Análise da distribuição espacial de voçorocas na bacia do rio Pandeiros-MG: uma abordagem geomorfológica

Abstract

This work investigates factors associated with the spatial distribution of 215 gullies that occur in 5 well-defined groups in the drainage basin of a tributary of the middle São Francisco River, MG, Brazil, based on the analysis of geological, declivity, hypsometric, knickpoints maps and sampling of the regolith material from a slope/gully of each group. The results of the Principal Component Analysis (PCA) of the physical (granulometry) and chemical parameters (pH -H2O/ KCl), electri-cal conductivity, organic matter, Ca2+, Mg2+, Fe2O3, Al2O3, and TiO2) of the regoliths, as well as the maps, indicate the existence of lithostructural controls on the occurrence of steep breaks of slopes, associated with the acceleration of surface runoff flows, favoring gullying in specific areas of the basin. The PCA made it possible to compare the regolith parameters of the five slopes/gullies, showing that the first principalcomponent (PC1), related to silt, and PC2, to coarse sand, account for 45% of the total variance of physical and chemical parameters. The PCAbiplot graphs indicate that there is heterogeneity in these parameters, meaning that there are variations between the physical and chemical characteristics between the five slopes/gul-lies, suggesting that they do not directly account for the grouping of the gullies.