Sedimentary Dynamics of Estuarine Beaches on Marajó Island (Brazil)

Abstract

Beaches are composed of accumulations of sediments of varying sizes (fine sand, pebbles, gravel), under the influence of wave height and period and tidal amplitude. In general, they are variable natural systems that undergo continuous changes. This article aims to analyze the sedimentary dynamics on the estuarine beaches of the village of Jubim, as well as their morphology during a seasonal period (2023-2024). The methodology involved the following procedures: (1) capture of aerial images by means of drone photogrammetry; (2) positioning of the Geodetic GNSS base; (3) collection of control points using static-fast positioning with RTK (Real Time Kinematic); (4) measurement of wave height and (5) processing of topographic elevations previously collected with Total Station and previous sampling of surface sediments. The mapped results of the topographic elevations (2.7 to 5.5 m) show that the highest elevations occurred during the rainy season on the Meninas beach (4.3 m), Baleia beach (4.7 m) and Curuanã beach (5.5 m), while on the Salazar beach, the highest topographic elevation was during the dry season (4.7 m). Regarding the granulometric distribution, the interpolation of the data indicated mainly fine sand (2 to 3 ɸ) on the Salazar and Meninas beaches, and on the Baleia and Curuanã beaches, medium sand (1 to 2 ɸ). The beaches were classified as transitional: beach-tidal flat (RTR > 15), dominated by tides throughout the seasonal period.