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Journal of Environmental Hydrology
ISSN 1058-3912 |
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Electronic Journal of the International Association for
Environmental Hydrology
JEH Volume 20 (2012), Paper 6 Posted May 14, 2012 GROUNDWATER CONDITIONS IN THE MANGROVE SWAMPS OF THE WESTERN NIGER DELTA: CASE STUDY OF THE UGHOTON AREA, DELTA STATE, NIGERIA
Irwin Anthony Akpoborie ABSTRACT Groundwater conditions in the mangrove swamps of the western Niger Delta are described for the first time from the Ughoton area. The interconnected streams and creeks subdivide the 'swamps' into quasi-rectangular blocks that feature a slightly more elevated central area that slopes towards the demarcating creeks and streams. Vertical electrical soundings obtained with the Schlumberger configuration indicate the presence of four geo-electric layers with resistivity values of 31-2600, 31-2418, 323-1824 and 321-1626 ohm-m, respectively. A layered, more than 50 m thick aquifer of thin silty clay, fine-medium grained underlain by a thicker coarse sand is interpreted. The elevation of the water table above sea level is obtained from more than fourteen dug well measurements and water table contours indicate that flow is from a groundwater mound that occurs in the central area of the Ughoton 'block' westwards and north westwards towards the river. The preponderance of major ions in the wet season obtained from fourteen dug well water samples are in the order Na>Ca>Mg>K, and Cl>HCO3>SO4 for the cations and anions respectively. Chloride in ground water is low at a mean of 25.4 mg/l and 35 mg/l for the Ughoton River. The occurrence of fresh, low chloride ground water means that the brackish water conditions that support the mangroves that are confined to the river bank are maintained by tide related sea water that is propagated up river from the estuaries at high tide, as well as by slow drainage of bank storage. Mean lead level in ground water is .019 mg/l and cadmium is at 0.02 mg/l. Thus while lead is already at the threshold of the WHO and Nigerian Drinking Water Standards, cadmium level is at least one order of magnitude higher than these standards. Lead, cadmium and chromium occur at 0.05 mg/l, 0.5 mg/l and 0.06 mg/l respectively in surface water. These elevated levels in the river may be related to oil field activities to the west and south of the area. Reference: Akpoborie, I.A., and K.E. Aweto. 2012. Groundwater conditions in the mangrove swamps of the Western Niger Delta: case study of the Ughoton Area, Delta State, Nigeria. Journal of Environmental Hydrology, Vol. 20, Paper 6. CONTACT: Irwin Anthony Akpoborie Department of Geology Delta State University Abraka, Nigeria E-mail: tony.akpoborie@gmail.com |
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