This study seeks to use a multi-criteria decision analysis (MCDA) approach coupled with GIS to assess the spatial extent of flood vulnerability in the FCT. Thematic layers were created using Arc GIS 10.1. The data sets were integrated and using the analytical hierarchical process (AHP) of the MCDA, all the parameters were ranked and re-classified thematic layers were created. A 5×5 pair wise comparison matrix was created to determine the weights of parameters according to the AHP method. The consistency ratio of the pair wise comparison judgments was calculated CR=0.07988<0.10 which is acceptable. All parameters were converted to a raster grid with 50 x 50 m cells and raster calculator was used to multiply the parameters with the weights to create a composite flood vulnerability map. Further site visit for possible reasons was conducted and it was discovered that nature of terrain, non-availability and inadequacy of drains/culverts, blockage with refuse and polyethylene material, clogging of drains with silts and refuse coupled with the vulnerable nature of the area contribute to the flood problem of the FCT. It is obvious and one can conclude and rightly so, that the flood menace in the FCT is humanly induced and if all the anomalies in the built-up areas of the territory is checked, like provision of adequate amenities and infrastructures, good cultural practices by the residents, enforcement of building standards and codes, improved land use planning, vulnerability level not withstanding flood in the FCT can be a thing of the past.
Key Words: Multi-criteria Decision Analysis (MCDA), GIS, Analytical Hierarchical Process (AHP), Flood Vulnerability, Urbanization, Degradation