ANALYSIS AND MORPHOMETRIC COMPARTIMENTATION OF THE HIGH RIO DAS VELHAS HYDROGRAPHIC BOWL - CENTRAL REGION OF MINAS GERAIS

The Das Velhas River Basin, in central Minas Gerais state, Southeastern Brazil, has been studied since the beginning of the 20th century. Along this last century the conceptual and technical progress has allowed the reinterpretation of previous results under new aegis. Geoscientific studies developed for this river basin have focused its upper basin because of its correspondence to the core area of the Mineral Province of Quadrilatero Ferrifero, a peculiar mountainous landscape, marked by strong litho-structural and tectonic forcing. However, none morphometric analysis has been done for this river basin, in spite of the several regional geomorphological studies. This sort of spatial analysis allows defi ning major compartments compounded of sub-basins with similar features, which are essential for environmental planning and management of the territory and also for future geomorphologic studies. In this context, this paper aims providing such support for the Upper Rio das Velhas basin. For this, we have done the morphometric analysis and partitioning of this river basin, taking into account the Horton's Law of drainage basin composition and other morphometric parameters. The results show the grouping of sub-basins for nine (9) of the eleven (11) morphometric parameters taken in count. This behavior allows us to partitioning the upper Rio das Velhas basin into fi ve (5) major partitions, where structure plays a main role, followed by lithology and tectonics. Nevertheless, this control is quite moderate for the granitic area, where local base level control is predominant on dividing it into the eastern/ western portions.