Vulnerabilidade costeira em uma comunidade tradicional amazônica: estudo de caso na vila de Jubim, Salvaterra - PA

Abstract

Coastal vulnerability is a topic of great relevance on a global scale due to current climate issues and rising ocean levels. Understanding the degree of coastal vulnerability is essential to prevent socioeconomic and environmental losses, such as those resulting from erosive processes. This study aimed to quantitatively assess the conditions of vulnerability to coastal erosion in a traditional community on Marajó Island: Jubim, located in the municipality of Salvaterra, state of Pará. To achieve this objective, a Coastal Vulnerability Index (CVI) was used, considering two projections of sea-level rise proposed by the Intergovernmental Panel on Climate Change (IPCC): one with a rise of 4 mm/year and the other with 15 mm/year until 2100. To identify coastal vulnerability under the two sea-level rise scenarios, they were associated with geomorphological and physical characteristics along the estuarine coast of Jubim. Oceanographic variables (tidal range, significant wave height, and sea-level variation) and geological variables (coastal geomorphology, beach slope, and shoreline erosion/accretion rate) were analyzed and classified, with vulnerability indices ranging from very low to very high. The determination of the shoreline erosion/accretion rate was carried out through multispectral and multitemporal analysis (33 years) using Landsat satellite images and the Digital Shoreline Analysis System (DSAS) tool. The spatialization and integration of the data, based on the CVI, were performed using Geographic Information System (GIS) software. The study area was segmented into three sectors: North (Salazar Beach), Central (Meninas Beach), and South (Baleia and Curuanã Beaches). Between 1990 and 2023, the average linear retreat recorded for the entire study area was -35.24 m (NSM), while the average linear advance was 15.10 m (NSM), highlighting the predominance of coastal erosion. The North sector, with the lowest topographic gradient, showed a maximum retreat of 170 meters and an average retreat of 1.99 m/year (EPR), revealing the retreat of mangrove vegetation and the overlapping of Salazar Beach over this ecosystem. The CVI revealed that, under both sea-level rise projections, Jubim's coastline tends to present moderate to high vulnerability (30.3% and 27.3%) in areas with cliffs and extensive sandy stretches, respectively. The map developed based on the CVI proved to be a useful tool to support coastal management on the Amazonian coast and decision-making in the face of advancing erosion caused by estuarine hydrodynamics, associated with rising sea levels.