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1
Wu, Ming-Chang, e Ping-Cheng Hsieh. "Influence of nonuniform recharge on groundwater flow in heterogeneous aquifers". AIMS Mathematics 8, n. 12 (2023): 30120–41. http://dx.doi.org/10.3934/math.20231540.
Testo completoAbstract (sommario):
<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>
2
Hera-Portillo, África de la, Julio López-Gutiérrez, Beatriz Mayor, Elena López-Gunn, Hans Jørgen Henriksen, Ryle Nørskov Gejl, Pedro Zorrilla-Miras e Pedro Martínez-Santos. "An Initial Framework for Understanding the Resilience of Aquifers to Groundwater Pumping". Water 13, n. 4 (17 febbraio 2021): 519. http://dx.doi.org/10.3390/w13040519.
Testo completoAbstract (sommario):
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.
3
Maulana, Fivry Wellda, e Arie Noor Rakhman. "Aplikasi Geofisika Terpadu Untuk Penelitian Potensi Air Tanah Aquifer Batu Pasir Di Alasombo, Indonesia". Jurnal Multidisiplin Madani 2, n. 1 (30 gennaio 2022): 511–24. http://dx.doi.org/10.54259/mudima.v2i1.418.
Testo completoAbstract (sommario):
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.
4
Luo, Zhaoyang, Jun Kong, Chengji Shen, Pei Xin, Chunhui Lu, Ling Li e David Andrew Barry. "Effects of aquifer geometry on seawater intrusion in annulus segment island aquifers". Hydrology and Earth System Sciences 25, n. 12 (23 dicembre 2021): 6591–602. http://dx.doi.org/10.5194/hess-25-6591-2021.
Testo completoAbstract (sommario):
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.
5
Tsepav, Matthew Tersoo, Aliyu Yahaya Badeggi, Obaje Nuhu George, Usman Yusuf Tanko e 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, n. 1 (30 marzo 2021): 18. http://dx.doi.org/10.20961/jphystheor-appl.v5i1.51563.
Testo completoAbstract (sommario):
<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>
6
Salvador, N., J. P. Monteiro, R. Hugman, T. Y. Stigter e 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, n. 11 (6 novembre 2012): 3217–27. http://dx.doi.org/10.5194/nhess-12-3217-2012.
Testo completoAbstract (sommario):
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.
7
Zhang, Yi, e Dong Ming Guo. "Temperature Field of Single-Well Aquifer Thermal Energy Storage in Sanhejian Coal Mine". Advanced Materials Research 415-417 (dicembre 2011): 1028–31. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.1028.
Testo completoAbstract (sommario):
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.
8
Zhang, Yi, e Dong Ming Guo. "Temperature Field of Doublet-Wells Aquifer Thermal Energy Storage in Sanhejian Coal Mine". Advanced Materials Research 430-432 (gennaio 2012): 746–49. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.746.
Testo completoAbstract (sommario):
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.
9
Singh, K. P. "Nonlinear estimation of aquifer parameters from surficial resistivity measurements". Hydrology and Earth System Sciences Discussions 2, n. 3 (10 giugno 2005): 917–38. http://dx.doi.org/10.5194/hessd-2-917-2005.
Testo completoAbstract (sommario):
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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Jaka Yuwana, Ngudi Aji, Nora Herdiana Pandjaitan e Roh Santoso Budi Waspodo. "Prediksi cadangan air tanah berdasarkan hasil pendugaan geolistrik di Kabupaten Grobogan, Jawa Tengah". JURNAL SUMBER DAYA AIR 13, n. 1 (27 dicembre 2017): 23–36. http://dx.doi.org/10.32679/jsda.v13i1.139.
Testo completoAbstract (sommario):
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.
11
Camuñas Palencia, Carlos, Miguel Mejías Moreno, Jorge Hornero Díaz, Fernando Ruíz Bermudo e Olga García Menéndez. "Deep aquifers as strategic groundwater reservoir in Spain". BOLETÍN GEOLÓGICO Y MINERO 133, n. 3 (settembre 2022): 7–26. http://dx.doi.org/10.21701/bolgeomin/133.3/001.
Testo completoAbstract (sommario):
The objective of this paper is to establish a definition of deep aquifers, develop a methodological proposal to help select them as strategic groundwater reserves and develop a first inventory of deep aquifers in peninsular Spain, organized by hydrographic districts. The basic premises followed to consider a permeable formation as a deep aquifer are: water table depth greater than 300 m in free aquifers or the top of the permeable formation in the case of confined aquifers. A deep aquifer is also considered to be the lower horizon of very thick aquifers (from 300 m), from which the most superficial horizon is used. The definition of the potentially favorable areas and the initial characterization is based on a compilation and synthesis of geological and hydrogeological information, structured in 5 large blocks: location and identification, geology, hydrogeology, current status and bibliography. For its evaluation, a flowchart has been proposed with the basic lines of the evaluation process. The relevant aspects for suitability would be: stratigraphy and structural geology, prior knowledge of the conceptual model and water renewal, quality, viability of exploitation, effects, final knowledge, and management and governance. The final result allows the aquifer to be classified into three categories: strategic groundwater reserve, punctual reserve or non-viable reserve. The inventory carried out encompasses a total of 64 deep aquifers located in 13 basin districts. Finally, as example, three deep aquifers are presented: Amblés Valley, Madrid detritic aquifer and El Maestrazgo.
12
Guttman, J., J. Kronfeld e I. Carmi. "Dating of Groundwater Recharge in Two Small Adjacent Aquifers in Israel and Their Initial 14C Activities". Radiocarbon 53, n. 1 (2011): 137–49. http://dx.doi.org/10.1017/s003382220003441x.
Testo completoAbstract (sommario):
Radiocarbon and tritium determinations were carried out in 2 adjacent small aquifers in Israel. These aquifers have small storage capacities and good hydraulic properties. Darcy calculations suggest that the aquifers contain young waters, ≃50 yr in age. 14C concentrations in the Pleistocene aquifer are between 23–60 pMC, with the lowest activity related to contamination by petroleum-based fertilizers with no 14C. 14C concentrations in the Judea Group aquifer range from 62 to 95 pMC. An apparent difference of ≃1000 yr is indicated for the average recharge age between the 2 aquifers. The tritium data suggests that the water in both aquifers is quite young. The 1000-yr difference is an artifact of initial isotopic fractionation differences through the unsaturated zone as established elsewhere for these 2 aquifers. When these individual fractionation factors (0.54 for the Pleistocene and 0.62 for the Judea Group) are used, it is revealed that both aquifers contain young water, in agreement with the Darcy calculation, which was recharged at the beginning of the period of thermonuclear atmospheric testing in the early 1960s.
13
Sun, Lin Hua, He Rong Gui e Man Li Lin. "Hydro-Geochemistry of Deep Aquifers in Coal Mines in Northern Anhui Province, China: Implications for Water Rock Interaction and Water Source Discrimination". Advanced Materials Research 524-527 (maggio 2012): 604–7. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.604.
Testo completoAbstract (sommario):
Thirty-eight groundwater samples from three deep seated aquifers (the Quaternary, the Coal bearing and the Taiyuan Fm aquifers) had been collected from three coal mines in northern Anhui Province, China for analyzing their major ions, and the statistical methods (correlation, cluster and discriminant analysis) had been processed for evaluating the source of ions and relationship between aquifers. The results suggest that: (1) the chemical signatures of the groundwater are mainly controlled by dissolution of plagioclase, K-feldspar and calcite; (2) the aquifers had been mixed with each other, especially the mixing between the Quaternary aquifer and the Taiyuan Fm aquifer. Discriminant analysis has produced two functions and a diagram, which can be used for water source discrimination.
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Alla, Amani Jonas, N’Goran Jean Paul Yao, Diby Ferdinand Yao e Zéli Bruno Digbehi. "Caractérisation Lithologique, Hydrosédimentaire Et Cartographie des Aquifères par la Méthode des Indices d’Évolution : Cas de la Recharge des Aquifères de Bonoua (Sud-Est Côte d’Ivoire)". European Scientific Journal, ESJ 20, n. 9 (31 marzo 2024): 214. http://dx.doi.org/10.19044/esj.2024.v20n9p214.
Testo completoAbstract (sommario):
Ce travail avait pour objectif de déterminer la typologie et la source probable de recharge des aquifères rencontrés à Bonoua en vue d’une meilleure gestion de ceux-ci. Les travaux ont utilisé des échantillons de forages prélevés à Bonoua au Sud-Est de la Côte d’Ivoire. L’étude lithologique a révélé des sables, des argiles sableuses et des argiles bariolées. Les sables constituent l’essentiel des aquifères. La détermination des indices d’évolution totale (Nt) et segmentaire (Ns) a illustré trois aquifères. La variation de ces indices a révélé une direction NW-SE des paléocourants. Les indices Ns des sables montrent qu’ils ont subi un long transport (64 % à 86 %). Le principal aquifère se situe à 64,5 m en moyenne. Il est surmonté par un niveau imperméable (toit) d’argile bariolée et enregistre les meilleures arrivées d’eau. Il est dominé de sables grossiers (66,66 % à 85,71 %) à très grossiers avec une forme subarrondie (16 % à 53,57 %) et arrondies (13,04 % à 40 %). Les particules fines piégées par les grossières à l’équilibre lors du dépôt sont toutes les deux issues d’un courant cogénétique. Ces sédiments transportés majoritairement par saltation et déposés généralement selon un faciès logarithmique (Nt = 0) et rarement parabolique (0 ˂ Nt ˂ 1) sont très bien classés (83,33 % à 100 %). Cette étude a permis d’identifier deux nouveaux faciès qui sont le faciès subparabolique (0,05 ≤ Nt ≤ 0,09) et le faciès linéaire (Nt = 1). Le faible pourcentage de fine offre à l’aquifère une bonne porosité et une bonne perméabilité ainsi qu’une bonne transmissivité de l’eau souterraine. Ce travail révèle donc qu’un seul aquifère existe dans cette localité mais se présente en bicouche séparée par de l’argile bariolée qui constitue le toit de cette nappe captive exploitée dans le zone. L’écoulement souterrain de direction NW-SE suppose que l’eau stockée à Bonoua proviendrait du fleuve Comoé qui coule en direction de la localité de Bassam. D’où la nécessité de protéger les cours d’eau rencontrées dans la localité de Bassam ainsi qu’au Nord de la zone d’étude afin garantir l’eau à Bonoua.
The objective of this study was to determine the typology and likely recharge source of the aquifers found in Bonoua, aiming to enhance their management. Samples from boreholes in Bonoua, located in southeastern Côte d'Ivoire, were analyzed. The lithological examination revealed the presence of sands, sandy clays, and variegated clays, with sands comprising the majority of the aquifers. Analysis of total (Nt) and segmental (Ns) evolution indices highlighted the presence of three distinct aquifers. The fluctuation in these indices indicated a prevailing NW-SE direction of paleocurrents. The Ns indices of the sands indicate significant long-distance transport (ranging from 64% to 86%). The primary aquifer is typically found at an average depth of 64.5 meters. It is capped by an impermeable layer (roof) of variegated clay, leading to optimal water inflow. The predominant sands range from coarse (66.66% to 85.71%) to very coarse, exhibiting subrounded (16% to 53.57%) and rounded (13.04% to 40%) characteristics. Both the fine particles trapped by the coarse ones during deposition equilibrium originate from a co-genetic current. These sediments, primarily transported by saltation and typically deposited in a logarithmic (Nt = 0) and occasionally parabolic (0 ˂ Nt ˂ 1) facies, exhibit high classification accuracy (ranging from 83.33% to 100%). Additionally, this study identified two novel facies: the subparabolic facies (0.05 ≤ Nt ≤ 0.09) and the linear facies (Nt = 1). The low proportion of fines contributes to the aquifer's favorable porosity, permeability, and groundwater transmissivity. Consequently, this research confirms the presence of a single aquifer in this area, organized in a bilayer configuration separated by variegated clay serving as the roof of the exploited captive aquifer in the region. The NW-SE underground flow pattern suggests that the water stored in Bonoua originates from the Comoé River, which flows towards Bassam. Therefore, it is imperative to safeguard the watercourses encountered in the vicinity of Bassam and to the north of the study area to ensure a reliable water supply to Bonoua.
15
Sehah, Sehah, Hartono Hartono, Zaroh Irayani e 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, n. 3 (3 dicembre 2021): 344–57. http://dx.doi.org/10.5614/j.math.fund.sci.2021.53.3.1.
Testo completoAbstract (sommario):
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.
16
Zahid, Anwar, Farhana Islam, M. Rashidul Hassan, Kamrul Islam e Nur Ahmed. "Analysis of Aquifer Pumping Test Data to Determine Deep Groundwater Security in Southeastern Bangladesh". Journal of Natural Resources and Development 8 (1 dicembre 2018): 125–43. http://dx.doi.org/10.5027/jnrd.v8i0.12.
Testo completoAbstract (sommario):
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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Ducci, Daniela, e Mariangela Sellerino. "A Modified AVI Model for Groundwater Vulnerability Mapping: Case Studies in Southern Italy". Water 14, n. 2 (15 gennaio 2022): 248. http://dx.doi.org/10.3390/w14020248.
Testo completoAbstract (sommario):
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.
18
Han, Tao, Yong Xue, Weikui Lv, Yu Zhang e Tingting Luo. "Prediction and Analysis of Vertical Additional Force of Shaft Wall in Topsoil Containing Multiple Aquifers during Drainage". Sustainability 15, n. 4 (5 febbraio 2023): 2877. http://dx.doi.org/10.3390/su15042877.
Testo completoAbstract (sommario):
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.
19
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 e 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, n. 1 (8 giugno 2021): 46–52. http://dx.doi.org/10.46660/ijeeg.vol12.iss1.2021.561.
Testo completoAbstract (sommario):
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.
20
Sonthiphand, Prinpida, Pasunun Rattanaroongrot, Kasarnchon Mek-yong, Kanthida Kusonmano, Chalida Rangsiwutisak, Pichahpuk Uthaipaisanwong, Srilert Chotpantarat e Teerasit Termsaithong. "Microbial community structure in aquifers associated with arsenic: analysis of 16S rRNA and arsenite oxidase genes". PeerJ 9 (8 gennaio 2021): e10653. http://dx.doi.org/10.7717/peerj.10653.
Testo completoAbstract (sommario):
The microbiomes of deep and shallow aquifers located in an agricultural area, impacted by an old tin mine, were explored to understand spatial variation in microbial community structures and identify environmental factors influencing microbial distribution patterns through the analysis of 16S rRNA and aioA genes. Although Proteobacteria, Cyanobacteria, Actinobacteria, Patescibacteria, Bacteroidetes, and Epsilonbacteraeota were widespread across the analyzed aquifers, the dominant taxa found in each aquifer were unique. The co-dominance of Burkholderiaceae and Gallionellaceae potentially controlled arsenic immobilization in the aquifers. Analysis of the aioA gene suggested that arsenite-oxidizing bacteria phylogenetically associated with Alpha-, Beta-, and Gamma proteobacteria were present at low abundance (0.85 to 37.13%) and were more prevalent in shallow aquifers and surface water. The concentrations of dissolved oxygen and total phosphorus significantly governed the microbiomes analyzed in this study, while the combination of NO3--N concentration and oxidation-reduction potential significantly influenced the diversity and abundance of arsenite-oxidizing bacteria in the aquifers. The knowledge of microbial community structures and functions in relation to deep and shallow aquifers is required for further development of sustainable aquifer management.
21
Sonthiphand, Prinpida, Pasunun Rattanaroongrot, Kasarnchon Mek-yong, Kanthida Kusonmano, Chalida Rangsiwutisak, Pichahpuk Uthaipaisanwong, Srilert Chotpantarat e Teerasit Termsaithong. "Microbial community structure in aquifers associated with arsenic: analysis of 16S rRNA and arsenite oxidase genes". PeerJ 9 (8 gennaio 2021): e10653. http://dx.doi.org/10.7717/peerj.10653.
Testo completoAbstract (sommario):
The microbiomes of deep and shallow aquifers located in an agricultural area, impacted by an old tin mine, were explored to understand spatial variation in microbial community structures and identify environmental factors influencing microbial distribution patterns through the analysis of 16S rRNA and aioA genes. Although Proteobacteria, Cyanobacteria, Actinobacteria, Patescibacteria, Bacteroidetes, and Epsilonbacteraeota were widespread across the analyzed aquifers, the dominant taxa found in each aquifer were unique. The co-dominance of Burkholderiaceae and Gallionellaceae potentially controlled arsenic immobilization in the aquifers. Analysis of the aioA gene suggested that arsenite-oxidizing bacteria phylogenetically associated with Alpha-, Beta-, and Gamma proteobacteria were present at low abundance (0.85 to 37.13%) and were more prevalent in shallow aquifers and surface water. The concentrations of dissolved oxygen and total phosphorus significantly governed the microbiomes analyzed in this study, while the combination of NO3--N concentration and oxidation-reduction potential significantly influenced the diversity and abundance of arsenite-oxidizing bacteria in the aquifers. The knowledge of microbial community structures and functions in relation to deep and shallow aquifers is required for further development of sustainable aquifer management.
22
Lei, Kunchao, Fengshan Ma, Jiurong Liu, Yong Luo, Wenjun Cui, Yi Zhou, He Liu, Xinghui Wang, Miaozhuang Tian e 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 aprile 2020): 309–14. http://dx.doi.org/10.5194/piahs-382-309-2020.
Testo completoAbstract (sommario):
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.
23
Akanbi, Olanrewaju Akinfemiwa, e Moshood ‘Niyi Tijani. "Sustainability and Conceptual Groundwater Hydraulic Models of Basement Aquifers". Materials and Geoenvironment 66, n. 2 (1 giugno 2019): 87–98. http://dx.doi.org/10.2478/rmzmag-2019-0016.
Testo completoAbstract (sommario):
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.
24
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 (settembre 2011): 1195–98. http://dx.doi.org/10.4028/www.scientific.net/amm.99-100.1195.
Testo completoAbstract (sommario):
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.
25
Willems, Cees J. L., Andrea Vondrak, Dirk K. Munsterman, Marinus E. Donselaar e Harmen F. Mijnlieff. "Regional geothermal aquifer architecture of the fluvial Lower Cretaceous Nieuwerkerk Formation – a palynological analysis". Netherlands Journal of Geosciences 96, n. 4 (dicembre 2017): 319–30. http://dx.doi.org/10.1017/njg.2017.23.
Testo completoAbstract (sommario):
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.
26
Krogulec, Ewa, Jerzy J. Małecki, Dorota Porowska e Anna Wojdalska. "Assessment of Causes and Effects of Groundwater Level Change in an Urban Area (Warsaw, Poland)". Water 12, n. 11 (5 novembre 2020): 3107. http://dx.doi.org/10.3390/w12113107.
Testo completoAbstract (sommario):
Monitoring the data of groundwater level in long-term measurement series has allowed for assessment of the impact of natural and anthropogenic factors on groundwater recharge. It allows for assessing the actual groundwater quantity, which constitutes the basis for balanced and sustainable groundwater planning and management in an urban area. Groundwater levels in three aquifers were studied: the shallow and deeper Quaternary aquifers and the Oligocene aquifer in Warsaw (Poland). Statistical analysis was performed on a 27-year (1993–2019) cycle of daily measurements of groundwater levels. The studies focused on determining the range and causes of groundwater level changes in urban-area aquifers. The groundwater table position in the Quaternary aquifer pointed to variable long-term recharge and allowed for the identification of homogenous intervals with identification of water table fluctuation trends. A decrease in the water table was observed within the Quaternary aquifers. The Oligocene aquifer displayed an opposite trend.
27
Setyaningsih, D. L., K. D. Setyawan, D. P. E. Putra e Salahuddin. "Hydrogeological Conceptual Model in the Middle of Randublatung Groundwater Basin". IOP Conference Series: Earth and Environmental Science 926, n. 1 (1 novembre 2021): 012078. http://dx.doi.org/10.1088/1755-1315/926/1/012078.
Testo completoAbstract (sommario):
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.
28
Cerar, Sonja, e 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.
Testo completoAbstract (sommario):
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.
29
Trieu, Duc Huy, Ngoc Thanh Tong, Van Lam Nguyen, Ba Quyen Pham, Dai Phuc Hoang e Hoai Thu Trinh. "Classification of hydrogeological structure along the Red River in the Hanoi area". Tạp chí Khoa học và Công nghệ Biển 21, n. 3 (30 settembre 2021): 299–310. http://dx.doi.org/10.15625/1859-3097/16431.
Testo completoAbstract (sommario):
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.
30
Zuurbier, Koen Gerardus, e 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, n. 2 (27 febbraio 2017): 1173–88. http://dx.doi.org/10.5194/hess-21-1173-2017.
Testo completoAbstract (sommario):
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.
31
Neupane, Sharmila, Ananta Prasad Gajurel, Nir Shakya, Maartin Lupker e 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 luglio 2019): 73–78. http://dx.doi.org/10.3126/jngs.v59i0.24991.
Testo completoAbstract (sommario):
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.
32
Babagana, Saleh Mustapha, e Satendra Sharma. "GEOPHYSICAL CHARACTERIZATION OF AQUIFER SYSTEMS USING VERTICAL ELECTRICAL SOUNDING METHOD IN DEMSA, NORTHEAST NIGERIA". International Journal of Research -GRANTHAALAYAH 8, n. 11 (4 dicembre 2020): 175–84. http://dx.doi.org/10.29121/granthaalayah.v8.i11.2020.2379.
Testo completoAbstract (sommario):
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.
33
Παναγόπουλος, Γ., E. Πυτικάκης, K. Κατσάνου e N. Λαμπράκης. "HYDRO GEOLOGICAL CONDITIONS AND GROUNDWATER QUALITY DEGRADATION IN MESSINI REGION". Bulletin of the Geological Society of Greece 36, n. 4 (1 gennaio 2004): 2031. http://dx.doi.org/10.12681/bgsg.16702.
Testo completoAbstract (sommario):
The aquifers of the Messini region were categorized on the basis of lithology of different geological formations and are presented in this study. They are classified in two main categories: the porous media aquifers, in which are included the alluvial deposits and the Pleio-pleistocene formations, and the karst aquifers of carbonate rocks. Based on field and laboratorial chemical analyses, a relatively increased salinity of the karst aquifer was confirmed and is attributed to natural mixing mechanisms between fresh and seawater. Also, high concentrations of nitrates and nitrites were determined in the groundwater of the Pleiopleistocene aquifer, as a consequence of intensive fertilization with ammonium and sulfate fertilizers.
34
Wumu, Rizky Hizrah, Ahmad Zainuri e Noviar Akase. "Karakteristik Akuifer Menggunakan Metode Geolistrik Resistivity Di Kecamatan Kota Tengah Kota Gorontalo". Jambura Geoscience Review 4, n. 1 (24 gennaio 2022): 60–68. http://dx.doi.org/10.34312/jgeosrev.v4i1.12752.
Testo completoAbstract (sommario):
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.
35
Shirazi, Sharif Moniruzzaman, Md Ibrahim Adham, Noorul Hassan Zardari, Zubaidah Ismail, Hosen Md Imran e Munir Ahmed Mangrio. "Groundwater quality and hydrogeological characteristics of Malacca state in Malaysia". Journal of Water and Land Development 24, n. 1 (1 marzo 2015): 11–19. http://dx.doi.org/10.1515/jwld-2015-0002.
Testo completoAbstract (sommario):
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.
36
Fabbri, Paolo, e Leonardo Piccinini. "Assessing transmissivity from specific capacity in an alluvial aquifer in the middle Venetian plain (NE Italy)". Water Science and Technology 67, n. 9 (1 maggio 2013): 2000–2008. http://dx.doi.org/10.2166/wst.2013.074.
Testo completoAbstract (sommario):
Defining aquifer permeability distribution accurately over large areas is often debated in hydrogeology. The operational efforts to calculate hydraulic conductivity with classical aquifer tests are significant; however, accurate knowledge of permeability areal distribution is fundamental both from a hydrogeological and a modeling standpoint. This paper presents an empirical relationship between the transmissivity (T) and the specific capacity (SC) values obtained from experimental aquifer and well tests. All experimental values were obtained from 50 mm wells in middle Venetian plain artesian gravel aquifers. Many other authors have presented empirical relationships between T and SC, but most are related to fissured/karst aquifers, and only a few concern alluvial porous aquifers. Analysis of the T vs. SC relationship standardized residuals shows that a linear relationship produces statistically significant normal residuals compared with an exponential relationship.
37
Al-Kilabi, Joudah A. "HYDROCHEMICAL COMPARISON OF GROUNDWATER IN DIBBDIBA AND DAMMAM AQUIFERS IN THE KARBALA PLATEAU, CENTRAL IRAQ". Iraqi Geological Journal 51, n. 1 (30 giugno 2018): 101–12. http://dx.doi.org/10.46717/igj.51.1.7ms-2018-06-29.
Testo completoAbstract (sommario):
Fifty groundwater samples of water wells drilled in Karbala Plateau by the General Commission for Groundwater, twenty samples from Dibdibba and thirty from Dammam aquifers. The samples were anlaysed for major ions (Ca2+, Mg2+, Na+, K+, SO4 2+, Cl–, HCO3 –, and NO3 –), in addition to pH, EC and TDS. The aim of this study is to compare these aquifers hydrocamically and identify factors controlling their chemistry. Rock weathering is the main process affecting chemistry of Dammam groundwater in addition to cation exchange process. Evaporation process plays an important role influenced the chemical composition of groundwater in Dibdibba aquifer. The (Ca + Mg) SO4 and Na – (SO4 + Cl) are the predominant hydrochemical facies in Dibaiba and Dammam aquifers respectively. The alkaline water in some wells of Dibdibba aquifer may reflect the mixing with the Dammam aquifer.
38
Long, A. J., e B. J. Mahler. "Predictability, stationarity, and classification of hydraulic responses to recharge in two karst aquifers". Hydrology and Earth System Sciences Discussions 9, n. 8 (16 agosto 2012): 9577–609. http://dx.doi.org/10.5194/hessd-9-9577-2012.
Testo completoAbstract (sommario):
Abstract. Karst aquifers, many of which are rapidly filled and depleted, are likely to be highly susceptible to changes in short-term climate variability. Here we explore methods that could be applied to model site-specific hydraulic responses, with the intent of simulating these responses to different climate scenarios from high-resolution climate models. We compare hydraulic responses (spring flow, groundwater level, and stream base flow) at several sites in two karst aquifers: the Edwards aquifer (Texas, USA) and the Madison aquifer (South Dakota, USA). A one-dimensional, lumped-parameter model simulates nonstationary soil moisture changes for estimation of recharge, and a nonstationary convolution model simulates the aquifer response to this recharge. Model fit to data was 4% better for calibration periods than for validation periods. We use metrics that describe the shapes of the impulse-response functions (IRFs) obtained from convolution modeling to make comparisons in the distribution of response times among sites and among aquifers. Combined principal component analysis and cluster analysis of metrics describing the shapes of the IRFs separated those sites with IRFs having a large ratio of the mean response time to the system memory from those with large skewness and kurtosis. Classification of the IRF metrics indicate that there is a range of IRF characteristics for different site types (i.e., spring flow, groundwater level, base flow) within a karst system. Further, similar site types did not necessarily display similar IRFs. Results indicate that the differences existing within either aquifer are larger than the differences between the two aquifers and that the two aquifers are similar according to this classification. The use of multiple metrics to describe the IRFs provides a novel way to characterize and compare the way in which multiple sites respond to recharge. As convolution models are developed for additional aquifers, they could contribute to an IRF database and a general classification system for karst aquifers.
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Rathinasamy, Vynotdni, Edy Tonnizam Mohammad e Ibrahim Komoo. "Review on Rock Aquifers Researches Conducted in Malaysia". MATEC Web of Conferences 250 (2018): 01007. http://dx.doi.org/10.1051/matecconf/201825001007.
Testo completoAbstract (sommario):
The exploration of groundwater in Malaysia was not very welcomed due to few misconceptions such as it is very expensive to extract, could give negative impacts to the environment and not reliable. Yet, in recent times, rock aquifers such as limestone, sedimentary rocks, volcanic rocks, igneous rocks and metasedimetary rocks are being explored. This paper aims to review the researches that have been carried out on rock aquifers in Malaysia. In general, the topics studied were potential zonation, groundwater quality and quantity, occurrence and flow of groundwater as well as characterization of rock aquifers. The highest yielding aquifer was metasedimentary rock aquifers meanwhile the quality was good in general. Most of the aquifers were having neutral pH values and the total dissolved solids more than 100 mg/l. Moreover, granitic aquifers contained more hardness than the metasedimentary rocks. The iron content in the aquifers was higher than the limit set by World Health Organisation which is 0.3mg/l while salinity of aquifers were not tested in many aquifers. It can be vividly seen that many research were focused on quality. Hence, more researches on characterization of rock aquifers must be done for proper understanding on occurrence, flow and recharge.
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Darsono, Darsono, Ahmad Marzuki, Nuryani Nuryani e G. Yuliyanto. "Detection of groundwater aquifers using geoelectrical resistivity method (case study : Plupuh Sub-district, Sragen District )". Journal of Physics: Conference Series 2498, n. 1 (1 maggio 2023): 012004. http://dx.doi.org/10.1088/1742-6596/2498/1/012004.
Testo completoAbstract (sommario):
Abstract An aquifer is a layer below the ground surface that contains groundwater. Inside the earth there are unconfined aquifers and confined aquifers, where unconfined aquifers are located near the surface while confined aquifers are located very deep beneath the earth. This study aims to find the location, depth, and thickness of aquifers that have the potential to contain large amounts of groundwater. The instrument used in this research is a resistivity meter OYO Model 2119C Mc OHM-EL, with a Schlumberger configuration with a current electrode length of AB/2 to 350 meters. Data acquisition were carried out in the Plupuh sub-district, Sragen district as many as 5 sounding points, and data processing using IP2win software. Based on the interpretation of resistivity geoelectrical data, it can be concluded that the area has the potential to have a lot of groundwater content, for unconfined aquifers at the TS1 sounding point with a depth of 7.7 meters to 19.2 meters with a thickness of 11.5 meters. and TS4 with a depth of 15.4 meters to 30 meters with a layer thickness of 14.6 meters. This aquifer layer is dominated by sand layer lithology, while the confined aquifer layer is located around TS1 and TS2. The two sounding points are located in the east and northeast of the research area. TS1 was detected at a depth of 39.9 meters to 110 meters with a layer thickness of 60.1 meters and TS2 was at a depth of 40.2 meters to 66.5 meters and 80.2 meters to 139.7 meters with a thickness of 84.8 meters. This aquifer layer is dominated by the gravel sand layer in TS1 and the sand layer in TS2.
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De Paoli, Caroline, Thierry Duren, Estelle Petitclerc, Mathieu Agniel e Alain Dassargues. "Modelling Interactions between Three Aquifer Thermal Energy Storage (ATES) Systems in Brussels (Belgium)". Applied Sciences 13, n. 5 (24 febbraio 2023): 2934. http://dx.doi.org/10.3390/app13052934.
Testo completoAbstract (sommario):
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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Lei, Jun Qin, Xiu Qing Zheng e Hong Fei Zang. "The Effect of Coal Mining on the Multi-Aquifer System". Advanced Materials Research 919-921 (aprile 2014): 1252–56. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.1252.
Testo completoAbstract (sommario):
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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Liu, Yu, Yin Li, Yucheng Hu, Khan M. G. Mostofa, Siliang Li e Zhenying Liu. "Adsorption Characteristics and Transport Behavior of Cr(VI) in Shallow Aquifers Surrounding a Chromium Ore Processing Residue (COPR) Dumpsite". Journal of Chemistry 2019 (3 novembre 2019): 1–10. http://dx.doi.org/10.1155/2019/4932837.
Testo completoAbstract (sommario):
This study explored the stratigraphic distribution and soil/shallow aquifer characteristics surrounding a chromium ore processing residue (COPR) dumpsite at a former chemical factory in China. Total Cr levels in top soils (5–10 cm) nearby the COPR dumpsite were in the range of 8571.4–10711.4 mg/kg. Shallow aquifers (1–6 m) nearby the COPR dumpsite showed a maximum total Cr level of 9756.7 mg/kg. The concentrations of Cr(VI) in groundwater nearby the COPR dumpsite were 766.9–1347.5 mg/L. These results display that the top soils, shallow aquifers, and groundwater of the study site are severely polluted by Cr(VI). Then, three aquifers (silt, clay, and silty clay), respectively, collected from the depth of 1.4–2.4 m, 2.4–4.8 m, and 4.8–11.00 m were first used to evaluate the adsorption characteristics and transport behavior of Cr(VI) in shallow aquifers by both batch and column experiments. The adsorption of Cr(VI) on tested aquifers was well described by pseudo-second-order equation and Freundlich model. The adsorption capacities of Cr(VI) on three aquifers followed the order: clay > silty clay > silt. The kinetics proved that Cr(VI) is not easily adsorbed by the aquifer mediums but transports with groundwater. Thermodynamics indicated that Cr(VI) adsorption on tested aquifers was feasible, spontaneous, and endothermic. Cr(VI) adsorption on tested aquifers decreased with increasing pH. Furthermore, the transport of Cr(VI) in adsorption columns followed the sequence of clay < silty clay < silt. Desorption column experiments infer that the Cr(VI) adsorbed on aquifers will desorb and release into groundwater in the case of rainwater leaching. Therefore, a proper treatment of the COPR and a comprehensive management of soils are vital to prevent groundwater pollution.
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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 e 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, n. 1 (13 febbraio 2024): 46–52. http://dx.doi.org/10.46660/ijeeg.v12i1.146.
Testo completoAbstract (sommario):
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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Katayama, Taiki, Reo Ikawa, Masaru Koshigai e Susumu Sakata. "Microbial methane formation in deep aquifers associated with the sediment burial history at a coastal site". Biogeosciences 20, n. 24 (21 dicembre 2023): 5199–210. http://dx.doi.org/10.5194/bg-20-5199-2023.
Testo completoAbstract (sommario):
Abstract. Elucidating the mechanisms underlying microbial methane formation in subsurface environments is essential to understanding the global carbon cycle. This study examined how microbial methane formation (i.e., methanogenesis) occurs in natural-gas-bearing sedimentary aquifers throughout the sediment burial history. Water samples collected from six aquifers of different depths exhibited ascending vertical gradients in salinity from brine to fresh water and in temperature from mesophilic to psychrophilic conditions. Analyses of gas and water isotopic ratios and microbial communities indicated the predominance of methanogenesis via CO2 reduction. However, the hydrogen isotopic ratio of water changed along the depth and salinity gradient, whereas the ratio of methane changed little, suggesting that in situ methanogenesis in shallow sediments does not significantly contribute to methane in the aquifers. The population of methane-producing microorganisms (methanogens) was highest in the deepest saline aquifers, where the water temperature, salinity, and total organic carbon content of the adjacent mud sediments were the highest. Cultivation of the dominant hydrogenotrophic methanogens in the aquifers showed that the methanogenesis rate was maximized at the temperature corresponding to that of the deepest aquifer. These results suggest that high-temperature conditions in deeply buried sediments are associated with enhanced in situ methanogenesis and that methane that forms in the deepest aquifer migrates upward into the shallower aquifers by diffusion.
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Pluymaekers, M. P. D., L. Kramers, J. D. van Wees, A. Kronimus, S. Nelskamp, T. Boxem e D. Bonté. "Reservoir characterisation of aquifers for direct heat production: Methodology and screening of the potential reservoirs for the Netherlands". Netherlands Journal of Geosciences - Geologie en Mijnbouw 91, n. 4 (dicembre 2012): 621–36. http://dx.doi.org/10.1017/s001677460000041x.
Testo completoAbstract (sommario):
AbstractGeothermal low enthalpy heat in non-magmatic areas can be produced by pumping hot water from aquifers at large depth (>1 km). Key parameters for aquifer performance are temperature, depth, thickness and permeability. Geothermal exploration in the Netherlands can benefit considerably from the wealth of oil and gas data; in many cases hydrocarbon reservoirs form the lateral equivalent of geothermal aquifers. In the past decades subsurface oil and gas data have been used to develop 3D models of the subsurface structure. These models have been used as a starting point for the mapping of geothermal reservoir geometries and its properties. A workflow was developed to map aquifer properties on a regional scale. Transmissivity maps and underlying uncertainty have been obtained for 20 geothermal aquifers. Of particular importance is to take into account corrections for maximum burial depth and the assessment of uncertainties. The mapping of transmissivity and temperature shows favorable aquifer conditions in the northern part of the Netherlands (Rotliegend aquifers), while in the western and southern parts of the Netherlands aquifers of the Triassic and Upper Cretaceous / Jurassic have high prospectivity. Despite the high transmissivity of the Cenozoic aquifers, the limited depth and temperature reduce the prospective geothermal area significantly.The results show a considerable remaining uncertainty of transmissivity values, due to lack of data and heterogeneous spatial data distribution. In part these uncertainties may be significantly reduced by adding well test results and facies parameters for the map interpolation in future work. For underexplored areas this bears a significant risk, but it can also result in much higher flowrates than originally expected, representing an upside in project performance.
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Mazi, K., A. D. Koussis e G. Destouni. "Intensively exploited Mediterranean aquifers: resilience to seawater intrusion and proximity to critical thresholds". Hydrology and Earth System Sciences 18, n. 5 (8 maggio 2014): 1663–77. http://dx.doi.org/10.5194/hess-18-1663-2014.
Testo completoAbstract (sommario):
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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Kovács, Attila. "Quantitative classification of carbonate aquifers based on hydrodynamic behaviour". Hydrogeology Journal 29, n. 1 (27 gennaio 2021): 33–52. http://dx.doi.org/10.1007/s10040-020-02285-w.
Testo completoAbstract (sommario):
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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Strehlow, K., J. H. Gottsmann e A. C. Rust. "Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring". Solid Earth 6, n. 4 (10 novembre 2015): 1207–29. http://dx.doi.org/10.5194/se-6-1207-2015.
Testo completoAbstract (sommario):
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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DAMAYANTI, BLESKADIT CHATERINE, VIRMAN VIRMAN e JOHNSON SIALLAGAN. "ANALISIS KEDALAMAN AKUIFER AIR TANAH DENGAN METODE GEOLISTRIK DI DISTRIK SENTANI KOTA KABUPATEN JAYAPURA". Jurnal Ilmu Pendidikan Indonesia 8, n. 2 (16 giugno 2020): 91–94. http://dx.doi.org/10.31957/jipi.v8i2.1238.
Testo completoAbstract (sommario):
Geophysical research on geoelectric method configuration schlumburger has been carried out in Sentani Kota area, Jayapura district to analyze the depth of groundwater aquifers. The data consisted of seven points measurement spread in Sentani Kota areas namely Kampung Harapan, Hawaii, Kampung Sereh, Kompleks 751, Pasar Lama, Doyo Baru, and Kampung Toware. The data obtained was done by processing data with IP2WIN software, and then made a subsurface profile likes log. Based on data processing, the results obtained showed that in Kampung Harapan the potential groundwater aquifer was found with a resistivity value of 18 Ωm at a depth of > 17.9 m. In the Hawaiian area potential groundwater aquifers are found with resistivity values of 8.92 Ωm at a depth of 64.7 m. In the Kampung Sereh area potential groundwater aquifers were found with resistivity values of 14 Ωm at a depth of 24 m. In the complex area of 751 a depressed groundwater aquifer is found in two layers with a third layer resistivity value of 106 Ωm at a depth of 13.3 m and a fifth layer 81.8 Ωm at a depth of >28.6 m. In the Pasar Lama area groundwater aquifers were found with resistivity values of 102 Ωm at depths > 17.4 m. In the Doyo Baru area, a potential depressed groundwater aquifer was found with a resistivity value of 50.1 Ωm at a depth of 123 m. And in the Kampung Toware a potential groundwater aquifer is found with a resistivity value of 11.5 Ωm at a depth of >27.7 m. From the results of the study, in the Sentani City area, groundwater aquifers were arranged by lithology of sandstone.