Drainage density and its relations to geomorphic and pedological factors in the upper Pardo River – states of São Paulo and Minas Gerais, Brasil

Abstract

Drainage density is one of the main parameters of morphometric analysis in hydrographic basins, corresponding to the average length of channels in the basin per unit of area. The spacial distribution of drainage density values in the upper course of Pardo river area, in the northeast of the state of São Paulo and southern Minas Gerais, was obtained measuring channel lengths in quadratic cells, covering all the area. An important spacial correlation was observed between anomalies of high drainage density and the distribution of main structures reactivated in the Mesozoic - Cenozoic, which suggests an increase of erosive processes controlled by neotectonics. The main anomalies of rarefaction of drainage were observed on sedimentary areas of the Parana Basin. A lower correlation was obtained with the soils, where is observed a general trend to high density drainage anomalous zones in podzolic soils and low to intermediate in latosols. The results indicate that the study of this morphometric parameter represents an important tool for the preliminary definition of areas, which may provide structural and tectonic evidence in field works with more probability of success.