Geomorphic Assessment of Flood Hazard within the Urban Area of Chanchaga Local Government Area, Minna, NIGERIA

Abstract

Pairwise comparison, Analytical Hierarchy Process (AHP), and Geographic Information System (GIS) have been recently used to assess flood hazard. It has been used to carry out Multi-Criteria Analysis (MCA) of various geomorphic factors by assigning weights based on the presumed impact of each factor on flooding. This study considered six factors which include: Slope, curvature, land cover, elevation, distance from river, and soil, using Rafinsenyi river in Chanchaga Local Government area, Minna-Nigeria, as a study area. Review of literature showed that methods of assigning weight are hypothetical and inconsistent; this research thus takes input from researchers in fields of hydraulics, hydrology, and disaster management. The weight with 0.029 as the least consistency ratio was used. Data used include: DGPS data, Satellite Images, Digital Soil Data. Landcover Maps, Digital Elevation Models (DEM), Soil Maps, and Profile Curvature maps were generated. A weighted overlay operation was carried out in ArcGIS to produce a Flood Risk Map. Livisol (Loam) soil reveals why farmers and traders indiscriminately settle along the floodplain. 6 of the 20 hectares of the study area lie between 216 and 220 metres above mean sea level, putting residential buildings at high risk of flooding