The spatio-temporal dynamic of land use in the Bonoumin and Gourou watersheds, over the last three decades (1990 to 2020), were analysed using Landsat images (1990, 2005 and 2020), remote sensing and a geographic information system (GIS). The main objective of this study was to analyse the impact of changes in land use in these two watersheds on stormwater runoff, which is responsible for flooding in the study area. The methodology adopted consisted of first downloading the Landsat images, which were then pre-processed, before undergoing several processes, leading to the classification and analysis of land cover dynamic. Maximum likelihood supervised classification was applied. Thus, the results of this classification showed that over the last three (03) decades, the impermeabilised surfaces in the two watersheds, represented by the medium and highly densified urban areas, have increased significantly, unlike the vegetated surfaces, which have decreased significantly. The increase in impermeable surfaces reduces the capacity for water to infiltrate the soil and increases the amount of runoff. The results also showed that in recent years, the upper reaches of the Bonoumin watershed have come under considerable anthropogenic pressure. This means that in a few years time, there will be a sharp increase in the amount of runoff water in the lowlying areas of this basin, and therefore an increase in the risk of flooding.