Figure 8 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
Phuket is well-known around the world as a popular tourist destination. Tourism-related population growth depends more on groundwater as the only available source of potable water in Phuket. The proper precautions must be taken to reduce the risk of spending large sums of money in sinking abortive boreholes, and a groundwater potential map would en...
Context in source publication
Context 1
... integration was based on the idea that good groundwater potential is related to low S and high T. Individual thematic maps were given equal weight, and ranks were assigned based on the importance of groundwater. In addition, as indicated in Figure 8, the groundwater potential was divided into three categories: (1) low, (2) medium, and (3) high. According to the groundwater potential map, a high aquifer potential zone can be found in the center of the northern part, as well as in some specific areas in the southern part, while low groundwater potential can be found in the top northern part, as well as the western and eastern flanks of the study area. ...
Citations
... Hydrogeologic zones with high overburden thicknesses are typically suitable for groundwater development because the thickness of the weathered layer is proportional to the groundwater's subsurface storage capacity Lubang et al., 2023;Rashid et al., 2023;Puttiwongrak et al., 2022;Othman et al., 2022;Ako and Olorunfemi, 1989). Overburden thickness refers to the distance from the topsoil to bedrock, and it is a significant factor in hydrogeology, particularly in basement terrains (Ifeanyichukwu et al., 2021;Caruthers and Smith, 1992). ...
... The groundwater potential map (Fig. 16) classified the Laniba subsurface into high, medium, and low groundwater-yielding zones, and such classifications were also observed in the studies of Puttiwongrak et al. (2022) and Ademilua and Olorunfemi (2000). The potential map was drawn from the geoelectric and hydrogeologic parameters in Tables 1 and 2. High groundwater potential zones had overburden thickness above 18 m with evidence of fault lines or fractured zones, which coincided with high VLF-EM fractured zones and the weathered basement isoresistivity map. ...
Groundwater potential regions were delineated using Very-Low Frequency Electromagnetic (VLF-EM) and Vertical Electrical Sounding (VES) geophysical techniques. The VLF-EM measurements were taken as fast reconnaissance to delineate shallow conductive features along seven traverses with 10 m station intervals. The data were qualitatively analyzed and indicated zones of hydrogeological relevance, pointing to regions for VES investigations. Thirteen VESs were mapped with 100 m intervals between current electrodes, and the data were processed manually and using WinResist software to generate sounding curves and geo-electric sections that revealed 3 (84.6%) and 4 (15.4%) layers of earth models. The aquifer units were found in the weathered and fractured layers. The subsurface was classified into high, medium, and low groundwater potential regions, with a larger area indicating low prospects. Regions with high potentials had overburden thicknesses above 18 m, while medium and low yields had overburden thicknesses of 13-18 m and below 13 m, respectively.
... The subsurface of Phuket is divided into three layers, the first of which is made up of clayey sand, sand, and sandy soil, and the second of which is made up of weathered and fractured rocks. The third layer is the bedrock, which is primarily made of granite and sedimentary-metamorphic rocks [26]. The granite that made up much of Phuket's soil was weathered in place, giving it its light color and moderate to good natural drainage [27]. ...
Understanding the technical properties of the subsurface soil is essential for carrying out any building project correctly. In sandy soils in Phuket, Thailand, a correlation between electrical resistivity and the SPT N-value should be established in design to cut down on the time and expense of engineering field work for site investigation operations. Using the least squares method, the data of electrical resistivity and SPT N-values were fitted for regression analysis, and the behavior of the fitting coefficients was examined under various soil conditions found in the field. The factors affecting the link between electrical resistivity and the SPT N-value were found using data classifications of geology and climate. Phuket is located in a humid tropical region with frequent heavy rainstorms and extended periods of high temperatures and is composed of two main distinct geological areas: (1) igneous rock and (2) sedimentary and metamorphic rocks. According to the geological classification, the regression parameter (R2) of the relationship between the electrical resistivity and SPT N-values somewhat increased from a straightforward plot (R2 = 0.0171) to 0.1721, and the geology and climate data categorization revealed the best fit which is an exponential model (R2 = 0.6175). By re-examining the two VES lines under the identical bedrock and climate characteristics as the original model, the relative R2 of 0.5519 validates the association between electrical resistivity and SPT N-values. It is important to emphasize that the geology and climate of the collected data have an impact on the correlation model. Furthermore, a geotechnical investigation should be used to confirm the findings of an electrical resistivity survey as a preliminary tool to assess any problematic subsurface zones. However, more field test data from diverse places must be acquired in order to establish the relationship between the SPT N-value and electrical resistivity of sandy soils.
... The geoelectrical method, with its three most widely used techniques (tomography, profiling and vertical drilling), has long been considered the most widely used geophysical method for the characterization of aquifer systems in the world [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. ...
Vertical electrical sounding (VES) as a geoelectrical method has proven its effectiveness throughout the history of groundwater geophysical investigation. In this sense, VES was carried out 47 in the study area with the aim of determining the geometry and limits of Quaternary basaltic aquifer formations and, above all, the location of electrical discontinuities in the area located in the north of Morocco, between the center of Almis Guigou and the city of Timahdite. This area is experiencing an overexploitation of the groundwater due to excessive pumping and the development of intensive agriculture activities, resulting in a continuous decrease in piezometric levels. The processing of the diagrams by WINSEV software showed the presence of an electrically resistant surface level, attributed to basaltic formations, of the Quaternary age, whose thicknesses reach at least 150 m to the SW of the area. This level is superimposed on a moderately conductive horizon which, according to local geology, corresponds to Pliocene marl and limestone alternations. The correlation of VES interpretation models allowed us to elaborate thematic maps and geoelectrical sections which illustrate the vertical and lateral extension of the basaltic reservoir as well as its thickness, which decreases in general from the south-west to the north-east; however, the main electrical discontinuities also correspond to faults and fractures, and they show a NE–SW direction sub-parallel to the major accidents of the Middle Atlas. A prospectivity map of the local aquifer was generated, coinciding with regional fault lines and confirmed by the alignment of very good flowing water boreholes. This geophysical study by electrical sounding shed light on the geometry and extension of the aquifer and opened avenues to draw further conclusions on its physical and hydrodynamic characteristics, as well as to optimize the future siting of groundwater exploitation boreholes through the elaboration of the local aquifer prospectivity map.
... The geoelectrical resistivity technique is the most widely used geophysical method to identify aquifers (Ndatuwong and Yadav 2015;Olubusola et al. 2018;Arunbose et al. 2021). Geoelectric properties from vertical electric sounding (VES) such as longitudinal conductance and transverse resistance have proven to be very useful in delineating aquifer zones (Batayneh 2013;Alabi et al. 2021;Puttiwongrak et al. 2022). Hydraulic conductivity and transmissivity are strongly related to the porosity and permeability of aquifers (Jasrotia et al. 2016;Sattar et al. 2016;Dewandel et al. 2017) and are very important for the characterization of GWPZs (Youssef 2020b;Vijayaprabhu et al. 2022). ...
The Kribi-Campo region is one of the most attractive areas in Cameroon due to its proximity to the sea. Despite its location, residents still have a lot of trouble getting enough water. The complex bedrock that dominates this area has an impact on the factors affecting groundwater recharge. The main objective of this study is to use the analytical hierarchical process (AHP), frequency ratio (FR), Shannon entropy (SE), and weight of evidence (WofE) through the geographic information systems (GIS) to determine groundwater potential zones in Kribi-Campo region. Fifteen (15) groundwater conditioning factors were selected using conventional, remote sensing and vertical electrical sounding data. Weights were assigned to the conditioning factors and their features based on the AHP, FR, SE and WofE methods, and then integrated into ArcGIS software to generate the groundwater potential maps. The maps that resulted were then classified into four zones: very low, low, moderate and high. The areas under the receiver operating characteristic curves (AUC) were used to evaluate the performance of the models. The results showed that the WofE model (success rate, 78.8%; prediction rate, 85.5%) have higher predictive accuracy, followed by the SE model (success rate, 83.1%; prediction rate, 83.4%), the FR model (success rate, 77.4%; prediction rate, 74.9%) and the AHP model (success rate, 49.3%; prediction rate, 61.9%). This article may serve as a roadmap for hydrogeological explorations and the management of groundwater resources in the study region.
Assessing groundwater potential for sustainable resource management is critically important. In addressing this concern, this study aims to advance the field by developing an innovative approach for Groundwater potential zone (GWPZ) mapping using advanced techniques, such as FuzzyAHP, FuzzyDEMATEL, and Logistic regression (LR) models. GWPZ was carried out by integrating various primary factors, such as hydrologic, soil permeability, morphometric, terrain distribution, and anthropogenic influences, incorporating twenty-seven individual criteria using multi-criteria decision models along with a hybrid approach for the Subarnarekha River basin, India, in Google earth engine (GEE). The predictive capability of the model was evaluated using a Multi-Collinearity test (VIF <10.0), followed by applying a random forest model, considering the weighted impact of the five primary factors. The hybrid model for GWPZ classification showed that 21.97 % (4256.3 km2) of the area exhibited very high potential, while 11.37 % (2202.1 km2) indicated very low potential for GW in this area. Validation of the groundwater level data from 72 observation wells, performed by the Area under receiver operating characteristic (AUROC) curve technique, yielded values ranging between 75 % and 78 % for different models, underscoring the robust predictability of GWPZ. The hybrid and LR-FuzzyAHP models demonstrated remarkable effectiveness in GWPZ mapping, indicating that the downstream and southern regions boast substantial groundwater potential attributed to alluvial soil and favorable recharge conditions. Conversely, the central part grapples with a scarcity of groundwater. It holds the potential to assist planners and managers in formulating strategies for managing groundwater levels and alleviating the impacts of future droughts.
The study documents the effectiveness of 2 D (Two Dimensional Electrical Resistivity Survey (Tomography) to map shallow subsurface geological formations namely recent Alluvium, Gondwana deposits and hard rock deposits. 2 dimensional Electrical Resistivity Survey (or tomography) was conducted at 2 locations at Valarpuram and one location Madurantakam areas. Gondwana deposits mask Valarpuram Thandalam, villages (at Kancheepuram District, Tamilnadu). To the east of Valarpuram alluvium thickness increases at shallow depths. Weathered and hard granitic gneiss and hard charnockite rocks overlie topsoil in Madurantakam areas (Chengalpettu District, Tamilandu). The survey was conducted to 12 m depth to decipher shallow permeable zones. Gondwana formations consisting of clays, siltstones are predominant in Valarpuram Thandalam and surrounding areas. Hard rock formations are found in Madurantakam areas. 2 Dimensional Resistivity Survey results indicate 2-D sections with very low resistivity values in the range of 2 to 4 ohm-m in Valarpuram Thandalam areas indicating predominant clay deposits with poor ground water potential. To the east of Valarpuram Thandalam resistivity data is of moderately higher value indicating sand deposits at shallow depths. These are ideal locations for dug wells. Low to moderate values at shallow depths indicating weathered thickness up to 12 m are observed at Madurantakam location. From 12m depth steep rise in resistivity values are observed in hard indicating presence of massive rock from 12m depth and below areas. Thus, 2 D Resistivity Imaging Technique are helpful in delineating shallow aquifer potential and this in turn helps in deciding the depth of open wells with high precision.
