As condições físicas do ambiente, pretéritas e atuais, determinam variações quanto à estrutura e distribuição dos manguezais ao longo das áreas litorâneas. O presente estudo visa caracterizar as tendências da dinâmica de bosques de mangue do Sistema Cananéia-Iguape. Tratamento de imagens digitais e dinâmica de feições sedimentares na região forneceram subsídios para o presente estudo. O Sistema Cananéia-Iguape está localizado no extremo sul do Estado de São Paulo (Brasil), latitude de 25oS. Imagens digitais TM/Landsat5, WRS 220/77 D, composição colorida (RGB) TM4/TM3/TM2, de duas datas (14/09/86 e 02/09/99) foram tratadas no SIG ILWIS (Integrated Land and Water Information System). Os pontos de amostragem de estrutura dos bosques de mangue e de topografia foram escolhidos considerando-se os resultados da classificação superviosionada e da dinâmica sedimentar das feições de deposição no sistema, segundo Tessler (1982) e Tessler & Furtado (1983). Para estudo da estrutura dos bosques de mangue adotou-se metodologia de Schaeffer-Novelli & Cintrón (1986). Análise de agrupamento por ligação simples confirmou os resultados obtidos no tratamento de dados de estrutura dos bosques de mangue. A dinâmica sedimentar e a topografia são fatores que determinam a colonização por determinadas espécies de mangue em feições de deposição. / Past and current environment conditions drive changes to mangrove structure and distribuition along the coast. This paper aims to caracterize mangrove forest dynamic tendencies at Cananeia-Iguape System. Digital image processing and region morphodynamics support the present study. Cananeia-Iguape System is located at the South of São Paulo State (Brazil), latitude 25oS. A colored composition (RGB TM4/TM3/TM2) of Landsat TM digital images (WRS 220/77D) from different dates (14/09/86 and 02/09/99) were processed with ILWIS SIG (Integrated Land and Water Information System). Mangrove forest structure and topographic sampling spots were chosen given the results of supervised classification and given its sedimentary morphodynamic deposition, following Tessler (1982) and Tessler & Furtado (1983). Mangrove forest structure study is based on Cintrón & Schaeffer-Novelli (1984). Single linkage cluster analysis has confirmed the results obtained from the mangrove forest structure study. Region sedimentary dynamics and topographic factors drive mangrove colonization by particular species on deposition shores.

As condições físicas do ambiente, pretéritas e atuais, determinam variações quanto à estrutura e distribuição dos manguezais ao longo das áreas litorâneas. O presente estudo visa caracterizar as tendências da dinâmica de bosques de mangue do Sistema Cananéia-Iguape. Tratamento de imagens digitais e dinâmica de feições sedimentares na região forneceram subsídios para o presente estudo. O Sistema Cananéia-Iguape está localizado no extremo sul do Estado de São Paulo (Brasil), latitude de 25oS. Imagens digitais TM/Landsat5, WRS 220/77 D, composição colorida (RGB) TM4/TM3/TM2, de duas datas (14/09/86 e 02/09/99) foram tratadas no SIG ILWIS (Integrated Land and Water Information System). Os pontos de amostragem de estrutura dos bosques de mangue e de topografia foram escolhidos considerando-se os resultados da classificação superviosionada e da dinâmica sedimentar das feições de deposição no sistema, segundo Tessler (1982) e Tessler & Furtado (1983). Para estudo da estrutura dos bosques de mangue adotou-se metodologia de Schaeffer-Novelli & Cintrón (1986). Análise de agrupamento por ligação simples confirmou os resultados obtidos no tratamento de dados de estrutura dos bosques de mangue. A dinâmica sedimentar e a topografia são fatores que determinam a colonização por determinadas espécies de mangue em feições de deposição. / Past and current environment conditions drive changes to mangrove structure and distribuition along the coast. This paper aims to caracterize mangrove forest dynamic tendencies at Cananeia-Iguape System. Digital image processing and region morphodynamics support the present study. Cananeia-Iguape System is located at the South of São Paulo State (Brazil), latitude 25oS. A colored composition (RGB TM4/TM3/TM2) of Landsat TM digital images (WRS 220/77D) from different dates (14/09/86 and 02/09/99) were processed with ILWIS SIG (Integrated Land and Water Information System). Mangrove forest structure and topographic sampling spots were chosen given the results of supervised classification and given its sedimentary morphodynamic deposition, following Tessler (1982) and Tessler & Furtado (1983). Mangrove forest structure study is based on Cintrón & Schaeffer-Novelli (1984). Single linkage cluster analysis has confirmed the results obtained from the mangrove forest structure study. Region sedimentary dynamics and topographic factors drive mangrove colonization by particular species on deposition shores.

Les travaux portent sur l’étude de la formation de motifs sédimentaires à l’aval d’un cylindre vertical soumis à un courant. Le cylindre simule une fondation monopieu d’éolienne en mer, ou une pile de pont. Une modélisation théorique est développée. Les résultats obtenus sont en bon accord avec les résultats expérimentaux acquis au cours de la thèse. Une étude préliminaire expérimentale et théorique sur le tri sédimentaire au voisinage du cylindre est également effectuée. / This work concerns the study of sediment patterns formation downstream a vertical cylinder under a steady current. The cylinder simulates an offshore monopile foundation, or a bridge pile. A theoretical modeling is developed. The results are in good agreement with the experimental results obtained in the framework of this PhD. An experimental and theoretical preliminary study on sediment segregation in the vicinity of the cylinder is also performed.

La rade de Brest constitue un cadre idéal pour étudier et restituer les transferts sédimentaires terre-mer dans un contexte de bassin côtier semi-fermé macrotidal. Dans cette perspective, deux axes majeurs, d’échelle temporelle différente, ont été développés avec pour objectifs (a) de caractériser le modèle sédimentaire et sa dynamique par charriage à l’actuelle, (b) de déterminer la mise en place des dépôts sédimentaires au cours de la dernière transgression marine.(a) L’analyse combinant une approche sédimentaire et analogique a permis de montrer le contrôle majeur des courants de marée sur la dynamique sédimentaire actuelle. La morphologie du littoral et des fonds marins renforcent l’intensité des courants tidaux qui facilite les échanges en sables coquilliers entre la rade interne et la mer d’Iroise. Le système est néanmoins en érosion et enregistre un déséquilibre en apports sédimentaires. Les sédiments fins sont remobilisés par les courants de flot et les actions anthropiques colmatant les secteurs peu profonds.(b) L’étude litho- et chronostratigraphique de la séquence sédimentaire, a mis en évidence le recul successif des processus estuariens lors de la dernière remontée du niveau marin (holocène). La morphologie héritée du substratum, combinée à la transgression marine, a fortement influencé l’architecture des dépôts, leur préservation et leurs variations lithologiques latérales et longitudinales. Après la stabilisation du niveau marin (3 000 BP), les variations climatiques (optimum climatique médiéval, et petit âge glaciaire) et les activités anthropiques impactent d’avantage la dynamique des particules en suspension.La rade a donc eu un impact différent sur le transfert des sédiments au cours de la remontée du niveau marin. Actuellement, elle acte comme un « piège à sédiment fin » et enregistre dans le même temps un déficit de stock sédimentaire grossier potentiellement remobilisable. Cette configuration favorise une érosion des parties les plus profondes du système. / The bay of Brest is a tide-dominated, semi-enclosed coastal basin, which is connected with two rivers (Aulne and Elorn). Its jagged shoreline and seabed morphology constitute an ideal setting to understand sedimentary transfer at the land-sea interface. In this aim, this study is divided in two different time scale. The first (a) focuses on the present-day sedimentary bedload dynamic and the second (b) on the reconstruction of the Holocene infilling, during the last marine transgression. (a) A analyse combining a sedimentology approach and numerical has highlighted the major control of the tidal currents. Swells and rivers have a minor impact, because the inherited morphology accentuates and promotes tidal currents. There are responsible of a shelly sandy exchange between the oceanic domain (Iroise Sea) and confined (bay of Brest). At present, the bay of Brest suffers from an imbalance of shelly sand. Fine sediments are eroded and redistributed in the shallow parts of the bay. In ideal conditions (strong tidal current) they can be exported.(b) From the stratigraphic and chronostratigraphic analyses, the successive landward retreat of estuarine processes, during the last marine transgression, has been observed. The sea level acts as the major factor control of the sedimentary geometry deposits. However, the morphological particularity of the bay of Brest influenced their preservation and it is possible to determinate the longitudinal and transversal asymmetry. After the sea level stabilisation (3 000 BP), the Holocene climatic variations and anthropic activities have disturbed the suspension dynamic.The bay of Brest had a different impact on the sedimentary transfer during the last marine transgression. At present, it acts as a « sediment trap » for the fine particles and has not enough sandy sediment. This configuration tends to an erosion of the system.