INVESTIGATION OF CLAY CONTENT IN UGBOWO CAMPUS, MAKING USED OF

2D ELECTRICAL RESISTIVITY (ERT) WITHIN ENGINEERING FIELD BENIN CITY

EDO STATE

BY

OSAKPANMWAN JOHN, OSAIGBOVO

MAT NO: PSC1809086

DEPARTMENT OF PHYSICS,

FACULTY OF PHYSICAL SCIENCE.

UNIVERSITY OF BENIN,

BENIN CITY.

SEPTEMBER, 2023
INVESTIGATION OF CLAY CONTENT IN UGBOWO CAMPUS MAKING USED OF

ELECTRICAL RESISTIVITY (ERT) WITHIN ENGINEERING FIELD BENIN CITY

EDO STATE

BY

OSAKPANMWAN JOHN, OSAIGBOVO

MAT NO: PSC1809086

A PROJECT SUBMITTED TO THE DEPARTMENT OF

PHYSICS, FACULTY OF PHYSICAL SCIENCES, UNIVERSITY

OF BENIN, IN PARTIAL FULFILMENT FOR THE AWARD OF

BACHELOR (B.Sc) DEGREE IN PHYSICS (APPLIED

GEOPHYSICS)

SEPTEMBER, 2023
 CERTIFICATION

This is to certify that this project report was clearly written by OSAIGBOVO JOHN,

OSAKPANMWAN department of physics, faculty of Physical Sciences, University of Benin

under the supervision of PROF. F.O. EZOMO.

__________________ _____________

Prof. F.O. EOZOMO Date

Project Supervisor

__________________ _____________

Dr. John Airen Date

Project Coordinator

__________________ _____________

PROF .O.D.OSAHON Date

HEAD OF PHYSICS DEPARTMENT

 …………………………..
External Examiner

DEDICATION

This work is dedicated to GOD ALMIGHTY for the grace to be a participant of this program,

for his kindness and steadfast love throughout my academic years.

 CERTIFICATION OF DESERTATION ON PLAGARISM

We the undersigned attest and declare that the dissertation of OSAIGBOVO JOHN

OSAKPANMWAN on INVESTIGATION OF CLAY CONTENT IN OVIA NORTH EAST

LOCAL GOVERNMENT AREA IN EDO STATE USING ELECTRICAL RESISTIVITY

METHOD has successfully passed the anti-plagiarism test and does not violate any copyright

regulations.

__________________ _____________

Prof. F.O. EOZOMO Date

Project Supervisor

__________________ _____________

PROF .O.D.OSAHON Date

HEAD OF PHYSICS DEPARTMENT

 ACKNOWLEDGEMENTS

The completion of this project has been a long walk to success. First, all thanks and glory goes to

God, the giver and sustainer of life for His mercy, favor and grace. In the midst of doubts, stress

and difficulties, His grace kept the researcher moving forward.

The researcher sincerely appreciates her supervisor, Prof. F.O.EZOMO for his academic support,

advice, constructive criticisms, technical assistance and encouragement throughout the course of

this study. Worthy of mention is his uncompromising stance on quality work. The researcher is

particularly grateful to his parents, Mr and Mrs osaigbovo for their prayers, advice,

encouragement, moral and financial supports which has brought him this far. Her warm thanks

go to his siblings, osaigbovo Emmanuel and osaigbovo miracle for their love, prayers, support

and encouragement throughout this programmed of study.

All thanks to lecturers in Faculty of physical science for their sound motivating lectures which

have contributed meaningfully to his success. The researcher similarly expresses his gratitude to

his friends for their support and encouragement.

ABSTRACT

This study investigates the use of 2D electrical resistivity methods, including the Wenner array,

dipole-dipole array, and Schlumberger array, to determine clay content in subsurface materials.

Clay content is crucial in geological and geotechnical studies due to its impact on soil properties,
groundwater flow, and engineering behavior. Traditional methods for assessing clay content are

labor-intensive and costly, leading to the exploration of non-invasive geophysical techniques.The

primary goal was to assess the accuracy and feasibility of these methods in diverse subsurface

profiles. Field surveys with varying soil compositions were conducted, and data collected in grid

patterns were processed to create 2D resistivity images.

These images helped identify areas with different clay content and establish quantitative

relationships between resistivity values and clay percentages.The investigation showed that 2D

electrical resistivity methods effectively estimated clay content. Each array had advantages: the

dipole-dipole array excelled in shallow depths, the Wenner array penetrated deeper layers, and

the Schlumberger array balanced between the two. The study emphasized careful data

interpretation and integration with other geotechnical information to improve accuracy,

addressing challenges like electrode spacing and survey geometry.

In conclusion, this research confirms the usefulness of 2D electrical resistivity methods for

investigating clay content in subsurface materials, advancing geophysical exploration for soil

characterization. It offers an efficient, non-destructive, and cost-effective way to evaluate clay-

rich formations. Future research could explore combining multiple geophysical methods and

integrating them with other geological data for comprehensive assessments in various geological

settings.

CHAPTER ONE
1.1 INTRODUCTION

Clay minerals play a fundamental role in various geotechnical and environmental applications,

influencing the behavior of soils, groundwater movement, and the stability of civil engineering

projects. Understanding the distribution and content of clay within the subsurface is essential for

assessing site suitability, planning infrastructure development, and managing potential

environmental risks. Conventional methods of clay content determination, such as laboratory

testing of soil samples, can be time-consuming, expensive, and limited in spatial coverage.

To address these challenges, the application of geophysical techniques, specifically 2D Electrical

Resistivity Survey (2D ERS), has gained recognition as a non-invasive and efficient means of

investigating clay content distribution within the subsurface. 2D ERS measures the electrical

resistivity of subsurface materials and provides valuable insights into lithological variations,

including the presence of clay-rich layers.

The resistivity of clay-rich materials is significantly different from other geological units, 2D

ERS a promising tool for Regenerate response variations across a study area.

The resistivity of clay-rich materials is significantly different from other geological units, making

2D ERS a promising tool for delineating clay content variations across a study area. By mapping

the resistivity distribution, geoscientists and engineers can identify clay-rich zones, characterize

subsurface litho logy, and gain a better understanding of the hydro geological properties of an

area.

In this research project, we aim to investigate the clay content distribution within ugbowo zone

using 2D ERS. Through systematic data acquisition, advanced processing techniques, and

rigorous interpretation methods, we intend to contribute to the growing body of knowledge on

the use of geophysics for clay content characterization.

By providing valuable insights into subsurface clay distribution, this study seeks to enhance

geotechnical and environmental as Regenerate response use planning, and promote processing

techniques, and rigorous interpretation methods, we intend to contribute to the growing body of

knowledge on the use of geophysics for clay content characterization.

By providing valuable insights into subsurface clay distribution, this study seeks to enhance

geotechnical and environmental assessments, assist in land use planning, and promote

sustainable engineering practices.

(Johnson, R. W., & Chen, Q. (2019). Integrating 2D electrical resistivity survey and borehole

data for comprehensive clay content assessment. Near Surface Geophysics)

Definition of some terms

1.2 CLAY

Clay is a common type of soil that plays a significant role in geophysical exploration due to its

unique electrical properties. Clays is a fine-grained soil composed of small mineral particles and

exhibits distinct electrical properties due to its composition and structure

1.3 ELECTRICAL PROPERTIES OF CLAY:

1.3.1 Clay Composition:

Clay minerals are primarily composed of layered structures with charged surfaces, resulting in

unique electrical behavior. This section discusses the composition of clay minerals and their

impact on electrical conductivity and resistivity.

(IMA Europe: "The Mineralogy and Processing of Clay Minerals." Available online: https://ima-

europe.eu/factsheets/7_the-mineralogy-and-processing-of-clay-minerals.pdf)

1.3.2 Clay Water Interaction:

Clay has a high affinity for water, which affects its electrical properties. The interaction between

clay and water influences the conductivity and resistivity of clay-rich soils. This section explains

the mechanisms behind the clay-water interaction and its impact on electrical measurements.

1.4 RESISTIVITY METHOD AND CLAY:

1.4.1 Principles of Resistivity Method:

The resistivity method measures the electrical resistance of subsurface materials to assess their

composition and properties. This section provides an overview of the resistivity method,

including the measurement techniques and equipment commonly used in geophysical

exploration.

1.4.2 EFFECTS OF CLAY CONTENT ON RESISTIVITY:

The presence of clay significantly influences resistivity measurements. This section explores

how the clay content affects the resistivity values and their interpretation. It discusses the factors

that control resistivity in clay-rich environments, such as clay type, water content, and

compaction.

1.5 APPLICATIONS OF RESISTIVITY METHOD IN CLAY-RICH ENVIRONMENTS:

1. Geotechnical Engineering:

The resistivity method is widely used in geotechnical engineering to assess subsurface conditions

for construction projects. This section explores how resistivity surveys can help identify clay

layers, determine their thickness and lateral extent, and assess their geotechnical properties.

2. Environmental Studies:

In environmental studies, resistivity methods assist in identifying clay-rich layers as potential

barriers or conduits for contaminant migration. This section discusses the application of

resistivity surveys in delineating clay aquitards, monitoring landfills, and investigating

groundwater contamination in clay-rich environments.

Therefore in Clay's electrical properties significantly influence resistivity measurements and

their interpretation in geophysical exploration. Understanding the relationship between clay and

the resistivity method is crucial for accurate subsurface characterization in clay-rich

environments.

(U.S. Geological Survey: "Clays Statistics and Information." Available online:

https://www.usgs.gov/centers/nmic/clays-statistics-and-information)

1.6 Importance of clay

Clay is an important natural resource with numerous economic uses. Its significance lies in its

wide range of applications across various industries, including construction, ceramics,

agriculture, cosmetics, and more. Here are some of the economic importance and types of clay:

1. Construction Industry: Clay is used in the construction industry for making bricks, tiles, pipes,

and other structural materials. It is valued for its strength, durability, and thermal properties,

making it an essential component in building infrastructure.

2. Ceramics Industry: Clay is a primary ingredient in the production of ceramics such as pottery,

porcelain, and sanitary ware. It provides the plasticity required for shaping objects and, upon

firing, forms a solid and durable material.

3. Agriculture: Clay soils have unique properties that make them important in agriculture. Clay

particles can retain moisture and nutrients, providing a fertile environment for plant growth.

Additionally, clay can be used as a component in agricultural amendments and soil conditioners.

4. Oil and Gas Industry: Certain clays, such as bentonite, have significant applications in the oil

and gas industry. Bentonite clay is used for drilling fluids, sealing boreholes, and as a lubricant in

the extraction process.

5. Pharmaceuticals and Cosmetics: Various types of clay, including kaolin and bentonite, are

used in pharmaceuticals and cosmetics. They are utilized in the production of medications,

skincare products, and cosmetics due to their absorbent, adsorbent, and purifying properties.

6. Environmental Applications: Clay is employed in environmental applications such as waste

management, water treatment, and soil stabilization. It can help in the removal of pollutants from

water and act as a barrier to prevent the migration of contaminants.

1.7 Types of Clay:

1. China clay: China clay, also known as Kaolin clay, is white, fine-grained clay that is used in

ceramics, papermaking, cosmetics, and pharmaceuticals. It is known for its high alumina and

silica content.

2. Bentonite: Bentonite clay is clay that swells when it comes into contact with water. It has

applications in drilling fluids, cat litter, foundry molds, and as a binder in iron ore pelletizing.
3. Montmorillonite: Montmorillonite is a type of clay belonging to the steatite group. It has

excellent adsorption and cat ion exchange properties and is used in various industries, including

agriculture, construction, and environmental applications.

4. Illite: Illite is a non-expanding clay mineral commonly found in soils. It is used in the

production of ceramics, as filler in paper, and as a component in drilling muds.

1.8 ELECTRICAL RESISTIVITY METHOD (ERT)

The electrical resistivity method is a geophysical technique used to study subsurface structures

and investigate the distribution of electrical properties within the Earth. It is commonly

employed in various fields such as geology, hydrology, environmental studies, archaeology, and

civil engineering. In this method, electrical measurements are made on the ground's surface or in

boreholes to infer information about the subsurface materials and their characteristics

1.8.1 Principle of Electrical Resistivity Method:

The electrical resistivity method is based on the fact that different materials have varying

electrical resistivity. Electrical resistivity is a measure of how strongly a material opposes the

flow of electric current. By injecting an electric current into the ground and measuring the

potential difference (voltage) resulting from the current flow, we can determine the apparent

resistivity at different depths. This data is then used to create subsurface models and interpret the

geologic features.

(Telford, W. M., Geldart, L. P., & Sheriff, R. E. (1990). Applied Geophysics. Cambridge

University Press.)

(Parasnis, D. S. (2005). Principles of Applied Geophysics. Springer)

1.9 FACTORS AFFECTING ERT MEASUREMENTS:

Several factors can influence electrical resistivity measurements, including the presence of water,

the mineral content of the subsurface materials, temperature, electrode contact quality, and the

presence of cultural interference

2. Application of ERT

The electrical resistivity method has a wide range of applications, including:

1. Archaeological site mapping and locating buried artifacts

2. Geotechnical investigations for civil engineering projects

3. Groundwater exploration and assessment

4. Environmental studies and contaminant plume mapping

5. Mineral and hydrocarbon exploration

(Reynolds, J. M. (2011). An Introduction to Applied and Environmental Geophysics. Wiley-

Blackwell.)

3.0 Aim and Objectives

AIM

The aim of the investigation is to determine the clay content in a subsurface region using

two-dimensional electrical resistivity tomography (2d ERT) technique.

OBJECTIVES:

The objectives of this study are to:

1. Characterize the distribution and thickness of clay layers.

2. Identify variations in clay content across the study area.

3. Determine the depth of clay-rich zones.

4. Provide insights for geological and engineering applications, such as foundation design and

land use planning.

5 LOCATION OF THE STUDY AREA

The location of the study area that was carried out during the project field work is situated within

the bounds of the University of Benin (UNIBEN) which lies in the Ovia North-East Local

Government Area of Edo State. Benin City,[Retrieved from the University of Benin official

website: https://www.uniben.edu/].

The location of these study areas covered during the project field work are: The Vice Chancellors

(VC) Lodge, close to Medical Health Center which was subjected to two (2) geo-electric

soundings: VES 8 & VES 10 which lies in N6°24'11", E5°37'29.388" andN6°24'11",

E5°37'31" respectively. The other geo-electric sounding location VES 9 was undertaken at an

Open field close to the University’s Main Gate which lies in N6°23'52.278", E5°36'34.272".

This project field work was conducted between the intervals of April 17th -20th, 2023
Fig 1 Base map of various study area

5 GEOMORPHOLOGY AND CLIMATE OF BENIN AND ENVIRONS

Geomorphology Information Benin Region is essentially an area situated in the coastal plains.

The region lies in the southern most corner of a dissected margin, a topographical unit which lies

north of the Niger Delta, west of the lower Niger Valley and south of the Western plains and

ranges. Several parts of the region are surrounded by the Benin historical moats. The region has

been described as a tilled plain in the south western direction. The local relief of the region is 91

m with its highest elevation around Ishan Pla-teau and Asaba Plateau applying the Digital

Elevation Model (DEM) observed that the highest eleva-tion can be found around the Benin-

Auchi Bypass which is about 170 m (500 feet) above mean sea level ap-proximately. The lowest

elevation of 0 m (0 feet) is found around the Ossiomo, Ikpoba and Ogba floodplains. observed

that other than the Ikpoba High which forms an integral part of the Ishan Plateau in the north
western corner of the region, the whole of the region is a relatively flat terrain. The areas around

Ugbowo, Ado-lor, Uwasota, Uselu, and Textile Mill Road slope heavily towards the five-junction

axis. Much of the western portion of the region is characterized by steep slopes all of them tilling

towards Ikpoba River. the western, eastern, central and southern sections of the region is

underlain by the Secondary and Tertiary Sedimentary Rock Formation of the Miocene—

Pleistocene age referred to as the Benin Formation. The Cretaceous Sedimentary rocks are of the

Upper Senonian group and occur mainly around Benin City. The sediments are some very fine

and others granular to moderately sorted. They possess thickness of 1.2 cm. Benin City lies on

the geomorphic unit referred to as the Benin low lands. This is a submission of a regional ter-rain

termed the coastal plain terrace . It is a tilled plain, slopping in the west direction with a general

reduction in attitude from the higher plateau landforms of about 1000 m (350 feet) above sea

level in the Ishan Pla-teau area which is about 70km northeast of Benin City.

Geomorphologic Process: The geomorphologic processes that operate in the Benin Region

include deep chemical weathering, slope processes and fluvial activity. Weathering In the tropics,

there is a great contrast between the forested lands and the vast rocky surfaces of the savannah

and semi-arid lands. The rocky hills which are more or less common in the intertropical regions

offer ideal conditions for the study of mechanical disintegration of rock mass. Mechanical rock

weathering is evidence by the processes of block and angular disintegration exfoliation basal

sapping and pressure release due to unloading. These processes are known to have operated in

this region in the early stages of landform development of the region. The weathering profiles

differ considerably as a result of variations in rock structure, differences in the condition of

groundwater amongst others. Boreholes records in the Benin Region show evidence of deep

chemical weathering overtime. Soil profile reveals that the region is composed mainly of reddish
brown sandy laterite. Intermittent layers of porous sands of sandy clays may reach a large depth

as found in the borehole drilled in the region. These are products of deep chemical decay of the

original parent rock materials. The terrain in Benin City is almost a flat plain with the northern

part of the city at a higher elevation of 122 m - 155 m (400 - 500 feet). The southern part at lower

elevations is of 30 m (100 ft) above sea level. The Ugbowo-Isiohor-Oluku-Ekiadolor area at the

northern fringes of the region constitutes a higher topography than the southern areas of the town

occupied by Ogba-

Ugbor area. The Ikpoba river valley constitutes a topographic depression across the region in a

north-east and south-east direction. This segments the town : the eastern “Ikpoba Hill” sector and

the “Western sector” sector, on which most of the town rests Within the western sector

prominent physiographic reddish earth levees encompass the region in a concentric outline. This

marks out the edge of the historical ancient Benin meat which was used as an outer defensive

perimeter of the ancient Benin kingdom. It is a cultural artifact.

Drainage:

Three river systems drain the Benin Region: the Ikpoba River, the Ogba River and Owigie-

Ogbovben River systems. They are small in size being (1 - 5 m) wide and (0.5 - 3.0 m) deep. The

major one is the Ikpoba River. Its’ headstream originates from the north east outside the Benin

Region and flows east to west across the northern quarter of the region and then swings south

and south east. This change in direction indicates structural control. There is a prominent

artificial man-made lake referred to as the Ikpoba Lake along its course in Okhoro. The lake is

about 1 km2 in area and is used mainly for water supply for drinking, fishing etc.

6 BRIEF REGIONAL, LOCAL AND HYDROGEOLOGY GEOLOGY OF BENIN-CITY

6.1. Regional Geology:

Benin-City is located in the southern part of Nigeria, specifically in the state of Edo. The

regional geology of the area is primarily composed of sedimentary formations belonging to the

Benin Formation, which is part of the larger Niger Delta Basin. The Niger Delta Basin is a

prolific sedimentary basin formed by the deposition of sediments carried by the Niger River and

its tributaries.

The Benin Formation consists of various layers of clay, silt, sand, and minor lignite deposits.

These sediments were deposited during different geological epochs and have been subject to

tectonic movements and compaction over millions of years. The region's geology has contributed

significantly to the formation of oil and gas reserves, making it an important area for petroleum

exploration and production.

6.2 Local Geology:

Within the city of Benin-City, the local geology mainly consists of the Benin Formation's

sedimentary layers. The exact composition and thickness of these layers may vary across

different parts of the city due to the localized geological processes. Local geological studies

might focus on understanding the sedimentary facies, depositional environments, and structural

geology of the region.

6.3. Hydrogeology:

Hydrogeology deals with the study of water in the subsurface, including groundwater flow,

distribution, and quality. In Benin-City, the hydro geological conditions are influenced by the

underlying geological formations. The Benin Formation, being a sedimentary sequence, is likely

to have varying aquifers and aquitards that control the flow and availability of groundwater.

The presence of clay and silt layers within the formation may act as aquitards, restricting

groundwater movement, while sand layers could serve as potential aquifers where groundwater
accumulates. Hydro geological investigations are essential for understanding the city's water

resources, identifying potential groundwater sources, and managing sustainable water supply for

domestic, agricultural, and industrial purposes.

Geological Map of Edo State Showing Benin City and other Locations (Nigerian Geological

Survey Agency, 2006)

 CHAPTER TWO

2.1 LITERATURE REVIEWE

Waisu (et al) carried out a geophysical survey using 2D electrical resistivity to image the extent

and economic quantity of clay deposit in Agbonmwoba village, Edo state. The Wenner-

Schlumberger electrode configuration was employed in five different locations within the study

area, and a total of ten (10) Wenner- Schlumberger soundings were acquired in the area with a

spread length of 200m along each traverse. The result showed clay deposits imaged along

traverses 1, 2, 4, 5, 9, and 10 are located at proximal depths within the subsurface and this

implies that the subsurface geology distribution along these profiles is slightly homogenous in

lithology, and clay deposits along these traverses are exploitable, while clay deposits along

traverses 3, 6 and 8 are found at the surface (0-8.9 m) as thin clay deposits and therefore not

commercially viable for exploitation. Clay deposits imaged in traverse 7 was relatively massive

in size (subsurface distribution) and was observed at profound depth of 26.8-35.7m (> 30m),

which makes it commercially viable for exploitation compared with other traverses.

K. O. Ozegin (et al) with the application of 2-D Electrical Resistivity Tomography (ERT) of the

electrical resistivity method using Wenner-Schlumberger array carried out geophysical

investigation for clay deposits in Ologbo Area of Edo State, Nigeria in order to establish and

characterize its presence. The field geometry was made up of three traverses each measuring

200.00 m. 2-D ERT data obtained were processed using Res2dinv software. The results of the

survey showed the presence of clay deposits occurring at 18-26.90 m and 7.75-13.5 m for

Traverse 1. Also, for Traverse 2, clay is meagrely deposited at 2.5-6.00 m and 2.5-4.00 m. The

resistivities of the clay deposit varied from about 50.00 to 116.00 Ωm. However, in traverse 3,

there is absence of clay deposits as this area is predominately lateritic (552 to 1804 Ωm) and

shale (2286 to 2897 Ωm). Areas of possible clay deposits have been established which would be

of economic importance, if exploited.

2.2 BASIC PRINCIPLES OF ELECTRICAL RESISTIVITY .

The fundamental property of materials and is an essential concept in electrical engineering and

geophysics Is known as electrical resistivity . It refers to the material's inherent ability to oppose

the flow of electric current. The electrical resistivity of a material is represented by the symbol

"ρ" (rho) and is measured in ohm-meters (Ω·m) or ohm-centimeters (Ω·cm), depending on the

unit system used

( Pelton, W. H., et al. "Electrical methods in geophysical prospecting," Society of Exploration

Geophysicists, 1978.)

Here are the basic principles of electrical resistivity:

1. Ohm's Law: Ohm's law is a fundamental principle in electrical engineering that relates voltage

(V), current (I), and resistance (R). It is expressed as:

V = IR

Where:

V is the voltage across the material (in volts),

I is the current passing through the material (in amperes), and

R is the electrical resistance of the material (in ohms).

2. Electrical Resistance: The measure of how strongly a material resists the flow of electric

current is known as electrical resistance. It depends on the material's properties, including its

resistivity (ρ) and its dimensions. The electrical resistance of a material is directly proportional to

its resistivity and its length (L) and inversely proportional to its cross-sectional area (A). It can

be calculated using the formula:

R = ρ× (L / A)
3. Electrical Conductivity: the reciprocal of resistivity and measures how easily a material allows

electric current to pass through it is known as Electrical conductivity (σ) . High conductive

materials have low resistivity, while insulating materials have high resistivity. The relationship

between resistivity (ρ) and conductivity (σ) is given by:

σ=1/ρ

Conductivity is usually measured in Siemens per meter (S/m) or Siemens per centimeter (S/cm).

4. Temperature Dependence: The resistivity of most materials changes with temperature. For

some conductors, such as metals, resistivity increases with temperature, while for

semiconductors, it usually decreases. For insulators, the temperature effect can vary significantly

based on their composition.(

Charles K. Alexander and Matthew N. O. Sadiku, "Fundamentals of Electric Circuits," McGraw-

Hill Education, 2012.)

2.1 THEORY OF ELECTRICAL RESISTIVITY METHOD

The electrical resistivity method is a geophysical technique used to study subsurface structures

and properties based on the variation of electrical resistivity of different materials. It involves

injecting an electric current into the ground and measuring the resulting voltage, from which the

electrical resistivity distribution can be determined. The method is widely used in various

applications, including groundwater exploration, mineral exploration, engineering studies, and

environmental investigations

(Kearey, P., Brooks, M., & Hill, I., "An Introduction to Geophysical Exploration," Blackwell

Science Ltd, 2002.)

Theory of the Electrical Resistivity Method:

1. Ohm's Law and Electrical Resistivity: The electrical resistivity method relies on Ohm's law,

which states that the voltage (V) across a material is directly proportional to the current (I)

passing through it and the electrical resistance (R) of the material. Mathematically, Ohm's law

can be expressed as:

V=IR

In the electrical resistivity method, the current is injected into the ground using two electrodes,

and the resulting voltage is measured between two other electrodes. The electrical resistivity of

the subsurface materials determines the magnitude of the measured voltage.

2. Relationship Between Resistivity and Geology: Different geological materials have distinct

electrical resistivity values due to variations in their pore fluid conductivity, mineral

composition, and porosity. For example, materials with high resistivity, such as dry rocks or clay-

rich formations, hinder electric current flow. In contrast, materials with low resistivity, such as

groundwater or metallic minerals, allow current to pass more easily.

3. Electrode Configurations: Various electrode configurations are used in electrical resistivity

surveys to investigate different subsurface targets. Common configurations include the Wenner

array, Schlumberger array, dipole-dipole array, and pole-dipole array. Each configuration offers

specific advantages and depth of investigation.

4. Inversion and Data Interpretation: The collected resistivity data are often inverted using

mathematical algorithms to create a subsurface resistivity model. Inversion methods aim to fit

the observed data to a model that best represents the distribution of resistivity in the subsurface.

Interpretation of the results involves identifying geological features, such as bedrock,

groundwater zones, faults, and mineral deposits

(Nabighian, M. N., "Electromagnetic Methods in Applied Geophysics," Society of Exploration

Geophysicists, 1988.)

2.2 GENERALIZED APPARENT RESISTIVITY EQUATION

The apparent resistivity is a critical parameter in the electrical resistivity method that

characterizes the resistance to electric current flow as observed at the surface of the Earth. It is

derived from the measured electrical potential and current data collected during electrical

resistivity surveys. The apparent resistivity is a fundamental element for data interpretation and

subsurface modeling

(Nabighian, M. N., "Electromagnetic Methods in Applied Geophysics," Society of Exploration

Geophysicists, 1988.)

The generalized apparent resistivity equation relates the observed electrical potential and current

data to the apparent resistivity. The equation's specific form depends on the electrode

configuration used during the survey. Here, I'll provide the generalized apparent resistivity

equation for the Wenner array, which is one of the common electrode configurations.

Generalized Apparent Resistivity Equation for the Wenner Array:

The Wenner array is defined by four electrodes positioned in a straight line, where the current

electrodes (A and B) are spaced at a distance (a), and the potential electrodes (M and N) are

spaced at a larger distance (n). The apparent resistivity (ρ_app) for the Wenner array is given by

the following equation:

Ρ _app = (π * a * V) / (I * (1 - 0.5 * λ))

Where:

Ρ_app is the apparent resistivity (in ohm-meters or ohm-centimeters).

a is the electrode spacing (in meters or centimeters).

V is the measured voltage potential (in volts).

I is the injected current (in amperes).

λ is the geometric factor, which is calculated as (n / a).

The geometric factor (λ) accounts for the electrode geometry and distance between the potential

electrodes. The larger the value of λ, the deeper the depth of investigation in the subsurface

.(Loke, M. H., "Tutorial: 2-D and 3-D electrical imaging surveys," Explore. Geophysics. 2004.)

2.3 ELECTRODE ARRAYS

Electrode arrays are specific configurations of electrodes used in electrical resistivity surveys, a

geophysical method used to investigate the subsurface by measuring variations in electrical

properties. Different electrode arrays are designed to provide specific information about

subsurface resistivity distribution, depths of investigation, and the geometry of subsurface

structures. Here, explain some commonly used electrode arrays:

1. Wenner Array:

The Wenner array is a simple and widely used configuration for electrical resistivity surveys. It

consists of four equally spaced electrodes (A, B, M, N) arranged in a straight line. The current

electrodes (A and B) are positioned at the outer ends of the line, while the potential electrodes (M

and N) are placed between the current electrodes.

Measurement Procedure:

1. A known direct current (DC) is injected into the ground through the outer electrodes (A and

B).

2. The voltage potential difference is measured between the inner potential electrodes (M and N).
3. Multiple measurements are taken with varying electrode spacings (a) to obtain apparent

resistivity values at different depths.

2. Schlumberger Array:

The Schlumberger array is commonly used for vertical electrical sounding (VES) surveys, which

aim to determine the vertical variation of subsurface resistivity with depth.

Measurement Procedure:

1. The Schlumberger array uses four electrodes, with two current electrodes (C1 and C2) placed

at either end of the line and two potential electrodes (P1 and P2) positioned between the current

electrodes.

2. The current is injected through the outer electrodes (C1 and C2), and the voltage potential

difference is measured between the inner potential electrodes (P1 and P2).

3. The potential electrodes are moved outward from the center while keeping the current

electrodes fixed to obtain multiple readings with varying electrode spacing’s (a).

4. This array provides information on the subsurface resistivity distribution up to a certain depth.

3. Dipole-Dipole Array:

The dipole-dipole array is used for investigations that require deeper penetration and higher

resolution than some other arrays. It offers good depth of investigation and is suitable for

detecting thin, low-resistivity layers.

Measurement Procedure:

1. The dipole-dipole array uses four electrodes (A, B, M, N) like the Wenner array, but with

larger electrode spacing’s (n) and (n + m).

2. The current is injected between A and B, while the potential difference is measured between M

and N, which are positioned further apart.

3. The array provides data for multiple measurements with different electrode spacings (n) to

infer subsurface resistivity distribution.

4. Pole-Dipole Array:

The pole-dipole array is used for deep investigations and is advantageous for its ability to detect

deep and shallow anomalies.

Measurement Procedure:

1. The pole-dipole array uses three electrodes: one current electrode (A) and two potential

electrodes (M and N).

2. The current is injected through electrode A while the potential difference is measured between

the potential electrodes M and N.

3. The potential electrodes are moved outward while keeping the current electrode fixed to obtain

multiple readings with varying electrode spacing’s.

These are just a few examples of commonly used electrode arrays in electrical resistivity

surveys. Each array offers distinct advantages and is suitable for different geological and

exploration objectives. Choosing the appropriate array depends on the specific project

requirements, subsurface targets, and depth of investigation needed.

2.5 SCHLUMBERGER ARRAY

The Schlumberger array is commonly used for vertical electrical sounding (VES) surveys, which

aim to determine the vertical variation of subsurface resistivity with depth.

The Schlumberger array uses four electrodes, with two current electrodes (C1 and C2) placed at

either end of the line and two potential electrodes (P1 and P2 positioned between the current

electrodes. The current is injected through the outer electrodes (C1 and C2), and the voltage

potential difference is measured between the inner potential electrodes (P1 and P2).The potential
electrodes are moved outward from the center while keeping the current electrodes fixed to

obtain multiple readings with varying electrode spacing’s (a).This array provides information on

the subsurface resistivity distribution up to a certain depth.

2.5.1 ADVANTAGES OF SCHLUMBERGER METHOD

The Schlumberger method is a widely used technique in the field of geophysics and specifically

in electrical resistivity surveys for subsurface imaging. The method involves measuring the

apparent resistivity at various electrode spacing’s to characterize the subsurface geology and

locate potential targets like aquifers, minerals, or hydrocarbon reservoirs. Here are some of the

advantages of the Schlumberger method:

1. High Resolution: The method provides relatively high-resolution data, especially in

comparison to other electrical resistivity techniques. This makes it suitable for detecting subtle

changes in resistivity associated with geological structures, faults, or fractures.

2 easy Setup and Operation: The field setup for the Schlumberger method is relatively simple,

requiring only a current source, potential electrodes, and a data acquisition system. The

measurements are conducted at fixed electrode a location, which reduces operational

complexities.

3. Non-Destructive Testing: The Schlumberger method is a non-destructive technique, meaning it

does not cause any physical damage to the subsurface. This makes it suitable for use in

environmentally sensitive areas or areas with limited access.

4. Accurate Data Interpretation: When combined with appropriate data inversion and modeling

techniques, the Schlumberger method can yield accurate information about subsurface resistivity

distribution. This helps in creating detailed models of the subsurface and aids in geological and

hydro geological interpretation.

5. Applicability to Various Geological Conditions: The Schlumberger method is versatile and can

be applied to various geological settings, such as sedimentary, metamorphic, or igneous

formations. It is also useful in both homogeneous and heterogeneous subsurface environments. .

(Ezomo. F.O And Ifedili, S.0 (2006): Schlumberger array of vertical electrical sounding(VES)

African Journ Of Sci, 9(1), 2195-2203.)

2.6 WENNER ARRAY

The Wenner array is a widely used geophysical technique for investigating subsurface electrical

resistivity distribution. This method is valuable for various applications, including groundwater

exploration, mineral exploration, environmental studies, and civil engineering projects.

Therefore it involves a simple arrangement of electrodes to measure the apparent resistivity of

subsurface materials.

A and B are the current electrodes through which the electrical current is passed.

M and N are the potential electrodes used to measure the potential difference.

The electrode spacing "a" is the distance between A and B and is also equal to the distance

between M and N.

MEASUREMENT PROCEDURE

The measurement procedure involves the following steps:

1. Current is passed between electrodes A and B.

2. The potential difference (voltage) is measured between electrodes M and N.

3. The apparent resistivity at that specific electrode spacing (a) is calculated using the measured

voltage and known current value.

Therefore Wenner array has several advantages:

1. It is a simple and cost-effective method that requires minimal equipment.

2. Data can be collected quickly, making it suitable for large-scale surveys.

3. It provides good depth penetration and resolution.

2.7 DIPOLE-DIPOLE

The dipole-dipole array is a commonly used resistivity survey method in geophysics for

investigating the subsurface electrical resistivity distribution. Similar to the Wenner array, it

measures the apparent resistivity of subsurface materials, but it offers some advantages in certain

survey conditions. Let's delve into a detailed explanation of the dipole-dipole array:

DIPOLE DIPOLE ARRAY GEOMETRY:

The dipole-dipole array uses a specific arrangement of electrodes to measure the apparent

resistivity. It involves four electrodes: two current electrodes (A and B) and two potential

electrodes (M and N).

1 .A and B are the current electrodes through which the electrical current is passed.

2. M and N are the potential electrodes used to measure the potential difference.

The distance between A and M is "a

“And the distance between M and N is "n."

MEASUREMENT PROCEDURE FOR DIPOLE-DIPOLE

The measurement procedure in the dipole-dipole array involves the following steps:

1. Electrical current is applied between electrodes A and B, and potential differences are

measured between M and N.

2. By varying the electrode spacing (a and n), multiple measurements are made along the survey

line to obtain data for different depths of investigation.

ADVANTAGES OF THE DIPOLE-DIPOLE ARRAY:

The dipole-dipole array has several advantages over other resistivity survey methods:

1. Better depth resolution compared to Wenner array, making it suitable for investigating deeper

structures.

2. It can detect weak anomalies more effectively.

3. Provides higher signal-to-noise ratio in noisy environments.

LIMITATIONS FOR DIPOLE-DIPOLE ARRAY

The dipole-dipole array also has some limitations:

1. It requires more electrodes than the Wenner array, which may be challenging in certain survey

conditions.

2. It may not be suitable for very shallow investigations due to the larger electrode spacing’s.
2.7.1 VERTICAL ELECTRICAL SOUNDING (VES)

Vertical Electrical Sounding (VES) is an electrical resistivity method used to determine the

resistivity distribution of the subsurface along a vertical profile. It provides information about the

layering and resistivity contrasts at varying depths.(Loke, M.H. (2014). "Tutorial: 2-D and 3-D

Electrical Imaging Surveys." Geotomo Software.)

The Working Principle of VES

1. In VES, a set of electrodes is deployed with a fixed separation distance, typically in a straight

line or along a profile.

2. A direct current (DC) is applied between the outermost electrodes.

3. The potential difference (voltage) is measured between the inner electrodes.

4. By varying the electrode spacing and taking measurements at different depths, the apparent

resistivity is calculated.

5. The resistivity data are plotted against the electrode spacing to create a resistivity-depth curve

called a VES curve.

6. The VES curve is then interpreted to identify subsurface layers and estimate their resistivity

values.

(Loke, M.H. (2014). "Tutorial: 2-D and 3-D Electrical Imaging Surveys." Geotomo Software.)

ADVANTAGES OF VERTICAL ELECTRICAL SOUNDING (VES):

1. Depth Information: VES provides valuable depth information about subsurface resistivity

variations, making it suitable for studying layered geological structures.

2. Cost-Effective: VES can provide valuable subsurface information at relatively low costs

compared to other geophysical methods like drilling or seismic surveys.

3. Applicability to Different Terrains: It can be applied in various geological settings, from

sedimentary basins to mountainous regions, making it versatile for different projects.

4. Non-Destructive: VES is a non-destructive technique, meaning it does not cause any physical

damage to the subsurface, making it environmentally friendly.(Reynolds, J.M. (2011). "An

Introduction to Applied and Environmental Geophysics." John Wiley & Sons, Ltd.)

2.7.2 HORIZONTAL PROFILING TECHNIQUE

The principle of the Horizontal Profiling technique is to investigate lateral variations in

subsurface properties at a constant depth. Unlike VES, which provides information about the

vertical resistivity distribution, Horizontal Profiling aims to understand changes in resistivity

along a straight line at a fixed depth. Horizontal Profiling provides valuable insights into

subsurface lateral variations, such as changes in geological formations, the presence of

geological structures, or potential anomalies

THE WORKING PRINCIPLE OF HORIZONTAL PROFILING TECHNIQUE:

1. In the Horizontal Profiling technique, a set of electrodes is deployed in a straight line at a fixed

depth below the ground surface.

2. A direct current (DC) is applied between two outermost electrodes, and the potential difference

is measured between the inner electrodes.

3. The apparent resistivity is calculated, representing the average resistivity along the horizontal

profile.

4. By moving the electrode array along the profile and taking measurements at regular intervals,

a resistivity profile is obtained.

5. The resistivity profile is then interpreted to identify lateral variations in subsurface resistivity.
ADVANTAGES OF HORIZONTAL PROFILING TECHNIQUE:

1. Rapid Data Acquisition: Horizontal profiling can quickly cover a large area, making it useful

for regional-scale surveys.

2. Identification of Near-Surface Features: It is effective in mapping near-surface structures like

faults, fractures, and buried objects, which are crucial for engineering and environmental

projects.

3. Ease of Deployment: The method is relatively easy to set up and operate, requiring a simple

linear arrangement of electrodes.

(J.M. (2011). "An Introduction to Applied and Environmental Geophysics." John Wiley & Sons,

Ltd.)

(Nabighian, M. N. (1984). Electromagnetic Methods in Applied Geophysics - Theory. SEG

Geophysical Monograph Series No. 1.)

LIMITATIONS OF HORIZONTAL PROFILING TECHNIQUE:

1. Limited Depth Penetration: Horizontal profiling is generally more suitable for shallow

investigations and may not provide detailed information about deeper structures.

2. Low Vertical Resolution: The method may not offer high-resolution data for identifying thin

subsurface layers.

(Telford, W.M., Geldart, L.P., Sheriff, R.E., and Keys, D.A. (1990). "Applied Geophysics."

Cambridge University Press.)

2.7.3 COMBINE HORIZONTAL PROFILE & VERTICAL ELECTRICAL SOUNDING

Combining Horizontal Profiling and Vertical Electrical Sounding (VES) is a powerful approach

in electrical resistivity surveys to obtain a comprehensive subsurface image. This integrated

method allows for a more detailed characterization of the subsurface geology, providing

information about both lateral and vertical variations in resistivity.

WORKING PRINCIPLE:

1. The integrated approach involves performing both Horizontal Profiling and VES at the same

survey site or in nearby locations.

2. For Horizontal Profiling, a set of electrodes is deployed in a straight line along the ground

surface, and resistivity measurements are taken at regular intervals.

3. The Horizontal Profiling data provide information about lateral variations in resistivity,

mapping near-surface structures and identifying anomalies or buried objects.

4. For VES, a separate set of electrodes is used to measure the apparent resistivity at different

depths below the ground surface along a vertical profile.

5. The VES data yield insights into the layered subsurface structure, allowing the identification

of distinct geological formations and their resistivity values at varying depths.

ADVANTAGES OF COMBINING HORIZONTAL PROFILING AND VES:

1 Comprehensive Subsurface Imaging: The integrated approach provides a comprehensive view

of the subsurface, combining lateral and vertical information, thus enhancing the understanding

of the geological setting.

2. Improved Resolution: By using both methods, the limitations of each technique can be

mitigated. The Horizontal Profiling compensates for the limited depth penetration of VES, while

VES provides depth information that may not be evident in the Horizontal Profiling data.

3. Confirmation of Targets: When anomalies or features are detected in Horizontal Profiling,

VES can be conducted at those specific locations to obtain more detailed information about the

underlying structures.

4. Increased Confidence in Interpretation: By cross-referencing and integrating the results of

both methods, the reliability of the interpretations is enhanced, leading to more accurate

subsurface models.

APPLICATION EXAMPLES OF BOTH COMBINATIONS

1. Mineral Exploration: The integrated approach can aid in locating ore bodies and assessing

their depth and size for efficient mining operations.

2. Groundwater Exploration: The integrated approach can help identify potential aquifers

through Horizontal Profiling and then delineate their depth and extent using VES, crucial for

sustainable water resource management.

3. Environmental Site Characterization: Combining the methods can assist in mapping

subsurface contamination plumes and understanding the geological controls on contaminant

migration.

4. Engineering Site Investigations: By understanding both lateral and vertical variations in

subsurface resistivity, the integrated method assists in designing stable foundations and

mitigating geotechnical risks.

2.8 FIELD OPERATIONAL PROBLEMS OF ELECTRICAL RESISTIVITY METHOD

During field operations of the Electrical Resistivity Method, several challenges may arise that

can affect the quality of data and the success of the project. Understanding and addressing these

problems is crucial for obtaining reliable and accurate subsurface information.

Some of the common field operational problems:

1. Noise and Interference:

Electrical resistivity measurements are susceptible to environmental noise and electromagnetic

interference from nearby power lines, electronics, or stray currents. Noise can distort the

readings and affect data accuracy, making it essential to choose survey locations away from

potential interference sources.

2. Electrode Placement and Contact Issues:

Inadequate electrode contact with the ground can lead to poor data quality and erratic

measurements. Electrode spacing may be challenging to maintain consistently, especially in

rugged terrain or areas with limited access.

3. Weather Conditions:

Adverse weather conditions, such as heavy rain or extreme temperatures, can affect equipment

performance and compromise data quality. Wet ground conditions can alter subsurface resistivity,

and extreme temperatures may damage instruments.

4 .Limited Depth Penetration:

The depth of investigation is influenced by the electrode spacing, and the method may not

provide sufficient information about deep subsurface structures. Deep investigations may require

specialized equipment or other geophysical methods.

5. Time-Consuming Surveys:
 Electrical resistivity surveys can be time-consuming, especially when conducting multiple

measurements at various locations and depths. Long survey durations may limit the coverage

area or increase project costs.

2.9 LIMITATION OF ELECTRICAL RESISTIVITY METHOD

The Electrical Resistivity Method is a widely used geophysical technique for subsurface imaging

and exploration. In many geophysical methods, it has limitation

Below are the main limitations of the Electrical Resistivity Method:

1. Influence of Electrode Configuration: Different electrode configurations (e.g., Wenner,

Dipole-Dipole, and Schlumberger) are used to acquire resistivity data, and each configuration

has its advantages and limitations. The choice of electrode configuration should be carefully

considered based on the project's objectives and the geological setting.

2. Influence of Near-Surface Conditions: Near-surface properties, such as moisture content, clay

content, and soil type, significantly affect the resistivity measurements. Inhomogeneous near-

surface conditions can obscure or distort the subsurface resistivity information, leading to false

anomalies or limiting the detection of deeper features.

3. Environmental Interference: The Electrical Resistivity Method is susceptible to interference

from environmental noise, such as electromagnetic signals from power lines or other nearby

electrical equipment. Environmental noise can corrupt the data and affect the accuracy of the

results.

Many limitations include: Time-Consuming Surveys, Limited Depth of Investigation, Limited

Resolution and Assumption of Homogeneity

3.0INSTRUMENTATION AND METHODOLOGY FOR RESISTIVITY SURVEY

 Resistivity surveys are geophysical investigations used to measure the electrical resistivity of

the subsurface to infer information about its geology, hydrology, and potential mineral

resources. The survey involves the use of specialized instruments and methodologies to collect

data and interpret the subsurface properties. Below is a detailed overview of the instrumentation

and methodology used in resistivity surveys:

1. Electrodes: Four angular-shaped stainless steel electrodes, designed to be non-polarizing,

were utilized during fieldwork. They were securely inserted into the ground using a hammer.

Two of these electrodes functioned as current electrodes, responsible for injecting electrical

current into the ground when connected to the Terrameter's current component. The other two

electrodes served as potential electrodes, measuring electrical potentials.

There are different types of electrode: Surface Electrodes, Borehole Electrodes, and Special

Electrodes etc

1. Borehole Electrodes: Borehole electrodes are used in borehole resistivity surveys, where

electrodes are lowered into drilled boreholes to obtain vertical resistivity profiles.

2. Surface Electrodes: Surface electrodes are placed on the ground surface and are used for

most common resistivity survey configurations.

3. Special Electrodes: Specialized electrodes, such as Wenner, Schlumberger, Dipole-

Dipole, and Pole-Dipole, are used in different survey configurations to optimize data collection

for specific objectives.

The type of electrode used is the Surface Electrodes and Special Electrodes.
2. Reels of Cables: Insulated cables equipped with crocodile clips at their ends were employed

to establish connections between the electrodes and the battery, facilitating the flow of electrical

current to and from the resistivity meter

Figure 3.3: Reels of Cable

3. Measuring tap: A measuring tape was employed to accurately determine the positions and

spacing of the electrodes in the field, ensuring precise and consistent measurements.
Figure 3.4: Measuring tape

4. Data Recording: Recording sheets, specially designed for field use, were used to document

various survey-related information, including the survey location, electrode arrangements,

measurement data, and any notable observations made during the survey.

5. Power Source: A 12-volt direct current (DC) battery served as the power source for the

Terrameter. This battery was consistently connected to the Terrameter's base, providing the

necessary electrical energy for the instrument to function effectively throughout the survey.

Figure 3.5 showing Battery

6. Resistivity Meter (Terrameter): resistivity used for the field survey is ABEM Tetrameter

SAS 300C .This instrument measures the electrical resistivity of the earth's subsurface materials.
METHODOLOGY

Data Acquisition: The electrical resistivity survey encompassed four traverses and involved

vertical electrical sounding with the Schlumberger array and the constant separation technique

using the Wenner array. Data acquisition utilized specific equipment and accessories, including

the PASI Resistivity Terrameter for obtaining resistivity readings, a 12V, 60Ah battery to

supplement the Terrameter's current supply, a Garmin 12 Global Positioning System (GPS) for

acquiring VES point coordinates, a measuring tape to ensure precise electrode spacing, four

metal electrodes for transmitting current into the ground, four reels of cables for conveying

current to the electrodes, and four hammers for securely driving the electrodes into the ground.

Three Vertical Electrical Sounding Stations were established, and two 2D profiles were captured

at different points along the four traverses. The Schlumberger current electrode separation (AB)

ranged from 2.0m to 250m at the VES locations, while the Wenner array had a spread of 200m.
 CHAPTER 4

RESULTS AND DISCUSSION

4.1 VES (VERTICAL ELECTRICAL SOUNDING RESULTS)

The figures in Figure 4.1, Figure 4.2, and Figure 4.3 depict the variations in geo-electrical curves

across the study area, which differ significantly. Below, you'll find the resistivity curves and a

summary of the interpreted VES findings.

4.2 DIPOLE-DIPOLE INTERPRETATION

27-9-21 TRAVERSE-2 0m
a=10m n=5 Elevation = 92.76m 180m 6 24 17N 5 36 29N
250m

Apparent
Resistance Resistivity
Electrode position Geometric [Ω] [Ωm]
n C1 C2 P1 P2 factor Remarks
1 0 10 20 30 188.52 5.23 985.9596
2 30 40 754.08 0.932 702.80256
3 40 50 1885.2 0.729 1374.3108
4 50 60 3770.4 0.327 1232.9208
5 60 70 6598.2 0.129 851.1678
1 10 20 30 40 188.52 5.13 967.1076
2 40 50 754.08 1.131 852.86448
3 50 60 1885.2 0.489 921.8628
4 60 70 3770.4 0.111 418.5144
5 70 80 6598.2 0.027 178.1514
1 20 30 40 50 188.52 4.7 886.044
2 50 60 754.08 0.984 742.01472
3 60 70 1885.2 0.278 524.0856
3770.4

4 70 80 0.239 901.1256
5 80 90 6598.2 0.076 501.4632
1 30 40 50 60 188.52 3.18 599.4936
2 60 70 754.08 0.74 558.0192
3 70 80 1885.2 0.289 544.8228
4 80 90 3770.4 0.173 652.2792
5 90 100 6598.2 0.182 1200.8724
1 40 50 60 70 188.52 4.82 908.6664
2 70 80 754.08 0.91 686.2128
3 80 90 1885.2 0.358 674.9016
4 90 100 3770.4 0.229 863.4216
5 100 110 6598.2 0.15 989.73
1 50 60 70 80 188.52 5.31 1001.0412
2 80 90 754.08 1.092 823.45536
3 90 100 1885.2 0.692 1304.5584
4 100 110 3770.4 0.195 735.228
5 110 120 6598.2 0.125 824.775
1 60 70 80 90 188.52 3.88 731.4576
2 90 100 754.08 0.754 568.57632
3 100 110 1885.2 0.231 435.4812
4 110 120 3770.4 0.216 814.4064
5 120 130 6598.2 0.224 1477.9968
1 70 80 90 100 188.52 3.6 678.672
2 100 110 754.08 0.762 574.60896
3 110 120 1885.2 0.257 484.4964
4 120 130 3770.4 0.215 810.636
5 130 140 6598.2 0.121 798.3822
1 80 90 100 110 188.52 4.18 788.0136
2 110 120 754.08 0.768 579.13344
3 120 130 1885.2 0.329 620.2308
4 130 140 3770.4 0.199 750.3096
5 140 150 6598.2 0.196 1293.2472
1 90 100 110 120 188.52 3.23 608.9196
2 120 130 754.08 0.931 702.04848
3 130 140 1885.2 0.276 520.3152
4 140 150 3770.4 0.299 1127.3496
5 150 160 6598.2 0.109 719.2038
1 100 110 120 130 188.52 5.51 1038.7452
2 130 140 754.08 1.141 860.40528
3 140 150 1885.2 0.303 571.2156
4 150 160 3770.4 0.206 776.7024
5 160 170 6598.2 0.141 930.3462
1 110 120 130 140 188.52 4.26 803.0952
2 140 150 754.08 0.67 505.2336
3 150 160 1885.2 0.294 554.2488
4 160 170 3770.4 0.166 625.8864
5 170 180 6598.2 0.136 897.3552
1 120 130 140 150 188.52 3.29 620.2308
2 150 160 754.08 0.89 671.1312
3 160 170 1885.2 0.516 972.7632
4 170 180 3770.4 0.253 953.9112
5 180 190 6598.2 0.067 442.0794
1 130 140 150 160 188.52 3.11 586.2972
2 160 170 754.08 0.658 496.18464
3 170 180 1885.2 0.356 671.1312
4 180 190 3770.4 0.194 731.4576
5 190 200 6598.2 0.16 1055.712
1 140 150 160 210 188.52 3.66 689.9832
2 170 180 754.08 0.864 651.52512
3 180 190 1885.2 0.226 426.0552
4 190 200 3770.4 0.242 912.4368
5 200 210 6598.2 0.04 263.928
1 150 160 170 220 188.52 5.16 972.7632
2 180 190 754.08 0.437 329.53296
3 190 200 1885.2 0.334 629.6568
4 200 210 3770.4 0.21 791.784
5 210 220 6598.2 0.074 488.2668
1 160 170 180 190 188.52 4.24 799.3248
2 190 200 754.08 1.15 867.192
3 200 210 1885.2 0.564 1063.2528
4 210 220 3770.4 0.14 527.856
5 220 230 6598.2 0.132 870.9624
1 170 180 190 200 188.52 3.79 714.4908
2 200 210 754.08 0.871 656.80368
3 210 220 1885.2 0.251 473.1852
4 220 230 3770.4 0.134 505.2336
5 230 240 6598.2 0.135 890.757
1 180 190 200 210 188.52 3.31 624.0012
2 210 220 754.08 0.893 673.39344
 3 220 230 1885.2 0.358 674.9016
4 230 240 3770.4 0.363 1368.6552
5 240 250 6598.2 0.208 1372.4256
1 190 200 210 220 188.52 5.29 997.2708
2 220 230 754.08 0.926 698.27808
3 230 240 1885.2 0.382 720.1464
4 240 250 3770.4 0.194 731.4576
5 0
1 200 210 220 230 188.52 3.78 712.6056
2 230 240 754.08 0.724 545.95392
3 240 250 1885.2 0.263 495.8076
4 0
5 0
1 210 220 230 240 188.52 3.97 748.4244
2 240 250 754.08 0.743 560.28144
3 0
4 0
5 0
1 220 230 240 250 188.52 3.69 695.6388

4.2.1 2-D Resistivity Imaging along Traverse two (Dipole-Dipole)

Interpreted pseudo-sections of traverse-2 display color-coded zones representing various

subsurface rock types.

[A] Indicates a low-resistivity layer, which corresponds to clay-rich material.

[B] Represents relatively low resistivity, indicating clayey sand.

[C] Shows moderately high resistivity, likely wet sand.

[D] Signifies high resistivity, characteristic of dry coarse sand."

From the 2_D inverted resistivity interpretation results, four distinct geologic layers were

identified. These layers are: (A) Clayey, (B) Clayey Sand, (C) Sand, very wet (D) Very Dry Sand

Note A=blue, B=Orange/yellow, C= Green and D=RED / PURPLE

Therefore the 2D resistivity section as revealed from the pseudo-sections show that clay exist in

small amount within the subsurface at a depth between 5-20m and electrode spacing of 65-80m ,

95-110m , 140-160m , 171-187m , 201-219m

Figure 4.1 2-D Resistivity section along Traverse Two (Dipole-Dipole):

1. clay distribution and thickness of clay exist between electrode spacing’s of about 65-80m , 95-

110m , 140-160m , 171-187m , 201-219m and having a thickness of 11m

2. The variation in clay content are the same

3. From the pseudo-sections the clay deposit across the study area exist at a depth range of 8-
20m
.
4. In geological and engineering contexts, dealing with low clay deposits situated beneath the

surface, rather than within it, presents distinctive challenges concerning tasks like designing

foundations and planning land usage. To solve these challenges, thorough soil testing will be

conducted to evaluate the properties of the clay, encompassing aspects such as its composition,

plasticity, and moisture levels. This data will serve as a crucial foundation for well-informed

design decisions that take into account potential settling and load-bearing concerns

CHAPTER FIVE

5.0 FINDINGS, CONCLUSION AND RECOMMENDATION

5.1 FINDINGS

1. clay distribution and thickness of clay exist between electrode spacing’s of about 65-80m , 95-

110m , 140-160m , 171-187m , 201-219m and having a thickness of 11m

2. The variation in clay content are the same

3. From the pseudo-sections the clay deposit across the study area exist at a depth range of 8-
20m
4. In geological and engineering contexts, dealing with low clay deposits situated beneath the

surface, rather than within it, presents distinctive challenges concerning tasks like designing

foundations and planning land usage. To solve these challenges, thorough soil testing will be

conducted to evaluate the properties of the clay, encompassing aspects such as its composition,

plasticity, and moisture levels. This data will serve as a crucial foundation for well-informed

design decisions that take into account potential settling and load-bearing concerns

5.2 CONCLUTION

In summary, the application of the 2D Electrical Resistivity Tomography (ERT) survey has

demonstrated its effectiveness as a valuable geophysical technique in our research. Specifically,

it has proven highly beneficial for identifying various geological layers beneath the surface in the

University of Benin (UNIBEN) area. The data we collected, processed, and analyzed revealed

the presence of several distinct geological layers, including topsoil, sand, clay, clayey sand, very

dry coarse sand, and a notable abundance of wet sand. Despite the relatively low presence of clay

deposits, these findings indicate promising opportunities for exploring groundwater resources

within the University of Benin.

5.2 RECOMMENDATIO

Using 2d ERT is valuable for identifying subsurface geological layers, it doesn't offer results

with complete certainty. As a result, we propose additional research employing advanced

methods like 3d ERT and combining them with other geophysical techniques. This is particularly

crucial when investigating low levels of clay content within the subsurface
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