Évaluation du risque d’inondation par intégration du SAGA Wetness Index (SAGAWI) et de l’Analyse Hiérarchique des Procédés (AHP) : cas du District Autonome d’Abidjan

Abstract

The Autonomous District of Abidjan (ADA) is experiencing an upsurge in flooding. These hydroclimatic events, inherent to the morphology of the site and to uncontrolled spatial expansion, are likely to be exasperated by the effects of global change. With a view to preventive management of subsequent crises, this study aims to identify the sub-areas of the Autonomous District of Abidjan most prone to flood risks. The cartographic approach integrates a topographic wetness index, in this case the SAGA Wetness Index, and a soil impermeability index generated through the Analytic Hierarchy Process (AHP) of Saaty (1984) by normalizing the factors “slope”, “soil” and “land use and land cover”. Upon analysis, the susceptibility to flood hazards remains high in almost a quarter of the territory. This significant flooding concerns more than a third (36.43%) of the built-up area. The high risk of flooding remains particularly prevalent in heavily populated areas, where nearly three out of four (74.20%) DAA inhabitants reside. In the context of anticipatory management of crises associated with extreme rainfall events, the flood map appears to be an important tool for implementing early warning systems.

Keywords

• autonomous District of Abidjan
• flooding
• SAGAWI
• AHP
• vulnerabilities
• crises management