Modelagem dos níveis de base do rio Jacuípe, Bahia

Abstract

The development of anomalous features in the drainage network of the Jacuípe River Basin (BHRJ) has been a topic never addressed in the specialized scientific literature. The present work aims to spatially model the base levels of the Jacuípe River and its tributaries. Remote sensing products and geoprocessing techniques were implemented in a Geographic Information System (GIS) environment, in order to sectorize the BHRJ through slope, hypsometric, and longitudinal profile maps of the main channel, and morphometrically characterize each one of its parts (Strahler’s Hierarchy); automatically identify stepper gradients of the river channel, expressed in the form of knickpoints; determine the structural, tectonic, lithological, hydrological and anthropic controls of the river base levels, through the generation of thematic maps of structural indices (Lineament Map, Lineament Density, Lineament Frequency) and geomorphological indices (Drainage Density and Flow Frequency), which were integrated from Fuzzy Logic and Analytic Hierarchy Process (AHP), for the realization of the Structural Control Map, as well as morphotectonic maps (Drainage Basin Asymmetry Factor and Transverse Topographic Asymmetry Factor) and geological data combined with orbital images from Google Earth Pro; and to establish the possible relationships between the variations of the base levels with the neotectonics through seismic data. Among the main results of the research, the Upper (3,959.23 km2), Middle (4,905.32 km2), and Low (3,306.02 km2) basin course were delimited; being the main river of 6th order. There were recognized a total of 1.634 2nd order and 101 1st order drainage anomalies, with 90% of the latter features being concentrated in the upper course. The main conditioning factors of the variations of the base levels were structural and tectonic and according to the seismic information collected, no indicators of recent tectonic action where observed, related to the reactivation of faults and the formation of knickpoints.