Geomorfometric classification of the hydrographic basin of Ijuí river, RS

Abstract

The present study has been made in the basin of the Ijuí river, located in the north / northwestern region of Rio Grande do Sul state, with the objective of defining the geomrofmetric units in the study area by means of geoprocessing techniques associated with digital relief analysis. The geomorphometric units were compartmentalized from the use of topographic attributes obtained from a Digital Elevation Model (DEM) in a proposal of automated geomorphometric mapping that is performed through the cross of information and topographic attributes, generated through a GIS and hierarchized through of a decision tree. Four geomorphometric variables were used: altimetry, declivity, curvature profile and curvature plan that resulted in the definition of twelve relief units, which were obtained from samples taken in the upper, middle and lower basin courses, in which it was observed that the units are distributed in different ways along the basin, with predominance of the first six units on the upper course, in the middle course all twelve units have occurrence. Already in the low course only the last six units present, however, showing close relation with the fluvial hierarchy, though the profile and plan of slope formats vary in all the sectors analyzed, what do means the possibility of different surface processes along the entire basin.