An Assessment of the Physical and Environmental Aspects of a Tropical Lake: A Case Study of the Oguta Lake Watershed, Niger Delta Basin, Nigeria
Ahiarakwem, C. A.; Nwankwor, G.I.; Onyekuru, S.O.; Idoko, M. A.

Abstract
The assessment of very important physical and environmental aspects of Oguta Lake and its watershed, Niger Delta Basin was carried out using data obtained from satellite imagery (Landsat Tm 2000) and the Global Positioning System (GPS). The data were analysed and interpreted using the Integrated Land and Water Information System (ILWIS) and AutoCAD Land developer. False Colour Composite (FCC) map generated from the satellite imagery displayed the study area into portions covered by vegetation as red; built-up areas around the lake as cyan; areas covered by sediments as blue/cyan and eutrophication, pale red. Digitalization/processing of the FCC map indicated that areas covered by the Oguta Lake water body is about 1,870.4m2 (68.2%) while degraded portions of the lake occupied an area of 1152.25m2 (38.8%). The degraded portions of the lake is comprised of areas under intense environmental stress arising from anthropogenic activities (degradable portion) with a total area of 1099.97m (36.91%), areas covered by sediments and eutrophication with total areas of 41.3 m2 (1.39%) and 14.9m2 (0.5%), respectively. The study also showed that built-up areas outside the vicinity of the lake with an area of about 4,983.3m2 have very strong positive correlation (R2=1) with the degradable portions (areas characterized by human activities such as washing, bathing and sand mining) of the lake. Since the areas covered by degraded portions (including sediments and eutrophication) is relatively high (about 38.8%), there is thus an urgent need to ensure proper management of the lake and its ecosystem. This can be achieved through constant monitoring of the status of Oguta Lake’s environment and good government policies. Such steps would help in maintaining the resource status and usefulness of the Lake.

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