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Iso-apparent resistivity map for AB/2 = 70 m. Colour version of this figure is available in electronic edition only.
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An integrated approach of geoelectrical and hydrochemical investigation surveys was proposed for indicating contact regions between saline and fresh groundwater in the Khanasser valley region, northern Syria. The qualitative and quantitative interpretations of 34 vertical electrical soundings (VES) enable to characterize the salt water intrusion la...
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Context 1
... the well 97, where there is a significant difference between both EC and electrical resistivity distribution patterns (Figs. 4, 5, and 7). This punc- tual difference between the EC and the electrical distributions is justified by an interpolation artifact due to the irregular space-distribution of the obser- vation wells, with poor coverage in the valley axe, especially at the Jaboul salt lake neiborhood (Fig. 2). A more accurate assessement of the salt water ...
Context 2
... to the above equation, a mixing ratios map is established (Fig. 12), where a similar behavior distribution as the electrical resistivity distributions shown in Figs. 4 and 5 is obtained. However, differences between the iso-value maps for mixing ratios (Fig. 12) and the electrical resistivity distribution (Figs. 4 and 5) are partially due to different number and location of data points used to construct these iso-value ...
Citations
... Similarly to Asfahani and Abou Zakhem (2013), we concluded that increasing the well depths by 0.40, 0.60, 0.70, and 0.80 m with 0.50 m at base case decreased LSWI to 149.50,139,129.50,and 120 cm while the VSWI decreased by 57.50,43.50,34,and ...
Lateral Saltwater Intrusion (LSWI) and Vertical Saltwater Intrusion (VSWI) are the major problems in coastal aquifers. Coastal aquifers are subjected to natural and artificial changes, including sea‐level rise, decreasing inland recharge, and overexploitation of production wells’ water resources. Therefore, this study investigates the influence of changing the coastal aquifers boundary conditions considering climate changes' effect. Parameters describing the upward saline well parameters based on the abstraction conditions, also, the top layer properties were studied based on the erosion and sediments, irrigation, and drainage conditions. For this purpose, the SEAWAT model was employed to simulate lateral SWI based on Henry's problem principle. The sensitivity analysis of the mentioned parameters was accomplished considering as a case study the Biscayne aquifer in the Cutler Ridge area near Deering Estate, Florida, USA, where the LSWI and VSWI were also investigated. The results indicate that the boundary conditions, abstraction well parameters, and top layer cost significantly impact aquifer LSWI and water upconing. The simulation results of the Biscayne aquifer for a saline water head of 84.86 cm for 2060 indicate a decrease in freshwater recharge by 30% and increasing the saltwater concentration by 14.30%. At the same time, the LSWI increased by 3.30 22.80, and 8.70%, while the relative upconing heights reached 0.63, 0.60, and 0.47 compared with 0.42 for the current situation. Increasing the upward saline abstraction well discharge rates by 50% increases the LSWI by 9.40%. In contrast, increasing the depth by 10%; decreases the distance by 30%, the screen length by 30%, the LSWI decreased by 1.80, 25.10, and 1.30%, respectively. At the same time, the relative VSWI height reached 0.60, 0.39, 0.48, and 0.40, respectively. Moreover, decreasing the top layer hydraulic conductivity by 25% and increasing the aquitards layer depths by 200% decreased the LSWI by 4.90 and 7.80%, respectively. At the same time, the relative VSWI height reached 0.34 and 0.30, respectively. In addition, the saline water heads, a freshwater recharge should be controlled to manage SWI; the upward well should be utilized at a low abstraction rate, far from the seaside, and with minimum screen length. The agriculture activity for decreasing the soil permeability for the top layer must be extended for better management of the SWI. The solution‐oriented findings resulting from this study might be useful for decision‐makers and engineers to develop effective management measures to tackle the SWI issue in coastal aquifers. This article is protected by copyright. All rights reserved.
... The established geoelectrical models were calibrated with nearby wells (Channoufia Douara). Therefore, a high similarity degree (0.87-4%) between the measured and the calculated curves (error percentage) was obtained, which confirms the reliability of the established geo-electrical models (Gasmi et al. 2001;Mhamdi 2003;Asfahani and Abou Zakhem 2013). ...
The present study uses an integrate geoelectrical and hydrochemical approach to assess the processes of groundwater mineralization in the Plio-Quaternary shallow aquifer of the Garâat Douza-Tebeddit basin, Southwestern Tunisia. The interpretation of major ion analyses demonstrates that the mineralization is controlled by natural and anthropogenic processes. Natural processes include the dissolution of evaporate minerals namely halite, gypsum/anhydrite and epsomite, the cation exchange process and the encroachment of salt-water from the Sebkha of Garâat Douza discharge area. These processes are confirmed through the Kelley and expanded Durov diagrams, which indicate that the shallow aquifer groundwaters are likely, mixed with different types and have undergone sulphate and sodium chloride mixing with old stagnant sodium chloride dominated salt-water. The anthropogenic mineralization process corresponds to the contamination by the leached of nitrogen fertilizers through the return flow of irrigation waters. The geoelectrical survey demonstrated the predominance of relatively low resistivity values of the shallow aquifer near the discharge zone, which gradually increase as one moves away towards the recharge zones, indicating the encroachment of Sebkha salt water in the surficial water table.
... The direct current (DC) vertical electric sounding method is commonly used in geophysical exploration for geological prospecting (Zohdy 1974(Zohdy , 1989Fu 1990). Resistivity data can be used to determine properties such as the bedrock depth, thickness of sand and gravel deposits, water table depth and the distribution of aquifers (Barongo & Palachy 1991;Braga et al. 2006;Asfahani & Zakhem 2013;Attwa et al. 2014). This method relies on varying in electric properties in the substrate lithology, and resistivity changes in the strata are identified by via progressively increasing the distance between the DC source and electrode. ...
Stratigraphic classification and correlation are fundamental for the study of regional geology, tectonic structures and paleogeographic evolution. Geological structures have undergone a dramatic change since the Quaternary. However, the division of the Quaternary stratigraphic boundary in southeastern China is debated. In this study, we used a direct current vertical electric sounding method to study the Quaternary strata in Yixing, Jiangsu, China. Using one-dimensional resistivity inversion and analyzing the regional geology and geological core data, the electrical features of the study area were evaluated. We found good agreement between the geological core data and lithological data, and we were able to identify two stratigraphic groups: the hilly sedimentary area in the southwest and the Tai Lake plain sedimentary area in the northeast. The latter can further subdivided into two parts. Division and classification of the Quaternary strata in the study area provide a basis for locating areas likely to have a high pore-confined water content (such as Gaoteng, Heqiao and Wanshi town), whereby useful information is provided for groundwater exploitation for emergency use.
... One geophysical technique named vertical electrical sounding (VES) is utilized in our work. Geoelectrical techniques are often used to determine the thickness, depth, and aquifer boundary (Omosuyi et al. 2007;Asfahani and Abou 2013). The VES has been widely used for hydrology studies worldwide (Coker 2012;Asfahani and Abou 2013). ...
... Geoelectrical techniques are often used to determine the thickness, depth, and aquifer boundary (Omosuyi et al. 2007;Asfahani and Abou 2013). The VES has been widely used for hydrology studies worldwide (Coker 2012;Asfahani and Abou 2013). The Electrical Conductivity (EC) data is also used in this study to determine the salinity of groundwater. ...
... The VES method is the most commonly used method for underground water studies (Asfahani and Abou 2013;Dafalla et al. 2015). In our study, the VES survey data were obtained from the District Agriculture Engineering Department. ...
Owing to the climatic dryness and shortage of surface water, Pakistani farmers have been forced to rely on groundwater resources to meet the irrigation demand for crops. Pumping an excessive amount of water from the aquifers is turning it brackish. Our study aims to select a suitable depth of freshwater for installing tube wells in a study area, Tehsil Nankana Sahib. Sixteen vertical electrical soundings (VES) were arrayed in this study area, and water samples were also collected to record their electrical conductivity. The interpolation maps for different parameters were generated by using the inverse distance weighted interpolation method. The obtained results depict that the central and southeastern region has good groundwater at depths from 60 to 90 m, the northeastern region has marginally fit water, while the northwestern region is marked as having an unfit groundwater zone. This research article is not only a case study but also can be used for other areas of Punjab, Pakistan, facing similar groundwater problems. However, the comparison of VES results with borehole data is critical to achieve better accuracy. An extensive exploratory borehole study of the area is recommended to further characterize the subsurface lithology.
... In the last decade, there has been a significant increase of the use of geophysical methods for the characterization of hydrogeological sites [23]. Geophysical techniques were used by many authors to solve concerning hydrogeological issues [24]. This technique has also been utilized by many authors for vulnerability mapping and studies [2][3][4]. ...
... The true resistivity values obtained after IPI2W processing are used for deriving the Dar Zarrouk (DZ) parameters [37]. The DZ parameters help to identify the areas having saline groundwater in the area [24]. The DZ parameters are defined in terms of transverse resistance and longitudinal conductance. ...
Vulnerability analysis in areas vulnerable to anthropogenic pollution has become a key element of sensible resource management and land use planning. This study is intended to estimate aquifer vulnerability using the DRASTIC model and using the vertical electrical sounding (VES) and electrical conductivity (EC) outcomes. The model allows for the identification of hydrogeological environments within the scope of the research, based on a composite definition of each environment’s main geological, geoelectrical, and hydrogeological factors. The results from the DRASTIC model were divided into four equal intervals, high, medium, low, and very low drastic index values. The SW area and NE area depict drastic index values from medium to very high, making it the most vulnerable zone in the study area, while the NW and SW areas show low to very low drastic index values. In addition, the results from the VES and EC the freshwater aquifer in the NE area and brackish water in the SE area, while the rest of the area falls into the category of brackish water. Overall, it can be concluded that areas having freshwater assemblages are on the verge of becoming contaminated in the future while the rest of the NW and SW areas constitute less vulnerable zones. The validation conducted for DRASTIC and EC shows a nearly positive correlation. Wastewater treatment policies must be developed throughout the studied region to prevent contamination of the remaining groundwater.
... Alternatively, the plane distribution of water quality is usually based on the interpolated original apparent resistivity and measured TDS. Asfahani and Abou Zakhem (2013) demonstrated a good agreement between low resistivity areas in the original apparent resistivity plan distribution and TDS planar interpolation results. The Dar Zarrouk parameter, introduced for describing the relationship between transversal unit resistance and longitudinal unit conductance, was successfully used to determine the extent of saline water intrusion in coastal areas associated with TDS data (Khalil, 2006;George et al., 2015;Hasan et al., 2019). ...
In most coastal alluvial plains, the groundwater area of the aquifer is a rich environment that has experienced an extended period of marine deposition and is highly vulnerable to increasing urbanization. Excessive exploitation of groundwater has resulted in recent seawater intrusion and connate water leakage, leading to freshwater salinization. In this study, a novel workflow is designed for groundwater appraisal. First, revised one-dimensional direct transformation schemes were developed and applied to extensive vertical electrical sounding (VES) points sampled by a Schlumberger array to obtain the VES-based calibrated transformed resistivity (V-CTR), as calibrated by the modified reflection coefficient and novel depth correction factor. Next, the interfaces of all leaky confined aquifers (LCAs) and the saline water zone were quantitatively determined via hybrid interpretation methods. Finally, to better understand the salt level (i.e., fresh, brackish, or saline) and perform assessments of the groundwater quality, total dissolved solids (TDS) planar distributions were interpolated using two different power functions linking the V-CTR and measured TDS from the sampled boreholes for the corresponding aquifer unit. The workflow was examined based on hydrological and geophysical data acquired at the Yangtze River Delta (Nantong Region, Jiangsu Province, China). The interpreted results are of great significance for understanding the groundwater distribution associated with the Quaternary geology and hydrogeology and can be potentially used to analyze and guide the development and utilization of water resources in the study area.
... Using resistivity logs, researchers are determining the reservoir characteristics (Archie 1942). Electrical resistivity survey has been implemented in various parts of the world for different purposes (ahlin et al. 2004;Friedman 2005;De carlo 2013;Asfahani 2013;Lech et al. 2016;Koda et al. 2017;Kowalczyk et al. 2017;Rabarijoely 2018). Different methods were applied to invert electrical resistivity data (Dahlin 2001;Loke and Dahlin 2002;Loke et al. 2003;Loke and Lane 2004) A specially designed algorithm was implemented in this research work using the Adaptive Neuro Fuzzy Inference System (ANFIS) to invert geoelectrical resistivity data. ...
Geoelectrical inversion has some problems in inverting data due to the heterogeneous behaviour of Earth. One of the major concerns in inverting the data is due to the influence of noises, which comes from the disturbance due to human interventions, atmospheric variations, and electromagnetic disturbance, etc. . In this paper, we have presented a concept of Neuro Fuzzy algorithm which can interpret the noisy data successfully. Moreover, the data were tested with artificially generated random noise, gaussian noise and missing data. Kanyakumari field region having complex geological structures and its performance is validated with a maximum threshold. Kanyakumari field region having complex geological structures is used and the performance is validated with a maximum threshold. Neuro fuzzy technique has the dominant feature of training and testing the data with utmost accuracy. These implications are made to create the specific Graphical User Interface (GUI) for the algorithm and it works well for all types of Vertical Electrical Sounding (VES) data with good performance results.
... Hydrogeological investigations performed in a number of locations worldwide confirm the strong impact of the sea water percolating deep in the ground toward inland due to the difference in density between salt and fresh groundwater [1][2][3][4][5][6][7][8][9][10]. In the coastal zone, sea water forms an intrusion propagating under the non-saline rock layers just below the ground surface. ...
Numerous hydrogeological studies on the coastal zone describe the intrusion of sea water inland, salting underground aquifers. The phenomenon is commonly observed in the coasts outside polar areas. However, the impact of sea water has so far not been an object of detailed investigation in a periglacial environment devoid of subsea permafrost. Geophysical measurements at the west coast of the Wedel-Jarlsberg Land in Svalbard indicate that the border between the unfrozen seabed and the frozen ground onshore is not delimited by the shoreline. A zone of coastal unfrozen ground is located under a thin layer of permafrost reaching toward the sea. This state was observed with the use of electrical resistivity tomography under rocky headlands and capes, uplifted marine terraces located at the foot of mountain massifs and valley mouths as well as in the marginal zone of the Werenskiold Glacier. This short article presents the results of such a measurement, supplemented with electromagnetic detection. The measurements are unique in that they were conducted not only on the land surface, but also at the floor of the sea bay during the low water spring tide. The author proposes name structures detected in the coastal zone as a "permafrost wedge", extending an identification of the permafrost base between the coast and the glaciers of Svalbard. However, in the absence of boreholes that would allow determining the thermal state of the ground in the study sites, the concept is based only on the interpretation of the geophysical imaging. Therefore, further discussion is required on whether the identified contrasts in electrical resistivity indeed result from thermal differences between the rocks or if they only indicate the cryotic state of the ground (saline cryopeg) within the range of seawater intrusion.
... The electric imaging (or tomography) technique is an investigative method non-destructive to obtain an image of the subsoil in order to identify its internal structure such as geological heterogeneities, faults, depth and the thickness of the layers. Offering the possibility of acquiring a large number of measurements corresponding to the different combinations of four electrodes (Edwards, 1977;Asfahani & al., 2013). This allows continuous 2D or 3D imaging of variations in subsoil resistivity (Dahlin, 2001) in regions with complex geology characterized by lateral variations that make the use of electrical boreholes inadequate (Giang et al., 2013). ...
Groundwater resources in Morocco are increasingly scarce. The study area which is Central Haouz belonging to the Marrakech plain is not immune to this phenomenon. This is due to the semi-arid climate on the one hand, and on the other hand, due to accelerated population growth and the economic development implications. The Plio-Quaternary aquifer of the Central Haouz has been the subject of several studies, but its Hydrogeological characterization has been classically carried out using geological and pumping test studies. Our study is in this sense to show the importance of the contribution of GIS and Electrical Resistivity Tomography (ERT). The first GIS approach determined the Runoff coefficient, which helps to locate low runoff areas corresponding to recharge zones of the water table. These areas are chosen as the site for geophysical surveys. The second method consists to detect the effect of the recharge to increase the water table in the study area and the characterization of the aquifer. Four ERT surveys were performed showed on the aquifer the positive effect of the recharge dike recently built at the Wadi and dismantle the reliability of the GIS results concerning the infiltration zones founded.
... The method is based on the assumption that soil and rocks, as well as other materials, conduct electricity. As shown by previous studies [12,15,19,21,27], the method is affected by the soil moisture content and water saturation, its porosity and contamination level of water in the soil pores, in particular with salt [15,28,29] and NAPL (non-aqueous phase liquid) compounds [19,30], and change of stress conditions [8,16]. ...
Standard test methods may not be suitable or sufficient for determining the geotechnical conditions of a structure’s subsoil and the effects of the designed structures on the environment. Geophysical test methods, validated with other methods, may prove useful. In recent years they have found many new applications in engineering practice, both geotechnical and environmental. The advantages of geophysical methods include the non-destructive and non-invasive nature of the tests, their low costs and quick results, as well as compatibility with different materials, including soils, solid rocks, wastes and anthropogenic formations. The paper presents the analysis of laboratory and field investigations including research in a modified oedometer, resistivity chamber, electrical resistivity tomography (ERT) and resistivity cone penetration test (RCPT). Laboratory tests allowed for the assessment of the degree of saturation and porosity of sandy and clayey soils. The tests were carried out on saturated and unsaturated soil samples and allowed for the determination of some relationships between electrical conductivity and porosity. The proposed equations were used to assess parameters in in situ studies using RCPT tests and showed good agreement with reference values based on undisturbed soil samples. ERT tests confirmed the usefulness of electrical measurements in the quality assurance of subsoil and hydrotechnical structures. The tests showed weakening zones in the levee body, discontinuity of the vertical sealing system on the modernized section of the embankment, and location of the top of clay deposits.
