Coastal line mapping and vulnerability and susceptibility assessment the coastal erosion between the mouth of the São João River and the mouth of the River Una - Cabo Frio/RJ

Abstract

The present work carried out an assessment of vulnerability and susceptibility to coastal
erosion through the use of geoindicators and the mapping of the coastline between the mouth of the
São João river and the Una river, in Cabo Frio (Rio de Janeiro State). Due to high wave energy
events, erosive characteristics were identified in part of the beach arch, even though such area does
not have a verified coastal erosion scenario. The methodology involves the use of geoindicators for
the analysis of two points in the beach arch: the use of a temporal series of aerial photographs and
high-resolution images (1970, 2005 and 2018) for the classification of the land use of the seafront,
and shoreline vectorization in GIS environment. The results show that in the northernmost point of
the beach arch has a high vulnerability and susceptibility to coastal erosion, while in the southernmost
point there is a low vulnerability and susceptibility. It is observed a high urban growth and
intensification of occupation on the seafront, with buildings close to the beach dynamic profile,
which can result in a direct attack from high energy waves. Amid the possible changes in climate
projected in recent studies, such as increase in mean sea level, higher frequency of extreme events,
increased wave power and the massive occupation of coastal environments, studies that support
planning and management of waterfront occupation are required.

Keywords: geoindicators, sandy beaches, coastline, coastal erosion.