Susceptibility of River Basins to Flooding in Contact Zones Between Mountain Ranges and Coastal Plains: contributions of morphometric indices in the tropical Atlantic region of Southeastern Brazil

Resumo

The analysis of morphometric parameters has been widely employed to assess flood susceptibility; however, at
broader scales, it tends to homogenize and generalize results, concealing relevant local differences. This study aims to investigate flood susceptibility using fifteen morphometric parameters in a GIS environment, at scales ranging from basins and sub-basins up to the sixth order, located in the northern Mantiqueira range/coastal plain of Espírito Santo, Brazil. The methodological approach enabled comparative analyses and a more detailed assessment of morphometric susceptibility, while also providing a more consistent regional comprehension. Additionally, the results were related to the rainfall regime using the CHELSA 1.2 global precipitation model, which allowed for the identification of more critical sub-basins. The analyses highlight the relevance of parameters such as area, altimetric amplitude, perimeter, and main channel slope in defining areas more susceptible to flooding. In mountainous and small-sized basins, such characteristics may be more determinant than precipitation itself in intensifying surface runoff. The sub-basin level analysis revealed local susceptibility patterns, emphasizing the concentration of critical areas in the middle and lower courses of the Santa Maria River basin and the widespread distribution in the Jucu River basin, as well as the asymmetry observed on the right margin of the main channels of both basins.