Application of Remote Sensing in Monitoring the Oguta Lake Ecosystem, Imo State

Oguta Lake in Imo State is Nigeria's largest natural lake and a regionally significant freshwater ecosystem supporting tourism, artisanal fishing, and biodiversity. The lake faces threats from sedimentation, aquatic weed proliferation, and water quality degradation. This study applies remote sensing to monitor the ecological status of Oguta Lake using multi-temporal Sentinel-2 imagery from 2019 to 2023. Surface water extent, aquatic vegetation distribution, and water colour anomalies indicative of eutrophication are mapped using spectral indices including the Modified Normalised Difference Water Index and the Chlorophyll Index. Time series analysis reveals a progressive encroachment of floating aquatic macrophytes, primarily Nymphaea lotus, into previously open water areas, reducing the lake's navigable extent by approximately 9 percent. Turbidity increase correlated with upstream land use change suggests rising sediment loads from the Njaba River catchment. The study recommends establishing a remote sensing-based ecological monitoring programme for Oguta Lake under the Imo State Ministry of Environment. Keywords: lake monitoring, remote sensing, Oguta Lake, Imo State, eutrophication