the regional groundwater flow near the surface and the site topography, in order to confirm the preferred path of fluid flow. Geophysical data analysis indicates the presence of normal faults, notably the H fault, which may act as a conduit for the circulation of hydrothermal fluids and where the hanging wall can be a hydrogeological barrier within the hydrothermal system of the Asal Rift. The results from the 2D numerical flow and heat transfer modelling show the importance of groundwater flow responsible for thermal springs located at the periphery of Asal Lake. Reservoir temperature inferred by means of geothermometry ranging from 200 to 270 °C was shown to correspond to simulated temperature at potential reservoir depth. Moreover, simulated temperature between 600 and 1700 m depth is close to the temperature profile measured in the geothermal well Asal 6 of the area, with less than 20 °C difference. Simulations indicate that hydrothermal fluid circulation is likely influenced by the regional groundwater flow controlled by the topography and the major water bodies, the Ghoubbet Sea and Asal Lake, feeding buoyant fluids interacting with a deep magmatic source and where tectonic activity created normal faults offering a preferred path for fluid circulation.

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Kharitonova, N. A., L. A. Lyamina, G. A. Chelnokov, I. V. Bragin, A. A. Karabtsov, I. A. Tarasenko, H. Nakamura et H. Iwamori. « Chemical and isotopic composition of nitrogen thermal waters of the Kuldur Deposit (JAR, Russia) ». Moscow University Bulletin. Series 4. Geology, n^o 5 (28 octobre 2020) : 77–91. http://dx.doi.org/10.33623/0579-9406-2020-5-77-91.

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The article presents the results of the hydrogeochemical study of thermal groundwaters from the Kuldur spa (Jewish Autonomous Region, Russia). The main characteristics of these groundwaters are high temperature (73 ᵒС), low TDS (up to 0,38 g/l), and alkaline (pH 9). The dominated cation is sodium, and the anion is hydrocarbonate. Water is enriched with fluorine, silicon, aluminum, tungsten, molybdenum, and some other anionic elements. This study provides detailed data on the chemical and mineral composition of host rocks and sources of solutes. Isotopic data from bubbling gases show that the main component of the gas phase (N2) comes from an atmogenic source, while CH4 and CO2 are biogenic. Argon and oxygen are also derived from air, while helium is predominantly radiogenic. The ϬD and Ϭ18О in the aqueous phase indicate the undoubtedly meteoric genesis of groundwater with an extended circulation period. Our results suggest that the studied groundwaters are results of the penetration of meteoric waters to 4 km depth and heating up to 100 ᵒC. The solutes come to aquifer via the dissolution of rocks, but since groundwater circulates within the poorly soluble rock (granitoids), respectively, the water TDS remains low.

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Zdechlik, Robert, et Agnieszka Kałuża. « The FEM model of groundwater circulation in the vicinity of the Świniarsko intake, near Nowy Sącz (Poland) ». Geologos 25, n^o 3 (1 décembre 2019) : 255–62. http://dx.doi.org/10.2478/logos-2019-0028.

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Abstract Modern hydrogeological research uses numerical modelling, which is most often based on the finite difference method (FDM) or finite element method (FEM). The present paper discusses an example of application of the less frequently used FEM for simulating groundwater circulation in the vicinity of the intake at Świniarsko near Nowy Sącz. The research area is bordered by rivers and watersheds, and within it, two well-connected aquifers occur (Quaternary gravelly-sandy sediments and Paleogene cracked flysch rocks). The area was discretized using a Triangle generator, taking into account assumptions about the nature and density of the mesh. Rivers, wells, an irrigation ditch and infiltration of precipitation were projected onto boundary conditions. Conditions of groundwater circulation in the aquifer have been assessed based on a calibrated model, using water balance and a groundwater level contour map with flow path lines. Application of the program based on FEM, using smooth local densification of the discretization mesh, has allowed for precise mapping of the location of objects that significantly shape water circulation.

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Xiao, Yong, Qichen Hao, Yinfei Luo, Shengbin Wang, Xueya Dang, Jingli Shao et Linxian Huang. « Origin of brines and modern water circulation contribution to Qarhan salt lake in Qaidam basin, Tibetan plateau ». E3S Web of Conferences 98 (2019) : 12025. http://dx.doi.org/10.1051/e3sconf/20199812025.

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Lake Qarhan is the largest salt lake and potassium salt resource mining base in china. Understanding the origin of brines and the contribution of modern water circulation is extremely important to the sustainable development of the salt lake. Comprehensive tools including isotope, hydrochemistry and numerical simulation had been performed. Results suggest that brine groundwater in the salt lake area is the result of ancient brines migrated from the western Qaidam Basin due to the uplift of the western basin in the geological past. Shallow phreatic aquifers in the salt lake area are also recharged by the modern surface water in the flood period. The contribution of modern groundwater circulation to the salt lake area is very limited with only 3% of the total quantity of groundwater discharge for the watershed.

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Defourny, Agathe, Frédéric Nguyen, Arnaud Collignon, Patrick Jobé, Alain Dassargues et Thomas Kremer. « Induced Polarization as a Proxy for CO2-Rich Groundwater Detection—Evidences from the Ardennes, South-East of Belgium ». Water 12, n^o 5 (14 mai 2020) : 1394. http://dx.doi.org/10.3390/w12051394.

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CO 2 -rich mineral groundwaters are of great economic and touristic interest but their origin and circulation paths in the underground are often poorly understood. A deeper understanding of the system plumbery and the development of non—to minimally—invasive near-surface geophysical methods for the prospection of potential productive areas is therefore of great interest to manage future supply. The objective of this contribution is to assess the ability of the time-domain induced polarization (TDIP) method, combined with the electrical resistivity tomography (ERT) method, to make the distinction between CO 2 -rich groundwater from non-gaseous groundwater. Three combined ERT/TDIP tomographies were performed above known uplift zones in the south-east of Belgium where thousands of CO 2 -rich groundwater springs exist. On all profiles, important contrasts in both electrical resistivity and chargeability distributions were observed in the vicinity of the upflow zone, also reflected in the normalized chargeability sections computed from the measured data. Low resistivity vertical anomalies extending in depth were interpreted as a saturated fracture network enabling the upflow of deep groundwater to the surface. High chargeability anomalies appearing directly close to the CO 2 -rich groundwater springs were inferred to metallic oxides and hydroxides precipitation in the upper part of the aquifer, linked to pressure decrease and changing redox conditions in the up-flowing groundwater approaching the land surface. The combined interpretation of electrical resistivity and induced polarization datasets provides a very promising method for a robust prospection of CO 2 -rich groundwater.

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ZDECHLIK, Robert, et Małgorzata PARTYKA. « GROUNDWATER FLOW MODELlING USING the FINITE DIFFERENCES METHOD AND the FINITE ELEMENTS METHOD – COMPARATIVE MODEL STUDIES ». Biuletyn Państwowego Instytutu Geologicznego 471 (1 octobre 2018) : 201–8. http://dx.doi.org/10.5604/01.3001.0012.5057.

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The filtration of groundwater is a complicated process, which is determined by natural environmental factors (hydrogeological conditions) and anthropogenic impacts. Reliable predictions of the impact of the established extortions on the groundwater environment require the use of an appropriate research method that will allow for a precise representation of groundwater circulation. Such methods include numerical modelling of filtration processes, using a mathematical description of groundwater flow, based on assumed parameters and boundary conditions. For groundwater flow modelling, software based on the finite differences method FDM, using Modflow simulators, is most commonly used. Due to the numerous advantages, mainly in terms of greater precision in the representation of the complex geometry of the aquifers and objects affecting the water circulation, the alternative FEM finite elements method is becoming increasingly important. The article presents characteristic features of modelling using both methods. Based on the established imaginary research site, representing typical valley hydrogeological conditions, the paper presents the methodology of model implementation and numerical calculations of water flow using FDM and FEM methods, each in two variants of grid density. Obtained results are presented, with an attempt to compare the advantages and disadvantages of both methods.

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Kong, Yanlong, Zhonghe Pang, Jumei Pang, Jie Li, Min Lyu et Sheng Pan. « Fault-Affected Fluid Circulation Revealed by Hydrochemistry and Isotopes in a Large-Scale Utilized Geothermal Reservoir ». Geofluids 2020 (15 juin 2020) : 1–13. http://dx.doi.org/10.1155/2020/2604025.

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A new significant aspect in the utilization of hydrothermal energy in China is the large-scale exploitation using multiwells from a single geothermal site. This requires detailed hydrogeochemical investigations to gain insight about deep groundwater circulation. At the Xiongxian karst geothermal site in North China, where the demonstration project of large-scale utilization was conducted, 40 boreholes with depths from 1000 to 1800 m were drilled in a region of 50 km2. A total of 25 water samples were collected, and temperature loggings were conducted in 16 of these wells. At the site scale, the hydraulic head was observed to decline from SW to NE, i.e., orthogonal to that at the regional scale. Moreover, the geothermal groundwater temperature, borehole temperature gradient, and heat flow in the caprock all exhibited the same spatial trend with the groundwater head. Based on the hydrogeochemical and temperature logging data, this was explained by mixing of lateral recharging groundwater with ascending thermal fluids through the Xiongxian Fault, after excluding the causes of pumping activities and geologic structure. In addition, geothermal groundwater 81Kr age was estimated to be approximately 760 k yr, which is much older than the 14C age of 20 to 30 k yr. The older 81Kr age implies a low renewability of deep groundwater circulation, which should be considered in terms of sustainable management in relation to the large-scale utilization of geothermal resources.

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Lan, Chia-Wei, Yen-Ting Hwang, Rong-You Chien, Agnès Ducharne et Min-Hui Lo. « Responses of Global Atmospheric Energy Transport to Idealized Groundwater Conditions in a General Circulation Model ». Journal of Climate 35, n^o 21 (novembre 2022) : 3291–303. http://dx.doi.org/10.1175/jcli-d-20-0753.1.

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Abstract The representation of groundwater dynamics in land surface models and their roles in global precipitation variations has received attention in recent years. Studies have revealed the overall higher soil moisture but rather diverse precipitation changes after incorporating the groundwater component in climate models. However, groundwater effects on large-scale atmospheric energy transport, the fundamental atmospheric variable regulating Earth’s climate, have not been explored thoroughly. In this study, a pair of idealized experiments corresponding to contrast globally fixed water table depths by AMIP-type simulations in the Community Earth System Model was conducted. In the wet (shallow water table) experiments, an increased meridional surface temperature gradient makes the mean meridional energy transports and Hadley circulation stronger than dry (deep water table) experiments over the tropics. Such energy transport changes are primarily attributed to the dynamic contribution (intensified Hadley circulation). The wet experiments make the simulated world be like an aquaplanet simulation with less land–sea temperature contrast and the enhancement (reduction) of mean meridional circulation (stationary eddies) energy transports. Furthermore, the South Asian monsoon circulation in the wet experiment shows a southward shift in the premonsoon season (April–June) and slight weakening in the mature phase (July and August). This study explores the impacts of the soil conditions caused by various water table depths on global energy transport and has further implications for climate model developments and experiment designs.

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Tawabini, Bassam, et Mohammed Makkawi. « Remediation of MTBE-contaminated groundwater by integrated circulation wells and advanced oxidation technologies ». Water Supply 18, n^o 2 (21 juin 2017) : 399–407. http://dx.doi.org/10.2166/ws.2017.128.

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Abstract The proximity of shallow groundwater systems to sources of contamination usually exposes them to severe environmental threats. Hazardous pollutants that leak from gas stations, landfills, and industrial facilities may eventually reach the underneath shallow groundwater aquifers, posing risks to human health and the environment. Cleaning contaminated groundwater sources has always been a challenge to the local authorities. This is even more challenging when dealing with difficult pollutants such as methyl tertiary butyl ether (MTBE) due its high solubility in water, poor biodegradability, and poor adsorption onto solids. This study aims to assess the efficiency of a pilot groundwater remediation system to treat a shallow aquifer contaminated with MTBE. The in-house designed and fabricated pilot system combines the technology of circulation wells and UV-based advanced oxidation technology for the breakdown and removal of MTBE from water. An ultraviolet/hydrogen peroxide (UV/H2O2) process was used in this study to remove MTBE from water. The concentration of MTBE was reduced from approximately 1,400 μg/L to as low as 34 μg/L within 30 minutes, with a treatment efficiency of about 98%. The study also assesses the effects of the UV intensity and the treatment time needed to remove the target pollutant.

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UCHIYAMA, Yusuke. « Tidal Circulation of Groundwater Flow Formed in Sandy-beach Aquifers. » Doboku Gakkai Ronbunshu, n^o 670 (2001) : 37–48. http://dx.doi.org/10.2208/jscej.2001.670_37.

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Qin, Dajun, Jeffrey V. Turner et Zhonghe Pang. « Hydrogeochemistry and groundwater circulation in the Xi’an geothermal field, China ». Geothermics 34, n^o 4 (août 2005) : 471–94. http://dx.doi.org/10.1016/j.geothermics.2005.06.004.

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Mojarrad, B. B., J. Riml, A. Wörman et H. Laudon. « Fragmentation of the Hyporheic Zone Due to Regional Groundwater Circulation ». Water Resources Research 55, n^o 2 (février 2019) : 1242–62. http://dx.doi.org/10.1029/2018wr024609.

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Donovan, Joseph J., et Arthur W. Rose. « Geochemical evolution of lacustrine brines from variable-scale groundwater circulation ». Journal of Hydrology 154, n^o 1-4 (février 1994) : 35–62. http://dx.doi.org/10.1016/0022-1694(94)90211-9.

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Elmore, Andrew Curtis, Ron Gallagher et K. David Drake. « Using wind to power a groundwater circulation well?preliminary results ». Remediation Journal 14, n^o 4 (2004) : 49–65. http://dx.doi.org/10.1002/rem.20021.

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Pang, Zhonghe, Jie Li et Jiao Tian. « Noble gas geochemistry and chronology of groundwater in an active rift basin in central China ». E3S Web of Conferences 98 (2019) : 01040. http://dx.doi.org/10.1051/e3sconf/20199801040.

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Stable noble gas isotopes are excellent groundwater tracers. Radioactive noble gases are emerging new tools in the study of groundwater circulation dynamics. Among these, the 85Kr and 81Kr, and 39Ar have advanced very fast in recent years and exhibit strong potential in the reconstruction of the history of groundwater recharge and evolution in sedimentary basins at different scales. Here, we report the findings in groundwater circulation dynamics as relative to intensive water-rock interactions, heat transfer and He gas flux in Guanzhong Basin located in Xi’an, the geographical centre of China, which is a rift basin created by collision between the Eurasia and Indian plates, with active neotectonic activities. The recent technological breakthrough in noble gas isotope measurements, i.e. the atomic trap trace analysis (ATTA) techniques on Kr and Ar gas radionuclei, has revolutionized groundwater dating. Noble gas samples from shallow and deep wells to 3000 m depth have been collected to study isotope variations to reconstruct the history of groundwater recharge and understand the water-rock interaction processes. Stable isotopes of water show strong water-rock interaction in the formation, creating a strong positive O-isotope shift up to 10 ‰, a phenomenon that is rarely seen in a fairly low temperature environment. Analysis of 85Kr and 81Kr show groundwater ages up to 1.3 million years old along both North-South and a West-East cross sections, which offers strong evidence about the slow moving flow, strong water-rock interaction, rich geothermal resources as well as He gas resources.

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Zhang, Feng Juan, Li Ting Xing, Tong Qiang Peng, Juan Zhou et Yi Yang. « Time and Space Evolution of Shallow Saline Groudwater Dynamic in Inland Area of Jiyang County，Shandong Province, China ». Advanced Materials Research 1092-1093 (mars 2015) : 1197–201. http://dx.doi.org/10.4028/www.scientific.net/amr.1092-1093.1197.

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Inland plain shallow saline water has great exploitation potentiality. Based on field water testing, water level monitoring, pumping test, as well as indoor leaching experiment, applying mathematical statistics, Pipers trilinear nomograph and PHREEQC chemistry simulation methods, saline water area of the town of Sungeng Jiyang was studied. The results showed as follows: (1) Inland shallow groundwater presents “weather-evaporative” dynamic type; (2)The shallow saline water and middle-deep groundwater belonging to different flow system; (3) Because of the creeping flow and aqueous medium riched in clay, inland shallow groundwater mineralized significantly. In saline water area inland plain, the unique features of groundwater circulation result in brackish water dynamic relative stability.

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Avila, A., A. Rodrigo et F. Rodà. « Nitrogen circulation in a Mediterranean holm oak forest, La Castanya, Montseny, northeastern Spain ». Hydrology and Earth System Sciences 6, n^o 3 (30 juin 2002) : 551–58. http://dx.doi.org/10.5194/hess-6-551-2002.

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Abstract. The importance of storm frequency as well as the groundwater and hyporheic inputs on nitrate (NO3-N) and ammonium (NH4-N) levels in stream water were studied in a small perennial Mediterranean catchment, Riera Major, in northeast Spain. NO3-N concentrations ranged from 0.15 to 1.9 mg l-1. Discharge explained 47% of the annual NO3-N concentration variance, but this percentage increased to 97% when single floods were analysed. The rate of change in nitrate concentration with respect to flow, ΔNO3-N/ΔQ, ranged widely from 0 to 20 μg NO3-N s l-2. The ΔNO3-N/ΔQ values fitted to a non linear model with respect to the storm flow magnitude (ΔQ) (r2=0.48, d.f.=22, P<0.01). High values of ΔNO3-N/ΔQ occurred at intermediate ΔQ values, whereas low ΔNO3-N/ΔQ values occurred during severe storms (ΔQ > 400 l s-1). N3-N concentrations exhibit anticlockwise hysteresis patterns with changing flow and the patterns observed for autumnal and winter storms indicated that groundwater was the main N3-N source for stream and hyporheic water. At baseflow, NO3-N concentration in groundwater was higher (t=4.75, d.f.=29, P>0.001) and co-varied with concentrations in the stream (r=0.91, d.f.=28, P<0.001). In contrast, NO3-N concentration in hyporheic water was identical to that in stream water. The role of the hyporheic zone as source or sink for ammonium was studied hyporheic was studied comparing its concentrations in stream and hyporheic zone before and after a major storm occurred in October 1994 that removed particulate organic matter stored in sediments. Results showed high ammonium concentrations (75±28 s.d. μg NH4-N l-1) before the storm flow in the hyporheic zone. After the storm, the ammonium concentration in the hyporheic dropped by 80% (13.6±8 μg N4-N l-1) and approached to the level found in stream water (11±8 μg NH4-N l-1) indicating that indisturbed hyporheic sediments act as a source for ammonium. After the storm, the ammonium concentrations in the stream, hyporheic and groundwater zones were very similar suggesting that stream ammonium concentrations are sustained mainly by input from groundwater. The present study provides evidence that storm flow magnitude is an important source of variability of nitrate concentration and fluxes in Mediterranean streams subjected to an irregular precipitation regime with prolonged dry periods. Keywords: nitrate, discharge regime, hyporheic zone, groundwater, Mediterranean, stream, Riera Major

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Tamburini, Andrea, et Marco Menichetti. « Groundwater Circulation in Fractured and Karstic Aquifers of the Umbria-Marche Apennine ». Water 12, n^o 4 (7 avril 2020) : 1039. http://dx.doi.org/10.3390/w12041039.

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The Umbria-Marche Apennine has a large number of springs that drain water stored in carbonate formations. Spring groundwater constitutes a crucial freshwater resource for many countries, regions, and cities around the world. This study aimed to understand the hydrological mechanisms behind groundwater circulation and their relationship to the structural and stratigraphic settings of specific aquifers. Recession analysis and time series analysis were applied to the daily discharge of six springs monitored over eight years. Both analyses indicated the presence of two types of aquifers: aquifer with unimodal behavior and aquifer with bimodal behavior. The first are characterized by two hydrodynamic sub-regimes, in which fracture networks control the baseflow and conduit networks control the quickflow. In contrast, other springs present only one hydrodynamic sub-regime related to fracture network drainage. Time series analysis confirms the results of recession analysis, showing a large memory effect and a large response time, implying the dominance of the baseflow sub-regime. These results indicate that the Maiolica Formation is characterized by a high degree of fracturation and slight karstification, which control infiltration and percolation, whereas the Calcare Massiccio Formation regulates groundwater circulation in the deeper zones of the aquifer, characterized by a high degree of karstification through moderately developed conduit networks.

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