Flood Disaster Forecasting: A GIS-Based Group Analytic Hierarchy Process Approach

Geographic Information System (GIS) was integrated with Group Analytic Hierarchy Process (GAHP) to facilitate the simulation of flood likely areas based on a total number of five set of criteria/factors believed to be triggering flood generation in the study area. Two categories of experts namely hydrologists and geologists were considered. Saaty’s 1-9 scale of preference was employed in rating each factor’s influence in flood generation and the ratings from the experts were aggregated using a Geometric Mean method. Having done with the aggregation, priory weights of the factors were calculated; weights were further normalized through the Analytic Hierarchy Process (AHP). The result was further integrated into GIS system for spatial simulation of the likely flood areas. The result forecasted 39.1% of the total area to be very highly susceptible to flooding. Validation was carried out by superimposing the known flood extent map from radar satellite data over the flood forecasting model developed herein.