Guilherme Borges Fernandez

Arquitetura deposicional e datação absoluta das cristas de praia pleistocênicas no complexo deltaico do Paraíba do Sul (RJ)

As cristas de praias sao feicoes deposicionais caracteristicas decostas progradantes, onde cada crista representa um paleolinha de costa.Essas feicoes armazenam registros de evolucao da paisagem costeira duranteo Quaternario, principalmente quando investigadas a partir de metodosde geocronologia e morfoestratigrafia. O complexo deltaico do Rio Paraibado Sul se destaca por duas extensas planicies de cristas de praia com idadesholocenicas e pleistocenicas, onde esta ultima apresenta significativaslacunas de investigacao. Nesse sentido, o objetivo do presente trabalho foicaracterizar a arquitetura sedimentar das cristas pleistocenicas por meio daaquisicao de dados por Radar de Penetracao do Solo (GPR) e sondagem apercussao e identificar as idades absolutas a partir de Luminescencia OpticamenteEstimulada (LOE) e 14C AMS. A estrutura interna das cristas depraia revelada pelos perfis de GPR possibilitou a identificacao de radarfaciesque compoem uma sequencia de barreira regressiva ou progradante,com espessura deposicional em torno de 8 metros. As cristas apresentaramidades absolutas referentes ao estagio isotopico 5a (~ 85.000 anos), emboraalgumas amostras tenham carecido de um maior numero de aliquotas nometodo do Protocolo Single-Aliquot Regenerative Dose (SAR) (LOE). A integracaodos metodos GPR e LOE permitiu identificar as unidades deposicionaisdas amostras datadas e identificar o contato entre as unidades deradarfacies eolica e praial, caracterizado como indicador de paleonivel domar. Este trabalho resultou em discussoes acerca da genese e evolucao dascristas de praia e sobre as potencialidades e limitacoes na associacao entre osmetodos para investigacao Quaternaria de planicies costeiras.

Formas glaciales y procesos glaciológicos del glaciar templado Wanda, Shetland del Sur

This paper presents the geomorphic mapping of the Wanda Glacier proglacial environment, King George Island, South Shetlands. All together investigates the glaciological dynamics related to the glacial landforms in the study area. The mapping was based on field analysis and image interpretation. The interpretation was also made by mean of identification and interpretation of the samples in laboratoty. Glaciofluvial, glaciomarine and subglacial processes predominate in the study area. As a result from the recent glacial retreat, several landforms and proglacial deposits, such as flutes, morainic ridges, striated rocks, have been exposed. Abraded and subglacially transported sediments predominate in the deglaciation environments, with meltwater flow in the bed. The generated map contributes in improving the knowledge about the processes that influence the glacial geomorphology and geodynamics. Furthermore this study serves as support to monitoring environmental change facing the glacier retreat processes as effect of climate variability verified in the study area.

Foredunes of rio de janeiro coast: genesis, structure and morphology

ABSTRACT Moulton, M.A.B., Oliveira Filho, S.R., Rocha, T.B., Fernandez, G.B. 2013. Foredunes of Rio de Janeiro coast: genesis, structure and morphology. Proceedings 12th International Coastal Symposium (Plymouth, England), Journal of Coastal Research, Special Issue No. 65, pp. 1319–1324, ISSN 0749-0208.--> The formation of foredunes is one of the most important processes that occur during the evolution of the coastal sandy barriers, and can be observed along the coast of Rio de Janeiro State (Brazil) in both regressive, aggradational or transgressive barriers. The aim of this paper is to demonstrate the main processes of foredune development in areas with distinct patterns of coastal sand barriers along the Rio de Janeiro coast, subject to onshore and/or offshore winds. For this purpose we studied three areas in which foredunes present a representative morphology and show different types of coastal barrier. In each area, morphological aspects and foredune sedimentary structure where analyzed. Using total station and DGPS to generate 2D and 3D profiles, and a GPR antenna (400 MHz) to examine the sedimentary structure, an overall picture of the foredune formation process and the barrier type associated was made. The results showed that, foredunes developed on top of the regressive barrier (Atafona Beach) represent less than 2 m of sediment accumulated above the well-preserved beach ridges, suggesting that the main source of sediment supply comes from the river. In the aggradational barrier (Peró Beach) the intense aeolian transport (onshore winds) masks any sequence of beach signal, forming significant sequences of foredunes/blowouts (in this case sediment supply comes from the shoreface). The last area (Massambaba Beach), where winds blow offshore as result to the change of coastline orientation, we registered overwash deposits and occasionally foredune development on top of the transgressive barrier.

Morphodynamics of Embayed Beaches. Case Study in Cape Buzios, Rio de Janeiro, Brazil.

ABSTRACT Bulhões, E., Fernandez, G.B., Rocha, T.B., 2013. Morphodynamics of Embayed Beaches. Case Study in Cape Buzios, Rio de Janeiro, Brazil. Cape Buzios is a balneary touristic county located 180 km east of Rio de Janeiro city, Brazil. The geological site is composed by metassedimentary and metavolcanic rocks originated from a Cambrian and Ordovician (530–490 Ma) collisional event named Buzios Orogeny. The main characteristic of Cape Buzios is distinct structurally controlled beaches. The objective of this paper is to present results of morphodynamics of embayed beaches exposed to distinct waves directions and relate it to the morphological response of beach profiles. Thirteen different beach profiles were monitored during four years in seven embayed beaches using standard topographic methods, resulting in over 250 beach profile data. Wind and wave data statistics; morphodynamic and embayment scale parameters; equilibrium profiles; closure depth; and planform stability were also calculated. Results led to the identification of three different morphodynamic conditions. The first two are low energy reflective and high energy intermediate beaches that are morphologically stable. In the first case beaches are narrow and equilibrated with their transversal profile. Closure depths vary from 3 to 6 meters. In the second case beaches are overfilled with sediments which even in high energy conditions permit rapid morphological recovery, closure depths are up to 20 meters. The third morphodynamic condition refers to unstable beaches that also have two different characteristics: one group of beaches presents permanently erosional profiles, while the other group presents episodic erosional profiles. The differences were in the range of exposition to higher waves and the volume of nearshore sediments available. Estimated maximum wave heights of 1,3; 2,4 and 5,4 meters can be respectively correlated for each one of the morphodynamic conditions described above.

Coastal Impacts Induced by Storm Waves between Cape Frio and Cape Buzios, Rio de Janeiro, Brazil.

ABSTRACT Bulhoes, E.; Fernandez, G.; Oliveira Filho, S.R., Pereira, T.G., 2016. Coastal Impacts Induced by Storm Waves between Cape Frio and Cape Buzios, Rio de Janeiro, Brazil. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1047 - 1051, Coconut Creek (Florida), ISSN 0749-0208. The wave field in deep waters is notable for its variability and dictates the energy that will be directed towards the coast. Morphological impacts on coastal environments depend on the magnitude of the meteorological and oceanographic forcings and the beach capabilities of absorbing this energy. In the analysis between Cabo Frio and Cape Buzios, we considered the textural characteristics of the inner continental shelf from the analysis of 394 sediment samples, the volumetric variability of 438 surveys along 17 beach profiles and characteristics of 75 storms between 2003 and 2014. Results showed that sedimentation in the nearshore, through the mean grain size parameter, reflects the areas with higher or lower wave energy. The results also indicated the occurrence of a “storm waves season” between April and September, and this is the main element associated with erosion and volume variation of subaerial sand stock on beaches. A period with no occurrence of these storm waves (extended summer season) lead to the recovery of this subaereal sandy stock. The different segments of beaches show the greater or lesser magnitude of these effects, depending primarily on the orientation and exposure of each beach segment and also beach morphodynamics. Isolated storms with greater magnitude tend to promote severe erosion, especially if they occur at the beginning of this “season of storm waves”.

Recent changes in the Wanda Glacier, King George Island, Antarctica

Recent glaciological changes in Wanda Glacier, King George Island (KGI), South Shetland Islands (61°54’ S and 62°16’S, 57°35’W and 59°02’W) off the Antarctic Peninsula, were quantified by ice flow velocity, direction and fluctuation of glacier termini measurements. Topographic changes and DGPS surveys as well as transverse and longitudinal profiles were carried out to generate a Digital Surface Model. Results show that Wanda Glacier has a small drainage basin, a high retreat rate through fusion processes and reduced ice thickness if compared to other glaciers in KGI. Surface-area changes are assessed using historical satellite imagery from 1979 to 2011. Wanda glacier lost about 31 % of its original (1.5 km2 of area in 1979). The current continuous and fast retreat phase is attributed to the recent regional warming. Maximum ice surface velocity, measured using a stake network, reached 2.2 cm d-1 during the period of 2007–2011. Transverse profiles show the influence of the topography on the ice flow. Due to its small size and thermal conditions, Wanda Glacier responds rapidly to climatic variations, revealing its relevance for environmental studies.Recent glaciological changes in Wanda Glacier, King George Island (KGI), South Shetland Islands (61°54’ S and 62°16’S, 57°35’W and 59°02’W) off the Antarctic Peninsula, were quantified by ice flow velocity, direction and fluctuation of glacier termini measurements. Topographic changes and DGPS surveys as well as transverse and longitudinal profiles were carried out to generate a Digital Surface Model. Results show that Wanda Glacier has a small drainage basin, a high retreat rate through fusion processes and reduced ice thickness if compared to other glaciers in KGI. Surface-area changes are assessed using historical satellite imagery from 1979 to 2011. Wanda glacier lost about 31 % of its original (1.5 km² of area in 1979). The current continuous and fast retreat phase is attributed to the recent regional warming. Maximum ice surface velocity, measured using a stake network, reached 2.2 cm d -1 during the period of 2007–2011. Transverse profiles show the influence of the topography on the ice flow. Due to its small size and thermal conditions, Wanda Glacier responds rapidly to climatic variations, revealing its relevance for environmental studies.

Changes in vegetation cover on the Younghusband Peninsula transgressive dunefields (Australia) 1949-2017: Changes in vegetation cover on the Younghusband Peninsula dunefields

Studies have shown that the impact of climate change, human and animal actions on coastal vegetation can turn stabilized dunes into active mobile dunes and vice versa. Yet, the driving factors that trigger vegetation changes in coastal dunes are still not fully understood. In the transgressive dunefields of the Younghusband Peninsula (south-east coast of South Australia) historical aerial photographs show an increase in vegetation cover over the last ~70 years. This study attempts to identify the causes of the changes in vegetation cover (1949 to 2017) observed in a typical section of the coastal dune systems of the Peninsula. Vegetation cover was first estimated for various years using the available historical aerial photography (long-term changes – 1949 to 2017) and recent satellite imagery (short-term annual changes – 2010 to 2017) for the area, and then results were discussed against the observed changes in climatic variables and rabbit density, factors that could have played a role in this transformation. Results of longterm changes show that the vegetation cover has increased significantly from 1949 to 2017, from less than 7% vegetation cover to almost 40%, increasing dune stabilization and forming parabolic dune systems. Periods with the largest growth in vegetation cover (1952-1956 and 2009-2013) coincide with a significant decline in rabbit numbers. Rabbit density was found to be the primary factor linked to the rapid vegetation growth and stabilization of the dunefield, for both decadal long-term (last 68 years) and annual shortterm changes (last 8 years). Other factors such as changes in rainfall, aeolian sediment transport, land use practices, and the introduction of invasive plants have apparently played a limited to negligible role in this stabilization process.

Foredune Morphological Changes by Offshore Winds Revealed By Ground-Penetrating Radar: Massambaba Beach – Rio de Janeiro, Brazil

ABSTRACT Fernandez, G.B.; Figueiredo, M.S.; Rocha. T.B.; Maluf, V.B.; Martins, C., and Moulton, M.B.A., 2016. Foredunes Morphological Changes by Offshore Winds Revealed By Ground-Penetrating Radar: Massambaba Beach – Rio de Janeiro, Brazil. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 278–282. Coconut Creek (Florida), ISSN 0749-0208. Foredunes are usually formed under particular conditions, more common from onshore winds and available medium to fine sediments coming from the beach, with the vegetation playing an important role fixing this material. In some specific conditions, foredunes can be observed in areas with prevalent offshore winds. Massambaba beach is 54 km long and orientated in east-west direction. This beach is under action of prevalent northeast winds (offshore) and storm surges frequently formed by south to southwest winds and high-energy waves. At the east side of Massambaba beach, storm surges are responsible for overwash processes that deposit sediments in the back dunes. These deposits are reworked by offshore winds and represent the main sediment source for the foredunes. In these specific environmental conditions, the objective of this work is investigate morphological aspects and sedimentary architecture of the foredunes at east Massambaba beach. For this purpose, 3D morphological representations were made using DGPS and sedimentary architecture was identified by use of ground-penetrating radar. The 3D morphological representations revealed susceptible areas to washover processes and aeolian morphological impact. The sedimentary architecture observed shows six radarfacies. The following structures stood out: an onshore structure (f1c – avalanche deposits) associated with storm conditions, an offshore structure (f1d – aeolian cross-bedding) associated with the action of offshore winds and another offshore structure at the top of one of the radar profiles (f1e – parabolic migration deposits) that reveals recent movement of sediments. The applied methods allowed the identification of morphologic characteristics and similarities and differences in the sedimentary architecture.

Avaliação dos critérios morfodinâmicos para a fase de diagnóstico do Projeto Orla: um estudo de caso em praias arenosas com desembocaduras fluviais

The aim of this study is to analyze part of diagnostic criteria of the integrated coastal management project (Projeto Orla), specifically considering the morphodynamics and physiography as justification for an analysis focused on the physical vulnerability. Therefore, this work was carried out on the coast area close to the mouth of the Paraiba do Sul River, whose area is recognized by the intense instability and morphological stages of severe coastal erosion. The methodology for delineation of the shore, the establishment of restricted or non-building areas and characterization of shore types, associated with the establishment of Landscape Units were investigated. The application of these criteria indicated some weaknesses warning for the need of some adaptations related to the geomorphological characteristics of the coast. Thus, suggestions were synthesized for adapting and complementing, for example, the application of geoindicators for performance evaluation of coast morphodynamic.