A multicriteria GIS-based analysis modelling and Analytical Hierarchical Process (AHP) for flood risk mapping in the Delimi catchment, Jos, Plateau state, Nigeria

Abstract

This study identified and mapped areas vulnerable to flood risk in the Delimi River Catchment of Jos area, Nigeria. The ALOS-PALSAR DEM  (12.5m) from the Alaska Satellite Facility downlinks was employed to generate relevant morphometric parameters namely corridor, slope,  and elevation which are identified drivers of floods in the catchment, while the area coverage of each soil type within the study  catchment was sourced from FAO Digital Soil Map of the World (DSMW) and Building Form shapefile from Eagle Eye Geographics. The  multi-criteria Analysis model and the Analytical Hierarchical Process (AHP) were employed in a Geographical Information system (GIS)  environment using the ArcMap 10 Software to map and synthesize these drivers. The hierarchy ratings of the drivers for the catchment  based on expert opinions are corridor, slope, elevation, and soil type (38, 37, 21, and 4 percent respectively), and a consistency ratio of  0.06. Results showed that about 9.3 km² (5.7%) of the catchment area is at risk of flooding. This at-risk area accommodates 5,306  buildings out of which 445 buildings are within the Very High-Risk zone. At the end of the study, the area at risk of inundation was  delineated and the number of buildings within the risk zone was ascertained. This information will assist decision-makers and watershed  managers in effectively developing strategies for the control and mitigation of future flood occurrences in these areas of the catchment.