Groundwater Zone Research Articles

Pemilihan Lokasi TPA Regional untuk Kota Medan dan Kabupaten Deli Serdang

The increase in the rate of development, population growth, and socio-economic activities has triggered an increase in waste generation, which is increasingly complex with conventional waste management that relies on collection, transportation, and disposal. This study aims to find a solution through three main stages: identification of waste conditions, preparation of a decision support system using the AHP Method, and analysis of the area with GIS application. The results of the study show that Limau Mungkur Village, STIM Hilir District, is considered the most appropriate location in the study area. Based on these results, the concept of selecting the criteria of Land Use, Hydrology, Groundwater Level Depth, Flood-prone Area, Settlement Distance, Zone Slope, Geology and Airport Distance became a determinant in the selection of location alternatives.

Submarine Groundwater Discharge at a Mega‐Tidal Beach

ABSTRACTTidally influenced groundwater systems in coastal environments represent important mixing zones of fresh groundwater and circulating seawater, manifesting as submarine groundwater discharge (SGD). Water circulation induced by tidal pumping enhances the exchange of chemicals between aquifers and coastal waters and thereby influences the biogeochemistry of coastal zones. Here, we report the results of an SGD field study conducted at a steep, mega‐tidal sand and gravel beach along the Canadian coast of the Bay of Fundy, a region with the world's highest tides (semi‐diurnal tidal ranges exceeding 10 m). Several physical and geochemical measurement techniques were employed to document the spatiotemporal SGD variability. SGD was directly sampled from seepage meters installed over multiple tidal cycles and two summer campaigns. SGD rates were estimated from tracer mass balances for radon (August 2020) and radium isotopes (July 2021) over multiple tidal cycles. Tidally averaged SGD estimates from seepage meters ranged from 12 to 87 cm d−1, with an average of 42 cm d−1, while radon tracing yielded a tidally averaged rate of 86 cm d−1. SGD estimates from radium tracing ranged from 23 to 43 cm d−1 along the shoreline and 6 to 71 cm d−1 offshore, depending on the estimated residence times. Radionuclide analyses of seepage meter waters suggest that the residence time of seawater circulation through the aquifer is less than 1 day. SGD measurements in mega‐tidal settings are rare, and the results suggest that the combination of the steep slopes, highly permeable sediments and high tidal range drive very high seepage rates for diffusive SGD. Salinity gradients in the intertidal zone demonstrate that SGD is primarily comprised of circulated seawater with negligible fresh groundwater. Although the freshwater proportion of SGD is relatively low, the large volumetric rates of total SGD can still contribute large amounts of terrestrially derived and remineralized nutrients to coastal waters.

Groundwater Geochemistry in the Karst-Fissure Aquifer System of the Qinglian River Basin, China

The Qinglian River plays a significant role in China’s national water conservation security patterns. To clarify the relationship between hydrogeochemical properties and groundwater quality in this karst-fissure aquifer system, drilling data, hydrochemical parameters, and δ2H and δ18O values of groundwater were analyzed. Multiple indications (Piper diagram, Gibbs diagram, Na+-normalized molar ratio diagram, chloro-alkaline index 1, mineral saturation index, and principal component analysis) were used to identify the primary sources of chemicals in the groundwater. Silicate weathering, oxidation of pyrite and chlorite, cation exchange reactions, and precipitation are the primary sources of dissolved chemicals in the igneous-fissure water. The most relevant parameters in the karst water are possibly from anthropogenic activities, and other chemicals are mostly derived from the dissolution of calcite and dolomite and cation exchange reactions. Notably, the chemical composition of the deep karst water from the karst basin is mainly influenced by the weathering of carbonate and cation exchange reactions and is less affected by human activities. The hydrogeochemical properties of groundwater in the karst hyporheic zone are influenced by the dissolution of carbonates and silicates, evaporation, and the promotion effect of dissolution of anorthite or Ca-containing minerals. Moreover, the smallest slope of the groundwater line from the karst hyporheic zone among all groundwater groups revealed that the mixing effects of evaporation, isotope exchange in water–rock interaction or deep groundwater recharge in the karst hyporheic zone are the strongest. The methods used in this study contribute to an improved understanding of the hydrogeochemical processes that occur in karst-fissure water systems and can be useful in zoning management and decision-making for groundwater resources.

Thoron, radon and microbial community as supportive indicators of seismic activity in groundwater

Earthquakes have a significant impact on groundwater environments as well as human life. However, identifying active and affected zones from seismic events using isotopic and microbial diversity indicators remains a challenging frontier. To validate the applicability of this coupled method for real-time analysis, we analyzed thoron (220Rn), radon (222Rn), microbial community compositions, and hydrochemistry in groundwater samples during the 2017 Pohang earthquake for the first time. We observed the detection of 220Rn in groundwater right before the aftershocks, with a high correlation to 222Rn concentrations. This indicates that 220Rn and 222Rn can serve as reliable seismic indicators for real-time analysis. The microbial data can assist in identifying affected groundwater zones, particularly when real-time detection of 220Rn is not feasible. At the phylum level, Peregrinibacteria and Firmicutes were only found in samples with detected thoron. At the genus level, hydrogen-oxidizing or sulfur-oxidizing bacteria could serve as indicators of active zones. Two statistical analyses, self-organizing map (SOM) and principal component analysis (PCA) using hydrochemical parameters, also correlated with the results from these coupled indicators. This study demonstrates the theoretical and practical applicability of 220Rn, 222Rn, and microbial community compositions as new multi-faceted ecological indicators, whether for real-time analysis or otherwise.

Delineation of Groundwater Potential Zones Using Geospatial Techniques. Case Study: Roman City and the Surrounding Area in the Northeastern Region, Romania

Effective groundwater management is crucial under the current climatic conditions, addressing both qualitative and quantitative aspects. An important step in delineating groundwater potential zones involves remote sensing (RS) data and geographic information systems (GISs), facilitating resource assessment, and the implementation of suitable field data management. This study introduces the delineation of potential groundwater zones using seven layers and the Multi-Criteria Decision Analysis (MCDA) method. Satty’s Analytic Hierarchy Process (AHP) was employed to rank the seven selected parameters, contributing to the advancement of groundwater research and resource assessment. All seven thematic layers (Rainfall, Geology, Land Use/Land Cover, Drainage Density, Elevation, Slope, and Soil) were prepared and analyzed to delineate groundwater potential zones. The resulting groundwater potential zone map was categorized into four classes, Very Good, Good, Moderate, and Poor, covering areas of 81.53 km2 (45.1%), 56.36 km2 (31.2%), 19.54 km2 (10.8%), and 23.17 km2 (12.8%) of the total area, respectively. The accuracy of the output was validated by comparing it with information on groundwater prospects in the area, and the overall accuracy of the method was approximately 72%. High-yield boreholes were drilled and concentrated in the Very Good groundwater potential zones, while low-yield ones were developed in the Poor areas.

Hydrological controls of a riparian wetland based on stable isotope data and model simulations.

Isotopic evidence of groundwater and stream water is frequently used to investigate water exchanges with groundwater. Monthly sampling of rain, stream water, and groundwater was conducted at Tims Branch watershed in South Carolina for the oxygen and hydrogen stable isotope (δ2H and δ18O) measurement, as well as pH and oxidation-reduction potential (ORP). Together with a mass balance perspective, it was determined that it takes a few weeks to one month for groundwater in the hyporheic zone to fully exchange with stream water. From hydrodynamic modelling, we show that substantial (up to 70 %) groundwater exchange occurs at gaining and losing sites. Groundwater exfiltration, i.e. inflow into stream water, contributes up to 4 % to stream water, with the remainder from upstream exfiltration. A 2-4 % per day renewal rate of adjacent groundwater would indirectly indicate a groundwater residence time in the order of half a month to a full month (assuming either a well-mixed case or large dispersion rate in pulse flow case), in agreement with a greatly reduced variability of δ2H and δ18O of groundwater compared to stream water and rain. This reduced variability of stable isotope signal from groundwater confirms our hypothesis that riparian groundwater mixing at Tims Branch is more of a mixed type rather than a pulse flow type. A monthly time scale is sufficient for groundwater to become anoxic at exit points into stream water resulting in the episodic production of natural organic matter- and iron-rich flocs upon oxidation.

Groundwater potential mapping and its sustainable management using AHP and FR models in the Jedeb watershed, Upper Blue Nile Basin, Ethiopia

ABSTRACT Groundwater potential mapping and its sustainable development are important aspects of the Jedeb watershed due to an increase in groundwater demand and the local population. This study aimed to delineate potential groundwater zones in the Jedeb watershed, using the analytical hierarchy process (AHP) and frequency ratio (FR) model. Nine thematic layers, including lithology, geomorphology, slope, drainage density, land cover and land use, lineament density, rainfall, soil, and static water level, were considered. The thematic layers obtained were integrated into a Geographic Information Systems (GIS) environment to generate the groundwater potential map. Four classes of groundwater potential have been identified: low, moderate, high, and very high. The low classes represent 12.8% and 7.02%; moderate 25.35% and 34.84%; high 38.8% and 33.11%; and very high 23.05% and 25.03%, for the AHP and FR models, respectively. The result map was also validated by using receiver operating characteristic (ROC) curve from which result accuracy was obtained is 85.6% and 88.3% for the AHP method and FR method, respectively. The study's validation verified that the FR model produced more efficacious results than the AHP model. This study, will be helpful in providing planners, and decision-makers with rapid decision-making when it comes to managing groundwater resources.

Groundwater Potential Zone Delineation through Analytical Hierarchy Process: Diyala River Basin, Iraq

Groundwater recharge zone identification is vital for managing water resources, particularly in semi-arid and dry climates. Accurate and quantifiable assessment is necessary for the sustainable management of groundwater resources, and it is possible to carry this method out using modern techniques and technical standards. To identify likely groundwater locations in the Diyala River Catchment, Iraq, which serves as an example study basin, the current research examines a new methodology that employs a geographic information system, and an Analytical Hierarchy Process connected with remote sensing data. The technique of ArcGIS was employed to generate spatially distributed thematic layers of rainfall, lithology, slope, drainage density, land use/land cover, relief and soil. The raster data from these layers were then converted and categorized. The weights assigned to thematic strata depended on their significance relative to groundwater occurrence. A pairwise judgement matrix for the Analytical Hierarchy Process was used, with the categorized ranking, to assess the standardized weights of the layers under consideration. The layers for the formation of groundwater zones have then been placed using the overlay-weighted summation approach. Three regions, which are classed as excellent, good and moderate, have been identified on the resulting groundwater potential zones map, representing roughly 29, 69 and 2% of the basin’s total area, respectively. The study’s conclusions indicate that, in such a climate, the adopted strategy would produce favourable results to promote the organizing of opinions and the sustainable use of groundwater resources.

Hobli wise hydro geomorphological evaluation of the groundwater prospects mapping

ABSTRACT Numerous studies highlight the urgent issue of groundwater depletion due to overexploitation. The United Nations’ World Water Development Report (2023) warns that if current extraction rates persist, many regions could face severe groundwater shortages in the coming decades. A 2021 study in Nature reports that about one-third of the world’s largest groundwater basins are depleting faster than they are replenished, escalating the risk of critical shortages. In Chickballapur District, excessive agricultural activity has led to an imbalance between groundwater loss and recharge. To address this challenge, a weighted overlay analysis of spatial layers in QGIS was employed to identify potential groundwater zones. This methodical approach involved mapping topographic features and integrating six spatial layers: slope, geomorphology, lithology, drainage, lineament and land use/cover. Each subcategory was ranked and scored based on expert opinion and existing literature. The Central Ground Water Board data was used to validate the resulting groundwater prospect map. The study further included an assessment of groundwater prospects across administrative units by superimposing the administrative boundaries on the final map. Calculating the percentage of land within each groundwater prospect category is crucial for effective groundwater management at the administrative level.

Integration of 2D and 3D electrical resistivity tomography and 2D gravity modeling to evaluate groundwater investigations in the Burka Uke catchment area, western Ethiopia

The increasing demand for water resources due to the expanding infrastructure and growing population of Uke town, West Ethiopia, necessitates a comprehensive understanding of groundwater potential within the Burka Uke catchment. The aims and objectives of this study are to identify a map of the aquifer by characterizing the subsurface earth, basement rock depth, resistivity and density of geological layers, their thicknesses, and structural features. The investigation integrates electrical resistivity tomography and gravity modeling to delineate potential groundwater zones and their structural controls. Electrical resistivity tomography profiles (1, 4, and 6) revealed low resistivity zones indicative of potential aquifers. The significant resistivity contrast (378 to 1412 Ω.m) suggests a high fracture density, potentially enhancing groundwater storage. The Bouguer gravity anomaly map, separated into regional and residual components, displayed values ranging from 51.79 to 41.59 mGal, highlighting density variations in the subsurface. As a result, analysis of the residual gravity anomaly map identifies north–south striking fault elements, indicating their influence on groundwater flow.The combined 2D and 3D ERT data also revealed a 2D gravity model of the aquifer from which the concentration extended throughout the study area. Data validation with previously drilled wells has confirmed the effectiveness of the geophysical methods used in identifying potential groundwater zones. This study provided critical information for the sustainable management of existing groundwater and demonstrated the effectiveness of integrating geophysical techniques to delineate and characterize aquifers in water-stressed areas.

Hydrogeological Resolution Using Composite Geophysical Methods: A Case Study of Inland Salinity in Part of Agra, Uttar Pradesh India

ABSTRACT This manuscript is an attempt at utilizing a combination of varied Geophysical methods (n = 4) – Vertical Electrical Sounding (VES), Electrical Resistivity Tomography (ERT), Time Domain Electromagnetic (TEM), and Borehole logging for finer resolution of potential fresh groundwater and saline groundwater aquifer zones in marginal alluvial plains of Agra district, Uttar Pradesh state. A conceptual model of sub-surface aquifer disposition displaying zones of fresh and saline groundwater zones was prepared using an interpreted and processed multi-parameter dataset. A positive correlation was found between TEM (44.6 m), Well log data (43.0 m), VES data (47.2), and ERT data (45.0 m) demarcating the boundary up to which fresh groundwater potential lies from the ground surface. Conventional methods rely on resistivity values to identify groundwater potential zones, and a rough estimation of salinity can be carried out. Instead of the conventional VES method, the combination of aforesaid methods results in finer resolution and easier demarcation of fresh groundwater zones from those of saline zones. This method can be successfully reproduced to demarcate the extent of saline water ingress in coastal areas and finding freshwater lenses within inland saline aquifers.

Using hydrochemistry and stable isotopes to character the karst water environment in a cave site, South China

For cave sites located within the seasonal fluctuation zone of groundwater, obtaining a comprehensive understanding of the hydrogeological conditions and hydrochemical environment is of utmost importance in assessing the preservation of cultural deposits. However, due to the heterogeneity of karst development, the hydrochemical environment of the overburden karst water-bearing unit may exhibit complex variations. In this study, the characteristics of the water environment in a foot cave system and its surrounding aquifer were investigated at the Zengpiyan site, employing hydrochemistry, hydrogen and oxygen isotope analysis, as well as sulfate isotope analysis, in conjunction with the hydrogeological background. Based on the exposure of the karst cave and the groundwater flow conditions, the water-bearing medium was categorized into five types. The aquifer exhibited either an oxidation or reduction condition, with a distinct "dissolved oxygen hole" observed in the saturated zone of the cave site. Ion concentration analysis revealed that the groundwater was influenced by the prior accumulation of cinders in the upstream region, leading to sulfate contamination within the foot cave system. However, during the groundwater movement from upstream to downstream, the attenuation rate of pollutants displayed significant variations. Notably, the sulfate content was unusually low within the site cave. Hydrogen and oxygen isotopes provided insights into the differing circulation and movement velocities of groundwater within the local environment. Additionally, sulfate isotopes confirmed the sources of sulfate and the occurrence of bacterial sulfate reduction within the site cave. Consequently, an environmental zoning classification was established based on these analyses. Although the concentration of dissolved ions appears low in the anoxic area, it does not imply a diminished environmental risk. Under reducing conditions, these pollutants can be converted into more aggressive gases, posing a substantial threat to the preservation environment of cave sites. Therefore, sufficient attention should be given to this aspect in order to ensure adequate protection.

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.

Comprehensive groundwater potential mapping in Nagaland, India using integrated geo-spatial techniques

Groundwater is essential for a sustainable future, yet identifying potential groundwater zones remains challenging in regions with varied hydro-geological conditions. Nagaland is a state in north-eastern India characterized by diverse terrain, complex geological formations, and seasonal variations in rainfall. The objective of the present study is to evaluate groundwater potential zones in Nagaland using an integrated Geographic Information System (GIS) and Analytical Hierarchy Process (AHP) methodology, resulting in the first comprehensive map addressing the region's diverse hydro-geological conditions. Several attributes like geomorphology, geology, slope, soil, rainfall, drainage density, and Land use/Land cover (LU/LC) were generated from available data resources like Landsat 8 and Sentinel-2 satellite imageries, the Geological Survey of India (GSI), Environmental Systems Research Institute (ESRI), the Food and Agriculture Organization (FAO), and the Climatic Research Unit (CRU). These datasets are extracted using the Arc-GIS (Arc-GIS Desktop 10.8.1), with weights assigned according to Saaty's scale, and subsequently normalized through the AHP. The findings reveal that 14% (2240km2) of the state has very good groundwater potential, 42% (6720 km2) is classified as good, 9% (1440 km2) as moderate, 27% (4320 km2) as poor, and 8% (1280 km2) as very poor. These insights are significant for regions like Mokokchung, Longleng, and Wokha, which require urgent intervention. Conversely, the study identifies Dimapur and Chumoukedima as areas with significant groundwater potential, capable of meeting rising water demands. The validation of these results using well discharge data from 12 monitoring wells supports these findings.

Characteristics of soil moisture transport in the aeration zone of subsidence areas under the disturbance of coal seam mining

High-intensity coal mining has induced a series of ecological and environmental problems issues, including surface subsidence, the development of ground cracks, and the deterioration of vegetation. The disruption of water circulation systems induced by mining, such as perched groundwater, groundwater of aeration zone, and phreatic water, is the root cause of vegetation withering. The aeration zone serves as a crucial nexus in the process of water cycling and exerts a significant influence on soil fertility. To explore the characteristics of soil moisture transport in subsidence areas under the mining disturbance, on-site monitoring of the size and morphology characteristics of subsidence areas and ground cracks was conducted in typical mining areas in Inner Mongolia, China. Subsequently, a typical soil moisture transport model was constructed in subsidence areas, the soil moisture transport patterns under the influence of different types of subsidence and cracks were analyzed, and the influence law of soil damage on soil moisture transport in the aerated zone was clarified. The results indicate that (1) Based on the occurrence and distribution characteristics of subsidence cracks, the subsidence area can be divided into tension zone, compression zone, and neutral zone; the ground cracks are divided into permanent tension cracks and dynamic cracks. (2) The drought stress effect of soil in the subsidence area is significant. Under the influence of soil structure variation, the water-holding capacity of the soil in the subsidence area decreases, and the soil moisture dissipation is strong. The soil moisture transport rate in the aeration zone of the subsidence area is ranked as follows: tension zone > neutral zone > compression zone. (3) Ground cracks can exacerbate the soil moisture transport rate in the aeration zone. After 15 d of crack appearance, the soil moisture transport reaches a relatively stable state, and the soil moisture transport rate in the surface layer of the crack is the fastest, and the loss of soil moisture is the most significant. The crack effect is not significant beyond 100 cm from the crack. This study provides a theoretical and data support for soil and vegetation remediation in mining subsidence areas.

Application of bagging and boosting ensemble machine learning techniques for groundwater potential mapping in a drought-prone agriculture region of eastern India

Groundwater is a primary source of drinking water for billions worldwide. It plays a crucial role in irrigation, domestic, and industrial uses, and significantly contributes to drought resilience in various regions. However, excessive groundwater discharge has left many areas vulnerable to potable water shortages. Therefore, assessing groundwater potential zones (GWPZ) is essential for implementing sustainable management practices to ensure the availability of groundwater for present and future generations. This study aims to delineate areas with high groundwater potential in the Bankura district of West Bengal using four machine learning methods: Random Forest (RF), Adaptive Boosting (AdaBoost), Extreme Gradient Boosting (XGBoost), and Voting Ensemble (VE). The models used 161 data points, comprising 70% of the training dataset, to identify significant correlations between the presence and absence of groundwater in the region. Among the methods, Random Forest (RF) and Extreme Gradient Boosting (XGBoost) proved to be the most effective in mapping groundwater potential, suggesting their applicability in other regions with similar hydrogeological conditions. The performance metrics for RF are very good with a precision of 0.919, recall of 0.971, F1-score of 0.944, and accuracy of 0.943. This indicates a strong capability to accurately predict groundwater zones with minimal false positives and negatives. Adaptive Boosting (AdaBoost) demonstrated comparable performance across all metrics (precision: 0.919, recall: 0.971, F1-score: 0.944, accuracy: 0.943), highlighting its effectiveness in predicting groundwater potential areas accurately; whereas, Extreme Gradient Boosting (XGBoost) outperformed the other models slightly, with higher values in all metrics: precision (0.944), recall (0.971), F1-score (0.958), and accuracy (0.957), suggesting a more refined model performance. The Voting Ensemble (VE) approach also showed enhanced performance, mirroring XGBoost's metrics (precision: 0.944, recall: 0.971, F1-score: 0.958, accuracy: 0.957). This indicates that combining the strengths of individual models leads to better predictions. The groundwater potentiality zoning across the Bankura district varied significantly, with areas of very low potentiality accounting for 41.81% and very high potentiality at 24.35%. The uncertainty in predictions ranged from 0.0 to 0.75 across the study area, reflecting the variability in groundwater availability and the need for targeted management strategies.In summary, this study highlights the critical need for assessing and managing groundwater resources effectively using advanced machine learning techniques. The findings provide a foundation for better groundwater management practices, ensuring sustainable use and conservation in Bankura district and beyond.

Identification of groundwater potential zones using geospatial technologies in Meki Catchment, Ethiopia

ABSTRACT Mapping groundwater potential zones helps in precisely planning well drilling. The Meki Catchment is currently experiencing irrigation expansion and water scarcity challenges, creating a strong need for groundwater exploitation. The goal of this study was to identify groundwater potential zones (GWPZs) in the Meki Catchment using geospatial technologies to enhance water resource management and support sustainable development in the region. Eight thematic components were used in this analysis. Analytical Hierarchy Process (AHP) method was applied to ensure consistency in judgments through paired comparisons. Weighted overlay analysis was then used to evaluate the GWPZs. The study found that out of the total Meki Catchment area (226,333.26 ha), 30.68% (69,448.31 ha) has high potential, and 34% (76,963.33 ha) has good potential. Validation was conducted using ground truth data, considering existing water point field data from borewells and springs. The results of this study can help prioritize strategies to ensure the sustainable use of groundwater in the area. Drilling organizations can utilize these findings as a resource for feasibility studies in groundwater prospecting projects to locate well sites. The validation results demonstrate that potential groundwater zones can be identified more accurately using GIS and RS approaches at a lower cost.

Groundwater Exploration and Management using Geophysical and Remote Sensing Techniques: a Review

The complex and heterogeneous nature of the subsurface poses’challenges in the accurate identification and characterization of the reservoir or groundwater resources. Because of these challenges, exploration methods have changed and evolved throughout history. Integrating remote sensing and geophysical techniques has also emerged as one of the improved approaches for groundwater exploration and management, enabling accurate identification of potential groundwater zones. This paper combines current knowledge of various geophysical techniques and remote sensing approaches and shows how their integration minimizes exploration uncertainties and reduces costs. This review examines several case studies conducted in different geological environments, such as non-sedimentary and sedimentary rocks. It also discusses the difficulties and limitations associated with combining remote sensing and geophysical exploration techniques and the potential for the future. The study results show how integrating geophysical and remote sensing methods can sustainably improve groundwater resource management.

Hydrogeology of southeastern coastal parts of Great Nicobar Island, India: development of an integrated conceptual model for a hitherto unexplored island in the Indian Ocean

The vulnerability of oceanic islands in the face of climate change, vis-a-vis human development, is a serious issue at present. The island of Great Nicobar in the Nicobar archipelago in the Indian Ocean will face major challenges owing to its impending development activities. The eastern coastal part of the island was investigated through exploratory drilling, geophysical investigations, and water-table monitoring. Field investigations show that coralline sand is the major groundwater repository and is commonly developed through dug wells. Exploratory drilling down to 100 m depth revealed that the underlying Tertiary consolidated aquifer is of limited potential and showed increased salinity with depth. Water is also present along the contacts of shale–sandstone. The mean seasonal fluctuations in the depth to the water table was 0.18 m. Geoelectrical sections identified promising fresh groundwater zones along the east coast, with freshwater-bearing semi-weathered coralline limestone and coralline sand having a resistivity of 146–622 ohm m. Based on generated data, a 3D model of the aquifer system was constructed. The observed soil infiltration rate was 0.3–0.5 cm h −1 . The specific capacity of the dug wells was c . 5 m 2 min −1 . The permeability of the phreatic aquifer was 5–11 m/day and the transmissivity was 0.11–0.2 m 2 min −1 . The optimum yield of the unconfined aquifer was 17–21 m 3 /day. The tidal influences on the aquifer system also added complexity to the island's hydrogeological dynamics. Despite the challenges of restricted access due to the presence of aboriginal tribes in the island, the present study provides the maiden set of hydrogeological data for the island, revealing the disposition of the aquifers, their properties and their spatio-temporal behaviour.

Identification of Groundwater Potential Zone Existence in GAR Housing Using Electrical Resistivity Method

The GAR (Grand Aceh Residence) housing estate is located in Baet Village, Aceh Besar District and was constructed on the land of a pond that has been filled in and is close to the coast. The majority of residents use clean water sources from PDAM because of the difficulty of obtaining clean water. The purpose of the research was to identify potential groundwater zones and determine the conditions. The research method used was electrical resistivity method, SuperSting R8/IP with Wenner-Schlumberger configuration. The research was conducted in 3 lines with 6 m spacing. RES2DINV software based on the least square inversion approach was used for data processing. The results obtained show resistivity values varying from 0.1 - 100 Ohm.m with a depth penetration of up to 28.8m. There are 3 lithological layers obtained, namely clay (0.1 - 1.5 Ohm.m), clayey sand (1.5 - 17.7 Ohm.m), and sand (17.7 - 100 Ohm.m). The groundwater presence zone is assumed to be in the sand layer. There are 2 types of groundwater obtained, which are shallow groundwater (phreatic) located from the center to the north of the lines to a depth of ± 13 m and deep groundwater, located varies in the middle of the lines from a depth of ± 15 m to the end with groundwater conditions may still be brackish due to the influence of seawater intrusion with a resistivity value of 0.1 Ohm.m identified to a depth of ± 25 m