Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O gráben do Tacutu, localizado no centro-nordeste do estado de Roraima, consiste em um segmento distensivo, correspondente a um rift intracontinental implantado no Mesozóico em uma zona de reativação do Cinturão Guiana Central, onde as principais estruturas estão orientadas preferencialmente a NE-SW. A profundidade da bacia pode chegar até sete mil metros, preenchida por uma sequência sedimentar que vai desde o Jurássico Médio ao Quaternário, incluindo termos vulcânicos relacionados à fase pré-rift. O atual nível de conhecimento geológico sobre esta bacia deve-se ao interesse à exploração de óleo e gás. Neste contexto, este trabalho visou aplicação de técnicas fotointerpretativas em imagens de Sensoriamento Remoto, a fim de se obter o mapa morfoestrutural, entender a evolução tectônica e caracterizar os principais compartimentos geomorfológicos do gráben do Tacutu e áreas adjacentes. A técnica fotointerpretativa aplicada seguiu os procedimentos do método lógico sistemático com a introdução de inovações como a geração em ambiente de SIG de mapas temáticos das feições lineares dos elementos de drenagem e das formas de relevo fotointerpretadas. O mapa morfoestrutural gerado mostrou dois conjuntos de morfoestruturas, um no interior e outro nas regiões de borda do graben, ambos possuem arranjos estruturais que refletem a evolução tectono-estratigráfica, a qual este gráben foi submetido. Enfim, através da metodologia empregada informações mais refinadas foram obtidas, contribuindo para o conhecimento sobre a evolução do relevo no gráben do Tacutu e suas relações com os processos tectônicos geradores, bem como deve auxiliar na elaboração de modelos prospectivos para exploração de óleo e gás. / The Takutu Graben, located in the central-northeast of the state of Roraima, consists of an extensional segment, corresponding to an intracontinental rift deployed in the Mesozoic in a reactivated zone of the Central Guyana Belt, where the main structures are preferentially oriented NE-SW. The depth of the basin can reachs even thousand meters, filled by a sedimentary sequences pans from the Middle Jurassic to the Quaternary include in related to the pre-rift. The current level of geological know ledge of this basin is due to the interest in the exploitation of oil and gas. In this context, the aim of this work is to apply photointerpretative techniques of the remote sensing, in order to obtain morphostructural maps, understand the tectonic evolution and characterize the main geomorphologic compartments of the Takutu graben. The photointerpretative techniques applied followed the procedures of system a logical method with the introduction of in novations like GIS environment generation of thematic map the linear elements of drainage and relief photointerpreted. The morphostructural map generated showed two sets of morphostructures, one inside of the graben and the other in the it sedge regions. Both of them possess structural arrangements that reflect thetectono-stratigraphic evolution of this graben. Finally, using the methodology employed more refine disinformation were obtained, contributing to knowledge about the evolution of the Takutu graben morphostructural and its relationship to the tectonic processes and should assist in developing models for the exploration of prospective oil and gas.

Com base nos procedimentos metodológicos da Geomorfologia Antropogênica (RODRIGUES 1997a, 1997b, 2004, 2005 e 2010) e na abordagem da Geomorfologia Urbana Histórica, esse trabalho objetiva avaliar as correlações entre as intervenções urbanas nos sistemas hidromorfológicos e as tendências espaciais e frequência das inundações na bacia hidrográfica do Córrego da Mooca. Para essa avaliação foram gerados o mapa da morfologia original na escala de 1:25.000, para o reconhecimento das tendências originais dos processos hidromorfológicos, e os mapas do uso do solo de diversos anos (1952, 1962, 1972, 1994 e 2008), para investigar a história cumulativa das intervenções urbanas e obter dados de indicadores morfológicos e de materiais superficiais para a avaliação dos impactos da urbanização (RODRIGUES, 2010). Foram também identificados os eventos de inundação que ocorreram na bacia do Córrego da Mooca entre os anos de 1971 e 2011, com base nos reportagens dos jornais Gazeta da Vila Prudente e Folha de Vila Prudente. Os 85 eventos de inundação identificados no levantamento histórico foram mapeados e suas informações sistematizadas no quadro de geoindicadores de mudanças. Com base nessa sistematização foram selecionados indicadores para a avaliação das variáveis antrópicas e naturais na ocorrência das inundações. Os resultados obtidos permitiram avaliar que as inundações ocorrem em setores da antiga planície de inundação onde as tendências da morfologia original foram potencializadas pela morfologia antropogênica. Identificou-se também que os eventos de inundação relatados ao longo de 40 anos foram mais frequentes nas faixas de precipitação com o total diário de até 60 mm, sendo que 82,5% ocorreram na faixa entre 0,1 e 15 mm. Além disso, concluiu-se que há uma tendência positiva entre o aumento da frequência e magnitude das inundações e as transgressões nos sistemas hidromorfológicos pela urbanização. Dessa forma, as derivações antrópicas são variáveis indispensáveis para o entendimento das tendências espaço-temporais das inundações em bacias hidrográficas urbanizadas. / Based on the methodological procedures of Anthropogenic Geomorphology (RODRIGUES 1997a, 1997b, 2004, 2005 and 2010) and the approach of the Urban Historical Geomorphology, this work aims to evaluate the correlation between urban interventions in hydromorphological systems and spatial trends and frequency of flooding in the Mooca Stream basin. For this evaluation and for the recognition of original hydromorphological processes trends were generated a map of the original morphology on the scale of 1:25,000 and land use maps from different years (1952, 1962, 1972, 1994 and 2008). Those maps were used to investigate the cumulative history of urban interventions and obtain data from morphological indicators and surface materials for assessing the impacts of urbanization (RODRIGUES, 2010). Flood events that occurred in the Mooca Stream basin between the years 1971 and 2011, were also identified based on newspaper reports of Gazeta da Vila Prudente and Folha de Vila Prudente. The 85 flood events identified in the historical survey were mapped and their information were systematized in framework geoindicators changes. Based on this systematic indicators were selected for the assessment of natural and anthropogenic variables on the occurrence of floods. The results obtained allowed us to evaluate the occurrence of floods in particular sectors of the old floodplain where original morphology probably were potentiated by anthropogenic morphology. It was also found that the flood events reported over 40 years were more frequent in total daily precipitation of up to 60 mm, and 82.5% occurred between 0.1 and 15 mm. Furthermore, the major positive correlationshipe between the analised variables is the frequency and magnitude of floods with the rate of spatial transgressions in hydromorphological systems by urbanization. Thus it was concluded that more studies that discriminate in the derivations anthropogenic are indispensable for modeling and understanding the spatial and temporal trends of flooding in urbanized watersheds.

A presente pesquisa objetiva a análise qualitativa e quantitativa das mudanças, decorrentes da urbanização, no sistema hidro-geomorfológico correspondente à Bacia Hidrográfica do Rio Tamanduateí, localizada na Região Metropolitana de São Paulo. O estudo, desenvolvido a partir de metodologia denominada Geomorfologia Antropogênica ou Antropogeomorfologia, sistematizado por meio de cartografia e orientado por indicadores morfológicos, de materiais superficiais e de processos hidro-geomorfológicos, baseia-se em análises retrospectivas cartográficas hidro-geomorfológicas, voltadas às condições originais desse sistema e subsistemas suas condições pré-urbanas -, e às condições representativas de diversos momentos do processo histórico de expansão urbana e produção do espaço urbano metropolitano de São Paulo. Assim, a identificação e análise das características originais e das mudanças promovidas por intervenções antrópicas desenvolveram-se de forma articulada, a partir da cartografia geomorfológica e da pesquisa em fontes historiográficas e iconográficas, considerando-se diferentes recortes temporais e, conseqüentemente, o contexto histórico e sócio-econômico da produção do espaço urbano que promoveu tais modificações. Como resultado da pesquisa, foram produzidos dados que expressam as mudanças no sistema hidro-geomorfológico, decorrentes do processo de urbanização. Esses dados foram obtidos a partir dos documentos cartográficos elaborados, tais como: Mapa da Geomorfologia Pré- Urbana, mapas evolutivos (Mapa da Urbanização e Mudanças Morfológicas de 1881, 1930, 1952, 1983 e 2001), Mapa da Morfologia Antropogênica e Mapa de Unidades Morfológicas Complexas. Além de possibilitar avaliações a respeito do grau de derivação ambiental progressivamente gerado pela intervenção urbana, o estudo colabora na identificação de agentes sociais históricos relevantes no processo de produção do espaço metropolitano. / This research aims at qualitative and quantitative analysis of the changes - arising from urbanization - on hydro-geomorphological system corresponding to Tamanduateí River Basin, located in the Metropolitan Region of São Paulo. The study, developed from the methodology called \"Anthropogenic Geomorphology\" or \"Anthropogeomorphology\" through systematic mapping and guided by morphological indicators of surface materials and hydrogeomorphological processes, based on retrospective cartographic hydro-geomorphological analysis, directed at the original conditions of that system and subsystems - its pre-urban conditions - and representative conditions in different moments of the historical process of urban expansion and production of urban space in São Paulo metropolitan area. Thus, the identification and analysis of the original features and changes promoted by human interventions developed in a coordinated way, from geomorphological mapping and research in historiography and iconographic sources, considering different time periods and, consequently, the historical context and socio-economic production of urban space that promoted such changes. As a result of the survey, were produced data that express the changes in hydro-geomorphological system, arising from the urbanization process. Those data were obtained from the cartographic documents produced, such as: Map of Pre-Urban Geomorphology, Evolutionary Maps (Maps of Morphological Changes and Urbanization, 1881, 1930, 1952, 1983 and 2001), Map of Anthropogenic Morphology and Map of Morphologic Units Complex. Besides enabling assessments about the degree of environmental derivation progressively generated by urban intervention, the study helps to identify relevant historical social agents in the process of production of the metropolitan space.

O objetivo deste trabalho de pesquisa é o de buscar entender os tempos e eventos que determinaram as grandes mudanças climáticas no Éon Fanerozoico. Técnicas são constituídas, metodologias estabelecidas, e por vezes são aceitas como sendo as verdades científicas. Com as inovações nas técnicas, com o mudar das ciências, mudam as evidências, mudam as verdades, fazendo mudar nossa percepção do passado. Este trabalho apresenta elementos para um debate sobre o clima da Terra no Fanerozoico, estabelecido a partir de pesquisas bibliográficas sobre evidências passadas e atuais. / The goal of this research work is to understand the times and events that determined the great climatic changes in the Phanerozoic Eon. Techniques are constituted, methodologies are established, and are sometimes accepted as scientific truths. With innovations in techniques, with the change of science, change the evidence; change the truths, making change our perception of the past. This paper presents elements for a discussion on the Earth\'s climate in Phanerozoic established from bibliographical research on past and current evidences.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-06-29T15:50:34Z No. of bitstreams: 1 derikribeirodepaiva.pdf: 8307169 bytes, checksum: 3b1448fabaff436fa6ccdfcbe5e4e90d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-07-03T13:52:19Z (GMT) No. of bitstreams: 1 derikribeirodepaiva.pdf: 8307169 bytes, checksum: 3b1448fabaff436fa6ccdfcbe5e4e90d (MD5) / Made available in DSpace on 2018-07-03T13:52:19Z (GMT). No. of bitstreams: 1 derikribeirodepaiva.pdf: 8307169 bytes, checksum: 3b1448fabaff436fa6ccdfcbe5e4e90d (MD5) Previous issue date: 2018-03-28 / O crescente interesse na representação dos aspectos do relevo tem como justificativa a ampla gama de possibilidades de aplicação dos produtos oriundos dessa técnica cartográfica no que se refere ao planejamento. Diante disso, a demanda por documentos cartográficos que subsidiem os processos de intervenção no relevo tem aumentado. Essa crescente atenção facultada à cartografia geomorfológica nas pesquisas ambientais tem culminado num subsidio não só a Geomorfologia especificamente, como também às diversas ciências que envolvem as mais distintas esferas do planejamento. Diante dessa realidade tornam-se de substancial importância os esforços em prol da pesquisa e desenvolvimento de trabalhos voltados para a produção de mapas e cartas geomorfológicas em escala de alto nível de detalhamento, visando que estas possam vir a subsidiar o processo decisório, em âmbito local, acerca da disposição espacial e tipos de intervenção passíveis ou não de serem desenvolvidas no ambiente em questão. Assim, a presente dissertação tem como objetivo geral a elaboração da carta geomorfológica da bacia hidrográfica do rio Novo, intentando-se que esta possa subsidiar futuras pesquisas que visem a compreensão dos processos e fatores responsáveis pela conformação do relevo local. Como objetivos específicos intenta-se que a mesma possa subsidiar o processo decisório voltado para o planejamento na Zona da Mata Mineira, podendo também vir a fornecer dados básicos de entrada para outras pesquisas. A metodologia adotada para o alcance dos objetivos supracitados concerne à proposta elaborada no âmbito do IBGE, cujo princípio básico trata-se da ordenação dos fatos geomorfológicos conforme uma classificação que leva em consideração aspectos temporais e espaciais, e que viabiliza a distinção dos modelados como unidade básica do relevo, bem como os grupamentos que mantém relações hierárquicas com essas unidades básicas. Dessa forma, foram identificados os tipos de modelados, sendo estes posteriormente diferenciados e caracterizados de acordo com fatores intrínsecos à sua natureza estrutural, litológica, pedológica, climática e morfodinâmica. Como forma de expandir a compreensão acerca dos processos e dinâmicas condicionantes da conformação das paisagens da região foi levada a efeito uma interpretação de cunho morfoestrutural da área, tendo esta possibilitado a identificação de cinco distintos compartimentos morfoestruturais regionais que, em parte, abrangem a área cerne da presente pesquisa. / The increasing interest in the representation of the aspects of the relief has as justification the wide range of possibilities of application of the products coming from this cartographic technique when it comes to planning. In view of this, the demand for cartographic documents that subsidize relief intervention processes has increased. This growing attention given to geomorphological cartography in environmental research has culminated in a subsidy not only to Geomorphology specifically, but also to the various sciences that involve the most distinct spheres of planning. Faced with this reality, efforts to research and develop geomorphic maps and geomorphic charts on a high level of detail are becoming of great importance, aiming at supporting the decision-making process at the local level, about the spatial arrangement and types of intervention that may or may not be developed in the environment in question. Thus, the present dissertation has as general objective the elaboration of the geomorphological chart of the river basin of the rio Novo, trying to be able to subsidize future researches that aim at the understanding of the processes and factors responsible for the conformation of the local relief. As specific objectives, it is intended that it can support the decision-making process geared to planning in the Zona da Mata Mineira, and may also provide basic input data for other surveys. The methodology adopted for the achievement of the aforementioned objectives concerns the proposal elaborated within the scope of the IBGE, whose basic principle is the ordering of geomorphological facts according to a classification that takes into account temporal and spatial aspects, and which makes possible the distinction of those modeled as a unit as well as the groupings that maintain hierarchical relationships with these basic units. In this way, the types of modeling were identified, being later differentiated and characterized according to factors intrinsic to its structural, lithological, pedological, climatic and morphodynamic nature. As a way to expand the understanding of the processes and dynamics conditioning the landscape's conformation, a morphostructural interpretation of the area was carried out, making possible the identification of five distinct regional morphostructural compartments that, in part, cover the core area of this research.

Les séismes sont connus comme des catastrophes naturelles destructrices et meurtrières. Particulièrement dans les régions montagneuses, les effets des séismes sont encore beaucoup plus aggravés à cause des effets de site topographiques. La présence d'une pente est à l'origine d'une amplification du signal sismique notamment dans le voisinage de la crête. De nombreux séismes anciens tels que le séisme de Lambesc (1909, Ms=6.2) qui a conduit à la destruction du village de Rognes (Bouches-du-Rhône, France), ou plus récemment le séisme d'Athènes en Grèce (1999, Ms=5.9) qui a endommagé la ville d'Adames ainsi que les séismes de Chichi à Taiwan (1999, Mw=7.6), du Salvador (2001, Mw=7.6) et du Sichuan (2008, Mw=7.9) responsables de très nombreux glissements de terrain particulièrement catastrophiques sont des exemples représentatifs. Les investigations post-sismiques ont montré une contribution importante des effets de site topographiques au bilan des dommages humains et matériels. Dans le but d'améliorer les connaissances de ce phénomène, de nombreuses simulations numériques ont été réalisées sur des modèles de versant isolés en utilisant le logiciel FLAC 2D (Itasca). Les résultats obtenus ont été analysés en considérant plusieurs critères comme les facteurs d'amplification, les surfaces et les dimensions des zones d'amplification ainsi que la distribution spatiale de ces zones dans le massif de versant. Des études paramétriques ont permis de mettre en évidence le rôle principal de la fréquence adimensionnelle, rapport de la hauteur du versant à la longueur d'onde du signal sismique, dans l'évaluation des effets de site topographiques. Ces résultats montrent également que la pente est le deuxième paramètre important, suivie du coefficient de Poisson et de la géométrie de la crête et du pied de la pente.Ces résultats numériques ont également permis de définir des relations empiriques, nommées ANS, qui permettent d'estimer les effets de site topographiques selon les différents critères d'interprétation. Ces formules sont adaptées pour les signaux sismiques avec une bande de fréquences prédominantes relativement étroite. Pour les autres cas, la Méthode de Décomposition des ondes (MD) a été développé dans ce travail. Cette méthode est basée sur la décomposition du signal complexe multi-fréquentiel en plusieurs ondes mono-fréquentielles par transformée de Fourier. L'effet du signal complexe est alors évalué en faisant une combinaison des effets individuels de chaque onde élémentaire. Ces approches développées dans ce travail (ANS et MD) permettent d'évaluer les effets de site topographiques, en tenant compte de plusieurs paramètres géomorphologiques et sismiques du massif de versant ainsi que du contenu fréquentiel du signal sismique, sans avoir recours à des simulations numériques. / Earthquakes are known as destructive and murderous natural catastrophe. Particularly in the mountainous regions, the effects of earthquakes are still much aggravated due to the topographic site effects. The presence of a slope causes an amplification of the seismic signal, particularly in the vicinity of the crest. Numerous earthquakes in the past such as the 1909 Lambesc earthquake (Ms=6.2) which led to the destruction of the Rognes village (Bouches-du-Rhône, France), or more recently the 1999 Athens, Greece earthquake (Ms=5.9) which damaged the Adames city as well as the 1999 Chichi, Taiwan earthquake (MW=7.6), the 2001 El Salvador earthquake (MW=7.6) and the 2008 Sichuan earthquake (MW=7.9) responsible for numerous catastrophic landslides are representative examples. Post-seismic investigations demonstrated a significant contribution of topographic site effects on the human and material damage assessment.In order to improve the knowledge of this phenomenon, numerous numerical simulations were performed on the step-like slope models by using the FLAC 2D software (Itasca). The obtained results were analyzed by considering various criteria such as amplification factors, dimensions and area of amplification zones as well as spatial distribution of these zones inside the slope mass. The parametric analyses allow underlining the principal role of the dimensionless frequency, ratio of the slope height to the wavelength of the seismic signal, in the evaluation of topographic site effects. These results also show that the slope angle is the second important parameter, followed by the Poisson's ratio and the geometry of the crest and of the toe of slope.These numerical results allow pointing out empirical equations, called ANS, which can be used to estimate the topographic site effects according to different interpretation criteria. These formulas are suitable for seismic signals with a relatively narrow band of predominant frequencies. For other cases, the method concerning decomposition of seismic incident wave (MD) was developed in this work. This method is based on the decomposition of the complex multi-frequency seismic signal into multiple mono-frequency waves by using Fourier transform. The effect of the complex signal is then evaluated through a combination of the effects of elementary waves. The approaches developed in this work (ANS and MD) allow evaluating the topographic site effects, by taking into account geomorphologic and seismic parameters of the slope as well as the frequency content of the seismic signal, without recourse to numerical simulations.

Esta dissertação objetiva investigar a evolução geomorfológica dos ambientes proglaciais (geleiras Ecology, Sphinx, Baranowski, Tower e Windy) da margem leste do campo de gelo Warszawa (62°12’0” S - 58°30’0” W) na Ilha Rei George, Antártica, entre 1956 - 2017. Dados obtidos por sensores remotos, como Aster GDEM2, imagens Sentinel-2 (2017) e WorldView-2 (2014), possibilitaram o mapeamento geomorfológico das formas de relevo de mesoescala proglaciais. A variação frontal e de área total das geleiras foi estimada e mapeada com dados de imagens de satélite (Sentinel-2 de 2017 e WorldView-2 de 2014) e vetores de variação frontal de 1956, 1979, 1988 e 2000. Evidenciou-se um contínuo processo de retração nas geleiras Ecology, Sphinx, Baranowski, Tower e Windy, com perda total de área de 33%, 25%, 37%, 71% e 30%, respectivamente, no período. A geleira Windy apresentou mudanças recentes em seu término de maré para terrestre, formando uma área proglacial com a exposição de formas de relevo deposicionais glaciais. Estimou-se um aumento das áreas livres de gelo de 6,3km² no período entre 1956-2017. Em resposta ao processo de retração glacial, há exposição de formas de relevo nos ambientes livres de gelo na área de estudo com a formação da rede de drenagem fluvioglacial e glaciolacustre e a formação de ambientes proglaciais com exposição de morainas laterais, frontais, latero-frontais e eskers. As áreas livres de gelo recentes são suscetíveis a processos de retrabalhamento por ação gravitacional, eólica e pluvial. Foram determinados três estágios de evolução do ambiente proglacial das geleiras associadas às feições geomorfológicas geradas em cada fase. Como mudança ambiental detectada está a sucessão de ambientes proglaciais, paraglaciais e periglaciais. / This dissertation aims to investigate the proglacial geomorphological evolution (Ecology, Sphinx, Baranowski, Tower and Windy glaciers) in the western sector of Warszawa Ice Cap (62°12’0” S 58° 30’ 0” W), Admiralty Bay coast, King George Island, Antarctica between 1956 and 2017. Data obtained by remote sensors, such as Aster GDEM2, Sentinel-2 (2017) and WorldView-2 (2014) images, were applied in geomorphological mapping of the proglacial mesoscale landforms. Glacial retreat and fluctuations of glaciers areas were estimated (using Sentinel-2 images, acquired in 2017, WorldView-2 data, acquired in 2014, and outline data of the 1956, 1979, 1988 and 2000). The results evidenced the continuous retreat processes in period for Ecology, Sphinx, Baranowski, Tower and Windy glaciers, with of 33%, 25%, 37%, 71% and 30% of the area lost, respectively. The Windy glacier changed of outlet glacier for land terminus conditions in latest decades, with a recent proglacial environment development. In response to glacial retreat processes there is a glacial landforms exposition in new ice-free environments in the study area. Was recorded an increase of the 6.3km² in ice-free land areas between 1956 and 2017 in in the western sector of Warszawa Ice Cap. As response the retreat processes there are the development of the glacio-fluvial drainage network, glacio-lacustrine landforms and the formation of proglacial ice marginal environments with lateral moraines, lateral-frontal moraines, frontal moraines, eskers. Recent ice-free areas are susceptible to gravitational, wind and pluvial reworking process. Three stages of evolution of the proglacial environments of the glaciers associated with the geomorphological features formed in each phase and environmental changes in response the glacier retreat was determined. Was detected the succession of proglacial for paraglacial and periglacial environments as evidence of the environmental change.

<p>Hyporheic exchange is key to buffer water quality and temperatures in streams and rivers, while also providing localized downwelling and upwelling microhabitats. In this research, the effect of geomorphological parameters on hyporheic exchange has been assessed from a physical standpoint: surface and subsurface flow fields, pressure distribution across the sediment/water interface and the residence time in the bed.<br></p><p>First, we conduct a series of numerical simulations to systematically explore how the fractal properties of bedforms are related to hyporheic exchange.We compared the average interfacial flux and residence time distribution in the hyporheic zone with respect to the magnitude of the power spectrum and the fractal dimension of riverbeds. The results show that the average interfacial flux increases logarithmically with respect to the maximum spectral density whereas it increases exponentially with respect to fractal dimension.<br></p><p>Second, we demonstrate how the Froude number affects the free-surface profile, total head over sediment bed and hyporheic flux. When the water surface is fixed,the vertical velocity profile from the bottom to the air-water interface follows the law of the wall so that the velocity at the air-water interface has the maximum value. On the contrary, in the free-surface case, the velocity at the interface no longer has the maximum value: the location having the maximum velocity moves closer to the sediment bed. This results in increasing velocity near the bed and larger head gradients, accordingly.<br></p><p>Third,we investigate how boulder spacing and embeddedness affect the near-bed hydrodynamics and the surface-subsurface water exchange.When the embeddedness is small, the recirculation vortex is observed in both closely-packed and loosely-packed cases, but the size of vortex was smaller and less coherent in the closely-packed case. For these dense clusters, the inverse relationship between embeddedness and flux no longer holds. As embeddedness increases, the subsurface flowpaths move in the lateral direction, as the streamwise route is hindered by the submerged boulder. The average residence time therefore decreases as the embeddedness increases.<br></p><p>Lastly, we propose a general artificial neural network for predicting the pressure field at the channel bottom using point velocities at different level. We constructed three different data-driven models with multivariate linear regression, local linear regression and artificial neural network. The input variable is velocity in x, y, and z directions and the target variable is pressure at the sediment bed. Our artificial neural network model produces consistent and accurate prediction performance under various conditions whereas other linear surrogate models such as linear multivariate regression and local linear multivariate regression significantly depend on input variable.<br></p><p>As restoring streams and rivers has moved from aesthetics and form to a more holistic approach that includes processes, we hope our study can inform designs that benefit both structural and functional outcomes. Our results could inform a number of critical processes, such as biological filtering for example. It is possible to use our approach to predict hyporheic exchange and thus constrain the associated biogeochemical processing under different topographies. As river restoration projects become more holistic, geomorphological, biogeochemical and hydro-ecological aspects should also be considered.<br></p>

Orientador: George Luiz Luvizotto / Resumo: A formação das rias fluviais na Amazônia possui uma relação bem conhecida com o processo de avanço do nível do mar durante o Holoceno. Sugestões sobre a presença de controle estrutural e tectônico na gênese destas e de outros elementos do relevo amazônico tem sido levantadas por diversos autores, porém poucos elementos conclusivos foram apresentados até o momento. Este trabalho apresenta, no primeiro momento, uma série de evidências de diferentes fontes mostrando controle estrutural ao longo do ria do Tapajós e em áreas de terra firme adjacentes. A metodologia utilizada, é inovadora por integrar dados geomorfológicos, geológicos e geofísicos (sísmica, magnetometria e gravimetria) obtidos sem custo e disponíveis para grandes áreas, o que é uma grande vantagem em uma zona de difícil acesso como a Amazônia. Trata-se ainda de uma abordagem pouco usual dentro da geomorfologia na qual encontramos resultados muito promissores. Os resultados mostram a influência de elementos estruturais na configuração do relevo amazônico na região do baixo Tapajós. É proposto um modelo de horsts e grábens limitados por lineamentos com direção ENE-WSW com expressão regional. Em seguida apresentamos uma classificação para o canal do Tapajós baseado em variáveis morfométricas extraídas de perfil transversal. A classificação apresenta três trechos distintos para o canal do Tapajós no perímetro analisado, denominados Trecho do Canal Estreito, Baixo Trecho da Ria e Alto Trecho da Ria. Estes trechos possue... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The formation of the fluvial rias in the Amazon has a well-known relationship with the process of sea level transgression during the Holocene. Suggestions about the presence of structural and tectonic control in the genesis of these and other elements of the Amazonian relief have been raised by several authors, but few conclusive elements have been presented so far. This work presents, in the first moment, a series of evidences from different sources showing structural control along the Tapajós Ria and in adjacent land areas. The methodology used is innovative because it integrates geomorphological, geological and geophysical data (seismic, magnetometry and gravimetry) obtained at no cost and available for large areas, which is a great advantage in an area of difficult access such as the Amazon. It is also an unusual approach within geomorphology in which we find very promising results. The results show the influence of structural elements in the configuration of the Amazonian relief in the region of the lower Tapajós. A model of horsts and grabens limited by lineaments with regional expression is proposed. Next, we present a classification for the Tapajós channel based on morphometric variables extracted from transversal profiles. The classification presents three distinct sections for the Tapajós channel in the analyzed perimeter, here called Narrower Channel Reach, Lower Ria Reach and Higher Ria Reach. These reaches have statistical support and agreement with most of the s... (Complete abstract click electronic access below) / Doutor

<p>Rivers are constantly undergoing change due to erosion and sedimentation along their banks. Although these processes generally occur gradually, flood events can significantly accelerate river migration, creating a risk for human life and infrastructure. As a result, it is important to identify river reaches that are prone to channel migration and determine the extent of migration. However, detailed information about river migration across entire river networks is not readily available. This study seeks to develop a Python-based tool that can generate river migration rasters across large watersheds using Landsat imagery. The methodology involves extracting the centerlines of river features in Landsat imagery using the Modified Normalized Difference Water Index (MNDWI) and the Skeletonize function available in the scikit-image library, followed by the application of the Particle Image Velocimetry (PIV) algorithm to compute the river channel migration. The PIV algorithm generates a set of migration rasters that are analyzed to extract the long-term migration of each of the reaches. The tool also creates intermediate outputs, such as the MNDWI raster, binary land-water raster, and skeletonized river centerlines, which can be further analyzed to gain insights into the river's behavior. The methodology is implemented in the Wabash and Lower Mississippi River Basins, and the tool's effectiveness is validated against manual measurements of the river migration available for the Wabash Basin. In addition, this study analyzes the correlation between long-term migration and various factors, such as reach sinuosity, drainage area, geology, and streamflow. The results of the analysis show that drainage area is highly correlated with river migration. The correlation results are compared with the prior literature, thereby serving to validate the developed framework. This framework has the potential to aid decision-makers and policymakers in identifying the long-term patterns of river channel migration, facilitating their efforts to plan for infrastructure resilience. By utilizing this methodology, river managers and other stakeholders can gain insights into river migration across large watersheds and identify areas that require further monitoring and management.</p>