scholarly journals Detecção de um aquífero fraturado por múltiplas sondagens elétricas verticais e por caminhamento elétrico multinível

2019 ◽  
Vol 37 (4) ◽  
pp. 368
Author(s):  
Juliana Targino Batista ◽  
José Agnelo Soares

RESUMO O presente trabalho analisa o efeito da adoção de diferentes configurações do método da eletrorresistividade para investigar a ocorrência de potenciais aquíferos fissurais. Em uma área onde reconhecidamente existe uma zona de fraturas subverticais no embasamento cristalino foram aplicadas as técnicas de múltiplas sondagens elétricas verticais (SEVs), utilizando o arranjo Schlumberger, e o caminhamento elétrico utilizando o arranjo gradiente multinível. Três diferentes configurações foram testadas em uma mesma linha cuja direção é aproximadamente perpendicular aos planos das fraturas. Os resultados obtidos mostram que o caminhamento elétrico multinível pelo arranjo gradiente apresentou maior clareza na detecção da zona de fraturas em relação às configurações utilizando sondagens elétricas verticais. No entanto, tais estruturas subverticais ainda poderiam ser detectadas por sondagem elétrica, desde que adotado um afastamento adequado entre os centros das SEVs. As seções geoelétricas obtidas pelas configurações testadas indicam a presença de uma estrutura acumuladora de água subterrânea do tipo riacho-fenda. Adicionalmente, o caminhamento elétrico pelo arranjo gradiente apresenta vantagens operacionais em relação às demais configurações, sendo mais prático e rápido nos trabalhos de aquisição de dados no campo.Palavras-Chaves: Hidrogeofísica, eletrorresistividade, embasamento cristalino. ABSTRACT This paper analyzes the effect of adoption of different configurations of electric resistivity method to investigate the occurrence of potential fractured aquifers. In an area where there is a sub vertical fracture zone in the crystalline basement the techniques of multiple vertical electrical soundings (VES), using the Schlumberger array, and electrical profiling using the multilevel gradient array, were applied. Three different configurations were tested in a same line whose direction is approximately perpendicular to the fracture plan. The results show that the multilevel gradient array presented better clarity in detecting fracture zone than the settings using vertical electrical soundings. However, such sub vertical structures could still be detected by VES, since it is adopted a proper separation between the VES centers. Obtained geoelectric sections indicate the presence of a groundwater accumulating structure composed by a crack-induced stream. Additionally, the electric gradient profiling presents operational advantages in relation to other arrays, being more practical and fast for data acquisition in the field.Keywords: Hydrogeophysics, electric resistivity, crystalline basement.

2016 ◽  
Vol 33 (3) ◽  
Author(s):  
Eduardo M.S. Amarante ◽  
Olivar A.L. de Lima ◽  
Susana S. Cavalcanti

ABSTRACT. To investigate the subsurface geological and hydrological conditions around the area of the Alagoinhas county cemetery – Bahia State, Brazil, 38 vertical electrical soundings using Schlumberger electrode array were performed to a maximum AB/2 spacing... RESUMO. Para investigar as condições geológicas e hidrológicas da subsuperfície na área do entorno do Cemitério Municipal de Alagoinhas, Bahia, foram realizadas 38 sondagens elétricas verticais centradas em pontos acessíveis da área. As sondagens foram...


Geophysics ◽  
2011 ◽  
Vol 76 (6) ◽  
pp. B225-B236 ◽  
Author(s):  
Joëlle Riss ◽  
Juan Luis Fernández-Martínez ◽  
Colette Sirieix ◽  
Ouassima Harmouzi ◽  
Antoine Marache ◽  
...  

We demonstrated a simple methodology for the reinterpretation of sets of electrical vertical soundings and the production of 2D resistivity models. The method is applied to the northern central part of the subsiding Saïss basin (Morocco) where a series of vertical electrical soundings (VES) were acquired in 1982 and 1984, using the Schlumberger array with current electrodes semispacings between 3 and 3000 m. We describe a methodology used to estimate and sample apparent resistivities collected from traditional single soundings acquired by using a Schlumberger configuration. We then construct a resistivity pseudosection in a format compatible with a Wenner-Schlumberger array to perform 2D electrical tomography. The methodology takes into account the lateral and vertical spatial correlations shown by the apparent resistivities. The tomographic inversions are performed using a commercial inversion software commonly used in industry. Geostatistical tools are used to quantify the spatial correlation between apparent resistivity data. The result is a series of estimated pseudosections that are inverted to produce 2D resistivity models of the basin along geophysical profiles. We focus our attention on one of these profiles (i.e., one 2D resistivity model). The inverted geoelectrical model allows us to propose a geologic model of the basin. Our methodology allows historical and current data carried out using the Schlumberger configuration, to be rapidly reinterpreted in countries where only low-cost methods, such as VES soundings, can be used due to technology and economic constraints. It can also be applied to cases where continuous or pulled-array continuous vertical soundings method, where a tail of electrodes is towed behind a small vehicle while continuously and simultaneously measuring several electrode configurations, is inoperative due to field conditions (survey length, deep layers, and local environmental conditions).


2021 ◽  
Author(s):  
FOKO TAMBA Carlos ◽  
KENGNI Lucas ◽  
TEMATIO Paul ◽  
Bertile Ilalie MANEFOUET ◽  
Jean Victor KENFACK

Abstract The increasing demands on lateritic gravels in road construction nowadays make it necessary to quantify the available resources that can be used in road construction. The aim of this study is to estimate the tonnage and to valorize the lateritic gravels of the North flank of Mount Bangou (West, Cameroon) in road construction. Interpretation of 48 vertical electrical soundings coupled with 20 pedological wells from 05 lateritic gravel sites was carried out to determine the thickness of the gravelly horizon. The thickness of the gravelly horizon obtained from the geo-electrical soundings is the highest (8.88 to 12.45 m) compared to that obtained from the pedological wells (1.23 to 1.98 m) and thus shows the inadequacy of the pedological wells for the determination of the thickness of the lateritic gravels. Thus, the electrical resistivity method is appropriate to estimate the thickness of the gravelly horizon. The lateritic gravels studied are characterized by the electrical resistivity curves of type K, HK, Q, QH, KQ, HKH, H and KH. The medium (8 to 36 m) and thick (13 to 44 m) zones are areas of high potential lateritic gravels. The proven reserves of lateritic gravels at the Chenye, Sekakouo, Bamendjou 1, Bamendjou 2 and Bangam sites are respectively 3479 003 t, 1 389 522 t, 5 002 505 t, 839 455 t and 2 663 105 t and can build respectively 539 298 m; 226 167 m; 131574 m; 778314 m and 401068 m of road, either as a form layer or sub-base.


Geophysics ◽  
1980 ◽  
Vol 45 (7) ◽  
pp. 1205-1208
Author(s):  
B. B. Bhattacharya ◽  
P. K. Hazra

In this paper, the authors showed a series of electromagnetic (EM) profiles (Figure 20, p. 86) obtained from the ground follow‐up using a slingram system with a frequency of 1600 Hz and coil separation of 120 m. Measurements along all the profiles (A to E) show considerable in‐phase and quadrature anomaly. The host rock in this case is amphibolite. The vertical electrical soundings over the amphibolite (Figure 16, p. 82) indicate that the weathered amphibolite has mean thickness and resistivity of 8.5 ± 2.1 m and 29.7 ± 6.5 Ω-m, respectively. It would, therefore, be reasonable to assume that the in‐phase and quadrature anomalies have been influenced due to the presence of conducting overburden, and the response of the target in such a situation can be altogether different compared to the anomaly of the target in the presence of an insulating or highly resistive overburden.


2021 ◽  
Vol 4 (4) ◽  
pp. 547-560
Author(s):  
Aniefiok Akpaneno ◽  
S. Abdulwahab

A geophysical investigation involving Vertical Electrical Sounding (VES) using the Schlumberger array was carried out at the Isa Kaita College of Education specifically at the Male Hostel. The aim of the investigation is to explore the groundwater contamination of the area with the objectives: to determine the depth to basement of the study area, to determine the aquifer thickness, to determine the depth to aquifer, to determine the conductivity of the aquifer and to determine the thickness of topsoil and its variation in resistivity. A total of four (4) vertical electrical soundings were carried out using Schlumberger configuration. Terrameter signal averaging system (SAS) model 300 was the instrument used. The survey area is dominated by mainly four layers, namely: Topsoil, Weathered basement, fractured basement. The value of VES 03 and VES 04 have high electrical conductivities which likely shows they are contaminated, The topsoil resistivity along the profile ranges from approximately 1 to 154, The depth to basement (basement topography) Varies from 4.94 m to 7.59 m, The thickness of aquifer range from  1 m to 6.8 m.  Therefore VES 02 has high Potential for groundwater because it has retaining capacity and good aquifer thickness and is therefore recommended for borehole establishment. It is recommended that the management of Isa Kaita College of Education should provide a concrete dumping site to avoid leaching of waste in ground thereby contaminating the groundwater.


2018 ◽  
Vol 65 (6) ◽  
pp. 637-645
Author(s):  
Amobi C. Ekwe ◽  
Alexander I. Opara ◽  
Obialo S. Onwuka

Purpose The 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/approach In 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. Findings Incompetent 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/implications Some of the areas are not accessible because of community restrictions. Practical implications These 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 implications The 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/value This 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.


2020 ◽  
Vol 7 ◽  
pp. 19
Author(s):  
Joseph Olakunle Coker ◽  
Akindamola Julius Agbelemoge ◽  
Stephen Oluwafemi Ariyo ◽  
Victor Makinde ◽  
Aderemi Amidu Alabi ◽  
...  

Groundwater is described as the water found beneath the surface of the earth in underground streams and aquifers and has become popular as a source of drinking potable water in Nigeria due to its quality when compared to other water sources. The Electrical resistivity method was employed in Imakun Omi Community, a coastal town in Ogun Waterside Local government area of  Ogun State with the aim of determining the groundwater potential of the area. A total of twenty (20) Vertical Electrical Soundings (VES) points were carried out in the area using the Schlumberger configuration with maximum current electrode separation (AB) of 300m using the ABEM SAS 1000 Terrameter. The results obtained were interpreted quantitatively and qualitatively using partial curve matching and computer iteration programs WINRESIST and SURFER 11 for the interpretation from which the reflection coefficient was computed. The groundwater potential of the rock units were evaluated and  40% of the stations show  high yield, 50% of the stations show medium yield and 10% of the stations was observed to have low yield. The aquifer thicknesses are very thick with values ranging from 6.9 m to 79.3 m, hence an average of 43.1mand overburden thicknesses ranging from 9.7m to 96.5 m, with an average of 53.1m


1998 ◽  
Vol 41 (3) ◽  
Author(s):  
M. Giudici ◽  
L. Alfano

We present some results of a geoelectrical investigation program conducted in the Northern Apennines, namely in the Val d'Aveto and Bobbio window and surrounding areas. Field activity included the execution of more than 50 vertical electrical soundings with continuous polar dipole-dipole spread. We image the geometries of some deep geological structures; in particular we found a resistive background, whose resistivity is different along the geoelectrical profiles. In our interpretation the resistive background consists of subligurid and tuscan units underlying the alloctone Ligurid units in the area surrounding the Val d'Aveto and Bobbio window. The resistive background was not found, at least at the same depths, toward north-east. Therefore, the geoelectrical survey revealed the position of the front of the subligurid and Tuscan nappes toward the plain for a depth of about one kilometer.


2020 ◽  
Vol 21 (2) ◽  
pp. 123
Author(s):  
Bayu Buwana ◽  
Nurul Priyantari ◽  
Supriyadi Supriyadi

Faculty of Mathematics and Natural Sciences University of Jember located in Sumbersari District with lithological conditions in the form of volcanic rocks, lithosol soils, and regosol soils that are capable of absorbing water and potentially as aquifers. In point of fact, in the campus zona of the University of Jember including in the Faculty of Mathematics and Natural Sciences, there is always a shortage of freshwater for various academic and non-academic activities. Therefore, research needs to be conducted to assess the lithology of subsurface structures in the FMIPA zone so that the depth of groundwater layers and aquifer layers can be determined. The study was conducted using the Schlumberger array geoelectric resistivity method at 5 VES points. The results obtained in the form of resistivity log curves can be seen that at the five points VES has lithology in the form of clay, gravel, sandstone, and groundwater layer. Each VES point was identified the groundwater layer and some of them were identified as aquifers. The aquifer with the greatest thickness is found at point VES 2, which is to the west of the Baitul Ilmi Mosque, so it is recommended as the location of a new well.Keywords: lithology, aquifers, geoelectric resistivity method, groundwater.


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