Estudo da erodibilidade da chuva na bacia experimental de Sumé.

Abstract

The rainfall impact and the surface runoff contribute to modify the soil physical condition, which can modify the surface roughness, porosity and infiltration rate. In order to study the rainfall erosivity in the semiarid area of northeastern Brazil by the rainfall erodibility index, data from 226 rainfall events observed from 1982 to 1991 in a micro-basin installed in Sumé Experimental Basin, located in Paraíba State, were used. Although, the index presented the same values for some events, it was observed that the sediment yield was different, which led to a detailed study trough a distributed physically-based runoff-erosion model, where each erosion process was separately considered. The results revealed that the rainfall drop impact effect could be considered constant independently of the font event since that its effect tends to be attenuated by the runoff depth. Finally, it was concluded that the sediment yield, in the studied area, depends mainly on the runoff shear stress and, in particular, on the shear stress of the runoff concentrated in the channel elements.