Determinação do fator topográfico em bacias hidrográficas

Abstract

The use of USLE model and it’s derivations, for water erosion estimation, is increasingly common in academic literature and engineering works. However, this models has limitations in watershed application, because they were originally developed for hillside areas. Thus, this study aimed to conduct a sensitivity analysis of topographic factor (LS), considering the traditional calculation of MUSLE (WILLIANS, 1975), and calculation methods spatially distributed of Moore et al. (1991) and Desmet and Govers (1996), for two DEMs with topographic detailing of 1:10,000 and 1:50,000 in six watersheds of different scales. The results show that traditional calculation overestimates the values of the topographic factor, in relation to average value of the spatially distributed calculations. In relation the relief discretization influence, topographic factor values increase of the 1:50,000 DEM for 1:10,000 DEM in conventional method and method of Desmet and Govers (1996), while in method of Moore et al. (1991) reduce. This divergent behavior between spatially distributed methods, is due to form as the flows accumulation in the basin is inserted in each calculation. Based on correlation with relief indices, it was found that the calculation methods spatially distributed best expressing the reality of topographic factor compared to traditional method, being more accurate in 1:50,000 DEM. Regarding the scale effect, complex relationship between topographic factor of the three calculation methods and watershed set analyzed were found.