ABSTRACT

The description and location of the geologic formations and water bearing zones within the study area are discussed. The geologic aquifers in the area are the upper, medium and lower sands. Pumping test and soil sample data were obtained from Itiam Etoi, Iboko Offot and Anua Offot. The analysis reveals that the following aquifer characteristics such as storativity, transmissivity, yield and specific yield lie within the acceptable limit. Water quality analysis results indicate that boreholes have acceptable water quality. The following aquifer and well characteristics were obtained, specific capacity (q) 28.27 – 2.8.8m2/h/m, Transmissivity (T) 217.58 – 23784.88m2/day, Discharge/Yield 6123.1 – 7517.8m2/day, Drawdown 8.91m – 10.88m. The drawdown values of 24hrs of pumping reveals a good entrance velocity of water into the borehole and high storativity and transmissivity of the aquifer. The geologic formation has good water-bearing formation with medium sand being predominant. Generally, the aquifer in the study area is permeable and of high storage capacity.

CHAPTER ONE

INTRODUCTION

1.4            Background of the Study

The earth crust which is also referred to as lithosphere comprises of consolidated materials such as granite, diamond, sandstone and unconsolidated materials like sand, gravel, pebbles and boulders. The zone of the rock fracture which is the outer part of the earth’s crusts is porous to a certain degree. Subsurface geologic materials such as gravel and sand have openings between individual particles. There are also crevices, joint or fractures in hard rocks, solution channels, and caverns in limestone. These properties facilitate flow through these materials.

Geologic formation can be classified according to their ability to allow flow through their voids and subsequently transmit water from one point to another. A geologic formation which contains water and transmits it from one point to another in quantities sufficient to supply wells is called an aquifer. Moreover, groundwater is stored in the space and fracture within geologic materials such as soil, sand, gravel, pebbles, boulders and even sandstone with defined crevices, joints and rock that lie beneath the land surface. Aquifer is the geologic layer that is filled with water and that can transmit enough water to supply a well under normal hydraulic gradients. These materials have voids and can contain and transmit water from one point to another. When these materials called aquifers are found, below the water table, that is, in the zone of saturation, they act as reservoirs and conducts by holding and transmitting water from one point to another.

On average, 7000 million litres (ML) of water are abstracted from zone of these aquifers each day. Approximately, 50% of this vast amount of water comes from cretaceous chalk aquifer, 35% from Triassic sandstones and the remainder from smaller aquifers, the most important of these being Jurassic limestone.

The aquifer as a water bearing formation has the function of storage and transmission. It stores water as reservoir and transmits it as a pipeline. This is because the voids or pore spaces between particles in the water bearing formation serve both as storage spaces and network of conduits. The ground water is constantly moving slowly over extensive areas from recharge region to discharge area. The aquifer material detains large quantities of water in transit and can supply a well drilled to intercept flow.

Ground water storage within the aquifer can only be viable for water extraction, and the estimated volume of water discharged per unit time from the ground water is limited by the aquifer characteristics in Uyo metropolis.

1.5            Statement of the Problem

Since aquifer is the only geological formation that stores and transmit enough water at any given time and quantity hence there is need to examine and analyse its characteristics within the metropolis.

The determination of areas of potentially productive wells in Uyo metropolis will be difficult to identify.

The location of borehole within aquiclude and aquifuge always proves abortive hence this study will help minimize this incident.

1.6            Objectives of the Study

This research is aimed at:

a. determining and analyzing the aquifer characteristics in some locations in Uyo metropolis with respect to: Storativity, Transmissivity and Specific Yield.

b. pump testing to determine the performance characteristics of the boreholes and he aquifer characteristics namely; the transmissivity, specific capacity and the storativity in Uyo metropolis.

c. Recommendations for improvement where necessary.

 1.4     Significance of the Research

·        The outcome of the work will serve as a reference for future work on aquifer characteristics in Uyo metropolis.