Estudo da dinâmica da linha de costa na região de Mecúfi-Cabo Delgado utilizando o sistema digital de análise da linha de costa (DSAS)

Abstract

The present study analyzes shoreline variation in the Mecúfi region, Cabo Delgado, with the aim of understanding the patterns of erosion and accretion over recent decades. The adopted methodology was based on the use of the Digital Shoreline Analysis System (DSAS) version 4.3 to calculate shoreline change rates using Landsat images (TM, ETM+, and OLI). Shorelines were extracted using the Normalized Difference Water Index (NDWI), which allowed for the enhancement of water bodies and improved land-sea separation. Metrics such as the End Point Rate (EPR) and Linear Regression Rate (LRR) were applied to estimate shoreline dynamics. In parallel, environmental variables such as extreme precipitation, winds, significant wave height (using the 99th percentile), and mean sea level were analyzed based on data from the Copernicus and APDRC platforms. Land use and land cover analysis was conducted through Maximum Likelihood classification in ArcGIS 10.5. The results indicate that between 1994 and 2024, the Mecúfi region experienced an average shoreline retreat rate of -0.39 m/year, with displacements reaching up to 12.09 meters. However, the sectoral analysis revealed that Sector 3 was the most affected by erosion, showing the highest rates of shoreline retreat compared to Sectors 1 and 2. Overall, the shoreline retreat in the Mecúfi region resulted from the combination of factors such as extreme precipitation events, strong winds, significant wave heights, and the increased exposure of bare soils, all of which directly contributed to coastal sediment instability and mobilization.