A morfometria como fundamento para a análise geoambiental: o caso da bacia do Rio Ribeira Fontão, Tarrafal - Cabo Verde

Abstract

Morphometric characterization of watersheds can be defined as a set of values that aim to investigate the natural aspects of a watershed. These studies use quantitative parameters to help scientists understand the morphodynamic processes of the landscape. In this sense, the general objective of this work is to analyze the morphometry of the Ribeira Fontão watershed, located on the island of Santiago - Cabo Verde, verifying its relevance for geoenvironmental analysis. The morphometric parameters used in the research were: area; perimeter; length of the main river; length of all the rivers; axial axis; length of the main river without sinuosity; maximum and minimum altitudes and altimetric difference; average declivity; compactness coefficient; shape factor; circularity rate; drainage density; hydrographic density; and sinuosity of the main river. All the data obtained and processed during this study was done entirely in a SIG environment and calculated according to the equations presented by Villela and Mattos (1975) and Chistofoletti (1980). The most important results for understanding the environmental dynamics of the watershed were: compactness coefficient; shape factor; circularity rate; drainage density; sinuosity of the main river; and average declivity. The circularity rate, shape factor and compactness coefficient were 0.382, 0.310 and 1.616, respectively. These results indicate a watershed with a low propensity to flooding. The drainage density showed a value of 2.137, considered high, showing that there is a high power of the river system to sculpt the landscape. The value obtained for the sinuosity of the main river was 1.084, which indicates a rectilinear shape that is more susceptible to erosion. This result corroborates the watershed's average declivity of 29.346%, which is considered high. Therefore, it may be concluded from the morphometric studies that the watershed's behavior is coherent with the environmental characteristics in which it is located