Topographic factor (ls) of the pasture areas of the hydrographic microbasin of the São Francisco stream, in the municipality of Ibitirama (ES)

Abstract

The topographic factor or LS factor represents the influence of relief on soil water erosion. In pasture areas and, mainly, at the watershed level, erosion becomes even more worrying. In this sense, the objective of this research was to evaluate the topographic factor of pastures in the São Francisco stream hydrographic mcrobasin (BHCSF), in order to support improvements in anthropic planning and conservation of local soils. The procedures were carried out using the ArcGIS® program. The survey was conducted from july to september 2020. At first, BHCSF was drawn up, as well as pastures. The LS factor was obtained through a method commonly used in the literature. The slope map was generated from the Digital Elevation Model extracted through features of contour lines. The LS factor was quantified and grouped into classes. The LS factor ranges from 0 to 50, with an average of 1.332 and standard deviation of 1.295. There is a greater presence of LS ≤ 1.5, followed by the class of 1.5 to 3. Values ​​above 1.5 indicate more irregular reliefs and, therefore, more prone to erosion. However, LS values ​​greater than 1.5 cover 40.737%. Most of BHCSF's pastures occupy areas with a low topographic factor and, therefore, more favorable to the practice of livestock. It is relevant to adopt conservationist practices, giving priority to the places with the highest LS, as well as the practice of cattle raising in places with a flatter relief.