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Groundwater resource management in drylands, characterized by climate variability and population growth, is difficult. Exploration and exploitation of groundwater, due to inadequate surface water is very costly. This study employed the analytic hierarchy process (AHP) and GIS to identify groundwater potential (GWP) areas in a semi-arid region of Nigeria. Land-use-land-cover, drainage density, slope, rainfall, static water level, soil, lithology, and aquifer were selected for GWP analysis. Parameter weights were determined using AHP and ranked based on their contribution to GWP by experts. The parameters were then integrated using the weighted overlay tool in ArcGIS 10.5 to produce a GWP map of the study area. Borehole yield data from 245 wells were collected to determine the model accuracy and model validation. Results classified the study area into very high GWP (1.9%), high GWP (8.8%), moderate GWP (62%), low GWP (20.70%) and very low GWP (6.6%). Areas with better GWP include Gurun, Dugol, Zago, Kumbo, Dukku, Doguwa, Riruwai, Dambazau, etc. Moderate GWP areas are widely spread across the state while areas with poor GWP include Sharawa, Kadewa, Koya, Dagar, Jigilawa, Galwanga, Yanganau, Kunchi, Tofa, Tsanyawa, etc. Validation of the AHP model with borehole yield data shows a correlation coefficient of 71.3% giving a good prediction. AHP and GIS can be used to successfully map GWP areas which could serve as an exploration guide for sustainable management of groundwater resources in semi-arid areas. [ABSTRACT FROM AUTHOR]

The growing expansion of the economy and population has resulted in an increased inclination towards the utilization of groundwater resources. Conducting a geophysical survey is a widely employed method for subsurface mapping and the detection of groundwater. A geophysical study was conducted in Nanshan township, Huarong County, located in the Hunan province of the South-Central region of China. The investigation involved the utilization of a 2D electrical resistivity imaging technique employing forward and inverse pole–dipole electrode arrays. A total of six survey lines were established, each with an electrode distance from the nearest measuring point exceeding 800 m. The maximum current electrode separation was utilized in this setup. The spacing between the electrical resistivity sounding points was established at regular intervals. The findings from the exploration indicate the existence of multiple faults within the surveyed region. The study additionally identified two regions of structural failure, which occurred due to the convergence of faults oriented in different directions. This convergence led to the fracturing of rocks, an increase in water content, and a decrease in resistivity. The findings from the exploration were utilized in the formulation of five verification target boreholes. The results of this study offer significant insights that can inform future investigations into groundwater exploration endeavors within the region. [ABSTRACT FROM AUTHOR]

This study explores the intricate relationship between land subsidence and urban development in the Quetta and Mastung districts, focusing on the challenges and opportunities for mitigating subsidence impacts on future development. Quetta, the capital of Baluchistan province in Pakistan, covers 3,447 km² and has a population of 1.001 million, having experienced significant growth over the past five decades. Mastung district, adjacent to Quetta, spans 3,308 km² with a population of 35,129 according to the 2017 Census. Over the past thirty years, both districts have undergone rapid urbanization across various sectors, including industry, trade, transportation, and real estate. This urban expansion, however, has led to environmental challenges, notably land subsidence, which threatens urban development plans and regional progress. Land subsidence in Quetta and Mastung is driven by several factors: excessive groundwater extraction, the collapse of the traditional Karez system, structural weight on compressible soils, and the natural consolidation of alluvial soils. "InSAR" (Interferometric Synthetic Aperture Radar) imagery highlights the extent of this subsidence, showing a maximum Line of Sight (LOS) rate of 15 cm/year in Quetta and approximately 4–5 cm/year in Mastung. These findings emphasize the urgent need to address land subsidence to ensure sustainable urban development in both districts. [ABSTRACT FROM AUTHOR]

The subsurface aquifer zone is significant groundwater source, hence this paper investigates subsurface aquifer zones in Kaiama Community, Kolokuma/Opokuma local government area of Bayelsa State, Nigeria with the purpose of exploring groundwater using geoelectric sounding (GES) surveys. Five survey points were examined using Schlumberger electrode configuration and deploying SAS 1000 Terrameter set, with data processed with IPI2win software. Each survey station revealed distinct layers with varying resistivity, depth, and lithology, offering crucial insights into subsurface features and aquifer systems. For GES 1, indicates five layers showing their resistivity values with respect to depth as 400.7Om with a depth of 0.6m as top soil, 16.14Om-51.01Om with a depth of 3.219-7.4356m as clay and layer 6 expressed as 19527Om with a depth of 30.01m as coarse sand and aquiferous layer. GES 2 along Kaiama's East-West Road delineated four layers with resistivity value of 467.2Om with a dpth of 1.264m as top soil, 54.5Om with a depth of 18.8m as clay and 2738Om with a depth of 40.01m as coarse sand, which also indicates as a potential aquiferous layer. GES 3 at R.PM School 1 Field identified five layers, highlighting 121.1Om with a depth of 0.6m as top soil, 16.67Om-5795Om with depth of 40.2m as clay with a resistivity potential of 237.7Om with a depth of 60.01m as medium sand and subsurface aquiferous layer. GES 4 at Kaiama Grammar School field revealed six layers, with resistivity value of 327.9Om with adepth of 0.6m as top soil, 6.383-20.51Om with depth of 3.219-7.456m as clay and 800Om with depth of 17.27m as medium sand and resistivity of 91599Om with depth of 30.22m as coarse sand medium sand indicating potential aquifer zones. GES 5 at Isokiwari Compound Kaiama showcased five layers: resistivity of 43.7Om with depth of 0.6m as top soil, 300.5Om-417.8Om with depth of 1.39-7,521m as medium sand, 65.17Om-112.5Om with depth of 17.33-40.07m as clay. The findings provide valuable information for groundwater management and resource exploration in the region, emphasizing the significance of understanding subsurface geology for sustainable water access. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the education of applied geophysics, innovative learning tools are essential to bridge the gap between theory and practical field experience. Fieldwork is critical for reinforcing classroom knowledge and fostering peer interactions. However, it faces financial costs, physical accessibility, and logistical challenges, which can deter student participation and create equity concerns. To address these issues, adaptable educational models and digitalization are crucial. Integrating Information and Communication Technologies (ICT) has significantly enhanced learning processes, with alternatives like recorded fieldwork videos, high-resolution imagery, and virtual outcrop models gaining prominence, particularly during the COVID-19 pandemic. Through thoughtful design, video games offer educational potential by enhancing motivation and engagement. This paper introduces Electromagnetic Odyssey, an immersive learning tool to overcome traditional field trips’ financial and logistical constraints. The video game considers the application of Electromagnetic methods for groundwater exploration. Electromagnetic Odyssey aims to promote equitable access to quality education and motivate students through well-designed, technology-enhanced activities, aligning with educational principles emphasizing motivation’s importance in learning.

Groundwater resource management in drylands, characterized by climate variability and population growth, is difficult. Exploration and exploitation of groundwater, due to inadequate surface water is very costly. This study employed the analytic hierarchy process (AHP) and GIS to identify groundwater potential (GWP) areas in a semi-arid region of Nigeria. Land-use-land-cover, drainage density, slope, rainfall, static water level, soil, lithology, and aquifer were selected for GWP analysis. Parameter weights were determined using AHP and ranked based on their contribution to GWP by experts. The parameters were then integrated using the weighted overlay tool in ArcGIS 10.5 to produce a GWP map of the study area. Borehole yield data from 245 wells were collected to determine the model accuracy and model validation. Results classified the study area into very high GWP (1.9%), high GWP (8.8%), moderate GWP (62%), low GWP (20.70%) and very low GWP (6.6%). Areas with better GWP include Gurun, Dugol, Zago, Kumbo, Dukku, Doguwa, Riruwai, Dambazau, etc. Moderate GWP areas are widely spread across the state while areas with poor GWP include Sharawa, Kadewa, Koya, Dagar, Jigilawa, Galwanga, Yanganau, Kunchi, Tofa, Tsanyawa, etc. Validation of the AHP model with borehole yield data shows a correlation coefficient of 71.3% giving a good prediction. AHP and GIS can be used to successfully map GWP areas which could serve as an exploration guide for sustainable management of groundwater resources in semi-arid areas.

Climate change has significantly impacted the availability of freshwater in several countries, particularly the African continent. In parallel, the increasing demand for water supply for domestic uses, irrigation and industry is putting more pressure on water reserves, leading to even more water scarcity. Groundwater on the other hand, still holds great potential for water supply reinforcement. aquifers remain largely underexploited in many regions, especially in inaccessible hard rock terrains. In this sense, remote sensing offers a cost-effective way to map groundwater occurrence in these geologically complex terrains. This research aims to delineate groundwater potential in the Sirwa massif, Anti-Atlas, Morocco. initially, a spatial analysis incorporating remote sensing and geophysical data was performed to create nine factors that impact groundwater occurrence including the lithology, fault density, lineament density, node density, slope, distance from rivers, drainage density, topographic wetness index, land use/land cover. Followed by a fuzzy analytic hierarchy process to evaluate the degree of influence of each factor on groundwater occurrence. The groundwater potential map shows that less than 8% of the total study area has high to very high groundwater potential. The remaining surface area (92%) is split between moderate (35.59%) and poor to very poor groundwater potential (55.51%). The predicted map was validated through receiver operating characteristic (ROC) using active borewell data (a success rate of 79.1%). Ultimately, the results shed light on suitable sites for groundwater resources, helping stakeholders to reduce the scale of prospection and make informed decisions for sustainable water management. [ABSTRACT FROM AUTHOR]

The subsurface aquifer zone is significant groundwater source, hence this paper investigates subsurface aquifer zones in Kaiama Community, Kolokuma/Opokuma local government area of Bayelsa State, Nigeria with the purpose of exploring groundwater using geoelectric sounding (GES) surveys. Five survey points were examined using Schlumberger electrode configuration and deploying SAS 1000 Terrameter set, with data processed with IPI2win software. Each survey station revealed distinct layers with varying resistivity, depth, and lithology, offering crucial insights into subsurface features and aquifer systems. For GES 1, indicates five layers showing their resistivity values with respect to depth as 400.7Ωm with a depth of 0.6m as top soil, 16.14Ωm-51.01Ωm with a depth of 3.219-7.4356m as clay and layer 6 expressed as 19527Ωm with a depth of 30.01m as coarse sand and aquiferous layer. GES 2 along Kaiama's East-West Road delineated four layers with resistivity value of 467.2Ωm with a dpth of 1.264m as top soil, 54.5Ωm with a depth of 18.8m as clay and 2738Ωm with a depth of 40.01m as coarse sand, which also indicates as a potential aquiferous layer. GES 3 at R.PM School 1 Field identified five layers, highlighting 121.1Ωm with a depth of 0.6m as top soil, 16.67Ωm-5795Ωm with depth of 40.2m as clay with a resistivity potential of 237.7Ωm with a depth of 60.01m as medium sand and subsurface aquiferous layer. GES 4 at Kaiama Grammar School field revealed six layers, with resistivity value of 327.9Ωm with adepth of 0.6m as top soil, 6.383-20.51Ωm with depth of 3.219-7.456m as clay and 800Ωm with depth of 17.27m as medium sand and resistivity of 91599Ωm with depth of 30.22m as coarse sand medium sand indicating potential aquifer zones. GES 5 at Isokiwari Compound Kaiama showcased five layers: resistivity of 43.7Ωm with depth of 0.6m as top soil, 300.5Ωm-417.8Ωm with depth of 1.39-7,521m as medium sand, 65.17Ωm-112.5Ωm with depth of 17.33-40.07m as clay. The findings provide valuable information for groundwater management and resource exploration in the region, emphasizing the significance of understanding subsurface geology for sustainable water access.

The growing expansion of the economy and population has resulted in an increased inclination towards the utilization of groundwater resources. Conducting a geophysical survey is a widely employed method for subsurface mapping and the detection of groundwater. A geophysical study was conducted in Nanshan township, Huarong County, located in the Hunan province of the South-Central region of China. The investigation involved the utilization of a 2D electrical resistivity imaging technique employing forward and inverse pole–dipole electrode arrays. A total of six survey lines were established, each with an electrode distance from the nearest measuring point exceeding 800 m. The maximum current electrode separation was utilized in this setup. The spacing between the electrical resistivity sounding points was established at regular intervals. The findings from the exploration indicate the existence of multiple faults within the surveyed region. The study additionally identified two regions of structural failure, which occurred due to the convergence of faults oriented in different directions. This convergence led to the fracturing of rocks, an increase in water content, and a decrease in resistivity. The findings from the exploration were utilized in the formulation of five verification target boreholes. The results of this study offer significant insights that can inform future investigations into groundwater exploration endeavors within the region.

One of the world's most pressing needs today is access to groundwater. Although hydrological parameters can generally be estimated using underground studies, these methods are time-consuming and expensive. By taking the direct relationship of these parameters with electrical resistivity and measuring it with a cheaper and faster geoelectric method, a qualitative estimate of these parameters will be obtained. The electrical resistivity method is one of the most widely used methods to probe aquifers. The main objective of this paper is to show how, by interpreting and modeling the data of this exploratory method along with other geological information, the hydrogeological modeling of groundwater reservoirs can be done, and then, with an informed vision, the wells can be drilled for exploitation. For this purpose, the electrical resistivity data at 189 points and 9 profiles in the Shahroud region with Schlumberger array, after reviewing and making some modifications, were subjected to one-dimensional inverse modeling. According to the peripheral vision, the electrode distance was considered to be 50 meters and the length of the profiles is different. The longest profile was 1000 meter and related to profile 3. Then, using the results of modeling along with other available information, the hydrogeological models of the area were prepared in the form of iso-resistivity contour map and interpreted in terms of resistivity and thickness of subsurface layer using computer software Geographic Information System (GIS). Similarly, the thickness map of the aquifer unit (s) was also prepared to classify the good and poor zones. Using the prepared models and also considering the direction and piezometric of the groundwater flow inside the aquifer, suitable places were identified and suggested for future exploitation. [ABSTRACT FROM AUTHOR]

Study region: Our study region is the Aconcagua basin, central Chile. The catchment, home to over 500,000 people, currently experiences a multiyear drought that threatens water security. In this context, there is an impending need to explore unconventional groundwater resources, such as peripheral hard rock and deep aquifers. Study focus: The focus of this study is the application of machine learning techniques to identify areas of potentially untapped groundwater resources in the middle and upper reaches of the Aconcagua basin. New hydrological insights for the region: Machine learning classifiers accurately depict those areas known for their high groundwater potential, including the San Felipe, Putaendo, Panquehue, Catemu and Llay-Llay sectors. The Mesozoic sedimentary sequences and intrusive units of the coastal range, together with the Neogene units of the Andes range, are correctly identified as areas of very low hydrogeological interest. A major novelty of this study is the delineation of several new areas of potentially high groundwater prospect, namely, the geological domain associated with the Pocuro fault system, the Teatinos-Volcan-River fault system, and the Las Chilcas volcano-sedimentary sequence, in the Chacabuco Range. These findings are in line with the results of complementary studies, thus suggesting that machine learning applications may successfully underpin groundwater exploration across other groundwater basins in the coastal Andean region.

Traditionally Borana people used to excavate a little depth in the stream alluvium, to collect the groundwater coming from side to side of outflow and use different purposes in arid and semi-arid regions, where there is no visible flow of water along the streams. In Borana semiarid region of southern Ethiopia, groundwater has been used as the source for almost all individual livestock and other domestic water supply systems. Therefore, the assessment and evaluation of traditional groundwater exploration methods is essential for the pastoral communities in arid zone like Borana of southern Ethiopia. Groundwater exploration method is the technique way to inquiry the ground formations, hydrologic cycle, nature of aquifers, and land cover of the study area. Traditional groundwater exploration method is an indigenous task to identifying the location of groundwater availability. Recently, more techniques have developed to explore the groundwater; classified as surface and subsurface methods. Traditional ground water exploration method is the part of the surface method. Traditional groundwater exploration and supply system in Borana is essential in modern hydrology. Traditionally, Borana explored groundwater by three indigenous methods. Traditional Groundwater Exploration Method for Pastoralist Community Water Supply Systems in semi-arid regions and others requires the basic concepts of position in the subsurface geological setup and natural land cover. [ABSTRACT FROM AUTHOR]

Groundwater exploitation requires better understanding of the resource availability and quality/vulnerability. Geophysical techniques, pumping test, hydraulic measurement, borehole logging and quality test analysis have been used in Ibulesoro, southwestern Nigeria, to understanding the hydrogeological system in terms of groundwater availability, aquifer delineation, and evaluate the groundwater physico-chemical and biological contents. The study utilized multi-criteria evaluation techniques (GWPIV) to assess the overall aquifer potential/vulnerability. The geology of the area comprises granite, migmatite, migmatite gneiss, biotitic granite, and gneiss. The main water-bearing unit was the weathered layer and fractured basement, which are usually unconfined aquifer. The hydraulic conductivity and formation factor is related by y = 0.239e0.0519x with correlation coefficient of 0.0961. The average hydraulic conductivity and transmissivity are 0.52 m/d and 5.78 m2/d respectively. The hydrogeological parameters viability increases southwardly, just as groundwater movement/flow is due south. The average thickness of the weathered layer and overburden are 8.6 m and 16.1 m respectively, with dominant resistivity in the range of 80 - 200 ohm-m. The best drilling points (migmatite/gneiss geologic units) are where the fractured basement underlies the weathered layer which most not necessarily exceed 30 - 35 m. The average depth to basement rock is 16.1 m. The obtained GWPIV varied from 1.12 to 1.71, with an average of 1.30 suggesting low potential but good for drinking and irrigation uses in its present state, however highly vulnerability to contamination, as the vadose zone thickness (5.68 m avg.), AVI (0.57 avg.), and LC (0.0818 mhos avg.) all point to the low protective capability. The water types is mixed Ca-Mg-Cl. The mechanism controlling the groundwater quality falls in the mixed zone, which indicates contribution from soil/rock-water interaction, precipitation, and evaporation; while carbonic weathering is more active than the silicate weathering process. [ABSTRACT FROM AUTHOR]

Water is an essential natural resource without which life wouldn’t exist. The study aims to identify groundwater potential areas in Vepapanthattai taluk of Perambalur district, Tamil Nadu, India, using analytic hierarchy process (AHP) model. Remote sensing and magnetic parameters have been used to determine the evaluation indicators for groundwater occurrence under the ArcGIS environment. Groundwater occurrence is linked to structural porosity and permeability over the predominantly hard rock terrain, making magnetic data more relevant for locating groundwater potential zones in the research area. NE-SW and NW-SE trending magnetic breaks derived from reduction to pole map are found to be more significant for groundwater exploration. The lineaments rose diagram indicates the general trend of the fracture to be in the NE-SW direction. Assigned normalised criteria weights acquired using the AHP model was used to reclassify the thematic layers. As a result, the taluk’s low, moderate, and high potential zones cover 25.08%, 25.68% and 49.24% of the study area, respectively. The high potential zones exhibit characteristics favourable for groundwater infiltration and storage, with factors as gentle slope of

Twenty (20) vertical electrical soundings were acquired using ABEM SAS 300 terrameter in order to determine the hydraulic characteristics of the identified aquifers within Adamu Augie College of Education Argungu near Birnin Kebbi, Northwestern Nigeria. The data were interpreted and seven sounding curves were obtained (KH, HQ, HA, HK, AA, A, and Q). The generated geoelectric sections characterized the subsurface into six lithologic units (topsoil, clayey sand, sandstone, clay, shale and sand) with sandstone and sand constituting the major aquifers in the area. The resistivity layer parameters delineated across the entire area were used to determine the hydraulic characteristics of the identified aquifers. The delineated layers above the aquifers showed transverse resistance ranging from 333.06Ωm2 to 23100.61Ωm2 , longitudinal conductance S from 0.025047 to 1.226506 mhos, hydraulic conductivity K from 0.44 m/day to 25.57 m/day, transmissivity T from 7.144 m2 /day to 465.374m2 /day, and coefficient of anisotropy from 0.98 to 1.0. The protective map shows that about 75% of the area falls within poor overburden protective capacity, 20% constitute moderate protective capacity, while the remaining 5% have good protective capacity rating. Therefore, the hydraulic characteristics of the area suggest that the materials above aquifers are less protected, and by implication vulnerable to infiltration.

Groundwater exploration is the most promising way to overcome water scarcity in hyper-arid regions around the world. Due to the scarcity of hydrogeological information in these regions, groundwater exploration is a challenging issue requiring the joint application of satellite and land-based information to delineate the groundwater aquifers in such harsh environments. In this research, an integrative approach was undertaken for groundwater exploration in the southwestern corner of Egypt as one of the most hyper-arid regions in North Africa. To fill the knowledge gap in this large area, two high-resolution satellite gravity datasets (EIGEN-6C4 and TOPEX-1min) were employed in combination with land-based geophysical surveys for a better understanding of groundwater potentialities in terms of structural controls. Further, the approaches of high-pass filter, tilt angle derivative, and enhanced horizontal gradient amplitude were used to analyze EIGEN-6C4 dataset. Additionally, 2D and 3D models along with a high-pass filtered gravity map were constructed to provide the subsurface barriers and preferential groundwater flow pathways. Several NNE windows have been recognized, particularly to the east of Gabel Kamel along Uweinat-Aswan uplifting allowing groundwater flow along northeastern structural trends. To verify this assumption, land-based magnetic and DC resistivity sounding surveys were executed at two selected sites based on the interpretation of satellite gravity and remote sensing data. The resistivity and 2D magnetic modeling reveal the presence of remarkable sub-basins with sufficient saturated sedimentary cover. Ultimately, the review of the different datasets, including satellite gravity and land-based geophysical investigations, facilitated the geological interpretation for detecting the structural controls on the groundwater flow paths and produced satisfactory results at shorter time frames and lower costs compared to typical groundwater exploration in arid or hyper-arid regions of the same characteristics elsewhere. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Groundwater is a strategic resource for economic development, social justice, environmental sustainability, and water governance. The lower Casas Grandes River Basin, located in the state of Chihuahua, México, is in a semi-arid region with increasing groundwater demand and regional challenges such as drought and depletion of aquifers. Even though there is official information about the availability of groundwater, a comprehensive aquifer characterization requiring an interdisciplinary investigation using a diverse suite of tools and multiple data sources has yet to be carried out. This study presents a multi-technique framework to evaluate potential sites to drill for groundwater resources and reduce the risk of unsuccessful drilling. The main components of the methodology include wellhead leveling correction with a differential global positioning survey to define piezometric levels, principal component analysis using LANDSAT-8 images, application of geospatial tools, geophysics analysis using time domain electromagnetic surveys (TDES) and vertical electric soundings (VES), and structural geohydrology to define aquifer characteristics. The results showed that using the proposed framework steps improved the possibility of identifying subsurface layers with lower resistivity values that could be related to groundwater. Low resistivity values (35 Ohm-m) were found at depths from 50 to 85 m at sites where the regional static water level reached a depth of 245 m, indicating the potential location of a shallow groundwater resource at a site where the intersection of a fracture trace was identified. This procedure can be used in other regions in the world where limited information is available for groundwater exploration, thus reducing the risk of drilling dry wells in complex hydrogeological environments. [ABSTRACT FROM AUTHOR]

Penang Island is the most water-vulnerable state in Malaysia. Groundwater is an alternative water source that has not been thoroughly explored within the state. This paper aims to delineate areas of high and low groundwater potential on the island via an integrated approach of remote sensing and geographical information system techniques, with validation using 2D resistivity data. Groundwater potential map was generated using weighted sum of 7 thematic layers: lineament density, geomorphology, rainfall, lithology, slope, drainage density, and land use. Model was validated by evaluating the (a) predictive accuracy of the map, and (b) Spearman's correlation between groundwater potential score and the potential groundwater (10–100 Ohm-m) within inverted resistivity model. Regions classified as "Low" on groundwater potential were predominantly hilly, forested areas with granitic lithology (e.g., Taman Negara). Regions classified as "Very High" were mainly coastal urban and agricultural areas with alluvial lithology (e.g., Georgetown). Inland Georgetown, inland Balik Pulau, and Ayer Itam were identified as regions of hard rock terrain with "High" groundwater potential. Strong relationship was found between groundwater potential score and the percentage of potential groundwater in inverted resistivity models, ρ(5) = 0.72, 90% CI [0.09, 0.94]. Furthermore, the map was 83% accurate in identifying regions with suitable groundwater abstraction zones. Findings corroborated with meta-analysis of five studies, where mean correlation of ρ = 0.77, 90% CI [0.67, 0.87] was found between groundwater potential score/classification and validation measure. This paper demonstrates the potential in utilizing geoelectrical data for groundwater potential map validation, especially for regions with limited well yield data. [ABSTRACT FROM AUTHOR]

Groundwater exploration is increasing in demand, including use in the domestic, industrial and agricultural sectors. The extracted groundwater is an alternative water supply in these sectors. However, there has also been unsuccessful groundwater exploration due to limited subsurface information. Therefore, geophysical methods were applied to obtain subsurface information to determine and classify the subsurface materials using selected geophysical properties. This research aims to evaluate the delineation of potential groundwater zones using 2D electrical resistivity imaging in Universiti Sains Malaysia, Penang Island, Malaysia. Nine resistivity survey lines are conducted within the research area in USM. The geology of the research area is underlain by igneous rock with a centrally located granitic range running in a north-south direction with low-lying elevations ranging from 5 meters to 20 meters above sea level. The electrical resistivity method measures the resistivity distribution by injecting a small current into the ground through two current and potential electrodes, respectively. The voltage reading is measured between two active potential electrodes alternatively. The instrument used for this research is an automated multi-electrode resistivity meter, ABEM Terrameter SAS 4000 system. Apparent resistivity values undergo an inversion process using RES2DINV software to produce the electrical resistivity topography model. The results show the resistivity values ranging from 1Ùm to 20000Ùm. The subsurface materials are classified into four subsurface materials according to the resistivity values ranges: water-saturated zones, topsoil, weathered bedrock, and fresh bedrock. Several anomalies are interpreted as potential water-saturated zones within the project area and suggested as proposed drilling locations for the groundwater drilling program. The extracted groundwater can act as an alternative source for water supplies in Universiti Sains Malaysia. [ABSTRACT FROM AUTHOR]

Drinking water shortage is a major concern in villages across southern Jiangxi, and this has impacted economic and social development. In order to address this challenge, groundwater prospecting was carried out in the villages under the support of Drinking Water Safety Project of China Geological Survey. In this study, we present two example sites in Ningdu County selected to demonstrate the combined hydrogeological survey, and the direct current electrical resistivity method was utilized for the present study for groundwater exploration in karst-granite distribution areas. First, a hydrogeological study was effectively used to delineate shallow severely weathered structural fissures as prospective target water-bearing beds. Then, a direct current electrical resistivity survey was used to confirm the distribution, thickness scale, and water-bearing features. The structural fractured zone whose distribution and trend were first established through hydrogeological surveys and whose development characteristics and water-richness were investigated by the direct current electrical resistivity method is the target layer for water exploration in the karst-granite rock areas. The water-bearing fracture zone shows a groove or strip-shape low resistivity anomaly and can be identified in its aquifer position according to its IP half decay time (Th), apparent polarizability (ηs), and apparent resistivity (ρs). The findings demonstrate that the above methods were successful in locating water potential areas, providing information for comparison and accurate borehole positioning. The results of the subsequent drilling and pumping tests supported the interpretation of the geophysical exploration data, and the water output from both boreholes met the objectives of this study. This groundwater search might serve as a guide for future exploration projects in similar areas. [ABSTRACT FROM AUTHOR]

The validity of the frequency selection method (FSM) in shallow (<150 m) groundwater exploration was illustrated by practical applications, and the relationship between potential electrode spacing MN and groundwater depth in FSM sounding method was analyzed and preliminary theoretical research was carried out by a simple geologic-geophysical model of sphere. Firstly, under the combined action of horizontal alternating electric field and alternating magnetic field, a simplified geophysical model of low resistivity conductive sphere in homogeneous half space was established, and the forward calculation was performed on the FSM sounding curve. Then, the water yield of 131 wells in the application of FSM in the Rural Drinking Water Safety Project of 12th Five-Year Plan in Guangxi Province was counted. In addition, detailed tabular statistical analysis was carried out on the drilling results of 98 drilling wells, and the relationship between potential electrode spacing MN at abnormal sounding curve and actual drilling water depth was compared and studied. Theoretical analysis and practical application show that FSM has obvious effectiveness in shallow groundwater exploration, and it is an effective method to determine shallow groundwater well locations in the future. The cause of FSM anomaly is the comprehensive effect of the natural 3D alternating electromagnetic signal underground. At the same time, the practical statistics show that there is 1:1 approximation between the size of potential electrode spacing MN at the anomaly curve of the frequency selection method and the actual drilling water depth, which verifies the correctness of the theoretical simulation results. FSM could be widely used in the shallow groundwater exploration in the future, and it is an effective, non-destructive, fast, and low-cost geophysical method. [ABSTRACT FROM AUTHOR]

Termite mounds are conventionally surmised as one of the best bio-geological indicator for groundwater occurrence in places where they inhibit. Ground magnetic survey was carried out to prove the assumption about termite mounds as an important indicator for groundwater exploration. Occurrences of 18 Termite mounds were mapped using handheld GPS to identify the suitable trend for magnetic survey. After considering all the criteria such as power lines, fences and fracture system, termite mound 2, 12 and 18 were selected in the NNE-SSW trend, and the ground magnetic survey was conducted in ESE-WNW direction which is perpendicular to the trend of the termite mounds using Proton Precession Magnetometer. Totally, 99 samples were collected with 5 m sampling interval and 50 m profile interval over an area of 22 500 sq.m. The magnetic values varied from –7 363 nT to 898 nT with the mean of –331 nT. Processed map of reduction to Equator indicates the presence of NNE-SSW and WNW-ESE magnetic breaks. Analytical signal map designated the presence of magnetic low in the WNW-ESE direction which coincides spatially with the magnetic breaks. The magnetic profile lines have also brought to light the structurally weak zones. Causative body depth range was estimated using power spectrum and Euler method which are from 120 m to 40 m and 100 m, respectively. The present study appreciably brings out the spatial relationship between the termite mounds and the hydro-fractures. This confirms the assertion with regard to termite mounds as an effective tool for groundwater exploration.

In western African cratonic regions, fractured crystalline bedrock, Neoproterozoic sedimentary covers, and regolith deposits constitute the most productive aquifer systems. Structural lineaments derived from remote sensing data and weathered cover thickness from borehole interpretations provide cost-effective methods for evaluating well productivity in regions with limited economic resources and hydrogeological knowledge, such as Houet province in Western Burkina Faso. Structural lineaments were interpreted using 1:200,000 Landsat TM images and 1:50,000 aerial photographs, revealing NE and NW as the most significant directions. An analysis of 101 borehole stratigraphic profiles from rural water supply program reports revealed the weathering depth and cover thickness. Borehole productivity exhibited a strong correlation with increased weathered cover thickness. Negative well results were concentrated in areas with less than 5 m of cover. In contrast, significant differences in specific yield rates were observed with greater thicknesses, ranging from 2.5 m³/d for 20 m of saturated thickness to 7.6 m³/d when the regolith reached a depth of 40 m. These preliminary groundwater exploration tools effectively target successful well sites by accounting for differing lithologies, regional tectonics, and regolith development. This approach is particularly relevant for cratonic regions with limited resources and hydrogeological knowledge, aiding in sustainable groundwater development and land-use planning. • Introduced a cost-effective approach using remote sensing lineaments and weathered cover thickness to predict well productivity in cratonic regions. • Demonstrated a strong correlation between increased weathered cover thickness and higher borehole productivity in the Houet province of Burkina Faso. • Identified NE and NW structural lineaments as critical factors influencing groundwater flow and storage in fractured crystalline bedrock and sedimentary aquifers. • Provided practical guidelines for selecting high-yield well sites in regions with sparse hydrogeological data, enhancing sustainable groundwater development. • The methodology applied in Western Burkina Faso offers valuable insights for groundwater management in similar Sahelian regions with economic and hydrogeological constraints. [ABSTRACT FROM AUTHOR]

Since 2002, the China Geological Survey has successively organized and implemented hydrogeological survey and groundwater exploration in water deficient areas, such as severe water shortage areas in west China, Wumeng Mountain area, Yimeng mountain area and red bed area in southern Jiangxi, obtained a large number of exploration data conducive to promoting discipline development, and summarized the law of water abundance. In recent decades, water prospecting and well drilling in bedrock mountainous areas serving poverty alleviation have not been systematically summarized based on water storage structures and their attributes. This paper takes the water storage structure as the theoretical guidance, considers geomorphic catchment, lithological water accumulation, structural water control and other control factors, and takes structure as the main control factor. The factors such as topography, formation lithology, vegetation development and actual value of development and utilization are systematically summarized and water storage structures are divided into 8 types, further divided into 20 types, and more into 35 types, such as the horizontal rock stratum, monocline formation, fold, fault, contact zone, weathered crust, composite and cave reservoir. The common characteristics of different scales and types of water storage structures are analyzed and summarized with reference to and in combination with the neotectonic water control theory and groundwater system theory. From the aspects of spatial combination characteristics of water storage structure, boundary hydrogeological properties, hydrodynamic conditions, scale effect, symbiotic characteristics of water control and practical value of development and utilization, this paper puts forward the correlation between the lithology and geological structure, the relativity of permeability and water separation, the balance between catchment and water storage, the unity of scale and system, the inheritance of formation and transformation and the matching of scale and purpose. The research results refine and improve the classification of groundwater storage structure types in bedrock mountain areas with water shortage, summarize the attribute characteristics of water storage structure, deepen the understanding of the concept and connotation of water storage structure, not only further promote the research of hydrogeology in bedrock mountain areas, but also provide references for water prospecting and well locating in water shortage areas, and guide the sustainable utilization of water resources in water shortage areas.

This paper presents a machine learning method to map groundwater potential in crystalline domains. First, a spatially-distributed set of explanatory variables for groundwater occurrence is compiled into a geographic information system. Twenty machine learning classifiers are subsequently trained on a sample of 488 boreholes and excavated wells for a region of eastern Chad. This process includes collinearity, cross-validation, feature elimination and parameter fitting routines. Random forest and extra trees classifiers outperformed other algorithms (test score > 0.80, balanced score > 0.80, AUC > 0.87). Fracture density, slope, SAR coherence (interferometric correlation), topographic wetness index, basement depth, distance to channels and slope aspect proved the most relevant explanatory variables. Three major conclusions stem from this work: (1) using a large number of supervised classification algorithms is advisable in groundwater potential studies; (2) the choice of performance metrics constrains the relevance of explanatory variables; and (3) seasonal variations from satellite images contribute to successful groundwater potential mapping. [ABSTRACT FROM AUTHOR]

Twenty (20) vertical electrical soundings were acquired using ABEM SAS 300 terrameter in order to determine the hydraulic characteristics of the identified aquifers within Adamu Augie College of Education Argungu near Birnin Kebbi, Northwestern Nigeria. The data were interpreted and seven sounding curves were obtained (KH, HQ, HA, HK, AA, A, and Q). The generated geoelectric sections characterized the subsurface into six lithologic units (topsoil, clayey sand, sandstone, clay, shale and sand) with sandstone and sand constituting the major aquifers in the area. The resistivity layer parameters delineated across the entire area were used to determine the hydraulic characteristics of the identified aquifers. The delineated layers above the aquifers showed transverse resistance ranging from 333.06Ωm² to 23100.61Ωm², longitudinal conductance S from 0.025047 to 1.226506 mhos, hydraulic conductivity K from 0.44 m/day to 25.57 m/day, transmissivity T from 7.144 m²/day to 465.374m²/day, and coefficient of anisotropy from 0.98 to 1.0. The protective map shows that about 75% of the area falls within poor overburden protective capacity, 20% constitute moderate protective capacity, while the remaining 5% have good protective capacity rating. Therefore, the hydraulic characteristics of the area suggest that the materials above aquifers are less protected, and by implication vulnerable to infiltration. [ABSTRACT FROM AUTHOR]

Study region: Regions of Bamako, Kati and Kangaba, southwestern Mali Study focus: Machine learning-based mapping of borehole yield. Three algorithms were trained on an imbalanced multiclass database of boreholes, while twenty variables were used as predictors for borehole yield. All models returned balanced and geometric scores in the order of 0.80, with area under the receiver operating characteristic curve up to 0.87. Three main methodological conclusions are drawn: (a) The evaluation of different machine learning classifiers and various resampling strategies and the subsequent selection of the best performing ones is shown to be a good strategy in this type of studies; (b) ad hoc calibration tools, such as data on borehole success rates, provide an apt complement to standard machine learning metrics; and (c) a multiclass approach with an unbalanced database represents a greater challenge than predicting a bivariate outcome, but potentially results in a finer depiction of field conditions. New hydrological insights for the region: Alluvial sediments were found to be the most productive areas, while the Mandingue Plateau has the lowest groundwater potential. The piedmont areas showcase an intermediate groundwater prospect. Elevation, basement depth, slope and geology rank among the most important variables. Lower values of clay content, slopes and elevations, and higher values of basement depth and saturated thickness were linked to the most productive class.

Groundwater is an important natural resource and has a significant role in the economy of any nation. The Dang district situated in the south-eastern part of the Gujarat state, Western India faces potable water problems in almost every summer season though the region receives heavy rainfall during monsoon months. The region has steep slopes causing heavy runoff during monsoon. The people of the district mainly rely on agriculture and the major source of the surface water is the perennial flows in Ambika, Purna and Khapri rivers that criss-crosses the district. In this study, we have employed an integrated approach to find out the groundwater potential regions in the Waghai Taluka based on geology, geomorphology, tectonic set-up, present wells’ static ground water level and slope length of the region. The field observations were also considered for the verification of our final inputs. The thematic maps are prepared with the use of remote sensing and GIS tools. The groundwater potential zones are classified into potential and non-potential zones based on integrated results and verified with existing well sites in study region. It was found that about 11% of the area comes under non-potential zones has least prospect of finding groundwater, while 89% of the region has more probability of finding groundwater under the potential zones.

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The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south India. It also aims to define depth to granitoid and structural elements which traverse the selected area. Magnetic data (n=84) measured, processed and interpreted as qualitative and quantitatively. The results of total magnetic intensities indicate that the area is composed of linear magnetic lows trending NE-SW direction and circular to semi-circular causative bodies. The magnetic values ranged from −137 nT to 2345 nT with a mean of 465 nT. Reduction to equator shows significant shifting of causative bodies in the southern and northern directions. Analytical signal map shows exact boundary of granitic bodies. Cosine directional filter has brought out structural element trending NE-SW direction. Results of individual profile brought to light structurally weak zone between 90 m and 100 m in all the profile lines. Sudden decrease of magnetic values from 2042 nT to 126 nT noticed in profile line 6 between 20 m and 30 m indicates fault occurrence. Magnetic breaks obtained from these maps were visualized, interpreted and identified two suitable sites for open and bore well. Radially averaged power spectrum estimates depth of shallow and deep sources in 5 m and 50 m, respectively. Euler method has also been applied to estimate depth of granitoid and structural elements using structural indexes 0, 1, 2, and 3 and found depth ranges from 90 m. Study indicates magnetic method is one of the geophysical methods suitable for groundwater exploration and site selection for open and borewells.

The Dodoma region located in Central Tanzania is a semi-arid area characterised by scarce surface water resources. Because of climate change and dependence on groundwater resources in the Dodoma urban area, there is currently an increased demand for water due to low groundwater recharge and high groundwater withdrawals due to the growing population. There is therefore a need to explore potential deep aquifer systems around the Dodoma urban area to meet the increasing water demand. This study uses lithological logs, pumping tests, and electromagnetic survey data to delineate the subsurface lithologies to locate potential deep aquifer system in the area. Results show that the shallow aquifer system is unconfined in some areas with resistivity values ranging from 11 to 28 Ωm and semi-confined in other areas with resistivity values ranging from 19 to 27 Ωm. The unconfined aquifer extends up to 60 m, while the semi-confined aquifer extends between 50–55 m and 65–120 m. The study found a potential deep aquifer system at a depth of between 200 and 290 m, with resistivity values ranging from 11 to 20 Ωm. Currently, this deep aquifer system has not been exploited as most boreholes in the area are only up to 150 m deep. The main lithology in the study area is weathered and fractured granite, with different degrees of weathering and fracturing, indicating a hard-rock aquifer system. This study adds valuable knowledge on the location of potential deep aquifer systems in the area for proper groundwater utilisation and management. [Display omitted] • Electromagnetic survey captures new deep subsurface information in the area • Pumping test and electromagnetic survey identify aquifer heterogeneity • The capacity of currently pumped aquifer system is of local consumption • A potential deep aquifer system has been identified [ABSTRACT FROM AUTHOR]

Lom River basin, associated with outflow from the Lom River system, is located in the East Region of Cameroon. The geology of the basin comprises Precambrian crystalline and crystallophyllian rocks, which are characterized by their compact nature and their low capacity to hold water. Permeable horizons observed in these rocks have developed through fracturing and weathering processes. Direct current (DC) geoelectrical surveys have been carried out in the Lom River basin, especially in the Betare Oya subdivision (administrative unit). The main objective of these surveys was to determine the major features of the permeable layers or aquifers of the hydrogeological network of the Lom River basin. Results from the collected data, interpreted with appropriate software and correlated with geological and hydrogeological field data, identified the conductive zones, characterized by vertical and lateral resistivity contrasts. The conductive zones represent the fractured and weathered horizons or permeable horizons, and these are protected from above by a variable overburden. This has enabled delineation of the shallow aquifer of weathered and decayed rocks and the deeper aquifer of the fissured basement. The groundwater flow direction in the deeper aquifer is NE–SW, i.e. parallel to the flow direction of Lom River. The study reveals the effectiveness of the DC electrical method in characterization of the flows of hydrogeological networks of river basins. [ABSTRACT FROM AUTHOR]

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Alamein City is one of the recently established cities along the Mediterranean coast in Egypt. Nineteen vertical electrical soundings (VES's) were measured in the study area with maximum current electrode separation of 600 m to examine the depth to water bearing layer, subsurface succession and structures controlling the distribution of the groundwater aquifer. The interpretation results of the VES data revealed that the subsurface section in the area is subdivided into three geoelectrical layers. The uppermost layer covers the ground surface and consists of alluvial deposits with moderately high electrical resistivity values (10.5–291 Ω.m.), with thicknesses ranging from 0.8 to 12.2 m. The second layer consists of Limestone (L. St.) intercalated with clay (water bearing layer) with low electrical resistivity values (0.2–10 Ω.m); with thicknesses ranging from 1.4 to 34 m. The third layer consists of saturated oolitic limestone with moderate electrical resistivity values (5.5–120 Ω.m). Gravity data were retrieved, corrected and analyzed. Gravity interpretation reveals that the depth of the basement rocks varies from 3600 to 6400 m with basement faults extending mainly in NW-SE direction, which is corresponding to the major trend in the Northern Western Desert.

Numerical modeling analysis was used to assess the suitable electrical resistivity arrays for the characterization of geological structures, including dyke, horst, graben, sub-vertical, and vertical structures. These geological structures usually make up the aquifers interested in the hydrogeological evaluation of crystalline basement terrains. Six electrode configurations, including Wenner alpha (α), Wenner beta (β), Wenner gamma (γ), Schlumberger array, dipole-dipole array, and pole-dipole array, were used to assess the geological structures for groundwater exploration. The synthetic models of the geological structures were generated using RES2DMOD code, and 5% noise was added to all the models. The generated models were inverted using the RES2DINV code. The results show that the most suitable arrays for dyke and graben structures are Wenner alpha, while Wenner beta is the most suitable for the horst structure. The Schlumberger array was the best for both sub-vertical and vertical structures. This study has demonstrated the efficacy of numerical modeling in assessing the best resistivity arrays for 2D electrical resistivity imaging for groundwater exploration prior to geophysical field investigation.

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The unavailability of water has been a major threat to agricultural and commercial activities in Ilora, Oyo central, Nigeria. This study combined GIS, remote sensing, and geophysical methods for groundwater potential zone mapping within the area in an attempt to identify prospective zones for borehole drilling activities. Landsat 8 OLI, ASTER DEM, geological, geophysical, and soil data of the research area were acquired for this study. To map the groundwater potential of the area, eight thematic layers that influence groundwater occurrences and movement controlling factors such as, geology, elevation, slope, land use land cover (LULC), fault proximity, soil, lineament density, and drainage density were mapped out from the acquired data of the area. The influence of each theme and subunit/class on groundwater recharge based on previous studies were evaluated using Analytical Hierarchical Process (AHP). The groundwater potential of the area of study was qualitatively classified into five classes, namely: very high, high, moderate, low, and very low which account for 0.3%, 7.8%, 54.8%, 35.6%, and 1.5% of the total area, respectively. The results were cross validated using well data from the area and 88.9% correlation and 0.74 kappa coefficient were achieved. The groundwater potential map generated in this research could be used as a preliminary reference in selecting suitable sites for groundwater resource exploitation in the area to ameliorate the current scarcity of water in this region. [ABSTRACT FROM AUTHOR]

The Wumeng Mountain Contiguous Zone in China always suffers from deficiency of groundwater resources.The Zhaotong area of Yunnan Provience belongs to the Wumeng Mountain area, which was the key area.We carried out geological survey, spring flow statistics and water quality evaluation in karst stratum.The strip karst area, which always located in ridge-valley area, with many target aquifers, karst shallow.Groundwater was concentrated in the core of anticlinoria and both wings, the core of syncline and fault zone.The buried karst water mainly concentrated in the paleo-karst stratum in Zhaolu fault basin, and covered below Tertiary system.Most chemical type of groundwater was determined as HCO3 and HCO3·SO4 type.The strip and buried karst water account for 96.73% and 92.93% respectively.The comprehensive water quality evaluation results of 80.84% simple analysis and 64.41% total analysis were classified as Ⅰ-Ⅲ.We suggest that large flow springs more than 50 L/s should be extracted, diverted and stored for winter use.Combined with geophysical exploration and drilling verification, the target aquifer was more successfully found in water-rich section of strip and shallow buried karst areas.Firstly, the high-density electrical method and combined profile method were conducted to find out the karst fracture zone and fault.Then, the IP sounding was set to explore the depth of the aquifer with high polarizability.Finally, the water supply segment and water inflow were determined by comprehensive logging and drilling.The rate of successfully extracting water was 86.67%.Then, we could recommend the well location.