Geo-Elecctric Exploration For Grounderwater In Oru-East, Imo State

ABSTRACT

The study is on “Geo-elecctric exploration for grounderwater in Oru-east, Imo State”. The study has three objectives. The method of research involved desk studies and field work. The desk studies encompasses planning and designs include map production, consultation with some materials relating to my research topic (including theories) that are relevant to the prospect in view, data acquisition, instrument and data processing. The instruments employed for the research work include: ABEM Terrameter SAS1000, Etrex GPS, Compass, Two 500m Current Cable reels, Two 70m Potential cable reels, Electrodes. Etc. The findings of this work is In line with the objective of this study, resistivity of the equiferous layers varies from about ohm – meter to about – ohm-meter. The greatest depth to water table in the area of survey was about at VES 4. The shallowest depth to water table was about as in VES 9. The aquifer is thick in some other place. It ranges from as in VES 9 to as in. VES 4. The resist suitable for sustainable groundwater development are Amiri, Akatta,Amagu and Umubochi. The study therefore recommended among others that, further work should be done in the area of study, more measurements points and more towns should be covered than was done in the present survey, Finally, water can be obtained from all corners of the study area, but to obtain good yield, it is recommended that the boreholes be sunk in places like Oteru, Umuowa, Ubahazu, Ubachima and Umuoji.

CHAPTER ONE

INTRODUCTION

 Background of the Study

Groundwater is the water found under ground in the cracks and space in soil, sand and rocks. It is stored in and moves slowly through geologic formation of soil, sand and rock called aquifers.

Inductive electromagnetic survey methods are now widely used to map near-surface geology by mapping variation in the electric conductivity of the ground. Such variation generally are caused by changes in soil structure (porosity), clay content, conductivity of the soil water and degree of water-saturator in the soil. McNeill.J.D. (1996). Some of the bore hole in the area is dried up due to poor or lack of pre-geophysical investigation. Surface water is few and not adequate. In some of the communities water is present in underground wells and this make the water to be contaminated.

The groundwater problem require determination of the depth to bedrock; location of resistive, high-porosity zones associated with fresh water; determination of formation resist to assess water quality; and determination of lithology and geometry, respectively. The transient electromagnetic sounding (TS) is best suited for location conductive targets, and has very good vertical resolution. David.V.Fitterman, (1986).

Locating potential groundwater targets is becoming more convenient and cost-effective with the advent of ground-satellite imageries, Sophocleous, Marios (2002). Remotely sensed based ground water exploration has made it feasible to explore the areas with limited human access, for the wide visual range, short-time circle, and increasing spatial resolution.

In this study, considering the ground water potential relating factors, lithology, lineament density, and topology, slope, and river density and with vertical electrical sounding (VES) method of groundwater exploration, were applied for predicting the groundwater potential in Oru East.

In this chapter, we shall discuss the Location and Geomorphology of the study area, geology and hydrogeology of the study area, aims and objective of the study, statement of problem, justification of study and scope of study.

1.2 The Location and Geomorphology of the Study Area

The study area (Oru East ) is located within the latitude of 5º39¹N through 5º50¹N and longitude of 6º50¹E through 6º59¹E.

Figure 1.0, below show the location map of Oru East. The area has some L.G.A neighboring it. In the East side, the study area shares boundary with Njaba and Orlu L.G.As of Imo State; in the North side, the study area shares boundary with Ihiala L.G.A. of Anambra State; in the West side, the study area shares boundary with Oguta L.G.A. of Imo State while in the South side, it shares boundary with Mbaitoli L.G.A. of Imo State. The communities in Oru East where I carried out the research work are: Akatta, Akuma, Amagu, Amefuo, Amiri, Awo-Omamma, Omuma, Ubahazu, Ubaheze, Umubochi, Umuezike, Umuezukwa, Umuokwu.

The dry season is between November and April while the rainy seasons are mostly between May and October. Average rainfall is between 1000 mm and 1500 mm with a temperature of as high as 36.7ºC (Udo, 1970).

The study area normally experiences a high amount of relative humidity which ranges from 35% to 60% during rainy season which is around April to October and harmattan season which starts from November through January; while it experiences a low relative humidity ranging from 0% to 35% during the hot (dry) season which occurs from January to April.

The study area can be reached via a network of roads as there are some good and accessible roads that link to the area; as other means of transportation such as rail, air and water transportations are completely lacking in the study area. Anybody trying to get to my study area (Oru East), if he is coming from Owerri, can get through either Orlu road through Amaifeke Orlu-Mgbidi road or Onitsha-Owerri road. Then if coming from Port-Harcourt, he follows through the Port-Harcourt-Owerri road, before getting to Owerri-Onitsha road and finally arrives at Oru East.

The study area is blessed with abundant plants and trees. This shows that the area falls within the tropical rainforest of the south-eastern Nigeria, where different abundant and different classes of plants such as grasses, shrubs, trees, exist. The area is dense and made up of many types of broad-leaved trees that are mostly evergreen i.e. the trees drop their leaves gradually throughout the year and new leaves grow continuously to replace them. The trees form three layers. The tree tops form a thick canopy that prevents sunlight from reaching the forest floor. As a result, the vegetation on the forest floor is sparse. Epiphytic plants and woody climbers known as lianas are common features of these forests.

Figure 1.0. The location map of Oru East

1.3 The Geology and Hydrogeology of the Study Area

 The Oru East is made up of two geological formation- The Benin formation and Ogwashi- Asaba. The Ogwashi-Asaba Formation was formally known as the “Lignite series” by Parkinson (1907) and Simpson (1948 and 1955).

Reyment, (1965) formalized it and described the lithology as consisting of alternation of seam and clays. The average thickness is 322ft, while Kogbe, (1976) suggested that part of the Formation may be of Oligocene age.

The Ogwashi-Asaba Formation is underlain by the Ameki Formation which is of Eocene-Oligocene age and consists of grey clayey sandstone and sandy clay stone. The Formation also consists of bluish calcareous silt with mottled clay, thin limestone and abundant calcareous shale. The Benin formation consist of friable sand with intercalation of shale and clay lenses occurring occasionally at some depth short KC and Stauble AJ (1967). The formation is partly estuarine, deltaic and fluid lacustrine in origin reyment RA (1965). The shale is grayish, brown, and sandy to silty and contains some plant remains and dispersed lignnites Short KC and Stauble AJ (1975). The formation has an average thickness of 600ft (196.85) Kobgo CA (1975). The two formations are known to have reliable groundwater that could sustain borehole production. The Figure 1.1 below show the geological map of the study area.

Figure 1.1: The Geology Map of the study Area (Edited from the Nigerian Geological Survey Agency Map of Old Imo State, 1991)

 1.4. Aims and Objective of the study.

The aim of this project is to study the occurrence of groundwater in Oru East in Imo State. To determine the depth to water table in this area and to determine the thickness of the aquifer and hence delineate site in the area suitable for groundwater development using electrical resistivity method.

1.5    Statement of Problem

 The importance of water in human endeavors cannot be overemphasized.

In Oru East, population of people is increasing as in 2006 census. The surface water in this area is grossly insufficient. Also, the study area is characterized by presence of many hand dug and cemented water reservoirs or wells. These wells are usually prone to contamination. Most of the boreholes dug in this area are dried up due to lack of standard subsurface geophysical investigations.

1.6 Justification of the study.

In Oru East, water plays a vital role in the development of activities in the area. In Oru East, they trek as far as Njaba River and Ubana River, a very long distance that is more than one kilometer just to fetch water and that was against the World Health Organization (W.H.O.) standard which states that no person should trek a distance up to one kilometer just to fetch water (W.H.O., 1982).

The surface water resources are inadequate to fulfill the water demand. Productivity through groundwater is quite high as compared to surface water, but groundwater resources have not been properly exploited. Keeping the view, the study attempts to select delineate various groundwater potential zones for the assessment of groundwater availability in Oru East. This justifies the research work.

1.7 Scope of the study.

The project is restricted to determine the groundwater potential in Oru East, by finding the depth to water table and thickness of aquifer in the study area using electrical resistivity method.

Pages:  80

Category: Project

Format:  Word & PDF        

Chapters: 1-5                                 

Material contains Table of Content, Abstract and References.