Caracterização da morfodinâmica das praias da Ilha da Trindade.

Abstract

Trindade Island, located in the South Atlantic Ocean, represents a tropical insular environment of high scientific and environmental relevance, yet remains poorly investigated regarding its coastal morphodynamics. This study aimed to characterize the morphodynamic behavior of six sandy beaches — Calheta, Cabritas, Tartarugas, Príncipe, Andrada, and Vermelha — through the analysis of topographic profiles collected during five field campaigns conducted between 2013 and 2024. Data were processed using Matlab®, allowing the calculation of volumetric variation (m³/m), beach mobility parameters (mean width, standard deviation, and coefficient of variation), and the identification of seasonal erosion and progradation patterns. The results revealed contrasting morphodynamic behaviors among the beaches. Critical erosion prevailed at Calheta, Cabritas, and Príncipe, reflecting their greater exposure to storm waves and limited geological protection. Conversely, Andrada and Tartarugas showed a stronger tendency toward progradation, related both to sediment supply and to biogenic disturbances, particularly sediment reworking caused by nesting green turtles. Vermelha Beach exhibited an intermediate response, influenced by reef structures and rip-current dynamics. Temporal variations in beach mobility highlighted the combined influence of cold fronts and southern swells, as well as possible indirect anthropogenic effects. The integrated approach combining long-term field surveys enabled the identification of the most erosion-prone sectors and provided valuable insights into sediment transport processes in Brazilian oceanic islands. These findings underscore the importance of continuous monitoring as a basis for conservation and coastal management strategies in vulnerable insular systems, particularly in the face of climate change and projected sea-level rise.