L'analyse des variations spatio-temporelles du charriage est un élément important pour la compréhension de la dynamique fluviale. Ce manuscrit présente les recherches réalisées sur le développement d'une méthode de mesure du transport solide par acoustique passive. Un capteur de pression acoustique est utilisé pour mesurer le bruit généré par le transport par charriage au fond du lit de la rivière. Cette méthode originale a fait l'objet de quelques explorations durant les dernières décennies, qui ont montré que la puissance et le contenu fréquentiel du son généré dépendaient de la granulométrie des matériaux et du flux solide. Mais les applications au milieu naturel sont restées très limitées ; elles sont donc au centre de cette recherche.La première difficulté de la mesure est liée à l'existence de bruit environnant qui se superpose au bruit du charriage. Des mesures acoustiques ont été réalisées dans différentes typologie de rivières, du torrent à la grande rivière navigable. A l'aide de ces différentes expériences et de la bibliographie, les éléments du paysage acoustique d'une rivière sont identifiés. Le paysage acoustique d'une rivière est composé par les processus hydrodynamiques que sont la turbulence, l'agitation de surface et le transport de sédiment par charriage. Le charriage produit des bruits larges bandes, dans la partie haute du spectre et peut être masqué par les bruits de surface dans la région du kilohertz. Des outils de traitement du signal sont proposés afin de repérer les différentes dynamiques contenues dans le signal acoustique mesuré.L'interprétation du signal ne peut être faite sans une bonne compréhension des phénomènes de propagation des ondes acoustiques dans la rivière. On montre que la rivière se comporte comme un guide d'onde et une résolution de l'équation d'onde par une approche modale est proposée. On comprend alors que la propagation des ondes acoustiques est limitée par une fréquence de coupure inversement proportionnelle à la hauteur d'eau. Les observations de terrain faites sur la variation du champ de pression acoustique dans la verticale sont bien reproduites par le modèle d'un guide d'onde de Pekeris. Le modèle est alors utilisé pour montrer l'importance de la profondeur, de la constitution du fond de la rivière ou encore de la géométrie du canal sur la constitution du signal.Finalement, trois chroniques de signaux acoustiques enregistrés dans des rivières différentes sont analysées. Un descripteur est proposé pour chaque chronique de signaux, en fonction des bruits ambiants présents dans l'environnement lors de la mesure. Ce descripteur acoustique est confronté à des mesures comparatives du charriage et de bonnes corrélations sont observée. Elles montrent que la mesure hydrophone permet d'identifier la phase de l'initiation du transport par charriage et qu'elle est intégrative du transport sur une surface importante de la rivière. Ces expériences confirment la simplicité de mise en œuvre de la méthode et précisent les limites d'utilisation de l'acoustique passive, particulièrement pour les rivières à fortes pentes. Elles confirment également la validité des méthodes d'analyse du signal qui ont été utilisées et le besoin de mesures comparatives du milieu pour interpréter le signal. / Analysing the spatio-temporal variability of solid transport processes is key to the study of fluvial morphodynamics. Our research focusses on the development of passive acoustics to monitor bedload transport. A hydrophone is used to sense the acoustic pressure in the river in order to record the sound generated by inter-particle collisions. This original method has been mostly developed in laboratories during the past decades. It has been shown that the acoustic power and the frequencies of the monitored signals are linked to bedload fluxes and granulometry. The use of passive acoustics in natural streams has encountered limited success. It is the core of our research.First we address the existence of multiple sound sources in the environment. Acoustic measurements have been realised in several types of rivers: steep channels and large gravel bed rivers. These multiple experiences along with the bibliography have allowed us to describe river soundscapes. Hydrodynamics govern the soundscape, namely turbulence, agitating surfaces, and bedload transport. Inter-particle collisions generate sound in a wide range of frequencies, which depend on their sizes. It can be masked by the occurrence of agitating surface noise in the kilohertz region. Signal processing tools are proposed to study the dynamics of the different processes composing the signal.Signal interpretation could only be achieved by understanding the propagation properties of the acoustic waves in the river. It is shown that the river acts as an acoustic wave guide. A modal approach is suggested to solve the wave equation. The model points to the existence of a cutoff frequency inversely proportional to the water depth. Observations made on the vertical variation of the field pressure are correctly simulated. The signal dependence on water depth, the structure of the bed, and the geometry of the channel are studied using this model.Finally, we analyze three chronicles of acoustic signals recorded in the field. A signal descriptor is constructed for each data set, depending on the ambient noise conditions. This descriptor is compared to other measurements of bedload transport and good correlations are found. Initiation of motion is monitored and the integrative aspect of the acoustic measure is shown. These experiences highlight the simplicity of the method and show some of its limits. It is also shown that measurements of other environmental parameters are needed to interpret the results.

Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2016-04-08T19:47:07Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Monitoramento hidrossedimentológico numa bacia hidrográfica do escudo sul-rio-grandense.pdf: 3298608 bytes, checksum: 197f42a8c4f63d0217bc52c6db4902f1 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-04-08T19:47:19Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Monitoramento hidrossedimentológico numa bacia hidrográfica do escudo sul-rio-grandense.pdf: 3298608 bytes, checksum: 197f42a8c4f63d0217bc52c6db4902f1 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-04-08T19:47:29Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Monitoramento hidrossedimentológico numa bacia hidrográfica do escudo sul-rio-grandense.pdf: 3298608 bytes, checksum: 197f42a8c4f63d0217bc52c6db4902f1 (MD5) / Made available in DSpace on 2016-04-08T19:47:39Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Monitoramento hidrossedimentológico numa bacia hidrográfica do escudo sul-rio-grandense.pdf: 3298608 bytes, checksum: 197f42a8c4f63d0217bc52c6db4902f1 (MD5) Previous issue date: 2015-04-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A construção e uso de redes de monitoramento hidrossedimentológicas, são extremamente importantes para compreensão da dinâmica dos fenômenos envolvidos, chuva, vazão e produção de sedimentos. O monitoramento hidrossedimentológico realizado para descrever e compreender o transporte e a produção de sedimentos em uma bacia hidrográfica. Assim o objetivo deste trabalho foi analisar relações entre os processos hidrossedimentológicos numa bacia hidrográfica rural, utilizando técnicas de monitoramento. O trabalho foi realizado na bacia hidrográfica do Arroio do Ouro, localizada entre os municípios de Pelotas e Morro Redondo/RS, com área de 17,17km2, elevação média de 194 metros, predominância de relevo ondulado. Os usos predominantes do solo são das atividades desenvolvidas em pequenas propriedades familiares, observando-se o cultivo de espécies como pêssego, milho e tabaco, além de atividades de pecuária leiteira e avicultura. O monitoramento hidrossedimentológico contínuo teve início em 2014, com sensores de precipitação (pluviógrafos), sensor de pressão (nível) e sensor de turbidez (turbidímetro). Durante o período de monitoramento de 6 meses (abril a outubro de 2014) foram monitorados 13 eventos de precipitação, com diferentes características e em diferentes condições de uso e manejo do solo. Os resultados demonstram que a produção de sedimento tem relação direta com a magnitude dos eventos de precipitação, na qual um evento extremo foi responsável pelo transporte de 1.335,58 toneladas de sedimento, correspondendo a 59,4% da produção total de sedimentos de todos os eventos monitorados. O sedimento transportado em arraste representou de 9 a 43,8% do total de sedimento transportado, destacando sua importância do transporte em arraste no Arroio do Ouro. O laço de histerese não apresentou predominância em um único sentido, observando-se eventos com sentido horário e anti-horário. No entanto os eventos que apresentaram histerese anti-horária foram caracterizados por serem de pequena magnitude, nestes eventos é possível que ocorra a deposição de sedimento na calha fluvial, limitados ao transporte de sedimento proveniente de áreas mais distantes como é o característico deste tipo de histerese. / The construction and the use of hydrosedimentological monitoring networks, are extremely important for the comprehension of the dynamics of phenomena involved, e.g. rain, discharge and sediment production. The hydrosedimentological monitoring is realized to describe and understand the transport and production of sediment in one catchment. Therefore the objective of this work was to analyze the relationship between the hydrosedimentological processes in one rural catchment, using monitoring techniques. This work was developed in the Arroio do Ouro catchment, situated between Pelotas and Morro Redondo/RS, with a drainage area of 17,27km², with average elevation of 194 meters, and undulating relief predominant. The soil uses are destined to activities in small farms, observing the cultivate of peach, corn and tobacco, apart from activities of livestock milk and aviculture. The continuous hydrosedimentological monitoring began in the beginning of 2014, with precipitation sensors (rain gauges), pressure sensors (pressure-sensing limnograph), and turbidity sensors (turbidity meter).During the 6-month monitoring period (April to October, 2014) 13 precipitation events were monitored, with different features and different condition of use and management. The results demonstrate that the sediment production has a direct relation with the magnitude of the precipitation events, in which one of these events was responsible for the transport of 1335,58 tons of sediment, corresponding to 59,4% of the total production of sediments of the all monitoring events. The bedload transported represented from 9 to 43,8% of the total of sediment rate, highlighting the importance of the total bedload in Arroio do Ouro. The hysteretic loops did not produce predominance of one type of way, presenting clockwise and counter-clockwise events. However, the events which presented counter-clockwise hysteretic loops were characterized by the lower magnitude. In these events it is possible the occurence of sediment deposition in the river channel, limited to transport of sediment from more distant areas, as it is typical in this type of hysteretic loops.

Un écoulement fluide (air ou liquide) au-dessus d’un matériau granulaire induit, au-delà d’un seuil, un transport de grains qui peut conduire à la formation de dunes. Dans une première partie, nous étudions la morphodynamique des dunes éoliennes. Grâce à une modélisation simplifiée des transports de sédiment, la description de la dynamique d’une dune formée sur un fond plat non-érodable sous un écoulement unidirectionnel peut se réduire à un système d’équations différentielles couplées du premier ordre. Le modèle développé permet d’identifier les mécanismes qui influencent la stabilité linéaire d’une dune transverse rectiligne. Lorsque la diffusion latérale de sédiment sur la face amont est dominante devant celle sur la face aval, notre modèle prédit la stabilité de la dune transverse. Lorsque la dune transverse est instable, elle se fragmente en dunes en forme de croissant, appelées barkhanes. Grâce aux caractéristiques morphologiques des dunes éoliennes issues des données de terrain, les paramètres macroscopiques qui influencent la stabilité sont déterminés. Dans une seconde partie, nous analysons l’influence de la présence de formes sédimentaires aquatiques sur les modes de transport de sédiment (charriage ou suspension). Des expériences en chenal hydraulique permettent de suivre la déstabilisation d’un lit plat de sédiment par un écoulement unidirectionnel. Le suivi de la morphologie du fond ainsi que le piégeage différencié des modes de transport de sédiment permettent de mettre en avant que l’apparition et la croissance de dunes s’accompagnent d’une augmentation du transport de sédiment. / Above a threshold, a flow (of liquid or air) over a granular bed leads to grain transport that can induce dune formation. In the first part of this thesis, we study the morphodynamics of eolian dunes. With a simplified sediment transport model, the description of the dynamics of a dune formed on an non-erodible bed under unidirectional flow is reduced to a system of first order coupled differential equations. With this model, we identify the mechanisms that influence the linear stability of a rectilinear transverse dune. When lateral sediment diffusion on the upwind side of the dune prevails over the downwind side diffusion, our model predicts transverse dune stability. When the transverse dune is unstable, it breaks into crescent-shaped dunes called barchan dunes. With morphological characteristics of aeolian dunes taken from field data, macroscopic parameters influencing the dune stability are calculated. In the second part, we analyze the effect of aquatic bedforms on the mode of sediment transport (bedload or suspension). With flume experiments we follow the destabilization of a flat sediment bed under a unidirectionnal flow. Recorded bed morphology and differentiated trapping of sediment allow us to distinguish between bedload and suspension and to show that the dune formation and growth come along with an increase of sediment transport.

Le transport par charriage reste un phénomène mal compris en raison notamment de la polydispersité des particules et de la ségrégation résultante. Nous avons mené une étude expérimentale à l'échelle de la particule dans le but de comparer le mouvement de billes de verre sphériques de 4~mm et 6~mm et d'analyser la ségrégation de mélanges de deux tailles. Les particules sont entraînées dans un mouvement quasi-bidimensionnel par un écoulement turbulent et supercritique dans un canal à forte pente sur un lit mobile sous des conditions d'équilibre de charriage. Les écoulements ont été filmés sur le côté et analysés par traitement d'image afin de déterminer les trajectoires des particules, leur état de mouvement (arrêt, roulement, saltation) et la hauteur d'eau. Alors que les billes de 6~mm des cas unimodaux sont principalement en roulement, la saltation est prédominante pour les billes de 4~mm et les billes du mélange. Nos données monodisperses supportent le modèle d'érosion-dépôt de cite{Char06}. Les profils de vitesse présentent trois zones (exponentielle, linéaire, logarithmique). De même que les profils de concentration, ils ont des similitudes avec les profils en charriage côtier et en écoulement granulaire sec. Nos expériences bidisperses ont révélé un phénomène de ségrégation assimilable au processus de "kinetic sieving". / Bedload transport remains poorly understood partly due to the polydispersity of particles and resulting segregation. Experiments were carried out at the particle scale to compare the motion of spherical 4~mm and 6~mm glass beads and to analyze the segregation of two-size mixtures. Particles were entrained by a turbulent supercritical flow down a steep two-dimensional channel with a mobile bed under bedload equilibrium conditions. Flows were filmed from the side and analyzed by image processing to determine the particle trajectories, their state of motion (rest, rolling, saltation), and flow depth. Contrasting with the 6~mm uniform case where rolling was frequent, saltation was dominant for 4~mm beads and the two-size mixtures. Our one-size data support the erosion-deposition model of cite{Char06}. The velocity profiles exhibit three segments (exponential, linear, logarithmic). As well as concentration profiles, they are similar to profiles in sheet flows and dry granular flows. Our two-size experiments also revealed a phenomenon of segregation comparable to the kinetic sieving process.

O objetivo deste estudo foi caracterizar a dinâmica das ondas de areia presentes no interior da Baía de São Marcos em São Luís, estado do Maranhão, utilizando dados de campanhas de batimetria bimestral e granulometria, para determinar a geomorfologia de fundo, além de séries temporais eulerianas de velocidade e variação da maré dos anos de 2011 e 2012 para validar um modelo hidrodinâmico local. O posicionamento horizontal e vertical nos conjuntos de dados batimétricos, digitalizados em transectos longitudinais, forneceu corredores de transporte que concordaram com os obtidos por meio do modelo numérico. Foram registradas ondas de areia com comprimento e altura superiores a 342 m e 6 m, respectivamente. A migração horizontal chegou a 1,8 m/dia e as intensidades de corrente a 1.84 m/s sobre o campo de ondas de areia e 2.58 m/s nos canais adjacentes. O Cabeço do Mearim e a Ilha do Medo são os principais responsáveis pela divisão dos regimes hidrodinâmicos locais forçados pela maré, os quais controlam os padrões morfológicos e migratórios das feições de fundo. Os mapas residuais de velocidade aliados aos coeficientes de dominância de maré calculados demonstraram que as principais forçantes do sistema são intensas nos canais e ao sul da Ilha do Medo e menos pronunciadas nas planícies rasas do sistema estuarino. As técnicas utilizadas neste estudo possibilitaram o estabelecimento de um modelo conceitual de corredores de transporte que rege o equilíbrio dinâmico do sistema local. Esses corredores são formados principalmente pelo canal principal da Baía de São Marcos localizado na porção oeste das feições submersas, predominando o transporte das correntes de vazante, pelo Canal do Boqueirão no qual predominam as correntes de maré enchente e pelo canal transversal situado a leste das ondas de areia, responsável por fluxos principalmente de maré enchente que podem transportar sedimentos ou energia para o sistema de canais principais. Este modelo forneceu conhecimento basal para o planejamento de atividades de uso, exploração e conservação dos sedimentos na Baía de São Marcos / The aim of this study was to characterize sand wave dynamics in São Marcos Bay (Maranhão state). Using data obtained from consecutive bathymetry campaigns, bottom sediment distribution, tide level and stationary current meters time series at this site from 2011-2012 years, bed morphology evolution was determined and a process-based hydrodynamic model was validated. Registering consecutive sand wave positioning in longitudinal transects provided bed features migration, generating transport pathways that agreed with model results. Sand waves observed were up to 6 m high and 342 m long and migrate up to 1.8 m/day, under depth-averaged current conditions up to 1.84 m/s above the sand wave field and 2.58 m/s in the adjacent channels. Cabeço do Mearim and Medo Island represents the features responsible for separate both tidal hydrodynamic regimes that control bottom migration and morphologic patterns. Residual current distribution and tide dominance coefficients showed that the controlling hydrodynamic forces of the system are more intense in the main channels and southward Medo Island, while weaken as depth reduces eastward. The methods used in this study provide a reliable conceptual model of transport pathways that control the local dynamic equilibrium, composed by the main channel of Sao Marcos Bay, where ebb dominance occurs, by the Boqueirão Channel strongly dominated by flood currents and by the transversal channel located eastward the bottom features, also flood dominated and responsible for transport sediment and energy to the sand wave field. This approach provided the bases for planning activities regard use, conservation and exploitation of sediments in São Marcos Bay

Chemical weathering of silicate rock consumes atmospheric CO2 and supplies the oceans with cations, thereby controlling both seawater chemistry and climate. The rate of CO2 consumption is closely linked to the rate of CO2 outgassing from the planetary interior, providing a negative feedback loop essential to maintaining an equable climate on Earth. Reconstruction of past global temperatures indicates that a pronounced episode of global cooling began ~50 million years ago, coincident with the collision of India and Asia, and the subsequent exhumation of the Himalayas and Tibet. This has drawn attention to the possible links between exhumation, erosion, changes in silicate weathering rates, and climate. However, many of the present-day weathering processes operating on the continents remain debated and poorly constrained, hampering our interpretations of marine geochemical archives and past climatic shifts. To constrain the controls on silicate weathering, this thesis investigates the lithium (Li) isotopic composition of river waters, suspended sediments and bed load sediments in the Alaknanda river basin, forming the headwaters of the Ganges. Due to the large fractionation of Li isotopes in the Earth’s surface environment, Li is sensitive to small changes in silicate weathering processes. As a consequence of the pronounced gradients in climate (rainfall and temperature) and erosion across the basin, the river waters show large variations in their Li isotopic composition (δ7Li), ranging from +7.4 to +35.4‰, covering much of the observed global variation. This allows a detailed investigation of the controls on Li isotope fractionation, and by extension silicate weathering. The Li isotopic composition is modelled using a one-dimensional reactive transport model. The model incorporates the continuous input of Li from rock dissolution, removal due to secondary mineral formation, and hydrology along subsurface flow paths. Modelling shows that the Li isotopic variations can be described by two dimensionless variables; (1) the Damköhler number, ND, which relates the silicate dissolution rate to the fluid transit time, and (2) the net partition coefficient of Li during weathering, kp, describing the partitioning of Li between secondary clay minerals and water, which is primarily controlled by the stoichiometry of the weathering reactions. The derived values of the controlling parameters ND and kp, are investigated over a range of climatic conditions and on a seasonal basis, shedding light onto variations in the silicate weathering cycle. In a kinetically limited weathering regime such as the Himalayan Mountains, both climate and erosion exert critical controls the weathering intensity (the fraction of eroded rock which is dissolved) and the weathering progression (which minerals that are being weathered), and consequently the fractionation of Li isotopes and silicate weathering in general. Modelling of the Li isotopic composition provides an independent estimate of the parameters which control silicate weathering. These estimates are then used to constrain variables such as subsurface fluid flux, silicate dissolution rates, fluid transit times and the fraction of rock which is weathered to form secondary clay minerals. The simple one-dimensional reactive transport model therefore provides a powerful tool to investigate the minimum controls on silicate weathering on the continents.

Le transport de sédiments en rivières et torrents reste un phénomène mal compris en raison de la polydispersité des particules et de la ségrégation résultante. Il a été mené une étude expérimentale sur un canal permettant d’étudier la ségrégation en charriage d’un mélange de deux classes de billes. Le déplacement collectif des billes est enregistré sous la forme de séquences vidéos. Cette thèse traite des méthodes de traitement d’images développées pour analyser les données obtenues. Premièrement, nous avons développé une méthode de segmentation d’images pour étudier l’influence de l’infiltration de particules fines sur l’évolution d’un lit mobile. Avec cette méthode d’analyse, une étude expérimentale a permis de montrer que l’évolution de la pente du lit présente une décroissance exponentielle. Deuxièmement, nous avons optimisé les algorithmes déterministes de suivi de particules pour permettre l’étude des trajectoires sur l’intégralité du phénomène de ségrégation, ce qui n’était pas possible dans les travaux précédemment effectués à Irstea. Nous avons de plus mis en place des mesures d’évaluation et conçu des vérités terrains afin d’apprécier la qualité des résultats. Des gains de temps, cohérence, précision et mémoire ont été quantifiés. Troisièmement, nous avons développé un nouvel algorithme basé sur le filtrage particulaire à modèles multiples pour mieux gérer les dynamiques complexes des particules et gagner en robustesse. Cette approche permet de prendre en compte les erreurs du détecteur, les corriger et ainsi éviter des difficultés lors du suivi de trajectoires que nous rencontrons notamment avec l’algorithme déterministe / Sediment transport in rivers and mountain streams remains poorly understood partly due to the polydispersity of particles and resulting segregation. Experiments in a channel were carried out to study bedload transport of bimodal bead mixtures. The behavior of the beads is recorded through video sequences. This work is about the development of image processing methods to analyse the obtained data. Firstly, we developed a method of image segmentation to study the infiltration of fine particles and its influence on the evolution of bed mobility. Thanks to this method, an experimental study shows that the bed slope evolution follows an exponential decay. Secondly, we optimised deterministic tracking algorithms to enable the study of trajectories on long-duration phenomena of segregation, which was not possible with previous work done at Irstea. Moreover we set up relevant evaluation measures and elaborated ground truth sequences to quantify the results. We observed benefits in execution time, consistency, precision and memory. Thirdly, we developed a new algorithm based on multiple model particle filtering to better deal with complex dynamics of particles and to gain robustness. This approach allows taking unreliable detections into account, correcting them and thus avoiding difficulties in the target tracking as encountered with the deterministic algorithm

Made available in DSpace on 2017-07-10T17:30:55Z (GMT). No. of bitstreams: 1 Andrey Luis Binda.pdf: 3846554 bytes, checksum: bff1c6b39e4b9f07d3cbffa410b26168 (MD5) Previous issue date: 2009-07-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Trees, twigs and leaves fallen inside of the channel, form a significant component of the fluvial environment and natural occurrence in fluvial systems that cut forested areas. All these vegetal materials that are found inside of the channel are called wood debris. The wood debris play a key function in the ecology and geomorphology of channels, being able to affect the processes of the channels in an ample reach: since the hydraulic roughness, retention and sized grain of bed sediments, until the creation of steps and pools, being able to the times to control the standard of the channel and distance and/variation of fluvial features that are basic for the formation of aquatic habitat. In this context, the present research had as objective, to verify the influence of accumulations of wood debris on the morphology and sedimentology of stream bed in the river Guabiroba, Guarapuava, Center-South of the Paraná. The used techniques had included: installation of permanent transversal profiles (to the upstream and downstream of the accumulations) and sections of batimetric measurement, survey of the longitudinal profile and grain sized characterization of bed sediments. The measurement was carried throughout 15 months (December of 2007 the March of 2009) in four sections located in the main course of the river. The rainfall during the measurement allowed to particularizing the occurrence of only one period with rains above average (3 - 4ª Campaign). The results indicate the occurrence of sedimentation in the second and fifth measurement and processes of erosion in the third and fourth measurement. These processes erosive-depositional can in part be attributed to the pluviometric regime, with the periods of high entailed concentration of rains to the erosion of the stream bed and periods of related scarce and not concentrated rains with the deposition of sediments. The analysis of the data allows to establish some consideration: 1) predominance of processes of erosion in the sections of batimetric measurement; 2) bigger rate deposition in downstream cross-sectional profiles of the accumulations; 3) predominance of coarser sediments (gravel medium - sand very coarse) to upstream and finer sediments (gravel fine - sand medium) to downstream; 4) bigger diversity of depths in the immediacy of the accumulations; 5) establishment of riffles by the forced deposition of sediments and pools for the scour of the stream bed. / Árvores, galhos e folhas caídos dentro do canal formam um significativo componente do ambiente fluvial e de ocorrência natural em sistemas fluviais que cortam áreas florestadas. Toda essa carga de material de origem vegetal que se encontra dentro do canal é chamada de detritos lenhosos. Os detritos lenhosos desempenham função chave na ecologia e geomorfologia de canais, podendo afetar os processos do canal em um amplo alcance: desde a rugosidade hidráulica, retenção e grânulometria dos sedimentos de leito, até a criação de degraus e depressões, podendo, às vezes, controlar o padrão do canal e a distância/variação de feições fluviais que são fundamentais para a formação de habitat aquáticos. Num contexto desses, a presente pesquisa teve como objetivo verificar a influência de acumulações de detritos lenhosos sobre a morfologia e a sedimentologia de leito no Rio Guabiroba, município de Guarapuava, mesorregião Centro-Sul do Paraná. As técnicas utilizadas incluíram: instalação de perfis transversais permanentes (a montante e a jusante das acumulações) e seções de monitoramento batimétrico, levantamento do perfil longitudinal e caracterização grânulométrica de sedimentos do fundo. O monitoramento foi realizado ao longo de 15 meses (dezembro de 2007 a março de 2009) em quatro pontos localizados em dois trechos no curso principal do rio. A pluviosidade durante o monitoramento permitiu individualizar a ocorrência de apenas um período com chuvas acima da média (3ª a 4ª campanha). Os resultados indicam a ocorrência de sedimentação na segunda e quinta campanhas e processos de erosão na terceira e quarta campanhas. Esses processos erosivo-deposicionais podem, em parte, ser atribuídos ao regime pluviométrico, com os períodos de alta concentração de chuvas vinculados à erosão do leito e períodos de chuvas escassas e não concentradas relacionados com a deposição de sedimentos. A análise dos dados permite estabelecer algumas considerações: 1) predominância de processos de erosão nas seções de monitoramento batimétrico (Blocos 3D); 2) maior taxa de deposição nos perfis transversais situados a jusante das acumulações; 3) predomínio de sedimentos mais grossos (seixo médio - areia muito grossa) a montante da acumulação do que a jusante (seixo fino - areia média); 4) maior diversidade de profundidades nas imediações das acumulações; 5) estabelecimento de soleiras pela deposição forçada de sedimentos e depressões pela escavação do leito.

Made available in DSpace on 2017-05-12T14:42:26Z (GMT). No. of bitstreams: 1 Andrey Luis Binda.pdf: 3846554 bytes, checksum: bff1c6b39e4b9f07d3cbffa410b26168 (MD5) Previous issue date: 2009-07-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Trees, twigs and leaves fallen inside of the channel, form a significant component of the fluvial environment and natural occurrence in fluvial systems that cut forested areas. All these vegetal materials that are found inside of the channel are called wood debris. The wood debris play a key function in the ecology and geomorphology of channels, being able to affect the processes of the channels in an ample reach: since the hydraulic roughness, retention and sized grain of bed sediments, until the creation of steps and pools, being able to the times to control the standard of the channel and distance and/variation of fluvial features that are basic for the formation of aquatic habitat. In this context, the present research had as objective, to verify the influence of accumulations of wood debris on the morphology and sedimentology of stream bed in the river Guabiroba, Guarapuava, Center-South of the Paraná. The used techniques had included: installation of permanent transversal profiles (to the upstream and downstream of the accumulations) and sections of batimetric measurement, survey of the longitudinal profile and grain sized characterization of bed sediments. The measurement was carried throughout 15 months (December of 2007 the March of 2009) in four sections located in the main course of the river. The rainfall during the measurement allowed to particularizing the occurrence of only one period with rains above average (3 - 4ª Campaign). The results indicate the occurrence of sedimentation in the second and fifth measurement and processes of erosion in the third and fourth measurement. These processes erosive-depositional can in part be attributed to the pluviometric regime, with the periods of high entailed concentration of rains to the erosion of the stream bed and periods of related scarce and not concentrated rains with the deposition of sediments. The analysis of the data allows to establish some consideration: 1) predominance of processes of erosion in the sections of batimetric measurement; 2) bigger rate deposition in downstream cross-sectional profiles of the accumulations; 3) predominance of coarser sediments (gravel medium - sand very coarse) to upstream and finer sediments (gravel fine - sand medium) to downstream; 4) bigger diversity of depths in the immediacy of the accumulations; 5) establishment of riffles by the forced deposition of sediments and pools for the scour of the stream bed. / Árvores, galhos e folhas caídos dentro do canal formam um significativo componente do ambiente fluvial e de ocorrência natural em sistemas fluviais que cortam áreas florestadas. Toda essa carga de material de origem vegetal que se encontra dentro do canal é chamada de detritos lenhosos. Os detritos lenhosos desempenham função chave na ecologia e geomorfologia de canais, podendo afetar os processos do canal em um amplo alcance: desde a rugosidade hidráulica, retenção e grânulometria dos sedimentos de leito, até a criação de degraus e depressões, podendo, às vezes, controlar o padrão do canal e a distância/variação de feições fluviais que são fundamentais para a formação de habitat aquáticos. Num contexto desses, a presente pesquisa teve como objetivo verificar a influência de acumulações de detritos lenhosos sobre a morfologia e a sedimentologia de leito no Rio Guabiroba, município de Guarapuava, mesorregião Centro-Sul do Paraná. As técnicas utilizadas incluíram: instalação de perfis transversais permanentes (a montante e a jusante das acumulações) e seções de monitoramento batimétrico, levantamento do perfil longitudinal e caracterização grânulométrica de sedimentos do fundo. O monitoramento foi realizado ao longo de 15 meses (dezembro de 2007 a março de 2009) em quatro pontos localizados em dois trechos no curso principal do rio. A pluviosidade durante o monitoramento permitiu individualizar a ocorrência de apenas um período com chuvas acima da média (3ª a 4ª campanha). Os resultados indicam a ocorrência de sedimentação na segunda e quinta campanhas e processos de erosão na terceira e quarta campanhas. Esses processos erosivo-deposicionais podem, em parte, ser atribuídos ao regime pluviométrico, com os períodos de alta concentração de chuvas vinculados à erosão do leito e períodos de chuvas escassas e não concentradas relacionados com a deposição de sedimentos. A análise dos dados permite estabelecer algumas considerações: 1) predominância de processos de erosão nas seções de monitoramento batimétrico (Blocos 3D); 2) maior taxa de deposição nos perfis transversais situados a jusante das acumulações; 3) predomínio de sedimentos mais grossos (seixo médio - areia muito grossa) a montante da acumulação do que a jusante (seixo fino - areia média); 4) maior diversidade de profundidades nas imediações das acumulações; 5) estabelecimento de soleiras pela deposição forçada de sedimentos e depressões pela escavação do leito.

L'objectif principal de cette thèse est d'étudier la dynamique des flux hydrosédimentaires dans le bas cours de l'Orénoque à partir de la mise en œuvre de diverses techniques qui combinent directement la mesure des données in situ et la modélisation par séries chronologiques d'images satellites. Cette thèse aborde pour la première fois trois méthodologies complémentaires pour analyser les flux hydrosédimentaires dans les grands fleuves : (i) un algorithme d'inversion robuste pour l'estimation de MES à l'aide de données Landsat-8(OLI)permet de suivre de façon systématique et fiable les variations spatio-temporelles des flux hydro-sédimentaires de surface, (ii) de même, il a été montré qu'il existe une forte relation entre le coefficient de rétrodiffusion du radar (images Sentinel-1) et les segments fluviaux d'écoulement turbulent. Cette nouvelle utilisation du radar en complément des approches classiques en géomorphologie et hydro-sédimentologie permet d'identifier des sections du fleuve où les MES sont homogénéisées, ce qui est fondamental pour le calcul des flux hydro-sédimentaires en suspension, enfin, (iii) une troisième méthodologie a été mise en œuvre pour mesurer durant le cycle hydrologique, les modifications géomorphologiques d'une île semi-submergée au centre du chenal principal. Grace à des séries topo-bathymétriques fines, associées à une modélisation 3D, l'on peut dorénavant quantifier le charriage de fond. Ces trois approches combinées permettent une évaluation plus précise du bilan hydro-sédimentaire en tenant compte des matières en suspension comme du charriage de fond. Ces études pourront servir aux gestionnaires du fleuve, confrontés à de complexes, lourdes et couteuses opérations de dragage périodiques pour maintenir sa navigabilité, ce qui est d'extrême importance pour les projets de développement socio-économiques de la frange pétrolière du bas cours de l'Orénoque. / The main objective of this thesis is to study the dynamics of hydro-sedimentary flows in the lower Orinoco from the implementation of various techniques that directly combine the measurement of in situ data and the modelling of time series of satellite images. This thesis addresses for the first time three complementary methodologies for the analysis of hydro-sedimentary flows in large rivers: i) a robust inversion algorithm for estimating suspended sediment concentration (SSC) using Landsat-8 (OLI) satellite data allows a systematic and reliable monitoring of spatial and temporal variations of surface hydro-sedimentary flows, (ii) it was shown that there is a strong relationship between the radar backscatter coefficient (Sentinel-1 images) and the turbulent flow segments in the river. This new use of radar, in addition to traditional geomorphological and hydro- sedimentological approaches, allows the identification of river sections in which suspended sediments are homogenized, which is fundamental for the calculation of suspended hydro-sedimentary flows, and finally (iii) a third methodology has been implemented to measure during the hydrological regime the geomorphological modifications of a semi-submerged island in the center of the mainstream. Thanks to a high spatial resolution topo-bathymetric series, combined with 3D modeling, it is now possible to quantify and to gain better understanding of river bed transport. These three combined approaches allow a more accurate evaluation of the hydro-sedimentary equilibrium taking into account suspended solids as well as bedload. These studies can be used by those responsible for river management, who face complex, heavy and costly periodic dredging operations to maintain their navigability, which is of extreme importance for socio-economic development projects in the Orinoco oil belt in the lower Orinoco.