Paty do Alferes (RJ), localized in the reverse of "Serra do Mar", shows the intense erosional processes that are characteristic of the hilly compartments developed on weathered bedrock along Southeastern Brazilian Plateau. The erosional features are related to sheetwash and gullies/rills connected or disconnected to the drainage network, sometimes discontinuous. Agricultural activities and cattle breeding contribute to this situation, by using unsuitable techniques. Aiming to analyse the controls of channeled erosion processes, geomorphological and pedological studies were carried out in representative areas of the three different geomorphic domains recognized. Following the environmental evaluation procedure proposed by Moura et al. (1997), maps of topographic compartments, erosional processes and filling up or emptying conditions of valley bottoms were obtained for zero, first and second order drainage basins, using cartographic basis and aerial photographs at a scale of 1:20.000. These maps were combined with the soil map developed by CNPS/EMBRAPA at the same scale, and based on them were selected sites for sampling to characterize physical properties of surficial materials (0-15cm and 15-30 cm depth).

The results demonstrated that connected gullies occur on drainage basins with hollows and valley bottoms filled up by alluvial-colluvial deposits or on partially emptied ones, ratifying the regional mechanism of drainage lines re-incision presented by Moura et al. (1991; 1993) for Paraíba do Sul River middle valley. These re-incision on paleogully channels are largely controlled, in Paty do Alferes Municipality, by local base levels of the bedrock. The disconnected gullies or rills, on the other hand, are mainly related to very dissected slopes in step-like compartments, where gradient and litho-structural controls (joints/dikes) play a major role. In hilly compartments, however, this type of erosion is associated to pedological properties like high microporosity, high bulk density values and/or significant silt content on the topsoil. The observed relationships are important for the forecast of erosional channelled processes and for identification of critical areas/basins to agricultural and urban uses. *Supported by PADCT-FINEP, FUJB/UFRJ and CNPq