Investigation of the hydrological quality of Ethiope River watershed, Southern Nigeria.
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Date
2007
Authors
Omo-Irabor, O.O
Olobaniyi, S.B
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Applied Sciences and Environmental Management
Abstract
The surface and groundwater resources of the Ethiope river watershed have been investigated for its
hydrological and quality characteristics. The results indicate that Ethiope River is perennial and fed by groundwater
seepages, precipitation and surface run-off from adjacent areas. The lowest discharge rate of the river is recorded in
June and increases steadily reaching its peak in October. The physico-chemical parameters of both water sources
include, pH (5.28-7.06), turbidity (1.16 – 8.12 NTU), conductivity (65.00- 127.0 µs/cm), dissolved oxygen (4.40-7.60
mg/l) and total hardness (25.50 – 45.0 mg/l). Others include, Na+
(3.91 – 27.05 mg/l), K+
(3.91 – 8.73 mg/l), Ca2+
(3.21 – 9.60 mg/l), Mg2+ (1.46- 5.84 mg/l), HCO3
-
(31.50-80.00 mg/l), Cl
(17.55 –35.10 mg/l), SO4
2- (0.25-0.58
mg/l), NO3
2- (0.19-0.55 mg/l) and PO4
2- (0.20-19.00 mg/l). This physico-chemical quality is generally compatible
with WHO guideline for domestic use. Nevertheless, the water samples consist of high microbial population
including total coliform bacteria counts (39.00 – 1100 MPN/100ml) and Escherichia coli (21.00 – 305.00
MPN/100ml), which render both surface and groundwater unfit for domestic use without disinfection. An assessment
of surface water-groundwater homogeneity using the parametric student’s t and F tests on selected constituents
(chloride, nitrate, sulphate, phosphate, sodium, potassium, calcium and magnesium), indicate non-significance in the
variation within the tested parameters except for nitrate. This suggests some groundwater-surface water intermixing
or communication, and the activity of denitrifying bacteria in surface water. A groundwater pollution vulnerability
assessment using DRASTIC model indicates moderately high pollution risk level for the aquifer system.
Description
Keywords
homogeneity , groundwater , river , conductivity , parameters
Citation
Omo-Irabor, O. O., & Olobaniyi, S. B. (2007). Investigation of the hydrological quality of Ethiope River watershed, Southern Nigeria. Journal of Applied Sciences and Environmental Management, 11(2).