The main aim of this research work has been to analyse the evolution of soil cover alteration at Serra do Mar State Park, Cubatão, State of São Paulo, Brazil. Through quantitative analyses, we have tried to identify the degrees of evolution and fragility of fifteen third order watersheds, aim at predicting and reducing the erosion process. The higher the relief ratios obtained, the higher the hillside instabilities, in all watersheds analysed, placed in distinct physiographic areas. The volume of lost material (soil removed from the watershed) has shown to be proportional to the difference (hipsometric-volumetric integrals); also, the relief evolution degree and the susceptibility of erosion of the watershed soils might be estimated by the concavity or convexity of the hipsometric curves.
relief; soils; erosion material; watershed
