ABSTRACT
A geoelectric survey of groundwater potential was carried out in the male hostel at Isa Kaita College of Education Dutsinma, Katsina State Nigeria using ABEM SAS 300 Terrameter. The Wenner and Schlumberger electrodes configurations were used for data acquisition. In the process, four Vertical Electrical Soundings (VES) were conducted at stations 01, 02, 03, and 04 covering the area. This was done in order to determine: the variation in resistivity of the topsoil of the area, the Depth and the thickness of the weathered basement, the depth and the thickness of the Aquifer, the Depth to basement, and to establish areas suitable for borehole development. The VES data obtained were interpreted using ipi2win computer software which showed that the area is composed mainly of three (3) layers, namely; the topsoil, weathered basement, fractured basement. The weathered and fractured layers constitute the aquiferous zone in all the stations. The results of the interpreted VES data showed that the first layer has resistivity of the topsoil varies from 18.2 to 172 Ωm with an average value of 95.1 Ωm. The thickness of the weathered basement varied from 10.8 to 16.2 m with an average value of 13.5m while depth to this layer varies from 10.8to27 m with an average value of 24.3 m. The thickness of the fractured basement varied from 16.2 to 2.14 m with an average value of 18.34 m, while depth to this layer varies from 27m to 4.33m with an average value of 15.67 m. The thickness of the aquifer varied from 16.2mto 2.14 m with an average value of 18.34 m, while depth to aquifer varies from 27 to 4.33m with an average value of 15.66 m. Depth to basement varies from 27 to 4.33m with an average value of 15.67 m. Based on the results, VES 01 has high potential for groundwater and are therefore recommended for borehole establishment
CHAPTER ONE
INTRODUCTION
1.1 Background of study
Water is useful natural resources that are not only essential for the survival of mankind but also for the survival of the natural environment. The availability of water has played a key role in development of all civilizations. Indeed especially in the ancient times, water scarcity prevents the development of settlement. Social welfare and economic development may be hampered in the absence of reliable water supplies. Water is essential to people and the largest available source of fresh water lies underground. Increased demands for water have stimulated development of underground water resources (Afuwai, 2013). This is particularly true of sub-sahara and sahara countries, such as Nigeria where water resources are extremely limited and highly valued as a social and economics good. However water is available in many forms such as ice caps, glaciers, ocean water, surface water and groundwater.
Groundwater happens to be a more reliable source of water for over half of the world population
(Alabi,A.A.,R. Bello, A.S.Ogungbe and H.O. Oyerinde, 2010). It is described by Otutu and Oviri (2010) as water found in the saturated layers of soil and rocks. In other to explore this natural resources for the benefit of sustaining life, various geophysical survey has been employed successfully. These method include electrical resistivity surveys, seismic refraction, electromagnetic, gravity, magnetic and magneto telluric (Karami, B.,K.N.Dhumal,M. Golabi and N. Jaafarzadeh, 2009; Majumdar and Das, 2011;Todd 2004). The choice of method used depends largely on the depth of investigation and sometimes cost (Todd, 2004; Majumdar and Das, 2011). Of all these method used in exploring for groundwater, electrical resistivity profiling has been the most widely used method (Molua and Eagbetere, 2005). This is because the operation of the field instrument is uncomplicated and the analysis of data is less unwidely and economical. Geo-electrical resistivity has been developed greatly and has become an important instrument in hydrological studies, mineral prospecting and mining as well as in environment and engineering application. (Alile , 2011; Griffiths and baker, 1993; Dahlin and loke., 1996). This underlying principle of measuring substance variation using electrical resistivity within the earth was developed by Schlumberger who conducted the first experiment in the field of Normandy and the same idea was also developed by frank Werner in the United States of America. This geo-electrical resistivity method has been found useful in locating groundwater in fissured rock, mapping of plumes, mapping of boundaries of saline groundwater and exploration of geothermal fluids. However; geo-electrical resistivity surveys have undergo significant changes in the last three decades. The traditional horizontal layering technique for investigating geo-electrical resistivity data are rapidly being replaced with 2-dimentional and 3dimentional models of interpretation especially in complex and heterogeneous subsurface media. Field techniques have advanced from manual measurements made at separate and independent points to the use of automated machine called terrameter with multi-electrode array along the measurement profile. Till 1980s, data acquisition was more or less carried out manually and this is demanding slowly and the quality of the measured data is poor. Therefore range of fast automated multi-electrode and multichannel data acquisition system now exists that follows flexibility in the acquisition of geo-electrical resistivity data. (Barker, 1981; Stummer and Maurer, 2001; Auken et al., 2006).As a result of these successful applications of electrical resistivity method over the years in groundwater exploration, this prompted the researcher to adopt Electrical resistivity method to carried out investigation on groundwater potential at male student resident at the Isa Kaita College of Education and geological structure of the sturdy area.
1.2 Aim and Objectives of the Survey
The aim is to use the Electrical Resistivity Techniques to investigate the groundwater potential at the male student hostel of Isa kaita College of Education Dutsin-ma, Katsina State. The objectives are as follow
- To determine the thickness and resistivity of the topsoil
- To determine the depth and thickness of the aquifer
- To determine the variation of the depth to the basement
- To determine areas suitable for borehole construction
- To produce contour maps of the thickness of Aquifer, resistivity of top soil and the Depth to fresh basement.
1.3 Justification of the survey
One of the major problems in Isa Kaita College of Education is lack of adequate water supply and failure of bore-hole. This prompts me to carry out a geophysical survey in the study area. Sources of water available there are wells and ineffective bore-hole. These sources of water failed during dry season as a result poor location of the bore-hole. Hence borehole drilled based on these geophysical investigations will reduce the demand for water.
1.4Scope of the Survey
This research work is to the male students’ hostel of the Isa Kaita College of Education Dutsin-ma.
There are different geophysical methods such as Electrical Resistivity methods, Seismic methods, Electromagnetic methods, etc. used for groundwater prospecting, but for the purpose of this research work, the application of electrical resistivity survey method will be employed. This is because, Resistivity Method is sensitive to tiny variation in the conductivity of the subsurface structure within the basement complex, which this survey area is part of.
1.5 Location and Extent of the Survey Area
Dutsin-ma LGA lies between latitude 12°17.00′ N to 12°17.84′ N and longitude 007°26′ E to 007°27′ E
(Abaje., 2014). It is bounded by Kurfi and Charanchi LGAs to the north, Kankia LGA to the east,
Safana and Dan-Musa LGAs to the west, and Matazu LGA to the southeast as shown in (Figure.1.1). Dutsin-ma LGA has a land size of about 552.323 𝑘𝑚2 with a population of about 169 829 as at 2006 national census (Federal Republic of Nigeria, 2012). The people are predominantly farmers, cattle rearers and traders.
Figure. 1.1: Map of Katsina State showing Dutsinma LGA and the study location (source: Gnes/spot image, 2014) Figure: 1.2. Map of Isa Kaita College of Education showing the study location (Adapted from the Dept of Works and planning, Isa Kaita College of Education)
1.6 Climate, vegetation and rainfall
The study area is the tropical wet and dry type (Tropical continental climate) classified by Koppen as Aw climate. Rainfall is between April and September with a peak in August. The average annual rainfall is about 700mm. The vegetation is Sudan savanna type which combine the characteristics and species of both the Guinea and Sahel savanna (among which are Isoberlina, Doka and Acacia spp) (Bala 2000). The pattern of rainfall in the area is highly variable. The can result in severe and wide spread droughts that can impose serious socio economics constraints. The highest air temperature normally occurs in April to May and lowest in December to February (Abaje 2007; Tukur, Adamu, Abdulrahid, and Rabiu, M. 2013)
1.7 Topography
The area of Isa Kaita College of education Dutsinma consists of low lying terrains and Southern and central parts of the site are typified by relatively flat and monotonous landscape underlain by biotite hornblende granite. The northern part of the site is remarkable for profuse outcrops, which is perhaps responsible for the rugged landscape (Akpaneno, 2014)
1.8 Accessibility
The study area is accessible through the Dutsin-ma, Kankara highway the site area has several footpaths connecting the site with the surrounding villages. Minor roads connecting different section of the campus having been open thereby making the entire project site easily accessible.
1.9 Choice of Geophysics Method
Among several geophysics method employed in groundwater exploration (electrical resistivity, gravity, seismic, magnetic, remote sensing and electromagnetic), the electrical resistivity method is depend largely on the depth of investigation and sometimes cost. Because electrical resistivity is sensitive to tiny variation in the conduction of the subsurface within the basement. As a result of these successful applications of electrical resistivity method over the years in groundwater exploration, this prompted the researcher to adopt electrical resistivity method to carried out investigation on groundwater potential at
Isa Kaita College of Education as geological structure of the study area is basement complex
1.9.1 Regional Geology
Nigeria is a country in West African continent with a surface area of 923,768km and lies within Latitudes 6°48ˈN – 650 N and longitudes 3° 58ˈE – 4° 00ˈE. The country is located in the Western portion of the African continent. This continent is a product of the breakup of Gondwanaland. The country is bounded by the Atlantic Ocean at the Southern part, on the Northern part by the Republic of Chad, on the East by the Republic of Cameroun and the West by the Republic of Benin. Nigeria is divided into two units geologically namely;
- The crystalline basement complex and
- The sedimentary terrain or basins
The Nigeria basement complex rocks consist of predominantly Archean polycyclic grey gneiss of granodioritictotonalitic in composition. The sedimentary basins of Nigeria consist of sedimentary rocks of ages younger than the Jurassic. There is a long gap in the geologic history of Nigeria between the
Precambrian and oldest sedimentary rocks, which are Cretaceous.
1.9.2 Geology of the Study Area
Katsina State is underlain by three major formations, namely; the Illo Gundumi Formation of the Sokoto Basin, the Chad formation and the Basement Complex area of Nigeria. The Illo Gundumi and the Chad formations make up 20% of the total area of Katsina State while 80% of the geology is underlined by the Basement Complex of Nigeria which is characterized by older granite, migmatite gneiss and metasediments.
Field studies revealed that the crystalline rocks present in the area are gneisses, schists (younger metasediments) and the older granites. All these are rocks of the basement complex of Nigeria.
Dutsin-Ma is basically underlain by the Basement Complex area. The name “Dutsin-Ma” is coined from the Hausa word ‘Dutse’ meaning rock(s). The entire area is predominantly underlain by gneisses schists and the Older Granite. The rocks are about 600 million years old pre – protozoic. These old granites are known as Granite Suite (GEO – INVEST (NIG) LTD Katsina, 2014) as shown in figure 1.2 below.
Figure: 1.3 Geologic map of the northern Katsina State showing Dutsinma LGA (Adapted from GEO- INVEST & BOREWELL (NIG) LTD Katsina; Modified)
1.10 Definition of Terms
Geophysics: The science that applies the principles of physics to the study of the earth
Delineate: Indicate the exact position of (border or boundary)
Lithology: Study of the general physical properties of rocks
Overburden: Rock or unwanted top layer of soil overlies mineral deposit or other underground
features.
Schlumberger Array: Configuration of electrodes that help to send direct current signal into the ground in other to obtain the resistivity of the ground. This process is also called resistivity method.
Porosity: The measure of the void (i.e. ‘empty’) spaces in the rock
Permeability: The property of the rock that allows water to diffuse through it to another medium without being chemically or physically affected.
Conductivity: The degree to which rock conduct electricity. (c = J/E; where c = conductivity, J =
Current Density and E = electric field whic0h causes current flow).
Resistivity: The resistance, R through a cross-sectional area, A per unit length, Ɩ of a conductor DC: Direct Current
VES: Vertical Electrical Sounding
LGA: Local Government Area
Aw Climate: Tropical wet and dry or savanna climate
RP: The probing or VES resistivity point
GPS: Global Positioning System
SAS: Signal Averaging System
Basement: The oldest formation of rocks underlying a particular area.
Fracture: The cracking or breaking of a hard object or material such as rocks.
Weathering: The processes by which rocks are broken down into small grains and soil. Weathering can happen through rainfall, ice formation, or the action of living things, such as algae and plant roots. Contour Map: A topographic map on which the shape of the land surface is shown by contour line; the relative spacing of the lines indicates the relative slope of the surface.
Faults: A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake – or may occur slowly, in the form of creep.
Aquifer: A body of saturated rock through which water can easily move.
Sounding: The action or process of measuring the depth of the sea or other body of water.
Profiling: Profiling is a method used to determine lateral variations in earth resistivity within a limited depth range.
Aquitard: An aquitard is a zone within the earth that restricts the flow of groundwater from one aquifer to another. Aquitards comprise layers of either clay or non-porous rock with low hydraulic conductivity.
