Caracteriza??o morfométrica da bacia hidrográfica do rio Debossan, Nova Friburgo, RJ

摘要

The objective of this work was to perform a morphometric characterization based on some physical parameters. In order to do so, a Hydrologically Consistent Digital Elevation Model (HCDEM) was generated from IBGE topographical maps, scale 1:50.000, using as database and analysis the system of geographic information, by means of the ArcVIEW and Arc/INFO version 8.3 systems. From this, some morphometric parameters of a previous study on the hydrologic behavior of the watershed were calculated. The drainage area was 9,9156 Km2 and 17,684 km in perimeter. The Debossan river watershed was proven not easily subject to floods as the compacity coefficient was far from the unit (1.5842) and its shape factor presented a low value (0.3285). Such fact can still be proven by the circularity index value (0.3985). The drainage density was 2,3579 Km/Km2, showing that the watershed has average draining capacity. The drainage system forms a dendritic pattern. This pattern occurs in high lands, in which the regolith and the parent rock relatively provide a uniform resistance to erosion. The more elongated watershed shape, as the circularity index, shape factor and compacity coefficient, indicates that the rainwater volume that falls within the watershed is concentrated in different points, contributing to reduce rain intensities that could cause greater flow variations.