The beaches of Rio de Janeiro

Abstract

This chapter presents the beaches of the state of Rio de Janeiro within a geomorphological perspective that includes the characterization of sediment types, exposure to waves, geology and relief and associated processes, especially the beach morphodynamic, their sedimentary budget and erosive tendencies. The study took as its foundation the knowledge of the coast acquired during the research carried out over several decades by the Marine Geography Laboratory of the Federal University of Rio de Janeiro, including the monitoring of the beaches and extensive field work. In addition to this knowledge, access to the publications of other research groups of this and other universities was also of crucial importance for a more complete overview. Thus the chapter presents the diversity of beach environments to be found in Rio de Janeiro state on the basis of a regionalization into two macro-compartments separated by Cape Frio where the shoreline undergoes an abrupt change of direction. This change is responsible for a considerable difference in the exposure of the beaches to southerly waves, resulting in distinct dynamic processes within these two compartments. Each of the compartments has then been divided into smaller regions, in the attempt to group segments with similar geomorphological characteristics. Thus, in the eastward-facing northern compartment which extends from the northern limit of the state to Cape Frio, there are two sub-regions. The first includes the beaches along the Paraiba do Sul coastal plain and the second encompasses the coastline from Macaé to Arraial do Cabo including the coastal plains between Rio das Ostras and Cape Frio. In this latter sub-region a second division was highlighted to address specifically the beaches of the Armação dos Búzios (Cape Búzios) and Arraial do Cabo (Cape Frio), which stand out from the rest of that set. Then in the second macro-compartment where the coast is exposed to the south, there are four sub-regions of the double barriers and the lagoon system between Arraial do Cabo and Maricá; the sheltered beaches of Guanabara bay; the exposed beaches of the metropolitan region; and the beaches in the vicinity of the Serra do Mar coastal range.