Coastline changes and sedimentation related with the opening of an artificial channel: the Valo Grande Delta, SE Brazil

The role played by human activity in coastline changes indicates a general tendency of retreating coasts, especially deltaic environments, as a result of the recent trend of sea level rise as well as the blockage of the transfer of sediments towards the coast, especially due to the construction of dams. This is particularly important in deltaic environments which have been suffering a dramatic loss of area in the last decades. In contrast, in this paper, we report the origin and evolution of an anthropogenic delta, the Valo Grande delta, on the south-eastern Brazilian coast, whose origin is related to the opening of an artificial channel and the diversion of the main flow of the Ribeira de Iguape River. The methodology included the analysis of coastline changes, bathy metry and coring, which were used to determine the sedimentation rates and grain-size changes over time. The results allowed us to recognize the different facies of the anthropogenic delta and establish its lateral and vertical depositional trends. Despite not being very frequent, anthropogenic deltas represent a favorable environment for the record of natural and anthropogenic changes in historical times and, thus, deserve more attention from researchers of different subjects.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [06/04344-2]info:eu-repo/semantics/publishedVersio

Fostering coastal resilience to climate change vulnerability in Bangladesh, Brazil, Cameroon and Uruguay: a cross-country comparison

© 2017, Springer Science+Business Media B.V. This paper describes a comparative study of four different cases on vulnerability, hazards and adaptive capacity to climate threats in coastal areas and communities in four developing countries: Bangladesh, Brazil, Cameroon and Uruguay. Coastal areas are vulnerable to sea-level rise (SLR), storm surges and flooding due to their (i) exposure, (ii) concentration of settlements, many of which occupied by less advantaged groups and (iii) the concentration of assets and services seen in these areas. The objective of the paper is twofold: (i) to evaluate current evidence of coastal vulnerability and adaptive capacity and (ii) to compare adaptation strategies being implemented in a sample of developing countries, focusing on successful ones. The followed approach for the case evaluation is based on (i) documenting observed threats and damages, (ii) using indicators of physical and socioeconomic vulnerability and adaptive capacity status and (iii) selecting examples of successful responses. Major conclusions based on cross-case comparison are (a) the studied countries show different vulnerability, adaptive capacity and implementation of responses, (b) innovative community-based (CBA) and ecosystem-based adaptation (EbA) and (c) early warning systems are key approaches and tools to foster climate resilience. A recommendation to foster the resilience of coastal communities and services is that efforts in innovative adaptation strategies to sea-level rise should be intensified and integrated with climate risk management within the national adaption plans (NAPAs) in order to reduce the impacts of hazards

Modern sedimentation in the Cabo Frio upwelling system, Southeastern Brazilian shelf

The analyses of Uk'37 paleotemperatures and sedimentological parameters in box cores from the Cabo Frio upwelling zone, southeastern Brazil, were used to understand the modern sedimentation as well as to evaluate the role played by the upwelling process in the sedimentary patterns. Three box-cores located closer to the upwelling area show a general trend of cooling waters taking place in the last 700 years. Since the present upwelling is dependent on local and remote wind regime, a phase of dominating NE winds favors a more effective upward transport of the cold thermocline level South Atlantic CentralWater towards the coast. The intensification in the upwelling regime for the last ca. 700 years can be associated with the strengthening of the NE winds off the area and a possible increase of the Brazil Current mesoscale activity. Nevertheless, the lack of significant correlation of the paleotemperatures and most of sedimentological parameters indicate that upwelling is not the only sedimentation mechanism in the area. Also, the comparison of sedimentological parameters reveals that eventual temporal changes are superimposed by the geographical variability. Sedimentation rates vary from 0.26 mm.yr-1 to 0.66 mm.yr-1.<br>As análises de Uk'37 paleotemperaturas e de parâmetros sedimentológicos em amostras de box-core da zona de ressurgência de Cabo Frio, sudeste do Brasil, foram usadas para compreender os processos de sedimentação moderna na área, bem como avaliar o papel desempenhado pela ressurgência no estabelecimento dos padrões sedimentológicos principais. Como observado em três box-cores localizados nas proximidades da área de ressurgência, é possível verificar uma tendência geral de resfriamento das águas nos últimos 700 anos (idade calibrada). Uma vez que o processo de ressurgência é dependente do regime de ventos local e remoto, uma fase de ventos predominantes de NE favorece um deslocamento mais efetivo das águas frias da Água Central do Atlântico Sul em direção à costa. Por outro lado, a falta de correlação significativa entre as paleotemperaturas e a maioria dos parâmetros sedimentológicos indica que a ressurgência não é o mecanismo prevalente na sedimentação da área. Além disso, a comparação dos parâmetros sedimentológicos entre os testemunhos revela que eventuais variações temporais são superimpostas pela variabilidade geográfica. As taxas de sedimentação variam de 0,26 mm.ano-1 a 0,66 mm.ano-1