AN APPROACH TO THE CONTRIBUTION OF ANTHROPOGENIC ACTIONS FOR THE ARARUAMA LAGOONAL SYSTEM (SE BRAZIL) GEOMORPHOLOGICAL EVOLUTION

• Main Authors: OLEGÁRIO NELSON AZEVEDO PEREIRA, MARIA ANTONIETA DA CONCEIÇÃO RODRIGUES, JOÃO MANUEL ALVEIRINHO DIAS
• Format: Article
• Language: English
• Published: Universidade do Estado do Rio de Janeiro 2018-06-01
• Series: Journal of Sedimentary Environments
• Subjects: environmental history; coastal environments; lagoonal formation; interaction man-nature; anthropogenic activities
• Online Access: https://www.e-publicacoes.uerj.br/index.php/jse/article/view/35533

The first studies regarding the constitution of the Araruama lagoonal system, located in the Rio de Janeiro state (SE Brazil), were carried out by Alberto Ribeiro Lamego. This author supported the thesis that it had resulted from the formation of a sand barrier (called Massambaba) due to the longitudinal transport of large quantities of sediments through coastal drift currents, and the growth of spits parallel to the shoreline. However, most recent studies largely rejected it, sustaining that the confinement of this hydric environment was the result of the growth of two sand barriers during the Pleistocene and Holocene times (120.000 to 7.000 years before present - BP) due to the sea level changes. The hypothesis that we suggest, is that both propositions are acceptable and complementary. This study aims to demonstrate that, despite the opinions on the formation of the double sand barrier, deposition of sediments by coastal drift currents at the end of the Holocene, and especially in recent chronologies, also contributed to the establishment of this lagoon system. In our opinion, the increased sediment supplies due to human activities contributed to the formation of the inner spits and the nearby sea sandbar. Its orientation was influenced by the existence of the island of Cabo Frio, that allowed the formation of the tombolo that almost connected it to the continent. Through the analysis of historical and cartographic documents related to the colonization and economic exploitation of the region, it is evident that the anthropogenic actions played a significant role in the sandy spits formation. Of these, special emphasis is placed on the agriculture and deforestation that contributed to the increase of sedimentary accumulation. This work demonstrate that the analysis of historical documents can provide information and contribute to the understanding of recent coastal developments.