Análise de um método de avaliação de vulnerabilidade à erosão costeira

Abstract

The historical occupation of coastal zones has been crucial for prosperity over the centuries, but it is essential to recognize the natural vulnerability of these areas to damages and negative impacts. Coastal erosion is directly linked to the continuous increase in occupancy along the coastline, driven by appreciation and real estate exploitation of coastal areas. With climate change, an increase in factors such as rising sea levels and a decrease in sediment supply is expected, further intensifying coastal vulnerability. Forecasts indicate a growing coastal erosion in the future, with previously stable areas potentially becoming erosive. To minimize negative impacts, it is crucial to implement preventive measures, such as vulnerability studies, for coastal planning and management. Such studies identify more vulnerable areas, helping develop effective management strategies to preserve the environment and well-being of local communities. The objective of this study was to analyze the vulnerability index in the study area using the methodology proposed by Sousa (2007). Bibliographic surveys, field visits to analyze the same reference points used in Sousa's study (2007), currently using geoindicators and photographic records, in addition to using the Coastal Analysis via Satellite Imagery Engine (CASSIE) tool for analyzing the variation in the coastline of the study area. The evaluation of geoindicators indicated that Paracuru beach exhibits significant vulnerability, with considerable variability in coastal erosion associated with different features along the coast. CASSIE presented rates of coastline variation, categorized based on classes proposed by Esteves and Finkl (1998), later adapted by Luijendijk et al. (2018) and Almeida (2021). Allowing a detailed analysis of each beach's erosive state, categorizing them as Critical Erosion (< -1m/year), Erosion (-1 to -0.5m/year), or Stability (-0.5 to 0.5m/year). No beach in Accretion (> 0.5m/year) was found during the considered period, categorizing the study area as 65.1% in Stable state, 30.2% in Critical Erosion state, and 4.8% in erosion state. The results showed relevant values regarding a moderate risk state, as expected. However, it was identified that, on a more detailed scale, the methodology failed to categorize the most vulnerable points to coastal erosion on the Paracuru coast. Thus, this work considers the method as effective on a general scale but with shortcomings on a smaller scale, proposing alternatives for method improvement.