This work presents the application of an environmental evaluation methodology based on headwaters dynamic evolution in hilly domains of Southeastern Brazilian Plateau (Moura et al.,1997) for definition of potential erosion areas and degradation conditions of tributary drainage basins of Paraiba do Sul River in Barra Mansa County (RJ), using geoprocessing techniques. Connected and disconnected gullies and rills were mapped on aerial photographs at a scale of 1:40,000, being distinguished as active or stabilized features, and also filling up or emptying valley bottoms in zero, first and second order drainage basins. They were crossed with topographic compartments, hipsometry, microbasins gradient, land use/vegetation cover and geology maps, all of them at a scale of 1:50,000, following the environmental analysis procedures proposed by SAGA-UFRJ. The environmental signatures obtained showed that connected gullies occur on drainage basins with hollows and valley bottoms filled up by alluvial-colluvial deposits (47.29% of active and 48,24% of stabilized gullies) or on partially emptied ones (45.5% of active and 39.87% of stabilized ones), mainly in second order basins (39.19% of active and 49.75% of stabilized features), ratifying an hierarquization control for drainage lines re-incision by gullies (Peixoto,1993). Disconnected gullies/rills occur largely on emptied microbasins (80.74% of active and 84.67% of stabilized), being also common on filled up valley bottoms, being related to high gradients of side slopes and head slopes, high erodibility of surficial materials and/or landl use. Cataclastic rocks and roads or urban buildings play an important role on generation of either connected or disconnected erosions. Based on these results and on gullies/rills dynamics knowledge, potential maps for connected and disconnected channeled erosions were developed, leading to recognition of main critical areas and/or drainage basins tributaries of Paraiba do Sul River concerning linear erosion, rivers silting and flooding. The results obtained testify the effectiveness of the methodologies integration proposed for definition of priority zones and strategic/caution actions in environmental planning and management.
*Supported by PADCT-FINEP, FUJB/UFRJ and CNPq