Estudo do processo de assoreamento da Enseada da Japuíba (Angra dos Reis, RJ)

• Autor(a) principal: Vieira, Yury Souto Simen
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/13854
• topic: Silting and Erosion; Anthropic Impacts; Japuíba Bight; Ribeira Bay; Assoreamento e Erosão; Impactos Antrópicos; Enseada da Japuíba; Baia da Ribeira; CNPQ::CIENCIAS EXATAS E DA TERRA::OCEANOGRAFIA::OCEANOGRAFIA GEOLOGICA

This study investigates the Japuíba Bight (Angra dos Reis municipality) aiming to characterize the process of silting up affecting the region and to infer on its causes. A multidisciplinary approach was undertaken which includes bathymetric measurements, sediment sampling and laboratory analysis, and aerophoto analysis. The integrated data interpretation enables to investigate the relationship between the spatial and temporal evolution of the bathymetry, the sediment texture, the area of mangrove and the variations on the urban population occupation at the at study area. The data was acquired during two bathymetric and sediment campaigns in 2018, which was compared with previous data obtained from previous campaigns in 1999 (Villena, 1999), in order to evaluate possible morphological variations in the period. The data analysis resulted in the maps of gradient, silting up/erosion and silting up rate for the last 39 years. The geophysical and the sedimentary analysis were integrated with granulometry results, enabling to qualify and quantify the Japuíba Bight. Our results provided basis that point out the occurrence of a silting up process at the study area, focused on 3 main zones: an E-W zone in front of the Airport area; proximal to the coast along the whole study area; between the Redonda and Bois islands. The results suggest that the Japuíba and Gamboa river s drainage along with smaller rivers are the main sources of sediments to the bight. The total volume of silting up calculated in this study was 1.252.642,75 m³, with an annual rate of 32.119,04 m³/y. At some areas, the peak rates reach up to 38 cm/y. The results presented here indicate that there is a direct relationship between the spatio-temporal of the urban occupation augmentation (and its associated direct environmental impact) with the decrease of the mangrove area and the increase of the silting up on the study area. It is proposed here that significant anthropic impact in the form of unplanned urban occupation, river form and native vegetation alterations and dredging was responsible for the process of silting up at the Japuíba Bight