Dynamics of Mass Movements in an Urban Basin: A Case Study in the Fradinhos Drainage Basin, Vitória, Espírito Santo, Brazil

Abstract

Landslides are a widespread problem in Brazil due to the heavy rainfall typical of tropical environments. In urban areas, landslides can be catastrophic and can lead to significant economic and social losses. To prevent such catastrophes, it is crucial to comprehend the spatial distribution of mass movements in local dynamics. The aim of this study was to evaluate the spatial distribution of areas susceptible to shallow translational slides in the Fradinhos Drainage Basin (FDB), situated in Vitória, state of Espírito Santo (ES). To achieve this, we used the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability (TRIGRS) model, along with geotechnical and hydrological data from five sampling points. An extreme rainfall event that lasted 24 days, with an accumulated rainfall of 744 mm was considered. The study revealed that 31% of the basin is unstable, with no significant increase in these areas during the rainfall period. Additionally, 86% of this area is in an Environmental Protection Zone. The results indicate that the FDB has a low susceptibility to shallow landslides, due to the existence of the Environmental Protection Zone, as this zone forms a protective belt at higher slopes. TRIGRS effectively identifies unstable zones and is an useful tool for identifying susceptibility, contributing to local management.