Assessing the impact of land use and land cover dynamics on flood risks in the urban areas of Abomey and Bohicon (Benin)

This study aims to analyze land use and land cover (LULC) dynamics in both cities between 2005 and 2025, and to assess their impact on flood risk. Flooding is one of the most concerning natural hazards for urban populations in West Africa, particularly in the Beninese cities of Abomey and Bohicon. In these areas, vulnerability is exacerbated by the combined effects of recurring extreme rainfall events and unplanned urban expansion.The adopted methodology is based on the analysis of multispectral Landsat satellite imagery, which was pre-processed and subjected to supervised classification using the Maximum Likelihood method. Five land use categories were identified and compared across three reference years: 2005, 2015, and 2025.

The results derived from thematic maps and transition matrices reveal a continuous expansion of built-up areas, increasing from 50.64% in 2005 to 70.46% in 2024, representing a gain of more than 1240 hectares in less than two decades. This growth has occurred primarily at the expense of croplands and fallows, fallows under oil-palm plantations, and natural vegetation formations, whose areas have significantly decreased. The reduction of vegetation cover, combined with increasing soil sealing, has profoundly altered the hydrological functioning of the territory and increased the basin's vulnerability to runoff and flooding.