The absence of an adequate drainage system in unpaved roads is one of the main factors for their degradation. For adequate planning knowledge of the resistance parameters of soil is necessary. This study had as its objective the determinatiom of the erodibility and critical shear stress of unpaved road soils. For this work, a runoff simulator was directly installed on road channels, under natural conditions. Different flow depths were applied and the soil loss was measured for each depth. The erodibility and the critical shear stress were determined through adjusted curves relating soil disaggregation and flow shear stress. The results showed variations in erodibility and in critical shear stress values of the roads. The erodibility values obtained, when compared with values observed in the literature, evidenced high susceptibility to the erosion for road conditions. These values were higher on silt loam and sandy soils. The critical shear stress values were similar to those observed in other publications.
erosion; earth roads; runoff simulator
