GEO-ELECTRIC SOUNDINGS FOR GROUNDWATER EXPLORATION IN PART OF PORT HARCOURT, RIVERS STATE, SOUTH-EASTERN NIGERIA

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GEO-ELECTRIC SOUNDINGS FOR GROUNDWATER EXPLORATION IN PART OF PORT HARCOURT, RIVERS STATE, SOUTH-EASTERN NIGERIA

CHAPTER ONE

 

 

               INTRODUCTION

 

        GENERAL STATEMENT

 

Groundwater is water that exists in the pore spaces and fractures in rocks and sediments beneath the water table. It originates as rainfall or snow, and then moves through the soil and rock into the groundwater system, where it eventually makes its way back to the surface streams, lakes, or oceans. Groundwater makes up about 1% of the water on the Earth (most water is in oceans. Groundwater is found beneath the unsaturated zone where all the open spaces between sedimentary materials or in fractured rocks is filled with water and the water has a pressure greater than atmospheric pressure. To understand the ways in which groundwater occurs, it is needed to think about the groundwater bearing formation properties such as porosity and permeability. The water bearing formation is termed AQUIFER.

  • Porosity: this is the property of a rock possessing pores or

 

  • Permeability: this is the ease with which water can flow through the

 

  • Aquifer: which is a geologic formation sufficiently porous to store water and permeable enough to allow water to flow through them in economic
  • Storage coefficient:this is the volume of water that an aquifer releases from or takes into storage per unit surface area of aquifer per unit change in the component of area normal to surface.

The occurrence of groundwater resources in a basement complex depends mainly on the secondary porosity (after deposition of sediments) and also permeability arising from weathering and fracturing of parent rocks and also the pattern of the fracture (Carruthers, 1984).

 

Fractures in rock are very important pathways for the flow of groundwater and the transportation of contaminants. In fractured rock systems, groundwater occupies voids that are formed by fractures, fissures, faults and joint planes which are constantly distributed inside the rock formation. Due to their nature, they exhibit unique problems in their investigation, evaluation and management largely because of their heterogeneous nature and the dependence of aquifer properties on fracture distribution and connectivity.

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