The influence of topography on floods in southern Brazil

ABSTRACT Understanding the characteristics of watersheds is fundamental for hydrological studies. This study investigates the influence of topographic and hydrological features in watersheds located in the extreme south of Brazil about flood events, which are recurrent in the region. Watersheds were classified based on their exposure to flooding, and differences in their characteristics were analyzed and compared. The results indicate that greater watersheds, with larger area, perimeter, and drainage network, are more exposed to flooding. These watersheds exhibit a floodplain relief profile resembling a “U” shape and possess a larger floodable area, in contrast to less exposed watersheds, which display a “V”-shaped relief profile. Furthermore, the specific discharge values of the more exposed to flooding watersheds are lower than those of the less exposed watersheds, suggesting that the larger floodplain area may contribute to flood attenuation. These findings offer valuable insights for preliminary watershed management and flood risk assessment.