20. Change Detection and Hydrological Implications in the Lower Ogun Flood Plain, SW Nigeria

The purpose of this study was to examine the immediate and future consequences of the processes taking place in the ecologically fragile coastal flood plain of the Lower Ogun River basin. Aerial photography and Landsat multi-spectral imagery were used to assess the land use and land cover of the basin as it was in 1965 and 2005, respectively. Calculations of the area of various units for the two scenarios were generated. Overlay analysis for change detection in a matrix format was carried out. The change matrix was used to assess the extent of degradation. The statistic land cover of the lower Ogun flood plain in 1965 was 38.01 x 10⁶ ha. The ecologically fragile wetland covered 82.45% of the total area. This figure decreases to 13 x 10⁶ ha or 36.31% in 2005 at an average rate of 0.439 x 10⁶ ha per annum. A conservation management approach to rescue the fragile ecosystem of the lower Ogun from complete destruction is proposed.