GROUNDWATER STUDIES OF OTULU AND ENVIRONS IN OSHIMILI NORTH LOCAL GOVERNMENT AREA OF DELTA STATE NIGERIA

Abstract
Otulu and its environs were mapped; the only distinctive lithostratigraphic unit is Ogwashi- Asaba Formation (Oligocene). The lithologies encountered were sandstones, shales, ironstone, baked shales, mudstones and clays. The ground water analysis (water from boreholes) was carried out to evaluate the ground water quality of the area. The analysis shows that the water resources evaluation of the area is quite satisfactory; however, the ground water resources should be improved. Due to lack of visible outcrops in the area, vertical electric sounding (VES) was carried out at five (5) to evaluate the subsurface geology of the study area and to evaluate the aquifer parameters of the area. The plots of the vertical electric sounding (VES) reveals the resistivity and thickness of different layers at each location. The water bearing units at each location are medium and coarse grained sands. The resistivity and the thickness are used to obtain the hydraulic conductivity and transmissivity of the aquifers. The transmissivity of an aquifer tells more about the aquifer because it determines the ease at which an aquifer transmits water; it is dependent on only the flow medium and independent on the flowing fluid. The water bearing unit for each VES point is given below; VES 1 is the 5th layer, with resistivity of 202Ωm thickness of 58.4m and transmissivity of 0.29m2/s. VES2 is the first layer with resistivity of 138Ωm, thickness of 2.73m and transmissivity of 0.02m2/s. VES 3 is the second layer with resistivity of 943Ωm, thickness of 3 .88m and transmissivity of 4.1 1x10-3m2/s. VES 4 is the sixth layer with the resistivity of 240.2Ωm, thickness of 50.41m and transmissivity of 0.21m2/s. VES 5 is the fifth layer with resistivity of 3 108Ωm, thickness of 25m and transimissivity of 8.04x10-3m2/s. The groundwater of the area was found to contain an appreciable amount of iron. This problem is as result of shallow well drilling which permits oxidation reaction to take place in the well. In order to control this effect the borehole should be drilled deep into the water bearing units.

Table of Contents
Cover Page -- -- -- -- -- -- -- -- -- --i
Title page -- -- -- -- -- -- -- -- -- -- ii
Certification -- -- -- -- -- -- -- -- -- --iii
Dedication -- -- -- -- -- -- -- -- -- --iv
Acknowledgement -- -- -- -- -- -- -- -- --v
Table of Contents -- -- -- -- -- -- -- -- --vi
List of Figures -- -- -- -- -- -- -- -- --ix
List of Tables -- -- -- -- -- -- -- -- -- --viii
Abstract -- -- -- -- -- -- -- -- -- --x
Chapter 1
Introduction
1.1 Location and Extent -- -- -- -- -- -- -- --1
1.2 Accessibility -- -- -- -- -- -- -- -- --1
1.3 Drainage -- -- -- -- -- -- -- -- -- --3
1.4 Objective of the Study -- -- -- -- -- -- -- --4
1.5 Geomorphology and Physiography -- -- -- -- -- --4

Chapter 2
Literature Review
2.1 Regional Stratigraphic Settings -- -- -- -- -- -- --9
2.2 Tectonic Evolution of the Study Area -- -- -- -- -- --14
2.3 Geology of the study area -- -- -- -- -- -- --17
Chapter 3
Outcrop Description
3.1 Introduction -- -- -- -- -- -- -- -- --19
3.2 Outcrop Description -- -- -- -- -- -- -- --19
3.3 Geophysical Studies -- -- -- -- -- -- -- --31
3.3.1 Vertical Electric Sounding (VES) -- -- -- -- -- --31
3.4 Materials and Methodology -- -- -- -- -- -- --32
3.5 The Method -- -- -- -- -- -- -- -- --32
Chapter 4
Results and Discussion
4.1 Vertical electric Sounding -- -- -- -- -- -- --49
4.2.1 Methodology for water analysis -- -- -- -- -- --49
4.3 Chemical Analysis -- -- -- -- - -- -- --50

4.3.1 Total Alkalinity (Titrimetric Method) -- -- -- -- -- --51
4.3.3 Total Hardness (EDTA Titrimetric Method)-- -- -- -- -- --52
4.3.4 Calcium Hardness (EDTA Titrimetric Method) -- -- -- --52
4.3.5 Magnessium Hardness (By Calculation Methods) -- -- -- --53
4.3.6 Chloride (Argentometric Method) -- -- -- -- -- --53
4.3 7 Nitrates (Phenoldisulphonicnacidnmethod) -- -- -- -- --53
4.3.8 Sulphates (Barium Sulphate Method ) -- -- -- -- --54
4.3.9 Total Iron (Eisen Phenanthroline Method) -- -- -- -- --55
4.4 Biological Analysis -- -- -- -- -- -- -- --56
4.4.1 Plate or Colony Count -- -- -- -- -- - -- --56
4.4.2 Total Coliform or Presumptive Coliform -- -- -- -- --56
4.5 Determination of E-Coli or Confirmatory Test -- -- -- -- --58
Chapter 5
Summary and Recommendation -- -- -- -- -- -- --60
References -- -- -- -- -- -- -- -- -- --61
Appendix -- -- -- -- -- - --- -- -- --66

List of Figures
Fig l.0: Accessibility map -- -- -- -- -- -- -- --2
Fig 1.1: Drainage map of the area -- -- -- -- -- -- --3
Fig. 2.1; Structural Units of Southeastern Nigeria (After Short & Stauble, 1967) --7

Fig. 2.2: Tectonic Map of Nigeria during Albian to Lower Santonian (Adapted from Murat 1970) -- -- -- -- -- -- -- -- --13
Fig. 2.3: Map of South Eastern Nigeria during the Campanian to Eocene (Adapted from
Murat 1970) -- -- -- -- -- -- -- -- --16
Fig.3.1 Borehole Log at Otulu -- -- -- -- - -- --30
Fig.3.2: Sketch diagram of Schlumberger array. -- -- - -- --33
Fig. 4.1: Schlumberger curve for VES 1 -- -- -- -- -- --41
Fig. 4.2 Schlumberger curve for VES2 -- -- -- -- -- --42
Fig. 4.3 Schlumberger curve for VES3 -- -- -- -- -- --43
Fig. 4.4 Schlumberger curve for VES4 -- -- -- -- -- --44
Fig. 4.5 Schlumberger curve for VES5 -- -- -- -- -- --45
Fig: 4.6 Correlation chart ofVES1, VES3 and VES 5 -- -- -- --48

List of Tables
Table 2.0: Correlation Chart for Early Strata In Southern Eastern Nigeria (Modified From
Nwajide, 1990) -- -- -- -- -- -- -- --13
Table; 3. 1Apparent Resistivity Values for VES 1 -- -- -- -- --35
Table; 3.2 Apparent Resistivity Values for VES 2 -- -- -- -- --36
Table; 3.3 Apparent Resistivity Values for VES 3 -- -- -- -- --37
Table; 3.4 Apparent Resistivity Values for VES4 -- -- -- -- --38
Table; 3.5 Apparent Resistivity Values for VES5 -- -- -- -- --39
Table: 4.1 Hydraulic conductivity and Transmissivity values for VES 1 -- --41
Table: 4.2 Hydraulic conductivity and Transmissivity values for VES2 -- --42
Table: 4.3 Hydraulic conductivity and Transmissivity values for VES3 -- --43
Table: 4.4 Hydraulic conductivity and Transmissivity values for VES4 -- --44
Table: 4.5 Hydraulic conductivity and Transmissivity values for VES5 -- --45
Table 4.6 Observation table for determination of total coliform -- -- --58


Chapter 1
Introduction
1.1 Location and Extent
The study area is located in the South Eastern Nigeria and covers Otulu and its environs. It is bounded by latitudes 60151N and 6022.301N with Longitudes as 60301E and 60451E.
1.2 Accessibility
The area is accessed by mainly minor roads and footpaths. Only one major road; issele-Azagba expressway connects the area. The minor roads and footpaths were of immense help in accessing the area, though some difficulties might be encountered during rainy season.



FIG l.0: Accessibility map

1.3 Drainage
The drainage system of the area is very effective due to the rivers surrounding the area such as Ingene River, iyiocha stream, River Niger, Ojoso Creek, Iyiocha ugbo stream and Okiti stream.


Fig 1.1: Drainage map of the area

1.4 Objective of the Study
Objective of the study is to extract all possible information from the study area as far as the scope permits. They include detailed study of the area in order to understand the following:
1. Geology of the area;
2. Groundwater quality of the area;
3. To obtain the aquifer parameter. 1.5 Geomorphology and Physiography
The Geomorphic features of an area are a result of gradual processes prevalent in the area, which are caused by a combination of both natural and anthropogenic factor. The main factor include; the nature of underlying geology, soil, hydrogeological characters, climate factor, differential mass wasting of land surface vegetation cover and poor land practices like quarrying. In the study area, the geomorphic features present resulted from lithology, temperature, moisture, attitude, and physiochemical conditions that prevailed in the area in the past. The landscape evaluation may have started in the tertiary period when erosion first affected the newly uplifted and eroded sediments (Simpson, 1954). The later stage of this geomorphologic reconstruction is characterized by laterisation of the formation

outcropping in the area. Quarry activity, which is mainly practiced by Egolgwe village in Western part of the study area, has affected the geomorphology of the area.

Tags: Geology Topics,

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