Relief characterization with morphometric indexes on the north and south faces of the Chapada do Araripe - northeast Brazil

Abstract

The Chapada do Araripe, located on the border between the states of Ceará, Piauí and Pernambuco, is part of the drainage divide of 3 important Brazilian watersheds, the Jaguaribe, São Francisco and Parnaíba watersheds. In the case of the Chapada do Araripe, the north and south faces have distinctive geomorphic characteristics, while the north face has steeper relief, the south face has longer and less sloping slopes. This article aims at illustrating the differences between the faces of the Chapada do Araripe from the comparison between relief attributes of two hydrographic basins with representative characteristics in the regional context. To achieve the objective, classical relief metrics, shape and symmetry indicators and the normalized stepness index Ksn were used. The basin of the Taquari is inserted in the Jaguaribe drainage basin and showed responses in the indices that indicate a more active relief, with greater variation throughout the entire basin. In contrast, the basin of the Brígida, located in the São Francisco river drainage, showed smaller geomorphic variations, with less altimetric amplitude and average slope. In the longitudinal profiles, the values of Ksn indicate a greater proximity of the equilibrium profile in the Brígida stream basin when compared to the Taquari basin. The application of morphometric indexes allowed detailing the two faces of the chapada, contributing to the morphological characterization.