Geoindicators of vulnerability to erosion and coastal risk in estuarine beaches on the Amazon coast

Abstract

Due to current climate change and the consequent sea level rise, combined with urban expansion near the shoreline, there is an increase in beach erosion. This process has worsened in some places on the Amazon coast, such as the fluviomarine Mosqueiro island. This article aims to analyze the erosion vulnerability on the estuarine beaches of this island, in addition to assessing the degree of risk to which they are exposed. Using environmental indicators, an index and classification of coastal vulnerability were obtained. The index is composed of the combination of semi-quantitative variables such as: collection of topographic and sedimentary data on 16 beaches; shoreline variation analysis (2006-2020) using remote sensing; application of checklist of environmental indicators of beach erosion. The results showed that 8 of the 16 beaches analyzed had a high vulnerability to erosion (CVI: 5.0-7.4) and coastal risk. The presence of active cliffs, retaining walls and high coastal human occupation (> 70% on most beaches) favored these results, given that the beaches are under the influence of anthropic action in erosion processes. It is noteworthy that the method applied in this research is a useful tool for identifying and mapping erosion, valid to coastal management, including estuarine beaches.