Geoelectrical Study Research Articles

Palaeoenvironmental evolution and decline of the harbours of the Roman and Early Byzantine city of Elaiussa Sebaste (southeastern Turkey): natural and anthropic causes

ABSTRACTThe ancient city of Elaiussa Sebaste, currently Ayaş, is located on the southeastern coast of Turkey. It was one of the main trading Mediterranean harbours from the Augustan period until the early Byzantine era. The Arab invasion in the 7th century ce marked its definitive abandonment. A significant historical topic concerns the palaeoenvironmental evolution of the northern and southern harbours of Elaiussa Sebaste, including their decline and burial. An interdisciplinary study analysed six cores drilled in the current plains corresponding to the former harbour basins. A geoelectrical study, integrated with borehole stratigraphy, reconstructed the geometry of the carbonate bedrock that forms the accumulation base of the marine sediments. Sediments deposited from the 8th century bce to the 6th century ce include the development phases of the ancient city from the 3rd century bce onwards. Sedimentology, micropalaeontology (foraminifers, ostracods), palaeobotany (pollen, non‐pollen palynomorphs, microcharcoals, plant macroremains) and Pb isotopes provided a model of the environmental evolution in both harbour basins. The main harbour expansion phase, marked by a change in Pb concentration, is hypothesized to have occurred between 140 and 220 ce, which is consistent with the historical sources indicating the development of the city during the mid‐Roman Imperial period.

Hydrochemical and geoelectrical investigation to determine the origin and spatial distribution of the salinization of the unconfined Plio-Quaternary aquifer of Tabeditt, Southern Tunisia

The expansion of irrigated agriculture and the overexploitation of groundwater in the Tabeditt region lead to a serious deterioration of the chemical quality of water. The compilation of hydrogeological and geophysical studies is essential in order to assess the quality of the Plio-Quaternary waters and to determine the origin of the salinization of these waters. In this study, hydrochemical analyses were carried out on groundwater samples in the Tabeditt region. Hydrochemical data have shown that the salinity in this area could exceed 6 g/L. The interpretation of major ion analyses demonstrates that mineralization is controlled by natural processes. The mineralization process consists of the dissolu-tion of evaporite minerals, namely gypsum, anhydrite, and halite. The geoelectrical study is carried out to obtain information about the distribution and quality of water in the Plio-Quaternary. Interpreta-tion of the resistivity models show the presence of two main zones: the first, near Tabeditt Wadi, is characterized by low values, indicating the influence of salt water in the groundwater and the second, located on the right bank of Wadi Jmal, is characterized by variable resistivity values, generally high, indicating the lateral changes in lithological facies, and the presence of fresh water. In such an arid region suffering from scarcity and degradation (or depletion) of water resources, it is important to implement a master plan that keeps under control the number of wells both known and unknown ones taping these aquifers.

Combined Application of Hydrogeological and Geoelectrical Study in Groundwater Exploration in Karst-Granite Areas, Jiangxi Province

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.

A geoelectrical study of aquifers in the Natar, South Lampung

The conditions for the development of population growth and development in the area around the City of Bandar Lampung are very fast and starting to get crowded, as happened in the District of Natar South Lampung, especially in the Village of Pemanggilan. This condition causes an increase in the need for clean water resources in line with the increase in groundwater exploitation. Therefore it is necessary to map the potential of groundwater through aquifer mapping and aquifer rock layers through geoelectrical measurements. This study aims to determine the potential of groundwater from volcanic aquifer systems based on geoelectrical measurements. The method used in this study is geoelectric resistivity using the Wenner-Schlumberger configuration with 3 measurement points. The results of the study show that using the geoelectrical resistivity method, layers with a resistivity value of ? 30.3 ?m are interpreted as shallow aquifers at depths varying from 1 to more than 24 meters with lithology suspected to be tuff and tuff sandstones, which according to geological data are included in the Lampung Formation. Using the 2D geoelectric method, the distribution of shallow aquifers in the study area to a depth of 24 meters can also be determined. The data obtained is expected to be used as supporting data for the sustainable use of water sources.

English

An integrated geoelectrical study combining electrical resistivity tomography (ERT) and induced polarization (IP) have been used to delineate potential zones of Lead-Zinc mineralization in Umuobuna, Uburu, Ohaozara local government area, southeastern Nigeria. The wenner array configuration was used to acquire resistivity and induced polarization data sets along three traverses of approximate length of 1 km each and spacing of 5 to 25 m, using ABEM Terrameter SAS 1000. The profiles were inverted using RES2DINV software for 2D imaging to delineate possible zones of Pb-Zn mineralization and the geological structures at selected locations in the study area. The ERT surveys were carried out along the IP lines for comparison of anomalies across the profiles. The potential zones of Pb-Zn mineralization display contrasting values of resistivity and chargeability along the traverses. Resistivity values ranging from 7.53 to 7525 ?m and corresponding chargeability values of between -15.6 and 354 ms, respectively were encountered at some intervals along the traverses. These zones occur at width range 19.5 to 74.5 m and depths of between 0.9 and 15.5 m. Having a low to moderate resistivity and a corresponding high chargeability values at similar width range may be suggestive of Pb-Zn mineralization and test drilling is needed at the anomalous sites for confirmation. Key words: Pb-Zn, ERT, IP, resistivity, chargeability, mineralization.

Geo-Electrical Study for Groundwater Potential of Gude and Environs, Adamawa State, Nigeria

Eighteen Vertical Electrical Sounding (VES) were carried out to evaluate groundwater potential and aquifer protective capacity of the overburden units in Gude and environs. The Schlumberger configuration with maximum current electrode of 100 m was used and H type curve accounted for 94.4%. Geo-electro stratigraphic sections revealed that the geologic sequence beneath the area is composed of topsoil and highly Weathered/Fracture basement. The first layer is topsoil and has resistivity values between 15 Ωm to 462 Ωm with thickness ranging from 0.82 m to 4.78 m. The second layer which is referred to as weathered/fractured has resistivity values between 23 Ωm to 119 Ωm and thickness value ranging from 15 m to 43 m. The third layer representing a weathered basement and has an average resistivity value of 316.10 Ωm. The Dar-Zarrouk parameter in Gude area showed that the transvers resistance varies from 140.83 to 4763.02 Ohm-m2 with average value of 1422.32 Ohm-m2. While the Hydraulic conductivity values determined from geoelectrical technique range from 7.028 to 48.554 m/day with average value of 17.145 m/day.

A Geo-Electrical Study to Determine the Geometry of Landslide Using a Physically-Based Model

A Geo-Electrical Study to Determine the Geometry of Landslide Using a Physically-Based Model

An appraisal of Chott El Jerid brine encroachment in the Tozeur-south shallow aquifer: Geoelectrical and hydrochemical approach

Geoelectrical data were used in conjunction with hydrogeological information and hydrochemical measurements to investigate and conceptualize the Chott El Jerid saltwater encroachment into the Tozeur-south shallow aquifer, southern Tunisia. The hydrogeological investigation shows that the over-pumping of the unconfined aquifer groundwater has resulted in a localized water level decline, which enhanced the encroachment of the brines of the Chott El Jerid discharge area into the shallow water table. This transitional hydrodynamic state is further complicated by the upward vertical flow of relatively fresh-water from the underlying confined aquifer. The geoelectrical study has confirmed the brines encroachment through the predominance of relatively low resistivity values of the shallow aquifer groundwater close to the discharge area, which become progressively high as we move away towards the recharge zones. In fact, the toes shaped resistivity zones in the isoresistivity map bring insight to the mixing of shallow groundwater with Chott brines. However, the presence of a positive resistivity leakage plume confirmed the mixing with upward fresh-water leakages. Hydrochemically, the Chott brines encroachment is manifested by an evolution of hydrochemical facies from Na-Cl end-member towards a Ca-HCO3/SO4 end-member. The variation in groundwater hydrofacies between these two end-members, indicates a progressive evolution as we move along way from the Chott, by mix/Na-mix/SO4 and mix/Na-SO4. These findings are well illustrated in the conceptual model, which shows the impact of the stressed hydrodynamic regime on the behaviors of the electrical and the hydrochemical facies of the PQ aquifer and its groundwater, respectively.

Application of geological and electrical resistivity methods for groundwater studies at Tatiko, North Central Nigeria

The success probability of water wells constructed in crystalline rock terrains is largely dependent on the size, location and interconnectivity of the fractures present in them as well as the amount and nature of the material that may clog the fractures. Geological and geoelectrical studies were proposed and conducted at Tatiko to determine the structures in the underlying basement rocks and evaluate their groundwater potential. Geological study was used to delineate the structural control on groundwater availability while the geoelectrical study (Vertical Electrical Sounding) was used to investigate the properties of the subsurface materials and determine their potential to host sufficient quantity of groundwater.Structural data were plotted on a rosset diagram and showed major structural control trending in the NW – SE direction. Quantitative interpretation of the geoelectric data indicates that the major fractures are within the weathered to competent basement indicating good hydraulic connection between the weathered and fresh basement. The fractures are deepest within the region that showed thicker weathering and are as shallow as 7 meters in other regions. Apparent resistivity of the fractures ranges between 100Ωm and 1200Ωm in most parts of the area with the highest values in the west. An integration of the result clearly showed that the NW and SW parts of the study area are the most favourable for drilling and further groundwater studies and drilling is recommended to a depth of 40m to 50m.
 Keywords: Groundwater, Geoelectrical study, Fractures, Tatiko, Resistivity, Basement Complex.

Assessment and management of water resources in Wadi El-Deeb using geophysical, hydrological and GIS techniques-Red Sea

Wadi El-Deeb is a transboundary sharing basin between Egypt and Sudan. Wadi El-Deeb lies in arid belt where sporadic rain fall occurs in the form of local storms which occasionally accompanied by flash floods. Objective of this research is to assess and evaluate the potentials of both surface and groundwater resources in the study Wadi within the challenge of data scarcity. By utilizing the physiographic features of the study basin, it could be deduced that the hydrological behavior has influenced by the geomorphological and the topographical aspects. This study was based on the integral coordination among physical properties of the study basin, geo-informatics and Watershed Modeling System (WMS) to create the hydrograph of Wadi El-Deeb and its study sub-catchments. Flash flood hazard of the study sub-catchments which are located in Egypt have been evaluated and classified into low hazard group (sub-basin 2) and high hazard group (sub-basins 1, 3 and 4). The groundwater recharge potentiality may increase at the sub-basin 2 and the surface runoff will be expected for sub-basins 1, 3 and 4. Therefore; some obstruction dams should be created at the fourth and fifth order of the high hazard sub-basins. The maximum volume capacity of the whole Wadi El-Deeb is about 781.6 × 106 m3 which covered a flooded area is about 62 km2, while for the study sub-basins the maximum flooded area ranges from 0.3 km to 17.2 km2 and the volume capacity ranges from 1.5 × 106 m3 to 125.7 × 106 m3. On the other hand, the geoelectrical study and the data of the hand dug wells, revealed the presence of two water bearing formations of Wadi deposits and weathered basement rocks. The groundwater potentiality is limited and it can be used only for Bedouin, cheeps and camels drinking through small desalination units working with solar energy. The geophysical exploration results of shallow groundwater are matching with the constructed hazard degree map.

Geoelectrical study of corrosivity and competence of soils within Uburu and Okposi areas of Ebonyi State, Southeastern Nigeria

PurposeThe corrosivity and competence of soils within Uburu and Okposi areas of the Southern Benue Trough, Nigeria, were evaluated using the electrical resistivity method. This paper aims to provide information that will aid pre-design of subsurface iron/steel pipe networks for distribution of pipe-borne water and construction of subsurface structures for agricultural and environmental purposes.Design/methodology/approachIn total, 22 vertical electrical soundings (VES) in the Schlumberger configuration were acquired with Allied Ohmega™ Terrameter with a maximum half current (AB/2) electrode spacing of 200 m. Layer parameters were determined using partial curve matching techniques, using the Schlumberger master curves, while processing and modelling were done with the IPI2win™ software. The VES results were interpreted qualitatively and quantitatively to obtain various curve types and layer parameters, respectively, which were used to categorize the area into different competence and corrosivity zones. The first layer isoresistivity and competence maps were used to delineate four zones (A,B,C and D) with varying apparent resistivities and competences.FindingsIncompetent soils with resistivity values ranging from 24.3-88.7 Om are found in Zone A. The soils in Zone A are mainly expansive clays which swell on absorption of water. Zone B contains moderately competent soils with resistivity values ranging from 273-308.6 Om, while Zones C and D are underlain by sandstones and contain competent to highly competent soils with resistivity values ranging from 511-750 Om and 835-1,525 Om, respectively. Zone E contains highly corrosive (24.3 Om) to mildly corrosive (102 Om) soils; Zone F contains soils that are essentially non-corrosive with resistivity values ranging from 271-1,525 Om, while the corrosivity of soils within Zone G varies from corrosive to mildly corrosive, with resistivity values ranging from 44.3-114 Om.Research limitations/implicationsSome of the areas are not accessible because of community restrictions.Practical implicationsThese findings are essentially very significant and should be taken into consideration when materials that are susceptible to corrosion are being considered for engineering, agricultural and environmental purposes in the area.Social implicationsThe findings will aid water resource planners and developers on how to protect metal pipes from corrosion, when used for water reticulation and agricultural purposes.Originality/valueThis paper fulfils an identified need to study the corrosivity of soils in the study area with a view to providing adequate protection to metal objects when being considered for water reticulation for domestic and agricultural purposes in the area.

Drought-induced recharge promotes long-term storage of porewater salinity beneath a prairie wetland

Subsurface storage of sulfate salts allows closed-basin wetlands in the semiarid Prairie Pothole Region (PPR) of North America to maintain moderate surface water salinity (total dissolved solids [TDS] from 1 to 10 g L−1), which provides critical habitat for communities of aquatic biota. However, it is unclear how the salinity of wetland ponds will respond to a recent shift in mid-continental climate to wetter conditions. To understand better the mechanisms that control surface-subsurface salinity exchanges during regional dry-wet climate cycles, we made a detailed geoelectrical study of a closed-basin prairie wetland (P1 in the Cottonwood Lake Study Area, North Dakota) that is currently experiencing record wet conditions. We found saline lenses of sulfate-rich porewater (TDS > 10 g L−1) contained in fine-grained wetland sediments 2–4 m beneath the bathymetric low of the wetland and within the currently ponded area along the shoreline of a prior pond stand (c. 1983). During the most recent drought (1988–1993), the wetland switched from a groundwater discharge to recharge function, allowing salts dissolved in surface runoff to move into wetland sediments beneath the bathymetric low of the basin. However, groundwater levels during this time did not decline to the elevation of the saline lenses, suggesting these features formed during more extended paleo-droughts and are stable in the subsurface on at least centennial timescales. We hypothesize a “drought-induced recharge” mechanism that allows wetland ponds to maintain moderate salinity under semiarid climate. Discharge of drought-derived saline groundwater has the potential to increase the salinity of wetland ponds during wet climate.

Geoelectrical and hydrogeological study to delineate the geological structures affecting the groundwater occurrence in Wadi El Khariq Basin, Northwest El Maghara, north Sinai, Egypt

Wadi El Khariq has a vast area that can be reclaimed. Upper Jurassic carbonates represent the main aquifer. The Desert Research Center has a pilot station in Wadi El Khariq that suffers from water deficiency. Therefore, the drilling of new wells is needed. As fault zones make fracture conduits for groundwater, detecting these faults is a vital process. Therefore, this study aims to trace the existing subsurface structures and their impact on groundwater occurrence. The interpretation of the results of the vertical electrical soundings leads to the detection of five geoelectrical layers. The third and fourth layers correspond to fractures and argillaceous limestone represents the water-bearing layers. The interpretation of the results of the eight 2D electrical resistivity tomography profiles gave more illustrative information about the lateral facies changes, the structures effect along the study area, distribution of the different types of water-bearing limestone, and the depth to their top. The deduced structures from electrical study are represented by the faults F1–F6. The faults F1 and F2 are confirmed from both 1D and 2D imaging profiles. The fault plains of F1, F2, F5, and F6 are continuous between the measured imaging profiles. The 2D imaging profiles revealed that the clay content increase eastwards. The correlation results of the natural gamma and lithological logs of the drilled wells as well as the constructed hydrogeological profiles revealed that the area of study affected by another group of faults (F6–F12). These faults affect on the groundwater occurrence and quality. These faults lead to the formation of graben and horst structures, lateral facies changes, variation in layers thickness, and the occurrence of the fractured limestone layer lying beneath the calcareous clay at variable depths. Most of the detected faults in the study area have NW–SE trends coinciding with the lineation analyses of the faults and fractures of El Khariq basin. The fractured limestone aquifer in the study area is recharged via the percolation of the surface runoff water of local precipitation on Gable El Maghara catchment area through the fracture lines, fault planes and bedding planes besides paleowater of the paleo-rainy seasons. The depth to water varies from 60 to 114 m. The groundwater salinity of the wells drilled in El Khariq plain varies greatly due to the effect of the lithological nature of the water-bearing formation and the well design. It varies from 2335 to 12548 mg/l. The discharge value (Q) varies from 60 to 12 m3/h. This variation is related to the extension and type of the effective fracture system affecting the concerned aquifer.

Subsurface fluid distribution and possible seismic precursory signal at the Salse di Nirano mud volcanic field, Italy

Mud volcanoes are geological systems often characterized by elevated fluid pressures at depth deviating from hydrostatic conditions. This near-critical state makes mud volcanoes particularly sensitive to external forcing induced by natural or man-made perturbations. We used the Nirano mud volcanic field as a natural laboratory to test pre- and post-seismic effects generated by distant earthquakes. We first characterized the subsurface structure of the Nirano mud volcanic field with a geoelectrical study. Next, we deployed a broad-band seismic station in the area to understand the typical seismic signal generated by the mud volcano. Seismic records show a background noise below 2 s, sometimes interrupted by pulses of drumbeat-like high-frequency signals lasting from several minutes to hours. To date this is the first observation of drumbeat signal observed in mud volcanoes. In 2013 June we recorded a M4.7 earthquake, that occurred approximately 60 km far from our seismic station. According to empirical estimations the Nirano mud volcanic field should not have been affected by the M4.7 earthquake. Yet, before the seismic event we recorded an increasing amplitude of the signal in the 10–20 Hz frequency band. The signal emerged approximately two hours before the earthquake and lasted for about three hours. Our statistical analysis suggests the presence of a possible precursory signal about 10 min before the earthquake.

Geochemical and geo-electrical study of mud pools at the Mutnovsky volcano (South Kamchatka, Russia): Behavior of elements, structures of feeding channels and a model of origin

This study presents data on the geochemical composition of boiling mud pools at the Mutnovsky volcano. The physicochemical characteristics of the pools and the concentrations of major, minor and trace elements in pool solutions vary widely. A comparison of the geochemical compositions of host rocks and solutions indicates that leaching from rocks is not the only source of chemicals in thermal solutions. Geophysical studies reveal the inner structure of thermal fields, which reflect the shapes of the underground reservoirs and feed channels. Using geophysical methods (electrical resistivity tomography and frequency domain investigations), it was shown that the vertical structure and complex geochemical zonation of the feed channels leads to a high contrast in the compositions of the mud solutions. These findings answer questions about the origin and composition of surface manifestations. To elucidate the mechanisms of solution formation, an attempt was made to describe the magmatic fluid evolution and the resulting mixing of waters by physical and mathematical models. The model illustrates fluid migration from a magma chamber to the surface. It is shown that the formation of brines corresponding to the mud pool composition is possible during secondary boiling.

Comparative Hydrological and Geoelectrical Study on the Quaternary Aquifer in the Deltas of Wadi Badaa and Ghweiba, El Ain El Sukhna Area, Northwest Suez Gulf, Egypt

El Ain El Sukhna area was selected in the last ten years to initiate many governmental and investmental programs. The different activities in that area depend mainly on the groundwater of the Quaternary aquifer, which forms the main water bearing strata. In the present work, twenty one geoelctrical soundings using the Schlumberger configuration are carried out at selected sites especially in missing parts from wells to delineate the groundwater setting in such sites. Eight of them are conducted in the close vicinity of water wells, where lithologs and pumping test data of these wells are available to relate hydrologic and geoelctric measurements. The pumping tests data are analyzed by using AQTESOLV program and the geolectrical sounding data were interpreted by partial curve matching technique to obtain the initial parameters. The results indicated that, the transmissivity is found to be closely related with transverse resistance and the hydraulic conductivity with average transverse resistivity, while the salinity is inversely related with resistivity. Finally, priority map for drilling water wells is constructed to make the results more illustrative and useful for decision maker. The promising area for drilling is located at the western portion of the study region.

The Programming Development for Processing and Interpretation of the Earth Resistivity Sounding

The research contains the explanation, exploitation and development of igital technique in design of stripping, partial and modification modeling or resistivity sounding data. Resistivity transforms of field observations are determined from the digital linear filtering operation which depends on fourier transform and convolutions of two functions. The calibration and adjustment of zonal parameters are conducted with the rule of excellent relationship between each field observations branch and associated zonal parameter section.The final model is computed according to equivalence rules with automate approach. The present designed program (MAK) has got three formats with 6 , 8 and 12 field measurements per the logarithmic decade depends on filter length.The type of geoelectrical study (environmental, engineering, hydrogeology, stratigraphy …etc ) is defined the format of the chosen filtar

Geoelectrical study for ground water in waste dump sites: A case study of Warri and its environ, Delta state, Nigeria

Geoelectrical study for ground water in waste dump sites: A case study of Warri and its environ, Delta state, Nigeria

Hydrogeological study of Hamdania area in the light of geoelectrical investigation

A geoelectrical study of the Hamdania area, east of Mosul city, indicates presence of four geoelectrical zones represent different geological formations. Correlation of VES data with boreholes information indicate that Injana Formation and the overlying beds, up to the topsoil surface layer, represent the main aquifer in the area. It is an unconfined aquifer and the movement of water is from north and north east to south and southwest towards Tigris river, following the topography.

Geological study for the southern plain of alan, north of iraq using geoelectrical sounding

The present research involves geoelectrical study of the southern allan's plain, which lies between allan and atshan anticlines, in the north of Iraq. The field measurements were carried out in sixty three sounding stations, using collinear and symmetrical schlumberger array, distributed on four traverses (NE-SW direction) across the axes of anticlines surrounding the study area. The maximum interval spacing between both current and potential electrode has reached 843 and 90 meters consequently. The final interpretation result were represented with four geoelectrical section. Continuous correlation with composite stratigraphic columns of surrounding anticlines was made and five electrical zones were distinguished reflecting the soil, quaternary deposits upper and lower members of Al-Fat'ha formation as well as Euphrates formation. This study has specified two strike slip faults affected by the alpine orogeny. One transversal fault with NE-SW direction is located and clearly affects the true resistivity data and the anticlinal structure plunges in the east of the currently studying area. In addition a rotational strike slip fault has been specified, extending E-W parallel to the axes of the anticlines surrounding the area the second fault is considered as an important tectonic element in the regional geology of the north of Iraq, this element divides between the northern and the southern blocks of Mosul, which is characterized by the existence of Taurus and zagros trends consequently.