Interest in flood risk prevention has been growing steadily in recent years, with multi-criteria analysis frequently used to develop prevention plans. One of the common factors included in these analyses is annual rainfall. This study aims to assess the role of annual rainfall in identifying flood-prone areas, using Geographic Information Systems (GIS) to conduct the research in two stages. The first stage involved identifying at-risk areas using factors such as the Topographic Wetness Index, Height Above Nearest Drainage, proximity to watercourses, and drainage density. In the second stage, these results were integrated with annual rainfall maps, applying consistent weights across both stages. The findings suggest that while rainfall is a crucial factor in flood assessment, its inclusion in multi-criteria analysis may inadvertently distort results. This distortion occurs because rainfall distribution is influenced by topography, making it the only variable criterion among otherwise stable basin characteristics. As a result, rainfall data may shift the focus from lower basin areas, which are typically at greater risk but receive less rainfall, to higher basin areas with more rainfall. Furthermore, the study argues that annual rainfall is not a reliable basis for prevention planning, as it fails to accurately represent the characteristics of rain events – such as intensity, duration, and frequency – that are critical in flood studies. The research highlights the need for more appropriate criteria tailored to the specific study area and emphasizes the importance of developing new methods that focus on the impact of rainfall rather than just its distribution.