Geomorfologia e sedimentologia da plataforma continental interna de Fortaleza – Ceará

Abstract

The west side of Fortaleza, with the civil constructions resulting from the economic and population advances, accompanied by dredging and deepening of canals and spigot constructions, passed and undergoes several modifications in its beach morphology and background in the sector of the internal continental shelf Over the last few decades. This has led to changes in the natural sedimentation patterns and consequent geomorphological changes. Natural forcings such as winds, waves, currents and tides cannot be ruled out of the beach and inland continental shelf modeling process. Both rework the sediments contributing in the configuration of the present emersed and submerged characteristics of said coastal zone. The main objective of this study was to characterize the background geomorphology through the application of the monochrome bathymetry on the inner platform of the west coast of Fortaleza, and also to relate the characteristics of the bottom forms with granulometry data from studies already Carried out in the area. The preparation of the bathymetric chart, made through the geoprocessing of depth data of 19 profiles collected in the field, allowed the highlighting of the geomorphological features of the bottom such as reefs, artificial channels of navigation and sand banks. The slopes found in the 19 topbatimetric profiles reveal mostly low - slope stretches, which characterize the inner continental shelf of the west coast of Fortaleza as a smooth relief and some points with a gentle elevation. The sections of the prominent profiles with sharp elevation and marked slope are associated to the artificial entrance channel of the large vessels in the Port of Fortaleza, and the reefs and shoals that have higher dimensions. Sedimentology, in terms of granulometric characteristics of grains or sediment grain size, reveals a deposition pattern associated with the hydrodynamic conditions of the area, defined by the main forcing as waves and currents. In the more protected zone of the port basin, as less action of forks, the granulometric fractions concentrate finer sediments, tending to lamosa fractions of silt and clay. In the less sheltered areas, further west of the port basin, forks use sedimentation patterns with medium to fine grain size fractions, sometimes gravel are also found, characterizing a higher hydrodynamic energy environment.