Erosion processes and dynamics of two gullies developed in residual soil on a steep slope (Espírito Santo State, Brazil)

Abstract

This study aims to understand the causes and processes that led to the formation of two gullies on a hillslope located in the municipality of Alegre, State of Espírito Santo (Brazil). The study involved the geological, pedological and mineralogical characterization, multitemporal analysis of remote sensing images, morphometric and morphological analysis of the gullies, and the description and identification of erosion features indicative of erosion processes. The results show that the gullies are installed on a steep slope, whose horizons and soil types have a heterogeneous distribution. The soil loss rate was estimated as 198 m3.year-1 for the years 2007 to 2021. The origin of the gullies appears to be related to the failures terracettes, due to intensive cattle farming. Once installed, the gullies evolved quickly, with short periods of stability. Gravitational mass movements and the presence of tension cracks contributed to the gullies expansio. The study exemplifies a typical case of soil degradation when management practices and soil conservation are lacking.