Assessment of Subsurface Profile at SILC, Nusajaya by 2D Resistivity Method

2014 ◽  
Vol 695 ◽  
pp. 823-827
Author(s):  
Siti Norsalkini Mohd Akip Tan ◽  
Edy Tonnizam Mohamad ◽  
Rosli Saad ◽  
Mustaza M. Nordiana
Keyword(s):  
Electrode Spacing ◽  
High Resistivity ◽  
Iron Mineral ◽  
Resistivity Method ◽  
Survey Line ◽  
2D Resistivity Imaging ◽  
Actual Profile ◽  
Grade Ii ◽  
Physical And Chemical ◽  
2D Resistivity

An assessment of subsurface profile of a study area at Nusajaya. Johor was conducted using 2D resistivity method. The aims of the study are to determine the subsurface profile hence contouring the appearance of outcrop by 2D resistivity imaging. Subsurface structure can be delineated based on the physical and chemical parameter which is apparent resistivity of the medium. A survey line of 80m and minimum 2m electrode spacing was adopted using Pole-dipole array. Data acquisition on the survey line was completed and processed by using Res2Dinv software. The inversion model resistivity shows sandstone contains iron mineral (30-250 ohm-m) and weathered sandstone (500-1000 ohm-m). The lower part of the layer represents sandstone and siltstone exhibit high resistivity values of 1500-5000 ohm-m. The range from 30-1000 ohm-m correspond to the grade IV and V of sandstone in the actual profile. Meanwhile, the high range of the resistivity value matched the material with weathering grade II and III in ground mass. The deterioration of most physical properties was associated with the increase number of weathering grade.

scholarly journals An Investigation of Groundwater Contamination around Nsukka Municipality Dumpsite using the Resistivity Method

2020 ◽  
Author(s):  
Olisah Nzemeka
Keyword(s):  
Electrical Resistivity ◽  
Groundwater Contamination ◽  
Low Resistivity ◽  
Electrical Resistivity Survey ◽  
Resistivity Method ◽  
Electrical Sounding ◽  
On Line ◽  
2D Resistivity Imaging ◽  
Resistivity Meter ◽  
2D Resistivity

An investigation using electrical resistivity method was conducted around a solid waste dumpsite at Nsukka in Nsukka L.G.A of Enugu State, Nigeria to investigate the level of groundwater contamination. Electrical Sounding (VES) and 2D resistivity imaging were used with a digital read out resistivity meter (ABEM SAS 1000) to acquire data in the area. A total of eight (8) sounding and six (6) 2D resistivity imagings were carried out in the area. A contaminant leachate plume was delineated in 2D resistivity sections as low resistivity zones while the VES shows the depth of aquifer. In 2D pseudosections where bluish colours with low resistivities (less than 20.80Ωm) with the depth ranging from 1.28m to 17.1m in the Line 1 and 2 are seen as contaminated zones. The rest of the lines are not contaminated because of their high resistivities (greater than 20.80Ωm). The result of the electrical resistivity survey also showed 4 - 5 layers geo-electric sections and an AA and AK type sounding curves. The VES result shows that VES 1A, 1B, 2A and 2B which are carried out on line 1 & 2 of the wenner lines showed signs of contamination with low resistivity values less than 20.80Ωm complementing the wenner results. The contamination has not yet got to where the aquifer is located on the lines. Since the depth to the aquifer ranges from 30.26m to 155.43m while maximum depth of contamination is 17.1m. It is believed that the leachate has not percolated down to the aquiferous zones as such aquifers are presumed to be free.

scholarly journals Time-lapse electrical resistivity investigation of seawater intrusion in coastal aquifer of Ibeno, Southeastern Nigeria

2020 ◽  
Vol 10 (11) ◽  
Author(s):  
Iniemem J. Inim ◽  
Ndifreke I. Udosen ◽  
Moshood N. Tijani ◽  
Uduak E. Affiah ◽  
Nyakno J. George
Keyword(s):  
Electrical Resistivity ◽  
Coastal Aquifer ◽  
Saltwater Intrusion ◽  
Time Lapse ◽  
Electrode Spacing ◽  
High Resistivity ◽  
Southeastern Nigeria ◽  
Salinity Changes ◽  
Survey Length ◽  
2D Resistivity

Abstract Saltwater intrusion, erosion, and periodic flooding during severe storms are some of the critical problems bedeviling the precarious coastal environment of Nigeria. A time-lapse study aimed at monitoring the dynamics of saltwater intrusion within the coastland surrounding Ibeno, southeastern Nigeria is presented. Three (3) vertical electrical soundings (VES) and four time-lapse electrical resistivity tomography (ERT) profiles with minimum and maximum electrode spacing of 5 m and 40 m and profile lengths of 120 m and 150 m respectively were acquired in 2016 and 2017 using the Wenner and Schlumberger arrays. Data acquired from the field surveys were modeled with WINRESIST and RES2DINV software to generate 1D and 2D resistivity images of the subsurface. The VES results with a maximum survey length of AB = 300 m revealed a four-layer KH curve. The 2D geo-electrical sections delineated contrast between the high resistivity values obtained for the saturated freshwater zones and the low resistivity values obtained for the saturated saltwater zone. Expectedly, the intrusion was dominant nearer the coastline than inland. The salinity changes are believed to have been caused by both incremental tides passing through highly porous materials in the active-salinity change area and over-pumping of groundwater. The time-lapse resistivity measurements showed significant, active lateral salinity changes rapidly intruding the freshwater aquifers. The study demonstrates the application of time-lapse 2D ERT and vertical electrical sounding in identifying the spatial and temporal changes of saltwater intrusion in the coastal aquifer.

A 3-D geoelectric model over mineralized zone of Ugonoba, Edo State, Nigeria

2021 ◽  
Vol 20 (1) ◽  
pp. 141-150
Author(s):  
V.B. Olaseni ◽  
J.O. Airen
Keyword(s):  
Mineral Resources ◽  
Electrode Spacing ◽  
High Resistivity ◽  
Clayey Sand ◽  
Resistivity Method ◽  
True Resistivity ◽  
Geological Features ◽  
Mineralized Zone ◽  
Formed Part ◽  
Block Models

The occurrence of solid minerals in Ugonoba community was investigated using the 3D electrical resistivity method. Data was acquired  using PASI 16GL Terrameter using the wenner electrode configuration with a view to delineating mineral deposits in the study area.  During the reconnaissance survey, the outlook of some geological features in the form of outcrops on the surface formed part of the motivation for the geophysical survey within the Ugonoba area. Ten traverses of 200 m maximum spread and 10m electrode spacing with total depth of 40.07 m were obtained in the study area to form a square grid. The acquired data was first processed and inverted using RES2DINV software to generate ten 2-D model images and later collated into 3-D using the inversion code of RES3DINV software which automatically determines a horizontal 3D depth slice, cubes and block models of resistivity distribution. These models generated were interpreted and used to ascertain the true resistivity, lithologic formation, depth extent to any buried mineral and aggregate deposited in the study area. The extracted 3D model images revealed evidence of some geological materials/minerals in the study area which fall within the high resistivity range of 2500 Ωm to 14376 Ωm. It can therefore be inferred from the standard resistivity table that the lithology of study area is composed of non-metallic type of mineral resources which are: clayey sand, lateritic clayey sand,  sandstone and limestone. The estimated quantity in metric ton for the dominant lithology (sandstone, granite and limestone) is ± 10% of 1,257,142.9 which can be commercially explored. Keywords: Wenner-wenner array, outcrop, minerals, RES3DINV, block models.

Uncertainties Analysis of Electrical Resistivity Tomography

2021 ◽  
Author(s):  
Yonatan Garkebo Doyoro ◽  
Chang Ping-Yu ◽  
Jordi Mahardika Puntu
Keyword(s):  
Model Resolution ◽  
Resistivity Data ◽  
Resistivity Method ◽  
Resistivity Model ◽  
2D Resistivity Imaging ◽  
Model Set ◽  
Different Depths ◽  
Measured Resistivity ◽  
2D Resistivity ◽  
Subsurface Cavities

<p>We examined the uncertainty of the resistivity method in cavity studies using a synthetic cavity model set at six-different depths. Conceptual models were simulated to generate synthetic resistivity data for dipole-dipole, pole-dipole, Wenner-Schlumberger, and pole-pole arrays. The 2D geoelectric models were recovered from the inversion of the synthetically measured resistivity data. The highest anomaly effect (1.46) and variance (24400) in resistivity data were recovered by dipole-dipole array, while the pole-pole array obtained the lowest anomaly effect (0.60) and variance (2401) for the target cavity T<sub>1</sub>. The anomaly effect and variance were linearly associated with the quality of the inverted models. The steeper anomaly gradient of resistivity indicated more distinct cavity boundaries, while the gentler gradient prevents the inference of the cavity boundaries. The recovered model zone above the depth of investigation index of 0.1 has shown relatively higher sensitivity. Modeling for dipole-dipole array provided the highest model resolution and anomaly gradient that shows a relatively distinct geometry of the cavity anomalies. On the contrary, the pole-dipole and Wenner-Schlumberger arrays recovered good model resolutions and moderate anomaly gradient but determining the anomaly geometries is relatively challenging. Whereas, the pole-pole array depicted the lowest model resolution and anomaly gradient with less clear geometry of the cavity anomalies. At deeper depths, the inverted models showed a reduction in model resolutions, overestimation in anomaly sizes, and deviation in anomaly positions, which can create ambiguity in resistivity model interpretations. Despite these uncertainties, our modeling specified that the 2D resistivity imaging is a potential technique to study subsurface cavities.</p>

scholarly journals 3D and Boundary Effects on 2D Electrical Resistivity Tomography

2019 ◽  
Vol 9 (15) ◽  
pp. 2963 ◽  
Author(s):  
Yin-Chun Hung ◽  
Chih-Ping Lin ◽  
Chin-Tan Lee ◽  
Ko-Wei Weng
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Geophysical Methods ◽  
Boundary Effects ◽  
Electrode Spacing ◽  
Resistivity Tomography ◽  
Buried Objects ◽  
Survey Line ◽  
Parametric Studies ◽  
2D Resistivity

Electrical resistivity tomography (ERT) is one of the most widely used geophysical methods in geological, hydrogeological, and geo-environmental investigations. Although 3D ERT is now available, 2D ERT remains state-of-the-practice due to its simplicity in fieldwork and lower space requirements. 2D ERT assumes that the ground condition is perpendicular to the survey line and outside the survey line is homogeneous. This assumption can often be violated in conditions such as geologic strikes not perpendicular to the survey line and topographic changes or buried objects near the survey line. Possible errors or artifacts in the 2D resistivity tomogram arising from violating the 2D assumption are often overlooked. This study aimed to numerically investigate the boundary effects on 2D ERT under various simplified conditions. Potential factors including resistivity contrast, depth and size of buried objects, and electrode spacing were considered for the parametric studies. The results revealed that offline geologic features may project onto the 2D tomogram to some extent, depending on the aforementioned factors. The mechanism and implications of boundary effects can be drawn from these parametric studies.

scholarly journals Evaluation and Delineation of Sulfur Groundwater Leakages Using Electrical Resistivity Techniques in Hit Area, Western Iraq

2021 ◽  
pp. 2239-2249
Author(s):  
Osama J. Mohammed ◽  
Ali M. Abed ◽  
Mohammed A. Alnuaimi
Keyword(s):  
Electrical Resistivity ◽  
Imaging Technique ◽  
Polluted Water ◽  
High Resistivity ◽  
Resistivity Imaging ◽  
Groundwater Movement ◽  
2D Resistivity Imaging ◽  
Array Position ◽  
Two Stages ◽  
2D Resistivity

      Electrical resistivity methods are one of the powerful methods for the detection and evaluation of shallower geophysical properties. This method was carried out at Hit area, western Iraq, in two stages; the first stage involved the use of 1Dimensional Vertical Electrical Sounding (VES) technique in three stations using Schlumberger array with maximum current electrodes of 50m. The second stage included the employment of two dimension (2D) resistivity imaging technique using dipole-dipole array with a-spacing of 4m and n-factor of 6 in two stations. The 1D survey showed good results in delineating contaminated and clear zones that have high resistivity contrast. Near the main contaminated spring, the 2D resistivity imaging technique was applied in four sections length (100 m) using a dipole-dipole array position coincided with the three points VES. We compared the results of the interpretation of imaging the techniques 2D and VES. We found that the 2D imaging resistivity technique was better than VES survey in determining the distribution of pollution under the surface in the area surveyed. It was also found that the polluted water is located about 5 m below the surface. The largest amount of leakage was found towards the northeast and coincided with the direction of the groundwater movement. Spring water has leaked from outside the region through the Kubaisah area. Most of this water is contained in quaternary deposits and karst gypsum fractures.

An Attempt to Image Um El-Adam Cavity Structure in the Karst Terrain at Hit Area, Western Iraq

2020 ◽  
Vol 54 (1A) ◽  
pp. 44-54
Author(s):  
Ali Abed
Keyword(s):  
3D Model ◽  
3D Models ◽  
Electrode Spacing ◽  
Karst Terrain ◽  
Resistivity Imaging ◽  
Cavity Structure ◽  
2D Resistivity Imaging ◽  
2D And 3D ◽  
2D Resistivity

Um El-Adam cavity is one of the well-known cavities inside gypsum rocks in the Hit region, western Iraq, where this was chosen as a case study to evaluate 3D resistivity imaging technique detection and imaging of this type of cavity in complicated lithology. 3D view fulfilled by collating four 2D resistivity-imaging lines. The 2D resistivity imaging survey was carried out by Dipole-Dipole array with (n) factor and electrode spacing (a) of 6 and 2m, respectively. Both conventional inversion methods obtained the 2D and 3D models: standard least-squares and robust constrain options. The two options were able to define clearly the cave, but the second was more accurate, the dimensions of the cave in the inverse model closer to the actual dimensions. Horizontal slices displayed the final 3D model to reveal a 3D resistivity distribution with depth. The effect of Um El-Adam cavity appears after 1.5 m on the model slices, which is represented by increasing resistivity contrast compared to surrounding sediments. At the seventh and eighth slices, it was found that the size of the cavity exceeded compared with the actual dimensions. The results of this study indicated the high potential of this method for the detection and delineation of subterranean caves.

Detection of the near surface structure through a multidisciplinary geophysical approach

2011 ◽  
Vol 3 (4) ◽  
Author(s):  
Eleni Kokinou ◽  
Apostolos Sarris
Keyword(s):  
Seismic Refraction ◽  
Geophysical Methods ◽  
Near Surface ◽  
The Road ◽  
Resistivity Method ◽  
Conductivity Anomalies ◽  
2D Resistivity Imaging ◽  
Limestone Rock ◽  
Ground Penetrating ◽  
2D Resistivity

AbstractThe present survey aimed to image the subsurface structure, including karstic voids, and to evaluate the extent of the heterogeneities that can result in potentially dangerous collapse of road segments overlying these features. A multidisciplinary geophysical approach (seismic refraction, frequency domain electromagnetic and ground penetrating radar) in combination with a detailed geological survey indicated the presence of tectonic faults as well as velocity and conductivity anomalies along an old road within the area of Akrotiri at Chania (Crete). Due to the presence of subsurface fuel pipes, perpendicular to the direction of the road, 2D resistivity imaging was excluded from the applied geophysical methods.Interpretation of the geophysical data revealed that the section of the road investigated overlies prominent voids attributed mostly to karst features. The conductivity and velocity anomalies are interpreted to indicate an area where the host limestone rock has been downthrown by faulting and associated karstification. The continuation of this fault zone was observed in the slope of the road during later excavations. Interpretation, using geographic information systems (GIS) to integrate data, allowed these controls and relationships to be understood and monitored. The above methodology was proved successful for areas where the application of resistivity method is not possible.

scholarly journals Application of the Electrical Resistivity Method for Site Investigation in University of Anbar, Ar-Ramadi City, Western Iraq

2020 ◽  
pp. 1345-1352
Author(s):  
Amina M. Salman ◽  
Jassim M. Thabit ◽  
Ali M. Abed
Keyword(s):  
Site Investigation ◽  
Inverse Model ◽  
Inversion Method ◽  
Resistivity Method ◽  
Electrical Imaging ◽  
Inverse Models ◽  
Weakness Zone ◽  
Weakness Zones ◽  
2D Resistivity Imaging ◽  
2D Resistivity

The 2D resistivity imaging technique was applied in an engineering study for the investigation of subsurface weakness zones within University of Anbar, western Iraq. The survey was carried out using Dipole-dipole array with an n-factor of 6 and a-spacing values of 2 m and 5 m. The inverse models of the 2D electrical imaging clearly show the resistivity contrast between the anomalous parts of the weakness zones and the background resistivity distribution. The thickness and shape of the subsurface weakness zones were well defined from the 2D imaging using Dipole-dipole array of 2 m a-spacing. The thickness of the weakness zone ranges between 9.5 m to 11.5 m. Whereas the Dipole-dipole array with a-spacing of 5 m and n-factor of 6 allocated the geoelectrical stratigraphic layers sequence in low-accuracy of weakness zones, but deeper than the inverse model of 2 m a-spacing. This survey was made to explain the correlation between the weakness zone and the deeper layers in the study area. It points out that the deeper layers were not affected in the weakness zones. The inverse model was produced using the Standard Least-Squares Inversion Method and the Robust Inversion Model Constraints Method. The first method had a gradational boundary of the weakness zones and the second had sharper and straighter boundaries of fractures and voids within the weakness zones.

Sign in / Sign up

Export Citation Format

Share Document