Assessment of Flood Inundation in Ibaji LGA, Kogi State Using SAR Remote Sensing

Ibaji Local Government Area in Kogi State experiences recurrent flooding caused by overflow of the Niger River, severely disrupting agricultural production and displacing communities. This study assesses the spatial extent and temporal dynamics of flood inundation in Ibaji LGA using Sentinel-1 SAR imagery for the 2021 and 2022 flood events. The SAR backscatter change detection approach compares pre- and peak-flood images to delineate inundated areas, with particular emphasis on the SAR water detection method using VH polarisation thresholding. Results indicate that the 2022 inundation covered approximately 78 percent of the LGA's total land area, affecting 34 communities and over 12,000 hectares of farmland. Temporal SAR composites trace the progression and recession of floodwaters over an 8-week period. The study integrates flood maps with a livelihood exposure dataset to estimate the number of farming households affected. Recommendations are directed at the Kogi State Ministry of Environment and the Nigerian Hydrological Services Agency for integrating SAR monitoring into flood early warning protocols. Keywords: flood inundation, SAR, Kogi State, Sentinel-1, flood mapping