Aquifer Layer Research Articles

Investigations on the saline groundwater pumping method and its impact on active saltwater intrusion on a layered aquifer system.

Active saltwater intrusion (ASWI) accelerates and intensifies salinization due to buoyancy force-induced density differences and concurrent inland fresh groundwater flow. This study investigates saline groundwater (SGW) pumping as a remediation technique for ASWI through experimental and field-scale analyses in a layered aquifer system characterised by diminishing permeability with depth. Experiments demonstrated that higher permeability layers reduced length of intrusion (Ltoe) whereas lower permeability layers restricted vertical displacement. The SGW pumping would be effective for gentler gradient and could be achieved by positioning the SGW wells at a distance of approximately one-third distance between the freshwater well and the coastal boundary. This hypothesis was tested by applying it to a layered case study with real aquifer settings with comparable conductivity anisotropy. Field study results confirmed the hypothesis, but cumulative impact of pumping rates and SGW well positioning showed smaller wedge penetration than experimentation due to higher field scale dispersion, resulting in optimal location within one-fourth of the distance. Diverging saddle points explain this phenomenon, which is necessary to provide a pulling force greater than freshwater abstraction. In contrast, an aquifer with passive saltwater intrusion location of wells should be near the shoreline to direct the hydraulic gradient towards the seawater boundary. Simulation results suggested that SGW pumping rates should be three to four times freshwater pumping rates to maximise Ltoe reduction. The findings from this study will aid in determining the optimal locations for placing subsurface intake wells for desalination operations in an aquifer that is impacted by ASWI.

Identification of Groundwater Presence Using ERT (Electrical Resistivity Tomography) in Berkas Village, Teluk Segara Sub-district, Bengkulu City

Kelurahan Berkas is a coastal area in Teluk Segara Sub-district, Bengkulu Regency, Bengkulu Province. The purpose of this research is to identify the presence of groundwater in Kelurahan Berkas. The method used was resistivity geoelectric method with Wenner-Schlumberger configuration. This research applied three lines, the first in the Southwest-Northeast direction and the second in the East-West direction, with a length of 240 metres each. The results show that the free aquifer layer in the first pass has a resistivity value of 1.61 Ω.m to 3.98 Ω.m at a depth of 7 metres to 24 metres. While the second pass has a resistivity value of 3.17 Ω.m to 9.23 Ω.m at a depth of 8 metres to 36.9 metres and the third pass has a resistivity value of 1.62 Ω.m to 7.05 Ω.m at a depth of 2 metres to 20 metres. The results also show that the lithology of the aquifer layer in the study area is interpreted as clay, sandy clay, and sand. This layer contains groundwater that has been affected by seawater intrusion. The influence of this intrusion causes the groundwater to have a relatively low percentage of salinity so that the groundwater at the research location feels brackish. The existence of seawater intrusion is caused by the kelurahan berkas right on the coast so that the kelurahan berkas community lacks clean water, so the well water becomes brackish, therefore with this research the community can find out the location or point where there is groundwater.

Aquifer Exploration Using the Resistivity Method with a Schlumberger Arrays in Sangubanyu Sub-Village, Banyuwangi Village, Bandongan Subdistrict, Magelang Regency

Sangubanyu sub-vilage is administratively located in Banyuwangi Village, Bandongan Subdistrict, Magelang Regency. During the dry season, it is common to find dry wells in the community, making it difficult for residents to access clean water. This situation is highly ironic, as Magelang Regency generally experiences high rainfall, is situated in the Progo and Bogowonto river basins, and is surrounded by mountains that, theoretically, act as water catchment areas. The investigation of aquifer depth was conducted using the Vertical Electrical Sounding (VES) method with a Schlumberger electrode configuration, which is used to map the vertical distribution of subsurface resistivity. VES field data collection was carried out at two measurement points using two current electrodes and two potential electrodes. The electrode spread at each measurement point was 400 meters. The sounding data from each measurement point was interpreted using IP2win software version 3.01, and the results were presented as resistivity logs showing resistivity values, depths, and the thickness of each layer. The interpretation results yielded a 1D resistivity model, showing variations in resistivity with depth. The aquifer layer was identified as sandy tuff with resistivity values ranging from 17 Ωm to 21 Ωm at depths of approximately 33 to 78 meters.

Evaluation and application of a multi-scale numerical model for determining subsurface drainage system design criteria in arid agriculture areas

Subsurface drainage is an effective measure for mitigating soil salinization, while few studies investigated the subsurface drainage design criteria in regional scale and its determining method and influencing factors. In this study, a multi-scale numerical model was established using SDR, MODFLOW-LGR and MT3DMS to simulate the regional groundwater and subsurface drainage. After the model was calibrated and validated by real-world data, a total of 1288 scenarios were simulated to evaluate the effect of subsurface drainage simulation method, grid size and study the influence of irrigation quantity, initial groundwater table depth (GWDini) and soil texture on subsurface drainage design criteria. The results show that utilizing the DRN package to simulate subsurface drainage led to substantial errors, with relative root mean square errors exceeding 120 %. The subsurface drainage amount simulated by SDR generally decreased with increasing grid size, because the groundwater level at the midway is averaged by a larger adjacent region. To balance simulation efficiency and accuracy, a 1 m grid size is appropriate for the SDR package in subsurface drainage simulation, with relative errors smaller than 4.8 %. The design criteria depends on the hydraulic conductivity of the first layer aquifer (Ka), followed by irrigation quantities during the winter irrigation (IWP), GWDini and irrigation quantities during the growth period (IGP). On average, for every 10 % reduction in IWP and IGP (i.e., 64 and 30.2 mm), the minimum pipe depth (MPD) increases by approximately 0.08 m and 0.03 m, respectively. For every 1 m reduction in GWDini, the MPD increases by approximately 0.13 m. When Ka is less than 0.5 m/d, there is a significant increase in MPD due to the decrease in Ka, especially at larger pipe spacing. This study provides references for accurate predictions of regional groundwater and salt dynamics, subsurface drainage and the determination of subsurface drainage design criteria.

Water availability development through groundwater investigations and estimates: Case study at Landungsari village, Malang regency

The population of Landungsari Village is very large, exceeding 9,000 people. With such a substantial population, the need for clean water and sanitation is also considerable. However, the potential sources of raw water for clean water reserves are very limited, especially surface water. The groundwater level at the study site is also quite deep, particularly in the southern parts of Landungsari Village. Rambakan and Bendungan hamlets have groundwater levels ranging from 15 to 25 meters deep. In contrast, Klandungan hamlet averages over 25 meters, and in the vicinity of Thursina Boarding School, it is more than 40 meters deep, making shallow wells impractical. Meanwhile, the clean water supplied by the PDAM is very limited. To address the issue of clean water availability, an investigation through groundwater estimation is necessary to ensure that the selected locations for deep well exploration are not in vain. The results of groundwater estimation must be representative and provide strong scientific justification for the accuracy of the findings. The method used in this investigation is the geoelectric resistivity method using ADMT-300H, which operates based on Darcy's law. It emits electromagnetic waves and measures soil resistivity to identify aquifer layers and determine the depth and thickness of the aquifer. The results obtained with ADMT-300H include: optimal discharge at well 1 (WL-1) of 3.07 l/s and well 2 (WL-2) of 3.14 l/s. Optimal discharge represents the sustainable limit for utilizing groundwater flow.

Review on the Impacts of the Samalas Eruption (1257 CE) to the Hydrogeological Conditions of Mataram, Lombok, Indonesia

This paper examines the local impacts of the 1257 CE Samalas eruption in the Mataram plain in relation to the hydrogeological conditions. Data from several previous studies in the Mataram plain is summarized and then reinterpreted. Data collected from new fieldwork is also presented. This review summarizes hydrogeological conditions into several categories, i.e. stratigraphy, aquifer formation, groundwater quality, and evolution. Two coring data were evaluated, which showed that Mataram plain has a relatively thick alluvial layer with a dominant material of sand mixed with pumice from the reworked deposit of the 1257 CE Samalas eruption. The sediment from this eruption formed a freshwater aquifer layer up to ~18 m deep. Using resistivity data, the aquifer layers in the studied area were characterized as unconfined aquifer, aquitard, and semi-unconfined aquifer. Seven water samples show that the groundwater in the studied area is in good condition, which indicates the bicarbonate water type. The results of the analysis show that the impact of the 1257 CE Samalas eruption on the hydrogeology of Mataram is considered a positive impact, i.e. forming an unconfined aquifer containing freshwater that is good for domestic uses.

Application of Combined Geoelectrical Techniques for Groundwater Exploration at Federal University Gusau, Zamfara and its Environ, Northwest Nigeria

Study’s Excerpt Integrated approach combining Electrical Resistivity Tomography (ERT), Natural Electric Field (NEF) method, and Vertical Electrical Sounding (VES) is used to delineate groundwater potential in the study area. The results revealed that the water bearing aquifers in the study area are fractured basement layers at varying depths between 15 and 105 meters. This research provided a robust framework for groundwater exploration in arid and geologically complex terrains. Full Abstract The area of study is currently facing an acute water shortage due to the dominant lithological framework that underlies the region and its fragile climate condition. As such, this study aimed at unearthing the groundwater potential of the area using a combined three geoelectrical techniques. Techniques such as Electrical Resistivity Tomography (ERT), Natural Electric Field (NEF) method, and Vertical Electrical Sounding (VES) were employed in the delineation of the groundwater potential of the area. Using an ABEM SAS-4000 Resistivity meter and a PQWT-TC150 water-detector equipment, respectively. Wennar array was employed for the conduct of ERT while Schlumberger configuration was used for VES data collection. The measured apparent resistivity value was inputted into RES2DIV software and subjected to an inversion process to generate the resistivity structural image of the subsurface. However, IP2WIN software was used for the VES data interpretation. The result of the ERT method revealed two to three geoelectrical resistivity layers: an overburdened layer of topsoil/laterite with resistivity values ranging from 6.86 Ωm to 1095 Ωm and thicknesses of 1-13 meters, a weathered/fractured basement layer, interpreted as the aquifer unit, with resistivity values between 28.7 Ωm and 345 Ωm, and thicknesses ranging from 6 - 30 meters; and a fresh/slightly fractured basement layer with resistivity values from 367 Ωm to 6899 Ωm. NEF method revealed the thickness and depth of the aquiferous layer across the six profile lines to range between 15-60m, 30-90m, 15-85m, 20-80m, 45-105m, and 20-40m respectively, with points on profile five (5) identified as the most promising site with regards to groundwater development. VES result identifies weathered and fractured layers as the major aquiferous units with resistivity values ranging from 9.965 Ωm to 9651 Ωm and 21.7 Ωm to 859 Ωm respectively with fracture thickness reaching up to 60m in some instances. The result goes in line with the outcome of both NRF and ERT techniques. The geological interference of this lithology on groundwater exploration reveals both the weathered overburden and fractured basement as aquiferous units in the study area. The study identified several promising aquiferous zones at depths ranging from 15 to 105 meters, with fractured basement layers serving as primary reservoirs for groundwater development.

Perforation design coupled with heterogeneity during underground hydrogen storage in steeply dipping anticline aquifers

Hydrogen has been recognized as a crucial energy carrier to reduce greenhouse gas emissions. However, as it is not always possible to meet current energy demands, underground hydrogen storage (UHS) is required for energy supply and consumption. UHS is an emerging field of study with limited investigations regarding structural conditions and wellbore perforation design in steeply dipping anticline aquifers. This study investigates different perforation schemes with respect to UHS within steeply dipping anticline aquifers to find the most suitable injection/production design while examining small-scale reservoir heterogeneities. Several UHS improvement techniques are evaluated, including water and CO2 injection through flank wells during hydrogen production. The results indicate that the highest hydrogen production is achieved with a fully perforated H2 well located at the crest as it provides the maximum contact between the hydrogen and aquifer layers during H2 injection/production. In contrast, hydrogen production is diminished with increased heterogeneity, as higher heterogeneities raise the chance of H2 being trapped. To enhance UHS performance, first H2 initialization before UHS beginning was evaluated but the results showed that it does not enhance UHS performance in a steeply dipped anticline aquifers, as effectively as it does in gas reservoirs. Water injection from flank wells during H2 production cycles showed improvement in hydrogen withdrawal, while water production experienced a slight increase. CO2 injection from flank wells was evaluated to effectively increase H2 recovery as a cushion gas and to maintain hydrogen purity during production. According to results, hydrogen purity was not affected only in high heterogeneity, since more hydrogen gets trapped in the small-scale high heterogeneity level, which prevents the mixing zone from reaching the H2 well during production. While the method prevents hydrogen contamination in anticline aquifers due to the high dip angle coupled with high heterogeneity levels, it leads to a lower hydrogen recovery.

Identification of Groundwater Aquifer Layers in Manyarejo Subdistrict Using the Schlumberger Configuration Geoelectric Method

Abstract Research was conducted to determine the groundwater aquifer layer in Manyarejo Village, Gresik Regency using the Schlumberger configuration 1D geoelectric method. This method is carried out by injecting an electric current into the earth through two electrodes and their potential current. If an electric current is injected into a medium and the potential voltage difference is measured, the resistance value of the medium can be estimated. This research was carried out at 8 points with a track length of 300-700 meters. Then measure with a resistivity meter. Then the data obtained is processed with the IP2Win application to create a picture of the subsurface structure. After interpretation, the results showed that the aquifer consists of 3 layers consisting of clay, clay sand, sand with clay and gravel. And groundwater in aquifer 1 is directed to the West (GL-8), while aquifer 2 is directed to the West and is directed to the North (GL-6). Aquifer 3. Groundwater is found in the resistivity value range of 1 to 100 Ohm Meters. In general, groundwater in aquifer 1 has a resistivity value 1 to 10 Ohm meters, while in aquifer 2 it has a resistivity value of 5 to 20 Ohm meters.

Groundwater Resilience Study for Sustainable Tourism Development Through Electrical Sounding Method in Mansinam Island, Manokwari Regency, West Papua, Indonesia

The sustainable exploitation of groundwater must be understood based on an understanding of geology and hydrogeological conditions. Water availability on small islands has limited reserves and is vulnerable to contamination. In addition, groundwater resources are vulnerable to decreasing groundwater levels in high abstraction without good management practices. Mansinam Island is one of the islands administratively located in Doreri Bay – Manokwari Regency for sustainable tourism development, which has an area of 410.97 Ha. The purpose of this research is to determine the condition and potential of groundwater in the Mansinam Island area. The geoelectric method is a technique that is widely used to characterize groundwater resources, which aims to identify the physical parameters of the subsoil and acquire information about its natural properties. The resistivity values obtained from the field measurement are thus interpreted and determined to be further correlated with geological characteristics as well as aquifer characteristics. On 11 geoelectric paths, good results are presented with a measurement depth of 20 – 23m. The northern area of the measurement on Mansinam Island has a resistivity value of 58.6 - 100Ωm for an aquifer layer containing groundwater potential with a groundwater level (MAT) of 12-20m and aquifer thickness of 3-8m. Meanwhile, the southern area of the geoelectric measurement has a resistivity value of 25.5-100Ωm for an aquifer layer containing groundwater potential, with a groundwater level of 6-12m and aquifer thickness of 8-16m. The southern segment of Mansinam Island has better potential for groundwater, with a relatively shallower depth and thicker aquifer than the northern segment.

Application of remote sensing and electrical resistivity technique for delineating groundwater potential in North Western Nigeria

Improving the living condition of residents of Palladan and Basawa community requires access to drinking water. The main objectives of this paper are to identify suitable groundwater zones for productive drilling and to assess groundwater mineralization in the coastal aquifers of the study area. Geographic Information Systems (GIS) and Analytical Hierarchy Process (AHP) were used in the methodology to generate the groundwater potential map. Slope, landcover/land use, lineament density, rainfall, soil cover and drainage density were taken into account to characterize the groundwater potential zones. Weights were assigned to the various parameters and their characteristics according to their impact on groundwater recharge. The groundwater potential map was classified into five zones namely: poor, fair, moderate, good, excellent. Based on the lineament density map, the distribution of these lineaments reveals the degree of porosity or permeability in each area and, consequently, its groundwater potential. Aeromagnetic data filtering permits the construction of a structural map that illustrates various geophysical lineaments that are known to be fault systems in the research area. These faults are the main routes via which groundwater seeps into the subsurface and granitoid-type magnetic rocks intrude into the basement. The research region is badly fractured/failed and made up of four lithologic units, including the aquifer layer (clayey sands in the cracked basement) with thicknesses varying from 12–55 m, according to the vertical electrical sounding (VES) applications. According to geoelectric cross-sections, the subsurface structures are made of granitic rocks that are surrounded by normal faults that trend both NW and NE. It is believed that groundwater flows into the hard rock aquifers in the studied locations through these notable geological features, such as faults and fractures. Two phenomena are responsible for the mineralization of water: a process of interaction between water and rock; and a process of salinization resulting from natural phenomena or anthropic activities. The present study could guide hydrogeological investigations and groundwater resource management planning in the study area.

Assessment of petrophysical properties of reservoirs by well data

The use of traditional research complexes is of great importance in solving such important problems as correlating well sections for the purpose of lithological assessment, determining the reservoir properties of reservoir layers that make up the section, namely, saturation, porosity, permeability and clay content, as well as identifying oil and gas-bearing and aquifer layers. The complexity of solving such important problems depends entirely on the petrophysical properties of reservoir layers. For example, the electrical resistivities of oil-bearing and aquifer reservoirs are similar in magnitude, which leads to high clay content and significant variation in porosity throughout the field, which, as a result, makes it difficult to separate oil-bearing and aquifer reservoirs from each other. On the other hand, it is also known that an increase in the amount of cementing clays in reservoirs leads to a decrease in porosity and an increase in residual water saturation. In this regard, in the article, based on a set of well data, the values of the petrophysical parameters of reservoir layers were determined, models were built that determine the correlation between them, and regression equations based on the statistical distribution of these parameters were established. The article also built models for the distribution of porosity, permeability, clay content and oil and gas saturation along well sections. The constructed models provide the basis for forming a definite opinion about the field and obtaining results of both a scientific and practical nature when studying the filtration and reservoir characteristics of reservoir layers, as well as when determining the relationship between petrophysical parameters. The object of the study was the on the Kirmakinskaya (KS) and Underkirmaky (UK) formations of the productive series (PS) selected from the wells of the Gyurgyan-Deniz field.

Groundwater Study in Limestone Area using Geophysical Methods

Applied geophysics is important for groundwater investigation. Drilling groundwater boreholes without geophysical survey is probably unsuccessful. Meth district, Vientiane Province is the study site due to the most area coving with limestone area. The objective of this study is to define the groundwater model including location, depth and thickness of aquifer using 2D resistivity measurement, groundwater flow direction using self potential measurement. In addition, basic groundwater quality (pH, Ec and TDS) is also defended. 2D-Electrical Resistivity Tomography (2D-ERT) meauremnt using Wenner arrray was conduced for 2 lines with 300m of length and a varying from a=5m to 100m. Self Potential measurment using fixed-base method was performed for 3 lines with 300m of leng and 10m spacing of each measurming point. The results of the 2D-ERT show that low resistivity from 10 to 80 ohm-m at depth of 20-28m interpreted as aquifer layer. But high resistivity from 200 to 600 ohm-m is resulted from base rock. The volage from SP measurment varying ranging from -14 to 24 mV can be defined the flowdirection from NE-SW direction. It is correlating with the topography of the area. The result of physical properties from 3 samples show that pH=6.8±0.5, Ec=480±115 mS/cm, and TDS=343.3±80.2 mg/l. are under the standard values issued by Minstry of Health, Laos.The water qulity is good . The geophysical survey is effective usful methods for groundwater suvey due to low cost and rapid for survey. Geophysical result could be intributed to comunity, government sectors in order to high effective management the groundwtater resources in the future. Moreover, the data is also usfull for researcher and students.

Effectiveness of different mixed physical barriers in controlling seawater intrusion in homogeneous and layered coastal aquifers

The intrusion of salt water into coastal regions threatens water resources, especially in arid and semi-arid regions. It damages large quantities of fresh water in these regions, and the productivity of the freshwater abstraction wells declines. Management of seawater intrusion (SWI) is therefore needed to improve fresh groundwater in these regions. This study investigated 12 different configurations of mixed physical subsurface barriers (MPBs) to control SWI in homogeneous and heterogeneous layered aquifers. The effectiveness of different MPB locations and configurations was tested, including (i) a barrier wall on the landward side and the subsurface dams on the seaward side, (ii) a barrier wall on the seaward side and a subsurface dam on the landward side, and (iii) the barrier wall was placed above the subsurface dam, both with different permeabilities. All simulations were based on the SEAWAT code. The numerical model was validated against experimental data. The results showed that a permeable cut-off wall above an impermeable subterranean dam (case MPB-3) with different permeabilities resulted in a reduction of the seawater wedge of 91% and 92% for homogeneous and heterogeneous layered aquifers, respectively. When the barrier wall was placed on the land side and the dam on the seaside (case MPB-1), the reduction of the seawater wedge reached 83% and 85% for homogeneous and heterogeneous layered aquifers, respectively. In contrast, when the dam was placed on the land side and the wall on the seaside (case MPB-2), the saltwater wedge was reduced by 73% for both homogeneous and heterogeneous layered aquifers. In addition, a case study was conducted on the Biscayne aquifer, southeast Florida, USA, with homogeneous conditions. Seawater intrusion was reduced by 36% and 44% in case MPB-1, 41% and 38% in case MPB-2, and 43% and 46% in case MPB-3. These seawater intrusion control methods offer numerous benefits, including improving freshwater storage, effectively controlling salinity during droughts, and potentially improving contaminant management.

The Effective Vertical Anisotropy of Layered Aquifers.

Many sedimentary aquifers consist of small layers of coarser and finer material. When groundwater flow in these aquifers is modeled, the hydraulic conductivity may be simulated as homogeneous but anisotropic throughout the aquifer. In practice, the anisotropy factor, the ratio of the horizontal divided by the vertical hydraulic conductivity, is often set to 10. Here, numerical experiments are conducted to determine the effective anisotropy of an aquifer consisting of 400 horizontal layers of which the homogeneous and isotropic hydraulic conductivity varies over two orders of magnitude. Groundwater flow is simulated to a partially penetrating canal and a partially penetrating well. Numerical experiments are conducted for 1000 random realizations of the 400 layers, by varying the sequence of the layers, not their conductivity. It is demonstrated that the effective anisotropy of the homogeneous model is a model parameter that depends on the flow field. For example, the effective anisotropy for flow to a partially penetrating canal differs from the effective anisotropy for flow to a partially penetrating well in an aquifer consisting of the exact same 400 layers. The effective anisotropy also depends on the sequence of the layers. The effective anisotropy values of the 1000 realizations range from roughly 5 to 50 for the considered situations. A factor of 10 represents a median value (a reasonable value to start model calibration for the conductivity variations considered here). The median is similar to the equivalent anisotropy, defined as the arithmetic mean of the hydraulic conductivities divided by the harmonic mean.

Advancing Sustainable Geothermal Energy: A Case Study of Controlled Source Audio-Frequency Magnetotellurics Applications in Qihe, Shandong

Geothermal energy is a key part of sustainable and renewable energy strategies, especially for clean heating in northern regions. This study focuses on Qihe County in Shandong Province, applying a controlled source audio-frequency magnetotellurics (CSAMT) method to investigate deep karst geothermal reservoirs. This research addresses the complex geological conditions and electromagnetic interference in the region, aiming to improve sustainable geothermal resource development. The findings indicate that the geothermal reservoir in the study area primarily consists of Ordovician limestone, characterized by moderate burial depth, high water volume, and elevated water temperature. Integrating CSAMT with vertical electrical sounding (VES) and radiometric surveying has clearly defined the deep aquifer layers and major water-controlling fault structures. Drilling verification results demonstrate the significant effectiveness of the integrated geophysical methods employed, providing reliable technical support for deep geothermal exploration in similar regions. This study makes a significant contribution to the scientific and technical foundation necessary for the sustainable development and utilization of geothermal resources, supporting the broader goals of environmental sustainability and renewable energy.

Identification of Aquifer Layer Using Geoelectric Method in Oil Palm Plantation Area of PT Unggul Widya Teknologi Lestari Pasangkayu Regency

Introduction: Aquifer layers have been identified in the oil palm plantation area of PT Unggul Widya Teknologi Lestari Pasangkayu Regency. This study aims to determine the lithology of subsurface rocks and the depth of the aquifer layer as a source of clean water in the study area. Method: This study uses the geoelectric method of type resistance with Wenner configuration, with the number of electrodes 24 rods and a spacing of 10 meters. 2D cross-sectional model using Res2Dinv software program. Results and Discussion: Based on the value of the type resistance of the subsurface constituent rock lithology at the research site is interpreted to consist of three layers, namely clay with a specific resistance value < 29.15 Ωm, sand and sandy clay with a specific resistance value of 29.15 Ωm to 72.89 Ωm, and conglomerate with a specific resistance value > 72.89 Ωm. The aquifer layer is interpreted with a specific resistance value of 29.15 Ωm to 72.89 Ωm. The aquifer layer is detected to spread from the northeast to the southwest of the research site with a depth of ±25-39 m. Conclusion: In the oil palm plantation of PT Unggul Widya Teknologi Lestari, the subsurface layer consists of clay (1.98 Ωm - 29.15 Ωm), sand and passive clay (29.15 Ωm - 72.89 Ωm), and conglomerate (72.89 Ωm - 1120.5 Ωm). Thin aquifers, with a thickness of 5-10 m and depth of 25-39 m, are detected in the sand and sandy clay layers.

Seismically-induced groundwater flow into confining clays: An experimental and numerical study

This study investigates seismically-induced hydraulic responses in an aquifer system focusing on the hydraulic interaction between a model aquifer and confining clays following shaking as experienced during seismic events. These responses are being investigated by both experimental and numerical methods. In contrast to the conventional assumption assuming a clay layer as a hydraulic barrier to seismically-induced hydrological responses in an aquifer, this study highlights that the excess pore pressure in the aquifer generated by shaking may facilitate water flow crossing the overlying clay layer. This hypothesis is supported by experimental results that show measurable surface settling, excess pore pressure and step-like wellbore water level increase following shaking-induced sand consolidation, and notably, upward flow of water from an aquifer into the clay layer indicated by sustained water level drops in the well after shaking experiments. Numerical simulations further reveal that perturbations influence water flow from the aquifer to the clay layer, modifying pressure distribution within both layers. Key factors such as aquifer flow regime, hydraulic conductivity of the aquifer and clay layer, and their effects on flow dynamics are addressed by numerical modeling. This study provides insights into hydraulic responses and contributes to risk assessments in the context of seismic perturbations.

Three-dimensional model and environmental fragility in the Guarani Aquifer system, SE-Brazil

The Guarani Aquifer System (GAS) is a vast transboundary continental sedimentary basin in southern South America, encompassing sedimentary rocks and basalt flows across Uruguay, Paraguay, Argentina, and Brazil. It serves as a crucial water resource for urban supply and irrigation. This study aims to propose geophysical, geometric, and fragility models of the GAS in a critical exploitation area, utilizing geological data, geophysical logs, geomorphometry, and information from tubular wells. The models define distinct geophysical ranges for each formation and identify contacts between sedimentary and basaltic rocks. Integration of horizontal and vertical spatial distributions of geophysical and geological data forms a 3D model, revealing basaltic flows and intrusions distribution in fragile areas between formations, and potentially connecting aquifer layers. Natural fragility zones, characterized by high fracture densities, are observed in the central-east region, while outcrop and recharge areas of the main aquifer hydrofacies are found in the north. The 3D model highlights similarities between the topography of the Botucatu Formation (KJb – eolian sandstones) and the potentiometry of GAS at local scales, and overexploitation zones in Ribeirão Preto's city center. The assessment prioritizes areas at risk and conservation strategies for sedimentary aquifers, emphasizing interactions between surface and groundwater and addressing issues of overexploitation, identifying high-impact risks on GAS hydrodynamics and water quality.

Radiological impact of hydrocarbon waste release on drinking water of ughievwen and udu communities, delta state Nigeria

Well water quality has been characterized with constant and continuous changes via the interaction of rock, soil and natural nano-filters which terminates at the aquiferous layer for clean well-water collection. The continuous exploration and production of crude oil has resulted significant increase of unwanted elements such as naturally occurring radionuclides in the water-bed which necessitates this study. The study determines the radionuclides based health impact or hazards associated with drinking water from crude oil exploration/production release in Ughievwen and Udu communities of Delta State, Nigeria. Sixty well water samples (three samples from each community) were collected and analyzed using sodium iodide (Nal (Tl)) detector. The obtained mean values of 238U, 232Th and 40K are 6.91 ± 1.62BqL−1, 4.39 ± 1.47 BqL−1 and 24.54 ± 1.59 BqL−1 respectively. The 238U, 232Th and 40K results showed that the measured values are higher than the world standard (UNSCEAR; WHO) and the control values The mean values of total annual effective dose of different age groups are: 11.08 mSvy−1, 2.54 mSvy−1, 1.93 mSvy−1, 2.52 mSvy−1, 7.03 mSvy−1 and 1.12 mSvy−1 respectively. While the mean committed effective dose of adult is 55.94 mSvy−1. The total annual effective dose, committed effective dose, cancer risks and hereditary effects are all lower than recommended limit (WHO; ICRP; USEPA) and reported scientific values except 11.08 mSvy−1 and 7.03 mSvy−1 that are higher than limit. It is evident from obtained results that the drinking water may not be radiologically safe for use by the public, which necessitates routine monitoring and caution to circumvent increase in radiation and the radiological of the studied communities’ drinking water. This is to avoid long term radiological risk arising from accumulation of such release in the studied communities.