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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

INFLUENCE OF LONG WAVES AND WAVE GROUPS ON SWASH ZONE SEDIMENT TRANSPORT AND CROSS-SHORE BEACH PROFILE EVOLUTION

Son Kim Pham Unknown Date (has links)
There are only a few detailed measurements of the cross-shore variation in the net sediment transport and beach evolution for single or multiple swash events, and no data showing the influence of long waves and wave groups on swash zone morphology. Novel laboratory experiments and numerical modeling have been performed to study the influence of long waves and bichromatic wave groups on sediment transport and beach morphodynamics in the swash zone. Due to complex processes, difficulties in measuring, and very significant difficulties in isolating the morphodynamic processes induced by long waves and wave groups on natural beaches, a laboratory study was designed to measure in very high detail the bathymetric evolution of model sand beaches under monochromatic waves, long wave and short wave composites (free long waves), and bichromatic wave groups (forced long waves). Net sediment transport, Q(x), and beach morphology changes under the monochromatic waves were analyzed and compared to conditions with and without the free long waves, and then compared with the bichromatic wave groups. A range of wave conditions, e.g., high energy, moderate energy, and low energy waves, were used to obtain beach evolution ranging from accretionary to erosive, and including intermediate beach states. Hydrodynamics parameters, e.g., instantaneous water depths, wave amplitudes, run-up and rundown, were also measured to study and test a sediment transport model for the swash zone, based on modifying the energetic-bedload based sediment transport equations with suspended sediment. The experimental data clearly demonstrate that for the monochromatic wave conditions, beach evolution develops erosion for high steepness waves and accretion for lower steepness waves. The model beach profile evolutions are similar to natural beaches, and form and develop bars and berms over time. Adding a free long wave to the short wave in the composite wave results in changes to the overall trend of erosion/accretion of the beach profile, but the net transport pattern does not change significantly. The short wave strongly dominates beach behavior and the net transport rate, instead of the free long wave in the composite wave. The free long wave, however, carries more water and sediment onshore, leading to an increase in shoreline motion and wave run-up further landward. The long wave influences the structure and position of the swash bar/berm, which generally tends to move onshore and forms a larger swash bar/berm for higher long wave amplitudes. The free long wave also increases overall onshore sediment transport, and reduces offshore transport for erosive conditions. The long wave tends to protect the beach face and enhances onshore transport for accretive conditions, especially in the swash zone. In contrast, for bichromatic wave groups having the same mean energy flux as their corresponding monochromatic wave, the influence on sediment transports is generally offshore in both the surf and swash zone instead of onshore. The swash berm is, however, formed further landward compared with the berm of the corresponding monochromatic wave. The sediment transport patterns (erosion or accretion) generated by the bichromatic wave group or corresponding monochromatic wave are similar, but differ in magnitude. The numerical model, starting in the inner surf zone to reduce the effect of poor breaker description in the non-linear shallow water equations, can produce a good match between observed data and the modeled hydrodynamics parameters in the SZ. The sediment transport model shows the important role of suspended sediment in the swash zone. In contrast with the observed data, energetic-based bed-load models predict offshore sediment transport for most wave conditions because of negative skewness. The modified sediment transport model, with added suspended sediment terms and optimized coefficients, produces a good match between model results and observed data for each wave condition, especially for low frequency monochromatic waves. The optimized coefficient set corresponding to particular monochromatic wave conditions can be used to predict the net sediment transport quite well for some composite wave conditions. Overall, the same optimized coefficient sets can be applied to predict the correct overall trend of net transport for most composite wave conditions. However, the predicted net transport for the bichromatic wave groups does not match well with the overall net transport patterns. There is no set of single transport coefficients that can be used to predict sediment transport for all wave conditions. This suggests that the present sediment transport models cannot predict evolution correctly, even for conditions which represent only perturbation from those for which they were calibrated.
32

Morfodinâmica de um delta artificial na margem oeste da Lagoa Mangueira – RS

Guimarães, Lisiane Silva January 2014 (has links)
O estudo, em corpos lagunares, de transportes de sedimentos pode apresentar significativa importância e abrangência. Para que haja compreensão dos mecanismos que ocorrem na linha de costa de um corpo aquoso é fundamental o estudo de sua morfodinâmica e morfologia do sistema. Estes evoluem conjuntamente, visto que a dinâmica determina a morfologia, entretanto uma vez estabelecida a morfologia, esta condiciona a dinâmica. A evolução de corpos lagunares segue a evolução de cinco processos naturais: a segmentação, a acresção vertical, a progradação de deltas, a acresção lateral, a sedimentação marinha e/ou lacustre. Neste estudo é abordado a progradação deltaica. Deltas são acumulações de sedimentos no final de um canal, no qual há uma descarga dentro de um corpo de água. A área selecionada para este estudo situa-se no sul da planície costeira do Estado do Rio Grande do sul, na região norte da Lagoa Mangueira, onde se localiza diversos deltas artificiais presentes no corpo lacustre. Pelo fato de estar inserido no popularmente conhecido “Parque das Capivaras”, a feição estudada ficou denominada como “Delta das Capivaras”. O objetivo do estudo foi desenvolver o modelo de evolução deste delta artificial construído pela atividade das lavouras arrozeiras na margem oeste da Lagoa da Mangueira e avaliar os impactos ambientais causados pelo manejo do solo. A metodologia empregada contemplou variadas técnicas de aquisição e interpretação de dados. As atividades iniciaram com uma revisão bibliográfica e preparação da logística necessária para aquisição de informações em campo, onde foram coletados dados de sedimentologia, batimetria e testemunhos. As atividades posteriores compreenderamm análises, processamentos e tratamentos das amostras e informações obtidas, em laboratório. A integração dos dados forneceu informações importantes sobre a dinâmica e morfologia do Delta das Capivaras. Foi possível concluir que o principal agente formador do delta é o canal artificial gerado pela atividade antrópica devido ao elevado potencial de aporte de sedimentos para o interior da lagoa. A flutuação de nível é pouco representativa e a ação das ondas é secundária na formação do delta, já que o mesmo é protegido por feições arenosas e vegetação. A atividade de orizicultura na margem oeste da Lagoa Mangueira causa rápida eutrofização no corpo aquoso, esse fato mostra que a atividade antrópica causada pelo cultivo de arroz modifica bastante as características naturais desse corpo hídrico, podendo causar impactos na vida e dinâmica da lagoa. O Delta das Capivaras se desenvolveu em um local inferior a 1 km, num intervalo de tempo de décadas; e, por fim, sua gênese foi controlada principalmente pelo aporte de sedimentos. Além disso, está inserido em uma bacia de drenagem litorânea com extensão de área bastante reduzida e relevo com cotas inferiores a 10 metros, não podendo, portanto, gerar uma feição do tamanho do Delta das Capivaras, em um curto espaço de tempo. Essas características classificam o delta como uma feição artificial de escala de engenharia e não geológica. / The sediment transport in lakes is very important and has a broad scope. In order to acquire comprehension on the processes occurring in the coastline it is vital that the system´s morphodynamics and morphology are studied. These last elements evolve together, since the dynamics determine morphology, however once morphology is established, it affects dynamics. The evolution of these bodies of water follows the evolution of five natural processes: segmentation, vertical accretion, marine and lagoonal sedimentation. In this study, deltaic progradation is analyzed. Deltas are deposits of sediment at the end of a water stream, which is discharged into a body of water. The selected area for this study is located in the southern portion of the coastal plain of Rio Grande do Sul state, in the north sector of the Mangueira Lake, where several artificial deltas are found in the lagoon. Since it is located in the popularly known “Capivaras Park”, the feature which is analysed in this study was named “Delta das Capivaras”. This study aimed to develop the evolution model for this artificially built delta, wich was formed due to rice farming on the west margin of the lake, and also, to evaluate the environmental impacts caused by the soil management. The methodology employed in the study comprised different techniques for the data acquisition and its interpretation. The work began by analyzing related bibliography and planning logistics for the field work, where data on sedimentology, bathymetry and core sample were collected. The later activities comprise analysis, processing and treatment of the obtained samples in the laboratory. The integration of data offered important information on the dynamics and morphology of the Delta das Capivaras. It was possible to conclude that the primary mechanism for the delta development is the artificial channel generated by anthropic activity, due to the elevated potential of sediment transport towards the lagoon. The water level variation has little significant contribution such as the wave action in the delta formation, since it is protected by sand “features” such as sandy spits and vegetation. The rice cultureon the west margin of the Mangueira Lake causes fast eutrophication of the water body, proving that anthropic activity caused by that specific activity strongly modifies the lagoon´s natural features and can possibly impact life and dynamics in this lagoon. The Delta das Capivaras developed in a location less than 1 km, in a time of decades and, finally, its genesis was controlled mainly by sediment supply. Moreover, it is inserted into a coastal drainage basin with little extension area and lower elevation with dimensions less than 10 meters, wherefore cannot generate a feature like Delta das Capivaras, in a short space of time. These characteristics classify the delta as an artificial feature of engineering scale and not geological.
33

Dinâmica da desembocadura do rio Itanhém, Alcobaça, BA / Morphodynamics at the Itanhaém Inlet, Alcobaça, BA

Mariana Coppede Cussioli 05 October 2010 (has links)
Os processos morfodinâmicos em sistemas de desembocaduras estão relacionados a uma variedade de condições forçantes que criam condições hidrodinâmicas únicas. Correntes de maré, ondas e descarga fluvial, interagindo em diferentes níveis resultam em complexos padrões dinâmicos. O objetivo do presente trabalho é entender os processos que controlam a dinâmica da desembocadura do estuário do rio Itanhém, Alcobaça, BA. A dinâmica do ambiente foi analisada através de imagens de satélite LANDSAT5-TM e da aplicação de um modelo numérico. As imagens de satélite disponíveis, para os anos de 1987, 1990, 1996, 2007, 2008 e 2009, foram utilizadas para extrair os contornos da linha de costa que, juntamente com dados batimétricos constituíram as malhas para o desenvolvimento de uma série de experimentos numéricos. O modelo numérico utilizado foi o MIKE 21 FM. Foram utilizados três módulos: propagação de ondas, hidrodinâmico e de transporte de sedimento, com retroalimentação entre as mudanças morfológicas e a hidrodinâmica. A descrição dos processos observados pelas imagens de satélite, juntamente com os resultados dos experimentos numéricos mostraram que na região ocorreu acúmulo de sedimentos com consequente crescimento de um pontal a barlamar da desembocadura entre 1987 e 2007. Em 2007 o pontal atingiu seu tamanho máximo, e em função de um evento de alta energia, se rompeu ao norte, deixando dois canais. No período quando o canal era mais estreito, houve maior transporte pela deriva verificado pelo crescimento do banco. Já no período de canal mais largo, houve interrupção na deriva e o banco não cresceu. O mecanismo principal de transporte de sedimentos na área de estudo deve-se principalmente à incidência das ondas do quadrante nordeste, que gera uma corrente de deriva litorânea para sul. As ondas do quadrante sul e sudeste, mais energéticas, e que poderiam gerar deriva na direção oposta, são refratadas pela presença dos parcéis e da progradação da linha de costa em Caravelas, localizados a sudeste e sul da área de estudo. O novo canal formado pelo rompimento do pontal tornou-se o principal meio de fluxo das correntes. Este fluxo atua como uma barreira, interrompendo a deriva litorânea de sedimentos, aprisionando-os a barlamar e limitando o suprimento de sedimentos responsáveis pelo crescimento do banco arenoso ao sul. Nota-se que o tamanho e a largura do novo canal definem a quantidade de sedimentos que atravessa a desembocadura, controlando o crescimento deste banco. / The morphodynamic processes at inlet systems are related to a variety of forcing conditions that create unique hydrodynamic conditions. The interaction of tidal currents, wave conditions, and river discharge at different levels result in complex dynamic patterns. The present work aims to understand the processes that control the dynamics of the Itanhaém River, Alcobaça (BA). The system dynamics was analyzed through the combined application of LANDSAT5-TM satellite images, field measurements and numerical modelling. A set of satellite images (for 1987, 1990, 1996, 2007, 2008 and 2009) was used to extract the coastline contours which, combined with the bathymetric data, defined the grids for a series of numerical experiments. Three modules of the MIKE 21 FM model have been applied: wave propagation, hydrodynamic and sediment transport, including the feedback between the morphological changes and the hydrodynamics. The description of the processes observed through the satellite images and the results of the numerical experiments show that there is a spit growth driving the inlet southwards between 1987 and 2007. In 2007 the spit reached its maximum extent and a high wave energy event breached the spit leaving the system with two openings to the ocean. The sediment supply to the southern sandbar is controlled by the longshore drift, with its quantities being apparently controlled by the inlet width. The main mechanism of sediment transport in the study area is mainly due to the northeasterly waves, moving sediments southwards. The more energetic southerly waves, which could lead to transport in the opposite direction, are refracted due to the wide shelf and the presence of coral reefs in the region. The new inlet formed by the spit breach became the main flow channel. This flow interrupts part of the littoral drift, retaining sediment updrift and limiting the sediment supply downdrift. The size and width of the new inlet define the amount of sediment being bypassed, controlling the growth of the sandbar.
34

Proposta metodológica de orientação à expansão urbana sob o viés geomorfológico: o caso da bacia do córrego Pau D’alho, Bauru (SP) / Methodological proposal for orientation to urban expansion under the geomorphological vision: the case of the watershade of the stream Pau D'alho, Bauru (SP)

Thomazini, Leonardo da Silva [UNESP] 08 December 2017 (has links)
Submitted by Leonardo da Silva Thomazini null (leothomazini@yahoo.com.br) on 2018-02-04T20:54:49Z No. of bitstreams: 1 Tese_leothomazini FINALcd.pdf: 19371418 bytes, checksum: 876dd1767e04d8d9c21be85839a12e69 (MD5) / Rejected by Ana Paula Santulo Custódio de Medeiros null (asantulo@rc.unesp.br), reason: Falta a capa on 2018-02-05T11:14:48Z (GMT) / Submitted by Leonardo da Silva Thomazini null (leothomazini@yahoo.com.br) on 2018-02-09T14:02:01Z No. of bitstreams: 1 Tese_LeoThomazini_repositorio.pdf: 19834279 bytes, checksum: 21a78a58f66c8e456ba67ecddcc0cf2b (MD5) / Approved for entry into archive by Ana Paula Santulo Custódio de Medeiros null (asantulo@rc.unesp.br) on 2018-02-09T15:50:30Z (GMT) No. of bitstreams: 1 thomazini_ls_dr_rcla.pdf: 19103501 bytes, checksum: 2f8981dbfd8ff8a1bbf8c988e2c3c63e (MD5) / Made available in DSpace on 2018-02-09T15:50:30Z (GMT). No. of bitstreams: 1 thomazini_ls_dr_rcla.pdf: 19103501 bytes, checksum: 2f8981dbfd8ff8a1bbf8c988e2c3c63e (MD5) Previous issue date: 2017-12-08 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A partir da segunda metade do século XX, intensificou-se o crescimento urbano do Brasil, acompanhando a tendência pós segunda Guerra Mundial dos Estados Unidos e da Europa. Os espaços agora ocupados pela urbanização são influenciados pelas ações antrópicas e passam a ser regidos pela morfodinâmica, a qual pauta-se no tempo de vida humana. Dentre os espaços urbanos, destacam-se as áreas periurbanas, as quais constituem um complexo mosaico de interações entre as regiões rurais e urbanas, desenvolvendo significativas transformações do relevo. Os impactos ambientais oriundos da interação entre os sistemas físicos e sociais têm incitado preocupações no meio científico, destacando-se os estudos geomorfológicos, em especial da geomorfologia urbana, por demonstrar a importância do conhecimento das características físicas do relevo na compreensão das ações humanas sobre a natureza e, consequentemente, sua função no planejamento territorial. Assim, este trabalho teve por objetivo o desenvolvimento de uma sistemática de análise cartográfica do espaço físico que permita orientar a implementação da urbanização em uma determinada área com características físicas específicas, auxiliando na gestão e no planejamento urbano-ambiental. A fim de alcançar o objetivo proposto, adotou-se como objeto de estudo a bacia hidrográfica do córrego Pau D’alho, marcada como um dos eixos de expansão urbana da cidade de Bauru (SP). Sob os preceitos teórico-metodológicos, de caráter holístico, da Teoria Geral dos Sistemas, foram investigadas as características físicas da bacia, por meio da construção de cartas morfométricas, geomorfológica, de fragilidade física e de materiais inconsolidados, com auxílio dos trabalhos de campo. Além do mais, analisou-se a evolução do uso e ocupação da terra e suas consequentes transgressões legais, permitindo compreender a influência das ações antrópicas no desenvolvimento dos processos erosivos, possibilitando a elaboração das cartas de cobertura vegetal, uso e ocupação da terra (dos anos de 1972 e 2016) e das derivações ambientais e transgressões legais. Diante do dados obtidos, desenvolveu-se uma sistemática de análise da expansão urbana sobre o relevo, com base nos matérias cartográficos elaborados e nos índices urbanísticos apresentados pelas legislações federal e municipal vigentes. Mediante tal análise, foi elaborada a carta de orientação a expansão urbana, na qual buscou-se sintetizar as características físicas da bacia hidrográfica com os índices urbanísticos e uma proposta de urbanização mais adequada. Com isso, a área de estudo foi dividida em 7 unidades físicas, divididas entre unidades propícias a urbanização, onde a urbanização é permitido sem restrições; unidades com restrições a urbanização, onde as caraterísticas físicas denotam cuidados e limitam certos tipos de urbanização; e áreas impróprias a urbanização, onde a urbanização traria sérios impactos ao relevo e, consequentemente, a população ali residente. Assim, o produto cartográfico gerado por meio da metodologia desenvolvida mostrou-se uma ferramenta importante para o planejamento urbano-ambiental das áreas periurbanas, alcançando o objetivo proposto. / From the second half of the twentieth century, Brazil's urban growth intensified, following the post-World War II trend of the United States and Europe. The spaces now occupied by urbanization are influenced by anthropic actions and are governed by morphodynamics, which are based on the human life span. Among the urban spaces, the periurban areas stand out, which constitute a complex mosaic of interactions between the rural and urban regions, developing significant transformations of the relief. The environmental impacts resulting from the interaction between physical and social systems have stimulated concerns in the scientific community, with emphasis on geomorphological studies, especially on urban geomorphology, since it demonstrates the importance of knowing the physical characteristics of relief in understanding human actions on nature and, consequently, its role in territorial planning. This work aimed to develop a systematic cartographic analysis of the physical space to guide the implementation of urbanization in a specific area with specific physical characteristics, assisting in urban-environmental planning and management. In order to reach the proposed objective, the area of Pau D'alho stream watershed was the object of study, marked as one of the axes of urban expansion of the city of Bauru (SP). Under the theoretical and methodological precepts of the General Theory of Systems, the physical characteristics of the basin were investigated through the construction of morphometric, geomorphological, physical fragility and unconsolidated materials maps, with the support of fieldwork. Moreover, the evolution of the use and occupation of the land and its consequent legal transgressions were analyzed, allowing the understanding of the influence of anthropic actions in the development of erosion processes, enabling the elaboration of vegetation cover, land use and occupation (1972 and 2016) and of environmental derivations and legal transgressions maps. In view of the data obtained, a systematic analysis of urban expansions over the relief was developed, based on the elaborated cartographic material and the urban indexes illustrated by the current federal and municipal legislation. A map of orientation to the urban expansion was elaborated through analysis, which tried to synthesize physical characteristics of the watershed with the urbanistic index and a more adequate proposal of urbanization. With this, a study area was divided into 7 physical units, divided between favorable units for urbanization, where urbanization is allowed without restrictions; units with restrictions to urbanization, where physical characteristics denote care and limit certain types of urbanization; and improper areas for urbanization, where an urbanization would bring serious impacts to the relief and, consequently, the resident population there. Thus, as the cartographic product generated through the developed methodology proved to be an important tool for the urban-environmental planning of the periurban areas, the objective is the proposition. / FAPESP: 2014/07017-9
35

Morfodinâmica de um delta artificial na margem oeste da Lagoa Mangueira – RS

Guimarães, Lisiane Silva January 2014 (has links)
O estudo, em corpos lagunares, de transportes de sedimentos pode apresentar significativa importância e abrangência. Para que haja compreensão dos mecanismos que ocorrem na linha de costa de um corpo aquoso é fundamental o estudo de sua morfodinâmica e morfologia do sistema. Estes evoluem conjuntamente, visto que a dinâmica determina a morfologia, entretanto uma vez estabelecida a morfologia, esta condiciona a dinâmica. A evolução de corpos lagunares segue a evolução de cinco processos naturais: a segmentação, a acresção vertical, a progradação de deltas, a acresção lateral, a sedimentação marinha e/ou lacustre. Neste estudo é abordado a progradação deltaica. Deltas são acumulações de sedimentos no final de um canal, no qual há uma descarga dentro de um corpo de água. A área selecionada para este estudo situa-se no sul da planície costeira do Estado do Rio Grande do sul, na região norte da Lagoa Mangueira, onde se localiza diversos deltas artificiais presentes no corpo lacustre. Pelo fato de estar inserido no popularmente conhecido “Parque das Capivaras”, a feição estudada ficou denominada como “Delta das Capivaras”. O objetivo do estudo foi desenvolver o modelo de evolução deste delta artificial construído pela atividade das lavouras arrozeiras na margem oeste da Lagoa da Mangueira e avaliar os impactos ambientais causados pelo manejo do solo. A metodologia empregada contemplou variadas técnicas de aquisição e interpretação de dados. As atividades iniciaram com uma revisão bibliográfica e preparação da logística necessária para aquisição de informações em campo, onde foram coletados dados de sedimentologia, batimetria e testemunhos. As atividades posteriores compreenderamm análises, processamentos e tratamentos das amostras e informações obtidas, em laboratório. A integração dos dados forneceu informações importantes sobre a dinâmica e morfologia do Delta das Capivaras. Foi possível concluir que o principal agente formador do delta é o canal artificial gerado pela atividade antrópica devido ao elevado potencial de aporte de sedimentos para o interior da lagoa. A flutuação de nível é pouco representativa e a ação das ondas é secundária na formação do delta, já que o mesmo é protegido por feições arenosas e vegetação. A atividade de orizicultura na margem oeste da Lagoa Mangueira causa rápida eutrofização no corpo aquoso, esse fato mostra que a atividade antrópica causada pelo cultivo de arroz modifica bastante as características naturais desse corpo hídrico, podendo causar impactos na vida e dinâmica da lagoa. O Delta das Capivaras se desenvolveu em um local inferior a 1 km, num intervalo de tempo de décadas; e, por fim, sua gênese foi controlada principalmente pelo aporte de sedimentos. Além disso, está inserido em uma bacia de drenagem litorânea com extensão de área bastante reduzida e relevo com cotas inferiores a 10 metros, não podendo, portanto, gerar uma feição do tamanho do Delta das Capivaras, em um curto espaço de tempo. Essas características classificam o delta como uma feição artificial de escala de engenharia e não geológica. / The sediment transport in lakes is very important and has a broad scope. In order to acquire comprehension on the processes occurring in the coastline it is vital that the system´s morphodynamics and morphology are studied. These last elements evolve together, since the dynamics determine morphology, however once morphology is established, it affects dynamics. The evolution of these bodies of water follows the evolution of five natural processes: segmentation, vertical accretion, marine and lagoonal sedimentation. In this study, deltaic progradation is analyzed. Deltas are deposits of sediment at the end of a water stream, which is discharged into a body of water. The selected area for this study is located in the southern portion of the coastal plain of Rio Grande do Sul state, in the north sector of the Mangueira Lake, where several artificial deltas are found in the lagoon. Since it is located in the popularly known “Capivaras Park”, the feature which is analysed in this study was named “Delta das Capivaras”. This study aimed to develop the evolution model for this artificially built delta, wich was formed due to rice farming on the west margin of the lake, and also, to evaluate the environmental impacts caused by the soil management. The methodology employed in the study comprised different techniques for the data acquisition and its interpretation. The work began by analyzing related bibliography and planning logistics for the field work, where data on sedimentology, bathymetry and core sample were collected. The later activities comprise analysis, processing and treatment of the obtained samples in the laboratory. The integration of data offered important information on the dynamics and morphology of the Delta das Capivaras. It was possible to conclude that the primary mechanism for the delta development is the artificial channel generated by anthropic activity, due to the elevated potential of sediment transport towards the lagoon. The water level variation has little significant contribution such as the wave action in the delta formation, since it is protected by sand “features” such as sandy spits and vegetation. The rice cultureon the west margin of the Mangueira Lake causes fast eutrophication of the water body, proving that anthropic activity caused by that specific activity strongly modifies the lagoon´s natural features and can possibly impact life and dynamics in this lagoon. The Delta das Capivaras developed in a location less than 1 km, in a time of decades and, finally, its genesis was controlled mainly by sediment supply. Moreover, it is inserted into a coastal drainage basin with little extension area and lower elevation with dimensions less than 10 meters, wherefore cannot generate a feature like Delta das Capivaras, in a short space of time. These characteristics classify the delta as an artificial feature of engineering scale and not geological.
36

Morfodinâmica de um delta artificial na margem oeste da Lagoa Mangueira – RS

Guimarães, Lisiane Silva January 2014 (has links)
O estudo, em corpos lagunares, de transportes de sedimentos pode apresentar significativa importância e abrangência. Para que haja compreensão dos mecanismos que ocorrem na linha de costa de um corpo aquoso é fundamental o estudo de sua morfodinâmica e morfologia do sistema. Estes evoluem conjuntamente, visto que a dinâmica determina a morfologia, entretanto uma vez estabelecida a morfologia, esta condiciona a dinâmica. A evolução de corpos lagunares segue a evolução de cinco processos naturais: a segmentação, a acresção vertical, a progradação de deltas, a acresção lateral, a sedimentação marinha e/ou lacustre. Neste estudo é abordado a progradação deltaica. Deltas são acumulações de sedimentos no final de um canal, no qual há uma descarga dentro de um corpo de água. A área selecionada para este estudo situa-se no sul da planície costeira do Estado do Rio Grande do sul, na região norte da Lagoa Mangueira, onde se localiza diversos deltas artificiais presentes no corpo lacustre. Pelo fato de estar inserido no popularmente conhecido “Parque das Capivaras”, a feição estudada ficou denominada como “Delta das Capivaras”. O objetivo do estudo foi desenvolver o modelo de evolução deste delta artificial construído pela atividade das lavouras arrozeiras na margem oeste da Lagoa da Mangueira e avaliar os impactos ambientais causados pelo manejo do solo. A metodologia empregada contemplou variadas técnicas de aquisição e interpretação de dados. As atividades iniciaram com uma revisão bibliográfica e preparação da logística necessária para aquisição de informações em campo, onde foram coletados dados de sedimentologia, batimetria e testemunhos. As atividades posteriores compreenderamm análises, processamentos e tratamentos das amostras e informações obtidas, em laboratório. A integração dos dados forneceu informações importantes sobre a dinâmica e morfologia do Delta das Capivaras. Foi possível concluir que o principal agente formador do delta é o canal artificial gerado pela atividade antrópica devido ao elevado potencial de aporte de sedimentos para o interior da lagoa. A flutuação de nível é pouco representativa e a ação das ondas é secundária na formação do delta, já que o mesmo é protegido por feições arenosas e vegetação. A atividade de orizicultura na margem oeste da Lagoa Mangueira causa rápida eutrofização no corpo aquoso, esse fato mostra que a atividade antrópica causada pelo cultivo de arroz modifica bastante as características naturais desse corpo hídrico, podendo causar impactos na vida e dinâmica da lagoa. O Delta das Capivaras se desenvolveu em um local inferior a 1 km, num intervalo de tempo de décadas; e, por fim, sua gênese foi controlada principalmente pelo aporte de sedimentos. Além disso, está inserido em uma bacia de drenagem litorânea com extensão de área bastante reduzida e relevo com cotas inferiores a 10 metros, não podendo, portanto, gerar uma feição do tamanho do Delta das Capivaras, em um curto espaço de tempo. Essas características classificam o delta como uma feição artificial de escala de engenharia e não geológica. / The sediment transport in lakes is very important and has a broad scope. In order to acquire comprehension on the processes occurring in the coastline it is vital that the system´s morphodynamics and morphology are studied. These last elements evolve together, since the dynamics determine morphology, however once morphology is established, it affects dynamics. The evolution of these bodies of water follows the evolution of five natural processes: segmentation, vertical accretion, marine and lagoonal sedimentation. In this study, deltaic progradation is analyzed. Deltas are deposits of sediment at the end of a water stream, which is discharged into a body of water. The selected area for this study is located in the southern portion of the coastal plain of Rio Grande do Sul state, in the north sector of the Mangueira Lake, where several artificial deltas are found in the lagoon. Since it is located in the popularly known “Capivaras Park”, the feature which is analysed in this study was named “Delta das Capivaras”. This study aimed to develop the evolution model for this artificially built delta, wich was formed due to rice farming on the west margin of the lake, and also, to evaluate the environmental impacts caused by the soil management. The methodology employed in the study comprised different techniques for the data acquisition and its interpretation. The work began by analyzing related bibliography and planning logistics for the field work, where data on sedimentology, bathymetry and core sample were collected. The later activities comprise analysis, processing and treatment of the obtained samples in the laboratory. The integration of data offered important information on the dynamics and morphology of the Delta das Capivaras. It was possible to conclude that the primary mechanism for the delta development is the artificial channel generated by anthropic activity, due to the elevated potential of sediment transport towards the lagoon. The water level variation has little significant contribution such as the wave action in the delta formation, since it is protected by sand “features” such as sandy spits and vegetation. The rice cultureon the west margin of the Mangueira Lake causes fast eutrophication of the water body, proving that anthropic activity caused by that specific activity strongly modifies the lagoon´s natural features and can possibly impact life and dynamics in this lagoon. The Delta das Capivaras developed in a location less than 1 km, in a time of decades and, finally, its genesis was controlled mainly by sediment supply. Moreover, it is inserted into a coastal drainage basin with little extension area and lower elevation with dimensions less than 10 meters, wherefore cannot generate a feature like Delta das Capivaras, in a short space of time. These characteristics classify the delta as an artificial feature of engineering scale and not geological.
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Definição dos pontos de contorno da linha de preamar máxima atual do litoral do município de goiana-pe e suas implicações ambientais. 2016

MADRUGA, Marcelo Menezes Diniz 01 August 2016 (has links)
Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2017-02-01T18:49:55Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DIssertação Marcelo Menezes.pdf: 4580515 bytes, checksum: ac44866119de747b2c71f8f144475144 (MD5) / Made available in DSpace on 2017-02-01T18:49:55Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DIssertação Marcelo Menezes.pdf: 4580515 bytes, checksum: ac44866119de747b2c71f8f144475144 (MD5) Previous issue date: 2016-08-01 / Esta pesquisa foi realizada no munícipio de Goiana, litoral Norte do Estado de Pernambuco (Bacia da Paraíba), entre as praias de Ponta do Funil e Carne de Vaca. O trabalho teve intuito de levantar informações sobre o sistema costeiro, com base na caracterização morfodinâmica e geoambiental, quantificando o balanço sedimentar e a vulnerabilidade das praias. Para isto fez-se um monitoramento bimestral com levantamento de perfis topográficos e coletas de sedimentos no estirâncio entre os meses de novembro/2014 e setembro/2015. Na correlação dos perfis topográficos associados à sedimentologia das amostras, os resultados indicaram que o balanço sedimentar foi positivo (deposicional) em seis pontos, sendo o perfil praial P5, na praia de Ponta de Pedras, onde houve a maior variação com +281,5m³/m. No perfil praial P1, na praia de Ponta do Funil, foi o único que obteve variação do volume negativa (retrogradacional). No levantamento da linha de preamar máxima, constatou-se a retrogradação no litoral sul e progradação no litoral norte. Os indicadores utilizados revelaram um litoral moderadamente preservado com 69% estabilizado apresentando feições geomorfológicas típicas do ambiente praial, como as escarpas de berma e 31% com obras de proteção costeira, na maioria dos casos sem fundamentação técnica adequada. A porção mais vulnerável da área encontra-se na praia de Catuama, local onde há grande número de casas construídas na pós-praia e até mesmo no estirâncio. / This research was conducted in an area in the municipality of Goiana, northern coast of the state of Pernambuco (Paraíba Basin), located between the Ponta do Funil and Carne de Vaca beaches. The main goal of the work was to obtain information concerning the coastal system, based upon the morphodynamic and environmental quantification of the sedimentary balance and the vulnerability of these beaches. To accomplish that, topographic profiles were conducted with intervals of two months and samples of sediments were collected in the foreshore during the period from November/2014 and September/2015. The correlation of the topographic profiles with the sedimentary characteristics of the collected samples, it was clear that the sedimentary balance was positive (depositional) for six points, with the P5 beach profile, located in the Ponta de Pedras beach, showing the larger variation +281,5m³/m. The P1 beach profile, located in the Ponta do Funil, was the only one to show negative variation of volume (retrogression). During the definition of the line of maximum high tide, it was observed a retrogression on the south coast and progradation on the north coast. The parameters used revealed a moderately preserved coast, with 69% of stabilization showing morphologic features typical of environment with berm scarps and 31% with civil engineering construction to protect the coast; most of them without technical support. The most vulnerable section of the coast was located in the Catuama beach, due to the large number of houses constructed in the post-beach and some involving the foreshore.
38

Fragilidade ambiental no setor norte do município de Juiz de Fora (MG): subsídios da geomorfologia ao planejamento urbano

Oliveira, Alexsander de 14 April 2016 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-17T17:15:35Z No. of bitstreams: 1 alexsanderdeoliveira.pdf: 12218792 bytes, checksum: 1c1d77ecefec5da6018a0cb065c39b7f (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T14:39:43Z (GMT) No. of bitstreams: 1 alexsanderdeoliveira.pdf: 12218792 bytes, checksum: 1c1d77ecefec5da6018a0cb065c39b7f (MD5) / Made available in DSpace on 2016-07-13T14:39:43Z (GMT). No. of bitstreams: 1 alexsanderdeoliveira.pdf: 12218792 bytes, checksum: 1c1d77ecefec5da6018a0cb065c39b7f (MD5) Previous issue date: 2016-04-14 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O crescimento populacional impulsiona a expansão urbana das cidades. A geomorfologia aplicada torna-se indispensável, à medida que o homem se apropria do relevo para construir sua moradia e reproduzir a vida, pois ocorrem alterações nos sistemas ambientais que constituem a base onde a sociedade se projeta. O urbano precisa ser entendido como um todo complexo, sobre o qual ocorrem processos que mudam as formas. Também acontecem mudanças nas formas que, alteram os processos. Qualquer tipo de alteração promovida pelos assentamentos urbanos, por mais sutil que seja, poderá provocar variações que se perpetuam no tempo e no espaço, muitas vezes irreversíveis e danosas às sociedades. O objetivo principal desse trabalho constitui-se em estudar a dinâmica do sistema geomorfológico pelo prisma da interpretação Ecodinâmica proposta por Tricart (1977). Objetiva-se também determinar a fragilidade ambiental a partir da proposta metodológica de Ross (1994), utilizando o conceito de Unidades Ecodinâmicas. Ao se estabelecer a fragilidade ambiental é possível avaliar as áreas nas quais poderão surgir quadros mais acentuados de instabilidade frente a projeção da sociedade sobre o meio. Assim, pode-se subsidiar ações de planejamento que restrinjam ou (re)direcionem o uso e ocupação da terra, de forma a prevenir ou minimizar o surgimento de problemas relacionados à qualidade ambiental. O estudo foi aplicado em uma área denominada de Setor Norte do Município de Juiz de Fora. Este setor foi selecionado por conter variados tipos de uso da terra e cobertura vegetal, com alguns ambientes naturais e outros antrópicos de uso urbano e rural. Como aporte foram utilizados dados secundários fruto de trabalho em gabinete e campo, para a caracterização de fatores primordiais: geologia, relevo (compartimentação, dissecação vertical, declividade), solos, uso da terra/cobertura vegetal e clima. / Population growth drives urban sprawl of cities. The geomorphology applied becomes indispensable, as the man appropriates relief to build your house and reproduce life, because there are changes in environmental systems that form the basis on which society projects. The city to be understood as a complex whole, on which there are processes that change the shapes. Also take place changes in ways that alter the processes. Any type of change promoted by urban settlements, however subtle it may be, may cause variations that are perpetuated in time and space, often irreversible and damaging to companies. The main objective of this work is constituted to study the dynamics of geomorphological system for the interpretation of the prism ecodynamic proposed by Tricart (1977). Lens will also determine the environmental fragility from the methodological proposal of Ross (1994), using the concept of Ecodinâmicas units. By establishing the environmental fragility it is possible to assess the areas which may appear more pronounced frames facing instability to the projection of society on the environment. So you can support planning actions that restrict or (re) to target the use and occupation of land in order to prevent or minimize the emergence of the environmental quality problems. The study was applied to an area called North Juiz de Fora Municipality Sector. This sector was selected because it contains different types of land use and vegetation cover, with some natural environments and other man-made urban and rural use. As input were used secondary data result of work in the office and field, for the characterization of key factors: geology, relief (compartmentalization, vertical dissection, slope), soils, land use / land cover and climate.
39

Multiple Scales of Beach Morphodynamic Processes: Measurements and Modelling

Cheng, Jun 20 November 2015 (has links)
Multiple scales of beach morphodynamic processes ranging from those of wave-breaking induced turbulence, individual wave, storm, seasonal, to inter-annual are examined in this dissertation based on both laboratory and field data. These processes were simulated using process-based numerical models and data-driven models. At a microscale, separating turbulence from orbital motion under breaking waves in the surf zone is essential to understanding wave-energy dissipation. Velocity data under monochromatic and random waves in the large-scale sediment transport facility (LSTF) were analyzed. Moving averaging provides a simple method for extracting turbulence from velocity measurements under random breaking waves collected at a reasonably high frequency. Various moving averaging time intervals were examined. An optimum moving averaging interval of approximately 30° to 42° phase angle (relative to peak wave period) allows a reasonable extraction of turbulence. An adaptive moving averaging with variable averaging time at wave crest and trough are proposed to improve the effect of turbulence extraction. At a mesoscale, hydrodynamic conditions associated with onshore migration of a sandbar and the subsequent equilibrium state of a stable bar were examined in the LSTF. Wave and near bottom velocity across the surf zone were measured during the onshore sandbar migration. The near-bottom velocity skewness indicates that before the sandbar reached equilibrium, the velocity was skewed offshore in the nearshore region, and skewed onshore seaward of the bar. The velocity skewness pattern reversed when the beach profile reached equilibrium and the sandbar became stable. The peak onshore directed acceleration was greater than the peak offshore directed acceleration throughout the surf zone during the periods of both onshore migrating and stable sandbar. The macroscale portion of the study examines the beach processes, particularly the morphodynamics of nearshore bar, at storm and seasonal scales. The bar height and bar position were extracted from bimonthly surveyed beach-profiles spaced at 300 m along the 22-km long Sand Key barrier island, West-Central Florida from October 2010 to August 2015. Seasonal beach cycle in the study area is illustrated by onshore sandbar migration during the summer and offshore sandbar migration during the winter, while subaerial beach remains rather stable. Alongshore variations of onshore and offshore sandbar migration were observed over storm events. The water depth over the pre-storm sandbar crest, or the bar crest elevation, is a major factor controlling the onshore or offshore sandbar movement. The offshore moving sandbar tends to have a shallower pre-storm bar crest, while the onshore moving sandbar tends to have a deeper pre-storm bar crest. A dynamic equilibrium bar height of 0.5 m for the study area was identified. The sandbar tends to evolve toward this equilibrium height during the seasonal cycle. The energetic conditions associated with Tropical Storm Debby caused a deviation from the above dynamic equilibrium conditions. The sandbar at most of the profile locations became higher than the pre-storm bar height regardless of the initial height of being greater or less than 0.5 m. After the storm, the higher and shallower bar experienced substantial erosion, the eroded sand was deposited in the trough landward. This resulted in a lower sandbar height, returning to the dynamic equilibrium height of 0.5 m. The Unibest-TC model (Walstra et al., 2012) is able to capture the measured trend of bar migration. The Modelling results suggest that offshore bar migration is dominated by suspended sediment transport. While onshore bar migration is driven mainly by bedload transport. At megascale, a data-driven model was developed to predict beach-profile evolution at multiple-annual scale. Empirical Orthogonal Function analysis was conducted on a time-series beach profile (R61) to identify temporal and spatial trends. Trends in the temporal EOF are modeled using a simple curve fitting. In this case, logarithmic and linear trends were identified. After the trend in temporal EOF values are identified, the curve fitting can be calibrated with 14-month data. The calibrated temporal EOF curve yielded accurate reproduction of profiles. The close examination of multiple scales of beach processes provides a comprehensive understanding of nearshore morphodynamics.
40

Dynamique de plages sableuses enclavées à la pointe Bretagne / Dynamics of sandy embayed beaches at the tip of Brittany

Quilfen, Victor 20 December 2016 (has links)
La thèse a pour objectif l'étude des plages sableuses enclavées, i.e. contraintes aux extrémités par des caps rocheux, soumises aux vagues et à un cycle de marée morte-eau vive-eau. Une double approche complémentaire liant études numériques et observations et mesures in situ sur un site-atelier a été retenue. Deux modèles déterministes basés sur les différents processus physiques (hydrodynamiques, hydro-sédimentaires et morphodynamiques) en jeu dans la zone littorale et moyennés sur la verticale (2DH) on été sélectionnés. Le code XBeach (Roelvink et al., 2009) utilise un maillage aux différences finies et intègre certaines spécificités tels qu'un modèle de propagation d'un rouleau d'écume ("roller"), un modèle de génération d'ondes longues et un modèle de développement d'un contre-courant de retour "undertow". Le code TELEMAC (Hervouet, 2007) utilise un maillage aux éléments finis. Pour le site-atelier, les plages enclavées adjacentes de La Palue et de Lostmarc'h en Presqu'île de Crozon (Finistère) ont été choisies pour leur bathymétrie complexe (présence de chenaux de baïne et d'un saillant) et leur géométrie complexe (caps rocheux de longueurs diverses, îlot). Une année d'observations et de mesures in situ (levés topographiques, pose de courantomètres ADV) a été entreprise entre le mois de septembre 2014 et le mois de septembre 2015, par diverses conditions météorologiques.Dans un premier temps, la dynamique globale des plages enclavées, représentées schématiquement par une échancrure rectangulaire, a été appréhendée. En particulier, la genèse d'une barre de déferlement en zone subtidale sous l'influence des dimensions de l'échancrure rocheuse, d'un cycle de marée morte-eau vive-eau et de houles énergétiques a été illustrée à travers plusieurs séries de simulations numériques à l'aide du code XBeach.Dans un deuxième temps, la modélisation hydrodynamique des courants sur les plages de La Palue et de Lostmarc'h a été effectuée, avec l'objectif d'étudier l'influence des caractéristiques des houles (hauteur, période et direction) et de celles de l'échancrure rocheuse (longueur des caps, espacement des caps, inclinaison des pointes) sur la prédiction des courants. Une ouverture sur la modélisation aux éléments finis (TELEMAC) en comparaison à celle aux différences finies (XBeach) a été présentée. Le code XBeach a été validé sur le plan hydrodynamique grâce aux mesures in situ d'une campagne de terrain réalisée en janvier 2015. Une étude numérique hydro-sédimentaire sur une lunaison complète (du 01 septembre 2015 au 29 septembre 2015) a alors été entreprise à l'aide du code XBeach, afin d'étudier l'intensité et la direction des flux sédimentaires instantanés et résiduels au gré des différents climats de houle et de marée, et selon les différents secteurs typologiques des plages de La Palue et de Lotsmarc'h. Cela a permis de mettre en évidence les particularités de la dynamique des plages enclavées par rapport aux plages ouvertes "quasi-infinies", tels que le phénomène de "contournement de cap", mais aussi les similitudes. Les résultats du code XBeach, pour différentes configurations du modèle, ont par ailleurs été comparés aux levés topographiques réalisés au cours du mois de septembre 2015.Dans un troisième temps, après une analyse statistique approfondie des climats de houle au large des plages de La Palue et de Lostmarc'h sur une période de 7 ans, l'impact morphodynamique de tempêtes extrêmes (houles décennale et cinquentennale) conjugué à celui de la hausse du niveau marin induit par le changement climatique, a été estimé sous la forme d'une étude numérique à l'aide du code XBeach sur un profil transversal au sud de la plage de La Palue / In this thesis, waves and neap-spring tide action on sandy embayed beaches constrained by rocky headlands is studied. A complementary approach combining numerical modeling and in situ measurements is used. Two deterministic model based on major physical processes (hydrodynamics, hydro-sedimentary and morphodynamics) present in the coastal zone and averaged over the water height (2DH) have been selected. XBeach (Roelvink et al., 2009) employs a finite difference scheme and incorporates some specific processes such as a roller, wave groups and the associated bound long wave and a undertow. TELEMAC (Hervouet, 2007) is a finite element scheme. Nearby sandy embayed beaches of La Palue and Lostmarc'h (Crozon Peninsula, Finistère) have been chosen for their complex bathymetry (rip channels, tombolo) and geometry (headlands, small island). One year of in situ measurements (topographical surveys, ADV velocimeters) between septembre 2014 and september 2015 has been undertaken, with different waves and tide climates.Firstly, the overall dynamics of embayed beaches built schematically in the form of a rectangular indentation has been caught. Especially, subtidal sandbar formation under the influence of waves, neap-spring tide and rocky headlands has been studied through several sets of numerical simulations.Secondly, hydrodynamic modelling on the embayed beaches of La Palue and Lostmarc'h has been made with the aim of study influence of waves characteristics (height, period and direction) and indentation's ones (headlands length, spacing between headlands, headlands inclination) on the prediction of currents. A simulation using finite element scheme (TELEMAC) has been achieved and compared to those using finite difference scheme (XBeach). XBeach currents predictions at two locations on the beaches of La Palue and Lostmarc'h over the period from the 21st January 2015 to the 23rd January 2015 have been compared to in situ measurements to validate the model. Whereupon, a numerical hydro-sedimentary simulation (using XBeach) over a full lunation from the 1st September 2015 to the 29th September 2015 has been undertaken on these two beaches, with the aim of study the intensity and direction of sediment flux (instantaneous and residual) for various waves and tide climates and for different morphological areas. This work has helped to highlight the dynamics features of embayed beaches compared to open beaches ones, such as headland sand bypassing, but also similarities. Moreover, XBeach morphodynamics predictions have been compared to in situ measurements for different model setup.Thirdly, after an in-depth statistical analysis of wave climates over a 7 year period offshore of La Palue and Lostmarc'h beaches, the morphodynamic impact of extreme storm waves (ten-yearly and fifty-yearly) combined to a sea level rise induced by climatic change on a cross-shore bottom profile south of La Palue has been estimated through a numerical study (using XBeach)

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