The aim of the present study was to estimate the loss of soil due to sheet erosion in ten sub-basins (SWDs) located in the lower course of the Itapecuru River based on different scenarios of land use and coverage in the years 2005, 2010 and 2015. For such, the Universal Soil Loss Equation (USLE), including the following factors: rainfall erosivity (R), soil erodibility (K), topographic factor (LS), soil use and conservation factor (CP). Annual R amounts were 11314.5 MJ mm ha -1 yr -1, with the greatest effects found in March and April. K values were related to soil types in the sub-basins, dominated by Plinthosols and Argilosols, with estimated contributions of 0.0429 and 0.030 t ha MJ -1 mm -1 , respectively. The LS factor demonstrated a flat, smooth topography with slopes ranging between 0 and 5° over 93% of the study area. The standard CP indicated that green areas were prevalent in all years analyzed and that the main changes in the ten-year period occurred in sub-basins 1, 2 and 10. Regarding the USLE, the "very low" class was the most representative throughout the time series. However, changes in the CP factor, especially in sub-basins 1 and 2, evidenced the expansion of areas susceptible to sheet erosion, with the increase in the occurrence of "moderate" and "moderate to strong" classes triggered by changes in landscape patterns. The present findings are important to environmental management and the prioritization of environmental conservation actions in the SWDs. Keywords: erosivity, erodibility, relief, soil conservation, USLE.
Potencial erosivo das sub-bacias hidrográficas do