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Valdes-Pineda, Rodrigo, Juan B. Valdes, and Pablo Garcia-Chevesich. "Mudflow Modeling in the Copiapo Basin, Chile." UNIV POLITECNICA VALENCIA, 2017. http://hdl.handle.net/10150/624084.
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Extreme precipitation events that occurred between March 24 and March 26 of 2015 in the region of the Atacama Desert (26-29 degrees S) left around 30000 victims, being one of the biggest events over the past 50 years, with total a cost of reconstruction of about 1.5 billion dollars. The mudflows which increased during the flashflood inundated much of the city of Copiapo and Tierra Amarilla. This manuscript aims to model the mudflow of March 2015 in the Rio Copiapo, specifically in the towns of Copiapo and Tierra Amarilla. The modeling process is performed using the Rapid Mass Movement Simulation Model (RAMMS) that allows modeling the dynamics of the mudflow in two dimensions, only using the topographic features of the modeling domain. Calibration of the model was carried out successfully using data from inundation heights captured around the city after the 2015 event. A detailed analysis of the hydrometeorological event is carried out using satellite images obtained from Multi-satellite Precipitation Analysis (TMPA), and pluviometric and hydrographic data available in the Copiapo River basin. The simulation of the flood is reproduced with maps of inundation heights associated with two modeling scenarios. The maximum flood heights are ultimately used for developing risk maps at both sites. According to our results, the RAMMS model is an appropriate tool for modeling mudflow and mapping flood risk to improve hydrological risk management in arid and semiarid basins of Chile.
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Kriyantono, Rachmat. "A critical ethnography of crisis management dealing with a mudflow crisis in Sidoarjo, Indonesia [thesis]." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2011. https://ro.ecu.edu.au/theses/407.
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This PhD research focuses on the crisis management approaches of the company and government during a mudflow crisis in Sidoarjo, Indonesia, and the victims perceived a crisis management including the communication strategy and the programs of public relations conducted by officials from the Lapindo Incorporation (Inc) during efforts to deal with a mudflow crisis in Sidoarjo, Indonesia. The community, ranging from academics through to the victims who lost their homes, told local news media that Lapindo Inc., an oil company, was responsible for the mudflow - through a drilling mistake. On the other hand, when the Sidoarjo survivors of the mudslide and others took Lapindo Inc to court, the Indonesian courts supported experts that said an earthquake had caused the mudflow. The thesis explored ethnographically how the Sidoarjo community reacted to and perceived the communication strategies of officials from Lapindo and the Indonesian government during their efforts to deal with the mudflow crisis. I am interested in how the different actors construed the situation and how those constructions triggered a conflict. The critical approach is also applied based on the evidence presented from the interviews and focus group discussions. If certain actors have more power over others, then this would be reflected in both actions and in how people construe the world they are living in or the events that are happening to them. The paper is not to judge the company‟s responsibility, but to show how the different actors interact and the consequences of those interactions for the victims. The mudflow itself continues and has not been restricted completely. The result of this research is a comprehensive overview of the mudflow crisis itself and the reactions of many involved in it. The thesis gives contribution to the public relations issues and crisis management field. The research found that the crisis management conducted by the company and the government were not effective. Both of them were perceived to not taking an immediate appropriate action. The crisis management failed to ensure reliable and regular information, causing uncertainty. In addition, the crisis management focused more on maintaining the company‟s reputation than on the victims‟ fate. There are conflicts of interest between the company Inc, the government and the victims. This research described how power created knowledge in society by creating a social construction of the reality. The victims have been oppressed by more powerful groups therefore they must struggle against both the government and the company to gain their right.
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Fiorot, Guilherme Henrique. "On unsteady open-channel flows : a contribution to nonstationary sediment transport in runoff flows and to unstable non-Newtonian mudflow studies." Thesis, Rennes, INSA, 2016. http://www.theses.fr/2016ISAR0020/document.
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L'objectif général de cette thèse est l'étude de d'écoulement instationnaire du type coulée de boue dans des canaux naturels. La pluie, source du débit liquide, entraine le ruissellement, responsable du mouillage du sol, de la réduction de sa cohésion et de l'érosion des petites particules de sédiments. A partir de là, le transport de sédiments peut augmenter avec le débit et la pente du sol jusqu'à ce que la concentration en particules atteignent des niveau très importants dans la composition du fluide. Dans une première partie, un banc expérimental a été conçu pour simuler des écoulements ruissellants sur un lit mobile. Un système de mesure a été inventé et implémenté pour mesurer le débit solide instantané et le frottement instantané. Ces systèmes sont utilisés pour étudier l'effet des ondes de surface libre sur le transport de sédiments. Ces données sont employées pour corréler les charactéristiques entr l'écoulement et le transport solide. L'analyse des résultats permet d'observer que pour un écoulement moyen donné, la présence des ondes réduit la quantité moyenne des sédiments transportés. Dans une deuxième partie, la dynamique des écoulements très concentrés est étudiée grâce à un modèle de roll waves de première ordre pour les écoulements laminaires des fluides de type Herschel-Bulkley. Les résultats présentés indiquent que des roll wave sont certainement présentes dans un événement naturel publié et pris comme cas d'étude. Les propriétés des ondes prédites sont estimées avec un écart de 8% par rapport à l'amplitude moyenne mesurée. Finalement, la solution théorique pour le profil de vitesse est modifiée pour prendre en considération l'effet de la porosité. La solution mathématique est comparée à des simulations faites avec FLUENT. Une analyse paramétrique est effectuée, et la comparaison avec le cas d'étude déjà publié est améliorée. En conclusion générale, les phénomènes instationnaires qui peuvent apparaitre lors de l'évolution d'une coulée de boue affectent la dynamique générale du système couplé (écoulement-transport sédimentaire) par rapport au cas permanent et uniforme. Vérifier que ce type de phénomènes peut apparaître lors d'un événement naturel comme les coulées de boue doit être un étape importante d'un projet d'ingénierie, afin de limiter les risques de dommagesThis thesis was motivated by the need to better understand time-dependent features related to mudflow evolution on natural sloped channels. Basically, the research is focused on events that are confined in channels formed due to the topography. The rain, source of the liquid discharge, generates the runoff flow which is responsible for wetting the soil surface, promoting reduction of soil cohesiveness and erosion of small particles such as clay and sand. From this point, the sediment transport can increase as small water flows merge and form greater streams. The scenario keeps its evolution until i reaches high concentration of particles in the fluid mixture. In the first part, to study the non-permanent feature of sediment transport, an open-channel experiment was designed for simulating runoff flow over a mobile bed. A measurement system was designed and constructed to instantaneously inspect the solid discharge of particles and the flow friction at the bed. This apparatus is further used to explore the influence of free-surface waves on the sediment transport. Hydraulic properties of flows are qualitatively and quantitatively studied and data are used to correlate characteristics of flow and sediment transport. A set of experimental runs is presented and explored. Analysis of results shows that for fixed flow conditions, waves induce an overall smaller quantity of transported sediment. In a second part, the dynamics of high concentrated flows is addressed and this thesis attempts to appl a first-order roll-wave model for Herschel-Bulkley laminar fluid flow to a registered natural event. Results presented point out that roll waves could have occurred during this already published case-study event. Simulations could predict wave heights within 8% on uncertainty with respect to the mea amplitude of measured waves. Finally a new theoretical solution for the velocity profile is proposed taking into account the porosity of the bed. Results are then compared with numerical simulation performed in FLUENT. A parametric analysis is employed and the case-study is once again evaluated. A: general conclusion, the non-permanent phenomena that can appear during the evolution of a mudflow event affect the overall dynamics of the coupled system (hydraulic-sediment transport) in comparison to the steady and uniform case. Verifying that such phenomena could appear should indeed be an important part in hydraulic engineering projects, especially when dealing with lives, which is the case of mud flows
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Fiorot, Guilherme Henrique [UNESP]. "On unsteady open-channel flows: a contribution to non-stationary sediment transport in runoff flows and to unstable non-Newtonian mudflow studies." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/143758.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Dentro da temática de riscos naturais, mais precisamente no contexto das corridas de lama, esta tese surge da necessidade que existe na literatura em melhor se conhecer as características temporais destes eventos. A chuva, fonte da vazão liquida, conduz aos escoamentos superficiais, responsáveis pela redução da coesão do material sedimentar do solo (areia e argila) e seu consequente transporte. Em locais de topografia íngreme, de montante a jusante, a vazão sólida do escoamento principal pode, eventualmente, evoluir devido às contribuições laterais de pequenos escoamentos, alterando não só as propriedades reológicas do fluido e dinâmicas do escoamento, como se manter até que o transporte sólido atinja elevada concentração na composição do fluido. Na primeira parte desta tese, um experimento de superfície livre foi projetado para reproduzir escoamentos superficiais sobre um fundo móvel, com o objetivo de estudar propriedades não-permanentes do transporte de sedimentos. Um sistema de medição foi projetado e construído com o intuito de medir quase instantaneamente a vazão sólida e suas correlações com as propriedades hidráulicas do escoamento. Este aparato é também utilizado para observar a influência de instabilidades de superfície livre sobre o transporte. Um conjunto de resultados é apresentado e analisado e mostra que a presença de ondas pode, em média, reduzir a quantidade total de sedimentos transportada. Na segunda parte desta tese, a dinâmica de escoamentos com elevada concentração de sedimentos é estudada. Neste trabalho, executa-se a aplicação de um modelo de primeira ordem de roll waves para fluidos de reologia Herschel-Bulkley para simular um evento natural registrado na literatura. Os resultados apresentados mostram que roll waves poderiam, de fato, ser identificadas no evento e que a amplitude média observada poderia ter sido estimada com 8% de incerteza. Assim, um modelo mais complexo para a solução do perfil de velocidade é proposto, adicionando a porosidade do solo ao problema. Resultados do modelo são comparados com simulações numéricas. Uma análise paramétrica é efetuada e o caso de estudo é novamente avaliado. Como conclusão geral do trabalho, a presença de fenômenos não-estacionários durante a evolução escoamento superficial - corrida de lama afeta a dinâmica global do sistema acoplado hidráulica-transporte de sedimentos, quando comparado ao caso permanente e uniforme. Assim, a verificação de que tais fenômenos podem aparecer deve constituir parte de projetos engenharia, especialmente quando estes, em situações de catástrofes, envolvem danos a infraestruturas civis e quase sempre perdas de vidas, como é o caso das corridas de lama.
This thesis was motivated by the need to better understand time-dependent features related to mudflow evolution on natural sloped channels. Basically, the research is focused on events that are confined in channels formed due to the topography. The rain, source of the liquid discharge, generates the runoff flow which is responsible for wetting the soil surface, promoting reduction of soil cohesiveness and erosion of small particles such as clay and sand. From this point, the sediment transport can increase as small water flows merge and form greater streams. The scenario keeps its evolution until it reaches high concentration of particles in the fluid mixture. In the first part, to study the non-permanent feature of sediment transport, an open-channel experiment was designed for simulating runoff flow over a mobile bed. A measurement system was designed and constructed to instantaneously inspect the solid discharge of particles and the flow friction at the bed. This apparatus is further used to explore the influence of free-surface waves on the sediment transport. Hydraulic properties of flows are qualitatively and quantitatively studied and data are used to correlate characteristics of flow and sediment transport. A set of experimental runs is presented and explored. Analysis of results shows that for fixed flow conditions, waves induce an overall smaller quantity of transported sediment. In a second part, the dynamics of high concentrated flows is addressed and this thesis attempts to apply a first-order roll-wave model for Herschel-Bulkley laminar fluid flow to a registered natural event. Results presented point out that roll waves could have occurred during this already published case-study event. Simulations could predict wave heights within 8% on uncertainty with respect to the mean amplitude of measured waves. Finally a new theoretical solution for the velocity profile is proposed taking into account the porosity of the bed. Results are then compared with numerical simulation performed in FLUENT. A parametric analysis is employed and the case-study is once again evaluated. As general conclusion, the non-permanent phenomena that can appear during the evolution of a mudflow event affect the overall dynamics of the coupled system (hydraulic-sediment transport) in comparison to the steady and uniform case. Verifying that such phenomena could appear should indeed be an important part in hydraulic engineering projects, especially when dealing with lives, which is the case of mudflows.
CNPq: 201557/2012-6
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Fiorot, Guilherme Henrique. "On unsteady open-channel flows : a contribution to non-stationary sediment transport in runoff flows and to unstable non-Newtonian mudflow studies /." Ilha Solteira, 2016. http://hdl.handle.net/11449/143758.
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Orientador: Geraldo de Freitas MacielAbstract: This thesis was motivated by the need to better understand time-dependent features related to mudflow evolution on natural sloped channels. Basically, the research is focused on events that are confined in channels formed due to the topography. The rain, source of the liquid discharge, generates the runoff flow which is responsible for wetting the soil surface, promoting reduction of soil cohesiveness and erosion of small particles such as clay and sand. From this point, the sediment transport can increase as small water flows merge and form greater streams. The scenario keeps its evolution until it reaches high concentration of particles in the fluid mixture. In the first part, to study the non-permanent feature of sediment transport, an open-channel experiment was designed for simulating runoff flow over a mobile bed. A measurement system was designed and constructed to instantaneously inspect the solid discharge of particles and the flow friction at the bed. This apparatus is further used to explore the influence of free-surface waves on the sediment transport. Hydraulic properties of flows are qualitatively and quantitatively studied and data are used to correlate characteristics of flow and sediment transport. A set of experimental runs is presented and explored. Analysis of results shows that for fixed flow conditions, waves induce an overall smaller quantity of transported sediment. In a second part, the dynamics of high concentrated flows is addressed and this the... (Complete abstract click electronic access below)
Resumo: Dentro da temática de riscos naturais, mais precisamente no contexto das corridas de lama, esta tese surge da necessidade que existe na literatura em melhor se conhecer as características temporais destes eventos. A chuva, fonte da vazão liquida, conduz aos escoamentos superficiais, responsáveis pela redução da coesão do material sedimentar do solo (areia e argila) e seu consequente transporte. Em locais de topografia íngreme, de montante a jusante, a vazão sólida do escoamento principal pode, eventualmente, evoluir devido às contribuições laterais de pequenos escoamentos, alterando não só as propriedades reológicas do fluido e dinâmicas do escoamento, como se manter até que o transporte sólido atinja elevada concentração na composição do fluido. Na primeira parte desta tese, um experimento de superfície livre foi projetado para reproduzir escoamentos superficiais sobre um fundo móvel, com o objetivo de estudar propriedades não-permanentes do transporte de sedimentos. Um sistema de medição foi projetado e construído com o intuito de medir quase instantaneamente a vazão sólida e suas correlações com as propriedades hidráulicas do escoamento. Este aparato é também utilizado para observar a influência de instabilidades de superfície livre sobre o transporte. Um conjunto de resultados é apresentado e analisado e mostra que a presença de ondas pode, em média, reduzir a quantidade total de sedimentos transportada. Na segunda parte desta tese, a dinâmica de escoamentos com eleva... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Melo, Danielle Fernanda Morais de. "Comportamento reológico de solos sujeitos a corridas de lama por liquefação estática." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-23122014-153333/.
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Os escorregamentos causados por precipitação intensa ocasionam grandes prejuízos a cada estação chuvosa no sudeste brasileiro. Essa dissertação estudou 2 amostras de solos da região serrana do Rio de Janeiro sob uma nova ótica de análise para escorregamentos. As amostras foram coletadas 4 meses após a ocorrência do megadesastre, onde chuvas com precipitação de 325mm em 48 horas causaram mais de 1500 mortes. Em relatos e vídeos obtidos de movimentos de massa que ocorreram nesse evento foi possível observar que o solo apresentou comportamento de um líquido denso e viscoso, escoando pelas encostas da cidade, ou seja, o solo, encharcado pelas chuvas intensas que ocorreram na região, sofreu liquefação. Esse material viscoso formado pela mistura de solo+água que foi caracterizado através da utilização da reologia. Para isso foram apresentados os conceitos da reologia e dos ensaios reométricos, e as possíveis aplicações para solos e na caracterização de corridas de lama. Foram utilizados três ensaios para caracterizar o solo no estado fluido, que foi o squeeze flow, o reômetro de torque com reometria planetária, e o reômetro de placas paralelas. O principal objetivo para utilização desses ensaios é a praticidade para realização dos ensaios, que tem como características: a rapidez na execução, a coleta de dados é realizada automaticamente, apresentam receptibilidade e a facilidade na execução. Com os resultados obtidos foi possível observar a mudança de comportamento do solo (de um material com comportamento elástico para um material como um fluxo de lama) com a elevação da umidade, para os dois ensaios. Os resultados demonstram que o valor do limite de liquidez calculado através do aparelho de Casagrande é confirmado com esses novos aparelhos, ii sendo que, para esses aparelhos é visível a mudança de comportamento que define o limite de liquidez. Através dos resultados também foi possível determinar que o solo em estado fluido tem seu comportamento regido pelo modelo de Herschel Bulkley. Para tornar os resultados obtidos aplicáveis foi apresentado um capítulo ligando os resultados obtidos da reometria com a possibilidade do solo sofrer liquefação, aliado com os resultados obtidos dos ensaios de caracterização geotécnica. Sendo realizadas análises de estabilidade com os resultados obtidos, correlacionando a inclinação do talude, o nível dágua e a ocorrência da liquefação.Landslide caused by rainfalls cause major damage each rainy season in southeastern Brazil. This dissertation studied two soil samples from the mountainous region of Rio de Janeiro in a new light analysis for landslides. Samples were collected four months after the occurrence of disaster, when rainfall with intensity of 325mm in 48 hours caused more than 1,500 deaths. In reports and video obtained from mass movements that occurred at this event was observed that the soil responded as a dense liquid, viscous draining the citys landscape. The drenched soil, by heavy rains that occurred in the region, suffered liquefaction. This viscous material formed by mixture of soil and water that was characterized by the use of rheology. In this dissertation was presented the concepts of rheology and rheometric tests for application in soils and characterization of fluid movements. Tree different rheometric tests were performed to characterize the soil in the fluid state, which was the squeeze flow, torque rheometer with planetary geometry and parallel plate rheometer. The main objective of these tests is to use the convenience for the tests, that presents the follow characteristics: the speed of execution, data collection is performed automatically and the testes present repeatability apart from ease of application. With the results we observed the change of soil behavior (of a material with elastic properties for a material that presents the behavior as a mud flow) with increasing humidity for the tests. The results show that the value of the liquidity limit calculated by the Casagrande apparatus is confirmed with these new devices, furthermore with the use of these devices is visible the behavior change that defines the liquid limit. iv Was determined that the Herschel Bulkley model is the one that best represents the behavior of the soil in the fluid state. Was presented a chapter with an application of the results obtained by adding the results of the rheometer with the results of geotechnical characterization tests to determine the possibility of soil suffer liquefaction. To this aim, were performed stability analysis considering the results obtained, correlating the slope inclination, the water level and the occurrence of liquefaction.
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Le, Mignon Gwennou. "Analyse de scénarios de mouvements de versants de type glissements-coulées : application à la région de Barcelonnette (Alpes-de-Haute-Provence, France)." Marne-la-vallée, ENPC, 2004. http://www.theses.fr/2004ENPC0001.
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Касіянчук, Д. В. "Оцінка екологічних ризиків для природної та техногенної складової екзогенних процесів Карпатського регіону." Thesis, Івано-Франківський національний технічний університет нафти і газу, 2016. http://elar.nung.edu.ua/handle/123456789/45.
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Дисертацію присвячено екологічній проблемі - оцінці еколого-геологічних ризиків розвитку екзогенних геологічних процесів шляхом розподілу на природні та техногенні процесоініціюючі фактори. Встановлено, що прогнозування екзогенних геологічних процесів слід здійснювати з урахуванням роздільного впливу факторів, які сприяють їх розвиткові та активізації. Визначено оптимальний для даної території комплекс природних та техногенних факторів. Величиною, що на кількісному ймовірнісному рівні враховує вплив просторових і часових чинників є інтегральний просторовий показник небезпеки проявів екзогенних геологічних процесів. Виконаний аналіз просторової імовірності небезпеки від проявів екзогенних геологічних процесів для території Івано-Франківської області з побудовою відповідних карт для природної та техногенної складових. На основі сформованих моделей ризиків проведена їх оцінка для окремих територій Карпатського регіону, що надає передумови для створення як просторового так і часового прогнозу.The thesis highlights the current scientific and applied problems of risk of exogenous geological processes that define the level of environmental safety of territory. The problem of public safety and numerous objects in the areas of dangerous exogenous geological processes is one of the major social and environmental problems of nowadays because of damages caused by these processes. The main kinds of EPG that cause the most negative effects are landslides, mudflows and karst. Theoretical and experimental researches made by the author, allow to summarize their main results. The development and widespread of exogenous geological processes and their impact on environmental safety in Ukraine and the Carpathian region in particular demonstrates the need for a detailed study of these processes in their relationship with the initiating factors. Having conducted the theoretical investigations allow to substantiate the analysis of algorithm groups of factors, based on the definition of the distribution factor characteristics of their unification, informative evaluation factors, the calculation of integrated indicators. In the analysis of natural and man-made component factors of development and activation of landslides, mudflows and karst, as technological conditioned advisable to consider the following: geological (distance to lots violation geological environment (water intakes and quarries), the rate of infestation and localities within an area, geomorphological (distance to the source of vibration, level of vibration, change the angle of inclination, stability factor, distance to roads, railways, distance to the village), hydrogeological (factor of disturbance, the level of ground waters) and landscape (changes in forest cover, distance to the border forest). The spatial analysis is based on communication between groups using factors weighing indicator informativeness factors and integral index. To improve existing methods for prediction of time use the new temporal factor characteristics as moon phase and global temperature. The final result of research is environmental geological risk assessment based on comprehensive integrated spatial indexes revitalization and development of exogenous geological processes, which are quantitative probabilistic take into account the level of total performance factors. The spatial analysis is done by mapping the spatial distribution of the integral index. Evaluation of ecological and geological risks manifestations of hazardous of exogenous geological processes will ensure the safe construction and operation of commercial engineering structures, plan measures to prevent emergency situations effectively protect the population from natural disasters, which in turn will lead to stability ekoheosystem and environmental security of the region and state as a whole.
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Zhang, Xueyan. "Mechanics of viscoelastic mud under water waves." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36710003.
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Zhang, Xueyan, and 張雪岩. "Mechanics of viscoelastic mud under water waves." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36710003.
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The Best M.Phil Thesis in the Faculties of Dentistry, Engineering, Medicine and Science (University of Hong Kong), Li Ka Shing Prize,2005-2006published_or_final_version
abstract
Mechanical Engineering
Master
Master of Philosophy
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Zhou, Gongdan. "The mechanisms of debris flow /." View abstract or full-text, 2010. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202010%20ZHOU.
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Kouah, Mohamed Amine Walid. "Μοdélisatiοn numérique des glissements de terrain : de l’initiatiοn à la transitiοn sοlide-fluide des géοmatériaux. : applicatiοn aux falaises des Vaches Νοires (Νοrmandie, France)." Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC004.
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En Normandie, les falaises des Vaches Noires constituent un secteur original à la morphologie de badlands, affecté par des processus hydrogravitaires (glissements de terrain, coulées de boue, …) emboités dans l’espace et dans le temps. Dans la phase d’initiation, les géomatériaux sont décrits par des lois de comportement élasto- plastique dans le cadre de la mécanique des sols. Toutefois, lorsque ces matériaux perdent leurs propriétés solides après cette initiation et se transforment en un fluide, leur comportement est décrit par la rhéologie des fluides. C'est le cas des coulées de boue argileuses où le comportement initial élasto-plastique des géomatériaux remaniés évolue vers un comportement visqueux sous certaines conditions spécifiques. Ce travail de recherche s’appuyant sur une approche pluridisciplinaire couplant géotechnique et géomorphologie vise à comprendre les comportements hydromécaniques de ces glissements de terrain et de ces coulées de boue dans leur phase d’initiation, à travers une modélisation numérique réalisée avec le logiciel FLAC qui repose sur une approche lagrangienne, utilisant la méthode des différences finies explicites. Par la suite, notre travail se concentre sur la modélisation de la transition solide-fluide du comportement des géomatériaux. Peu de modèles sont capables de prendre en compte à la fois les comportements solide et fluide, ainsi que la transition entre les deux. Nous avons proposé une loi de comportement élasto-viscoplastique, combinant une loi élasto-plastique (Cam-Clay Modifiée) et une loi viscoplastique (Herschel-Bulkley), et intégrant le critère du travail de second ordre locale pour suivre la transition entre les deux comportements. Ce modèle a été implémenté dans le logiciel FLAC. À travers une application concrète, il a été possible de démontrer la faisabilité de ce couplage dans la prise en compte des différents états de ces géomatériauxIn Normandy, the Vaches Noires cliffs present a unique badlands morphology, impacted by hydro-gravitational processes (landslides, mudflows, etc.) which are interrelated in space and time. During the initiation phase, the geomaterials are described by elasto-plastic behavior laws within the framework of soil mechanics. However, once these materials lose their solid properties post-initiation and transform into a fluid state, their behavior is characterized by fluid rheology. This is particularly evident in clayey mudflows where the initial elasto-plastic behavior of the reworked geomaterials transitions towards a viscous behavior under specific conditions. This research work, based on a multidisciplinary approach combining geotechnics and geomorphology, aims to understand the hydromechanical behaviors of these landslides and mudflows in their initiation phase. This is achieved through numerical modeling using the FLAC software, which employs a Lagrangian approach with the explicit finite difference method. Subsequently, our work focuses on modeling the solid-fluid transition of geomaterial behavior. Few models are able to take into account for both solid and fluid behaviors, as well as the transition between the two. We proposed an elasto-viscoplastic behavior law, combining an elasto-plastic law (Modified Cam-Clay) and a viscoplastic law (Herschel-Bulkley), and integrating the criterion of the local second- order work to monitor the transition between the two behaviors. This model was implemented in the FLAC software. Through a specific application, it was possible to demonstrate the feasibility of this coupling in accounting for the different states of these geomaterials
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White, Shannon M. "Drivers of change in mudflat macroinvertebrate diversity." Thesis, University of Portsmouth, 2018. https://researchportal.port.ac.uk/portal/en/theses/drivers-of-change-in-mudflat-macroinvertebrate-diversity(c4da7cba-f6c2-4b61-96d3-200975dd3cfe).html.
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Global biodiversity loss is an internationally recognized problem that has consequences for ecosystem functioning and provision of ecosystem services and warrants investigation into drivers of change in biodiversity. In the context of natural variability, multiple anthropogenic stressors, and a changing climate, the identification of drivers of change is a complex issue. Here, an integrated approach (analysis of long-term datasets and experimental simulation) was employed to investigate drivers of change in intertidal mudflat macroinvertebrate diversity, using the Solent, on England's south coast, as the study system. A model was developed to analyze survey datasets from the 1970s-2010s following a review process. Comparisons of the spatio-temporal patterns of change in diversity across an interconnected three-harbour system revealed differences at the harbour and within harbour scales, suggesting the relevance of local conditions for driving change versus dominance by a regional driver. Further, direct relationships were identified between diversity and within-harbour environmental conditions. In the context of a changing climate, temperature was investigated as a driver of change. The absence of a direct relationship between a regionally derived climate index and diversity and identification of the interaction of local seasonal water temperatures with local environmental conditions have highlighted the relevance of local context for predicting the way in which climate change effects may manifest. The results suggest the potential for macroalgal cover to act as a driver in this system, as direct relationships as well as relationships modified by the preceding seasonal temperatures were identified with respect to diversity, though the data available to test these relationships were limited. The effects of discrete temperature events were also investigated as a driver of change by simulating heat waves in a large outdoor mesocosm system designed to preserve natural sediment temperature profiles, solar and tidal cycles, and faunal densities. Community composition effects were not identified overall or for the abundance of shallow dwelling organisms that may be more vulnerable to extreme temperatures at the sediment surface. For the polychaete Alitta virens and the bivalve Cerastoderma edule, which exhibit different burrowing abilities, neither species exhibited higher mortality as a result of the heat wave simulations performed. Changes in energy reserves, however, suggested sublethal effects for both, which has implications for their vulnerability to the increased frequency, intensity, and duration of these events predicted for the future. The findings across these studies highlighted the relevance of local context to the patterns of change, suggesting that this must be accounted for in making predictions for how broad-scale climate change will drive change in biodiversity. For intertidal organisms potentially living close to their physiological limits, minimizing local anthropogenic stressors could benefit the current macroinvertebrate communities in the face of a changing climate.
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Davis, Helen. "A study of an estuarine benthic community subjected to petrochemical effluents." Thesis, University of Stirling, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249931.
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Pirot, Rachel. "Initiation zone characterization of debris flows in November, 2006, Mount Hood, Oregon." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/707.
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In November, 2006, a storm generated a minimum of 34 cm of precipitation in six days, triggering debris flows in many of the drainages on all sides of Mount Hood, Oregon. Of the eleven drainages surveyed, seven experienced debris flows; these include the White River, Salmon River, Clark Creek, Newton Creek, Eliot Creek, Ladd Creek and Sandy River basins. Flows in the White River, Eliot Creek, and Newton Creek, caused major damage to bridges and roadways. Initiation elevations averaged around 1,860 meters. Initiation zone material was predominantly sand (45-82%) with gravel (15-49%) and had few fines (3-5%). Four debris flows were triggered by landslides caused by undercutting of the river banks. Three developed through coalescence of multiple small debris flows within major channels and were termed "headless debris flows". Physical and morphological characterization of source areas was used to assess factors controlling debris flow initiation. Although findings indicate that all major drainages on Mount Hood are capable of producing debris flows, drainages with direct connection to a glacier, low percentages of vegetation, and moderate gradients in the upper basin were the most susceptible. Among basins not having debris flows, neither the Zigzag River nor Polallie Creek have a direct connection to a glacier, And the Muddy Fork and the Coe both have high percentages of vegetated slopes. The material in the upper basin of the Muddy Fork is predominately rock making initiation there weathering-limited. Additionally, the Muddy Fork and the Zigzag have two of the steepest gradients on the mountain. This pattern suggests that material there is regularly transported downstream through normal fluvial processes rather than building up to be catastrophically removed through debris flow processes.
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Dissanayake, Navodha G. "Biodiversity and ecological functioning of mudflat macrofauna in the Anthropocene." Thesis, Griffith University, 2019. http://hdl.handle.net/10072/388149.
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Humanity is altering natural systems, removing habitat, causing extinctions and altering of natural cycles. This era is so dominated by anthropogenic processes that has come to known as the ‘Anthropocene’. Coastal and marine ecosystems are among the many systems experiencing degradation, due to continuous resource consumption and waste disposal that feature prominently within environmental agendas. These changes are occurring against a backdrop of climate change. The effects of climate change are already apparent in marine systems at local and global scales. Coastal ecosystems are in close proximity to human developments and deliver a range of important ecosystem services that support human well-being (e.g. global fisheries, sea defences, and regulates nutrient cycling and the climate). With 44% of the world’s population living within 100 km of the coast, human activities are very likely to influence the functioning of coastal ecosystems that underpin these ecosystem services. This thesis provides insights on the biodiversity of a very wide spread coastal ecosystem: mudflats.
The macrofaunal assemblages inhabiting mudflats are globally and regionally important and mediate a number of ecological functions e.g. secondary production, nutrient and carbon cycling, and the creation of biogenic habitat. The biological traits of macrofauna are defined as the morphological, physiological and behavioural attributes of an organism that interact with the environment and as such they can describe the potential of an organism to contribute to these functional roles. This thesis aims to understand the biodiversity of macrofaunal assemblages inhabiting subtropical mudflats, differences in species composition on the functioning, functional redundancy and the resilience of mudflat functions in the presence of increasing human activities and climate change impacts.
Mudflats are widespread but are subjected to continuous alterations by human activities. In chapter 2, a systematic database search (WoS and SCOPUS) was conducted to identify published literature focusing on mudflat macrofaunal assemblages. The searches produced 277 papers addressing benthic macrofaunal assemblages and more than 50% of the published literature were from temperate regions, 33% from the subtropics, 10% from tropical mudflats and data from polar systems were rare. Of the 277 papers, only 68 papers contained sufficient methodological detail and original data and so were deemed relevant for inclusion in the analysis. In total 163 datasets on macrofaunal assemblages were extracted for the analysis including 448 taxa from 4 climatic zones and 10 biogeographic region. In the lower latitudes (tropical), traits such as smaller body sizes, shorter life spans and taxa that have exoskeletons were abundant while direct developmental modes are more prevalent at high latitudes (temperate). Despite these differences, the degree of similarity in biological trait composition of macrofaunal assemblages was higher relative to the taxonomic composition across both climatic and biogeographic spatial scales. This suggest that mudflats globally deliver similar functions such as carbon and nutrient cycling, secondary production etc. The functional redundancy observed across regional and climatic boundaries suggest that ecosystem functioning and service delivery may be expected to show some resilience to perturbations. However, increased human activities may continue to pose a threat to mudflat functioning.
Subtropical mudflats support a diverse macrofaunal assemblage consisting of a mixture of tropical and temperate species. Chapter 3 presents the most spatially and taxonomically comprehensive study to date of intertidal mudflat macrofauna along the SE Queensland coast. The effects of climate change were apparent among the studied macrofaunal assemblages. The results presented in chapter 3 showed that for the 24 mudflats sampled in SE Queensland, eight species have moved 146 km distance southwards since 1950s. The species substitutions (arrival of tropical range shifters) observed to date, do not appear to have altered the ecological functioning of these mudflats significantly, as indexed by biological trait composition, with ecosystem service delivery being maintained through functional redundancy. However, simple models of further species turnover suggest that the limits of this ‘buffer’ may soon be exceeded with consequences for a range of ecosystem services.
The World’s coastlines have become heavily modified over the last century, and the biodiversity and health of adjacent natural intertidal habitats have declined under increasing pressure from urbanisation. Similarly, the coastal urbanization activities in SE Queensland regions have shown an effect on the macrobenthic assemblages because the species composition of sub-catchments containing 4-12% industrial activity differed significantly from the species composition observed in sub-catchments with 53-90% residential coverage and sub-catchments with a mix (54-70%) of nature reserves and low intensity urban/rural activities. However, we did not observe a clear impact of urbanisation in structuring macrofaunal assemblages. It is likely that the impacts of urbanisation will vary depending on the nature of industry, rather than ‘urbanisation’ as a whole. Although changes in species composition were observed at varying degrees of urbanisation, the trait composition of the macrofaunal assemblages did not vary between the four sub-catchment land uses suggesting conservation in functioning and ecological redundancy in subtropical mudflat ecosystems.
The manipulation of biological traits in experimental studies is an important tool for understanding changes in ecological functioning under anthropogenic pressure, and exploring the relationships between biodiversity and functioning. In Chapter 5 I have experimentally investigated how the density manipulation of two common large taxa Macrophthalmus setosus (Ms) (sentinel crab) and Pyrazus ebeninus (Pe) (Hercules mudwhelk), that exhibit functionally distinct traits would influence the ecological assemblage and its functioning, e.g. the primary productivity, sediment oxygenation, carbon cycling and nutrient cycling. Theoretical biodiversity ecosystem functioning (BEF) models were used to explain the biodiversity functioning relationships observed in subtropical mudflats. A change in the species and trait composition of the resident macrofaunal assemblage was apparent when the densities of P. ebeninus was increased. The BEF models did show a degree of redundancy for some ecological functions (e.g. sediment oxygenation, carbon cycling and nutrient cycling) suggesting that initially subtropical mudflats may show some resilience to environmental perturbations.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Crooks, Stephen. "Sedimentological controls on the geotechnical properties of saltmarsh and mudflat deposits." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244710.
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Partridge, Valerie Ann. "Aspects of the winter ecology and spring recolonization of the Windsor mudflat." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0018/MQ54537.pdf.
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Scully, Malcolm E. "Modeling of Critically-Stratified Gravity Flows: Application to the Eel River Continental Shelf, Northern California." W&M ScholarWorks, 2001. http://www.vims.edu/physical/projects/CHSD/publications/reports/S2001%5FMS.pdf.
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Forster, Simon John. "Aspects of the ecology of free-living nematode assemblages in a temperate intertidal mudflat." Thesis, Queen Mary, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322118.
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Fox, Daniel. "Cohesive sediment dynamics on a mudflat within the macrotidal Conwy Estuary, North Wales, U.K." Thesis, Bangor University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327514.
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Dransfeld, Leonie. "The environmental and photo-physiological control of microphytobenthos primary production on an intertidal mudflat." Thesis, University of Southampton, 2000. https://eprints.soton.ac.uk/42087/.
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Microphytobenthos are important primary producers on tidal flats - ecosystems which are characterised by steep physical and chemical gradients. In this study some of the environmental factors that control the distribution and primary production of benthic microalgae were investigated in a series of field surveys conducted on Hythe intertidal mudflat, Southampton Water. The ecological and photo-physiological responses of microphytobenthos to changes in physical factors were studied in the field and in controlled laboratory experiments. Results from a weekly sample program at four stations along an intertidal transect were used to address the hypothesis that changes in incident irradiance defined by a combination of meteorological factors and the tidal cycle cause significant changes in the biomass of microphytobenthos. The light regime at each station was characterised by a model which combined the changes in daylight irradiance with the timing and duration of low tide. At the low shore stations total light availability during low tide was limiting in spring and autumn/winter, when daily photo-periods ranged between 0 and 6 hours. Microalgal biomass exhibited a strong seasonality with a distinct spring bloom in April which coincided with high irradiances at spring low tide. At the high shore station which was exposed to three times longer photo-periods light availability did not correlate with microalgal biomass at any time of the year. Biomass was three times higher at this station than at the three low shore stations and showed little seasonal variation. Taxonomic marker pigments were used to describe the changes in microphytobenthos composition. High correlation between chlorophyll a and fucoxanthin on a temporal and spatial (horizontal and vertical) scale combined with taxonomic analysis gave evidence that diatoms were the main primary producers on Hythe intertidal mudflat. Chlorophyll a and Ik (defined as PBmax/ aB) correlated strongly with incident irradiance at low tide, indicating that photoadaptation of benthic microalgae was occurring. A spatial comparison of photosynthetic parameters showed that benthic microalgae inhabiting the low shore compensated for reduced photoperiods by increasing their photosynthetic capacity (PBmax) and efficiency (aB) and decreasing their Ik. Photosynthetic parameters of microphytobenthos significantly changed during the low tide period under controlled laboratory conditions, suggesting that an endogenous photosynthetic rhythm was present, which caused an increase in PBmax and ocB towards the middle of the photoperiod. Irradiance levels at low tide enhanced the short-term variation in photosynthetic parameters due to photo-adaptation. The change in rates of photosynthesis was accompanied by a significant alteration of the cellular pigment composition, as the photoprotectant xanthophyll diatoxanthin increased and diadinoxanthin decreased in proportion. Short-term changes in cellular pigment composition induced in the laboratory were greater than seasonal pigment adaptation of microphytobenthos isolated from the field. Variation of PBmaxand ocB during one photoperiod occurred on a similar scale to the seasonal and spatial changes, suggesting that short-term photo-physiological adaptations are an important feature of microphytobenthos, aiding their successful survival in the intertidal environment, where strong gradients of incident irradiance occur on small temporal and spatial scales.
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May, Peter Ian. "Alternate state theory and tidal freshwater mudflat experimental ecology on Anacostia River, Washington, D.C." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7589.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Lindsay, Michelle Dawn. "Animal-sediment interactions : macrofauna community structure and sediments of an intertidal mudflat, Southampton Water, UK." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402235.
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Shen, Pingping, and 沈萍萍. "Benthic infaunal community at an intertidal mudflat and molecular analysis of the dominant species Neanthes glandicincta (Polychaeta)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40887996.
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Shen, Pingping. "Benthic infaunal community at an intertidal mudflat and molecular analysis of the dominant species Neanthes glandicincta (Polychaeta)." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40887996.
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Lai, Mei-yee, and 黎美兒. "Fractionation, mobilization and bioaccumulation of heavy metals and mineralogical characteristics of the Mai Po Inner Deep Bay mudflat." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29980069.
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Mazik, Krystina. "The influence of a petrochemical discharge on the bioturbation and erosion potential of an intertidal estuarine mudflat (Humber estuary, UK)." Thesis, University of Hull, 2004. http://hydra.hull.ac.uk/resources/hull:7047.
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The influence of sedimentary variables on the structure and function of infaunal estuarine and marine communities is well studied but less is known of the influence of biota on sediment properties. Feeding and burrowing activity, locomotion, the production of faecal pellets and biological secretions (bioturbation) have important implications for sediment structure, chemistry, transport characteristics and the flux of nutrients and contaminants. Although spatial and temporal patterns in bioturbation have been studied to some extent, little attention has been given to the effects of pollution. The present study examines the effects of an intertidal petrochemical discharge into the Humber estuary (UK), from BP chemicals (Saltend) Ltd on the structure and function of the communities. Field and laboratory techniques were used to determine the effects of community change on bioturbation potential. In addition, a laboratory flume was constructed to measure sediment erosion potential with field measurements being taken using a Cohesive Strength Meter (CSM). The physico-chemical properties of the sediment, changes to the infaunal community structure, bioturbation potential and the interaction of these variables were used to explain differences between the erosion potential of sediments subject to varying levels of contamination. The main study was carried out on the Saltend mudflats near Hull, with sites at various distances from the outfall being used. A further set of control sites on the adjacent, and largely unaffected, mudflat at Paull were also used. In terms of the sediment properties, sites closest to the outfall showed the greatest degree of anoxia and the highest chlorophyll-a and carbohydrate concentrations, with all three parameters being seasonally influenced. No consistent spatial or temporal patterns were found for any of the other parameters (water and organic content, particle size). Whilst the infaunal communities were characteristic of estuarine areas, macrobenthic community response followed the Pearson & Rosenberg (1978) model for organic discharges with high abundance and low species diversity being associated with the more polluted sediments. Close to the discharge, there was an impoverished community consisting predominantly of highly abundant oligochate worms. With increasing distance from the outfall, species diversity and biomass increased with Hediste diversicolor becoming increasingly dominant and the appearance of Corophium volutator, Streblospio shrubsolii and Macoma balthica. Bioturbation potential was significantly reduced (in terms of depth and burrow volume and density) by increasing effiuent concentrations and with proximity to the discharge. The diversity of both feeding and sediment modification guilds was also reduced as a result of the discharge. Both field and laboratory studies indicated a stabilising effect of this type of pollution. Using the CSM, critical shear stress values were found to be significantly lower from unpolluted sites, indicating higher erosion potential, than those from sites close to the discharge. As a result of this, the total mass of sediment eroded from unpolluted sites was significantly higher than that from polluted areas. A similar trend was observed in the laboratory with sediments treated with an effluent concentration of 32% being considerably more stable than untreated sediments. Flume studies also indicated the stabilising effect of pollution with suspended particulate matter (SPM) concentrations and mass of sediment being transported as bedload being significantly higher for unpolluted sediments. These differences in erosion potential were attributed to the direct effects of the effiuent on the physico-chemical properties of the sediment, the effects of the effiuent and sediment type on macrofaunal community structure and function and the differences in bioturbation potential between sites. The implications of these findings in the wider context of coastal management are discussed.
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Kiryu, Hamilton dos Santos. "Investigação reológica e análise mecânica de compósitos não-newtonianos /." Ilha Solteira : [s.n.], 2006. http://hdl.handle.net/11449/88892.
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Orientador: Geraldo de Freitas MacielBanca: Edson Del Rio Vieira
Banca: Jefferson B. Libardi Liborio
Resumo: Esta dissertação de mestrado traz à discussão o comportamento reológico de misturas formadas por água+colóides+detritos (areia fina), visando entender e esclarecer os processos físicos e mecânicos, tais como sedimentação e ressuspensão de materiais inertes no seio da massa fluida não-newtoniana (água+colóides), bem como verificar a validade ou adeqüabilidade do modelo reológico de Herschel-Bulkley (modelo previamente investigado e validado para misturas compostas de água+colóides) para misturas viscoplásticas com presença de grãos. A variação das propriedades reológicas das misturas, em função das características físicas dos grãos (diâmetro, massa específica e área superficial), é investigada, e um modelo de estimativa de tensão crítica é apresentado. Ademais foram realizados ensaios preliminares de escoamento de fluidos hiperconcentrados em canais inclinados, na tentativa de calibrar uma lei de atrito. Dentro dessas perspectivas, a dissertação é composta de 6 Capítulos com um denso Estado da Arte que descreve os fenômenos e mecanismos que regem os escoamentos desse tipo de compósito. Com base na literatura estudada e, a partir da análise dos resultados experimentais, pôde-se concluir que, para misturas compostas de água+colóides+detritos, o comportamento reológico das misturas é o mesmo que aquele do fluido intersticial (água+colóides), desde que a homogeneidade da mistura seja garantida (não ocorrência de sedimentação e ressuspensão sucessivas). Neste caso, o modelo reológico de Herschel-Bulkley continua sendo válido para explicar as curvas de escoamento ou de fluxo das misturas viscoplásticas com grãos. Para misturas que apresentem os fenômenos de sedimentação e ressuspensão, o modelo de Bagnold, adaptado a fluidos hiperconcentrados... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This work retakes the discussion about the rheological behavior of mixtures composed by water+ kaolinitic clay+fine sand in order to investigate the physical and mechanical processes such as sedimentation and suspension of inert materials into the non-Newtonian or interstitial fluid (water+colloids), as well as verify the adaptability of the Herschel-Bulkley rheological model (model previously investigated and validated for composed mixtures of water+ kaolinitic clay) for explain the viscoplastic+coarse materials rheological properties. The variation of the rheological properties of the mixtures in function of the coarse material characteristics (diameter, specific mass and superficial area) was investigated and a model predicting yield stress was proposed. Furthermore, some tests were performed in an inclined canal to determine a friction law for this kind of fluids. Inside of these perspectives, this dissertation is composed of 6 Chapters whit a dense State of the Art describing the phenomena and their mechanisms were pointed up. Based on literature and from the experimental results, one could concluded that the viscoplastic + coarse material mixtures behavior is the same of the interstitial fluid one, since that the homogeneity of the mixture is guaranteed (not occurrence of successive sedimentation and resuspension). In this case, Herschel-Bulkley rheological model is still valid to explain the curves of flow of the viscoplastic + coarse material. For mixtures that present the phenomena of sedimentation and resuspension, Bagnoldþs model, adapted to the hyperconcentrated fluids, describes well the variations of rheological parameters in function of the shear rates applied. Finally, it could be concluded that the experiments of free surface in canals, despite partial, can... (Complete abstract click electronic access below)
Mestre
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Silverman, Noah L. "Assessing the consequences of hurricane-induced fragmentation of mangrove forest on habitat and nekton in Big Sable Creek, Florida." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001751.
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McChesney, Stephen. "The benthic invertebrate community of the intertidal mudflat at the Mai Po Marshes Nature Reserve, with special reference to resources formigrant shorebirds." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31214435.
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McChesney, Stephen. "The benthic invertebrate community of the intertidal mudflat at the Mai Po Marshes Nature Reserve, with special reference to resources for migrant shorebirds /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18061977.
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Liu, Ha Trieu Hung [Verfasser], Harald [Akademischer Betreuer] Asmus, and Matthias [Gutachter] Leippe. "Macrobenthos diversity and ecology of a Chinese mudflat in the East China Sea / Ha Trieu Hung Liu ; Gutachter: Matthias Leippe ; Betreuer: Harald Asmus." Kiel : Universitätsbibliothek Kiel, 2015. http://d-nb.info/1213725879/34.
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Grieswald, Heike. "Ablagerungsfazies der Grobklastika der oberen Halle-Formation." Master's thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-204756.
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Die Sedimente des Halleschen Permokarbonkomplexes gaben schon immer Raum für Spekulationen. Aufgrund ihrer Dominanz an rhyolithischen Geröllen wurden sie über einen langen Zeitraum einheitlich als Postporphyrschutt ausgehalten. Vielfältig wechselnde Faziesbedingungen machten es jedoch notwendig, die Sedimente aufzugliedern. Neuere Erkenntnisse in der Erforschung des Halleschen Permokarbonkomplexes erfordern eine Überprüfung v. a. der nach KUNERT (1995) aufgestellten allgemeinen stratigraphischen Gliederung der Unterrotliegendsedimente in Halle,- Hornburg,- Sennewitz- und Brachwitz-Formation anhand einiger ausgewählter Beispiele. Der ursprüngliche Gedanke der Diplomarbeit bestand darin, eine Fazies- und eine Geröllanalyse der unterpermischen Abtragungsprodukte des Halle-Vulkanitkomplexes anzufertigen. Zur Verfügung standen zwei Kernbohrungen und zwei Aufschlüsse, sowie diverse Unterlagen zu angrenzenden Bohrungen in der Saale-Senke. Die beiden Oberflächenaufschlüsse Riveufer und Teichgrund sollten stratigraphisch aufgenommen werden, so dass eine Fazieszuordnung möglich ist. Die Bohrung Brachwitz 2/62 wurde mit dem Ziel aufgenommen, neuere Theorien über den Ablagerungszeitraum der Rotliegend-Sedimente in Bezug auf den permokarbonen Vulkanismus zu widerlegen oder zu bekräftigen. Die zweite Bohrung (Kb Lochau 7/65) wurde am Rande mit in die Diplomarbeit einbezogen, da sie das immense Spektrum der spätvulkanischen Aktivitäten im Halle Permokarbonkomplex erweitert. Ergebnis ist eine Neugliederung des Rotliegend im Halleschen Permokarbonkomplex, in der nur noch die Halle-Formation mit ihrem ausgeprägten Vulkanismus und die Hornburg-Formation, stellvertretend für alle jüngeren Abtragungsprodukte des Halle Vulkanitkomplexes, unterschieden werden. Mit einem großen Hiatus folgt anschließend die Eisleben-Formation.
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Kiryu, Hamilton dos Santos [UNESP]. "Investigação reológica e análise mecânica de compósitos não-newtonianos." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/88892.
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Esta dissertação de mestrado traz à discussão o comportamento reológico de misturas formadas por água+colóides+detritos (areia fina), visando entender e esclarecer os processos físicos e mecânicos, tais como sedimentação e ressuspensão de materiais inertes no seio da massa fluida não-newtoniana (água+colóides), bem como verificar a validade ou adeqüabilidade do modelo reológico de Herschel-Bulkley (modelo previamente investigado e validado para misturas compostas de água+colóides) para misturas viscoplásticas com presença de grãos. A variação das propriedades reológicas das misturas, em função das características físicas dos grãos (diâmetro, massa específica e área superficial), é investigada, e um modelo de estimativa de tensão crítica é apresentado. Ademais foram realizados ensaios preliminares de escoamento de fluidos hiperconcentrados em canais inclinados, na tentativa de calibrar uma lei de atrito. Dentro dessas perspectivas, a dissertação é composta de 6 Capítulos com um denso Estado da Arte que descreve os fenômenos e mecanismos que regem os escoamentos desse tipo de compósito. Com base na literatura estudada e, a partir da análise dos resultados experimentais, pôde-se concluir que, para misturas compostas de água+colóides+detritos, o comportamento reológico das misturas é o mesmo que aquele do fluido intersticial (água+colóides), desde que a homogeneidade da mistura seja garantida (não ocorrência de sedimentação e ressuspensão sucessivas). Neste caso, o modelo reológico de Herschel-Bulkley continua sendo válido para explicar as curvas de escoamento ou de fluxo das misturas viscoplásticas com grãos. Para misturas que apresentem os fenômenos de sedimentação e ressuspensão, o modelo de Bagnold, adaptado a fluidos hiperconcentrados...
This work retakes the discussion about the rheological behavior of mixtures composed by water+ kaolinitic clay+fine sand in order to investigate the physical and mechanical processes such as sedimentation and suspension of inert materials into the non-Newtonian or interstitial fluid (water+colloids), as well as verify the adaptability of the Herschel-Bulkley rheological model (model previously investigated and validated for composed mixtures of water+ kaolinitic clay) for explain the viscoplastic+coarse materials rheological properties. The variation of the rheological properties of the mixtures in function of the coarse material characteristics (diameter, specific mass and superficial area) was investigated and a model predicting yield stress was proposed. Furthermore, some tests were performed in an inclined canal to determine a friction law for this kind of fluids. Inside of these perspectives, this dissertation is composed of 6 Chapters whit a dense State of the Art describing the phenomena and their mechanisms were pointed up. Based on literature and from the experimental results, one could concluded that the viscoplastic + coarse material mixtures behavior is the same of the interstitial fluid one, since that the homogeneity of the mixture is guaranteed (not occurrence of successive sedimentation and resuspension). In this case, Herschel-Bulkley rheological model is still valid to explain the curves of flow of the viscoplastic + coarse material. For mixtures that present the phenomena of sedimentation and resuspension, Bagnoldþs model, adapted to the hyperconcentrated fluids, describes well the variations of rheological parameters in function of the shear rates applied. Finally, it could be concluded that the experiments of free surface in canals, despite partial, can... (Complete abstract click electronic access below)
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Toniati, André Luis. "Escoamentos pulsantes com superfície livre : caracterização e sua ação em fundo de canais /." Ilha Solteira, 2018. http://hdl.handle.net/11449/155857.
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Orientador: Geraldo de Freitas MacielResumo: No contexto de Desastres "Naturais", as corridas de lama têm sido objeto de estudo devido ao seu poder erosivo e, muitas vezes, destrutivo, acarretando perdas materiais vultosas e ceifando vidas. Nestes escoamentos, quando em condições favoráveis de vazão, inclinação e reologia do fluido, podem surgir instabilidades que se propagam em forma de trem de ondas na superfície, denominadas roll waves. A literatura acerca do assunto trata, geralmente, dos critérios de geração, estabilidade, e determinação das características principais do fenômeno, como amplitude, comprimento e celeridade de onda. Nesta dissertação buscou-se estudar a tensão de cisalhamento no fundo na presença de roll waves, em duas vertentes: a primeira apresenta as roll waves em água limpa, baseando-se no trabalho clássico de Dressler (1949); a segunda, dando continuidade aos trabalhos do Grupo de Pesquisa de Reologia de Materiais Viscosos e Viscoplástcos (Grupo RMVP), focou no estudo de roll waves desenvolvendo-se em fluidos do tipo Herschel-Bulkley, em duas situações - canal de fundo impermeável e fundo com condição de permeabilidade, grande contribuição desta dissertação. Os modelos matemáticos foram desenvolvidos com base nas equações de águas rasas, cuja implementação numérica permitiu confrontar resultados experimentais e numéricos, que apresentaram boa aderência. Para o modelo com condição de permeabilidade no fundo, verificou-se a influência do fator de porosidade nas características das roll waves (ampli... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Mudflows have been the focus of studies because of their erosive ability and often destructive power, causing material losses and taking away lives. Under favorable conditions of discharge, slope, disturbance, and rheology, these flows can develop a specific type of instability that is propagated downstream as shock waves, called roll waves. Most of the roll waves literature provides information on generation criteria, stability, and information of amplitudes, wavelengths, and celerity. This works brings a study of bottom shear stress in pulsating flows (roll waves) in 2 parts. In the first part, we present roll waves in clean water, based on Dressler’s work. In the second part, we continue the works of research team about roll waves developing in Herschel-Bulkley fluid under 2 conditions: impermeable bottom and porous bed. The mathematical models developed were based on shallow water equations. The results of these models were compared to Fluent and experimental results, showing a good agreement. For the mathematical model with porous bed condition, we evaluated the effect of porosity factor in properties of roll waves, and we observed that the amplitude of the roll wave usually increases, whereas the length and the celerity decrease with the presence of this factor. Finally, considering an impermeable bottom, the bottom shear stress presented an increase of 12% to 27%, depending on nature (laminar-turbulent) and dynamics (Froude number) of flow. Taking in account a porous b... (Complete abstract click electronic access below)
Mestre
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Barnett, Alexandre. "Régulation de l'activité photosynthétique du microphytobenthos et conséquence sur la dynamique temporelle de la production primaire dans les vasières intertidales de la côte atlantique de l'Europe de l'Ouest." Thesis, La Rochelle, 2013. http://www.theses.fr/2013LAROS412/document.
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Le microphytobenthos (MPB) des latitudes tempérées est dominé par les diatomées. Deux grands groupes se distinguent, les épipéliques (mobiles) des sédiments vaseux, et les épipsammiques (fixées) des sédiments sablo-vaseux. Afin de mieux comprendre la production des vasières, le MPB a été étudié par des approches du niveau physiologique au niveau écologique. Dans un premier temps, l’étude s’est focalisée sur des expérimentations en laboratoire. La réponse des différents groupes à la lumière a montré que la forme de vie et la mobilité sont en lien étroit avec la capacité de photoprotection physiologique. Ainsi, les diatomées non-mobiles présentent une meilleure photoprotection physiologique que les diatomées mobiles qui peuvent fuir les excès de lumière. Dans une deuxième partie, le travail s’est effectué sur des échantillons ramenés en laboratoire. Des profils de migrations ont été réalisés par mesure continue de la fluorescence. Il a été établi que le MPB présente un rythme de migration interne pouvant être modulé par la lumière. De plus la qualité de la lumière modifie les profils de migration. Il est communément admis que les phases de division cellulaire se dérouleraient en profondeur. La cytométrie en flux permet de vérifier cette hypothèse. Finalement les mesures effectuées en laboratoire ont été comparées à des mesures effectuées directement sur le terrain à l’échelle de la communauté. Il a ainsi pu être vérifié que la photoprotection sous lumière fluctuante est fonction de la population. Pour les populations épipéliques, la photoprotection physiologique ne varie pas au cours des fluctuations lumineuses, laissant supposer que la migration module ces fluctuations. Les populations épipsammiques, quant à elles, modifient leur réponse physiologique en fonction des fluctuations lumineusesMicrophytobentos (MPB) from temperate latitude is mainly composed of diatoms. Those microorganisms can be separated in two groups: the epipelic one from muddy sediments (composed of mobile diatoms) and the epipsammic one from sandy-muddy sediments (composed of diatoms living attached to their substrate). In order to investigate mudflats’ primary production, the MPB compartment was studied through diverse approaches from the physiological level to the ecological one. In the first place, laboratory experiments (in vitro experiments), focusing on light reaction of epipelic and epipsammic diatoms, showed that their life form and their mobility were strongly connected to their physiological photoprotection ability. Thereby, the motionless diatoms were characterized by higher physiological photoprotection abilities than the mobile ones, which could avoid excess of light. In the second place, the fluorescence of collected samples (in vivo experiments) was measured to acquire diatoms’ migration profiles. The results pointed out an internal and light-regulated migration pattern of the MPB and furthermore highlighted the effect of light quality on migration profiles. Besides, the commonly accepted hypothesis of deep cell division phases was tested and confirmed through flow cytometry experiments. Eventually, laboratory measurements were compared to in situ ones realized at the scale of the whole community. These comparisons revealed that diatoms photoprotection in fluctuating light depended on the targeted populations. Epipelic organisms were indeed characterized by an unvarying photoprotection, diatoms migration regulating alone the effect of light fluctuations. On the contrary, motionless epipsammic populations required a light-regulated photoprotection
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Savelli, Raphaël. "Study of microphytobenthos dynamics in temperate intertidal mudflats by using physical-biological coupled modelling and remote sensing data analysis." Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS030.
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La production primaire (PP) élevée des vasières intertidales aux latitudes tempérées est principalement assurée par le microphytobenthos (MPB), qui soutient les réseaux trophiques benthiques et pélagiques. Dans cette thèse, nous utilisons un modèle couplé physique-biologie pour étudier la variabilité spatio-temporelle de la dynamique du MPB sur une vasière intertidale de la côte Atlantique française. Le modèle simule explicitement la biomasse du MPB et du brouteur Peringia ulvae. Les résultats fournissent des conclusions clés sur la dynamique du MPB. À l’hiver et au printemps, une lumière et une température de surface de la vase (TSV) optimales pour la croissance du MPB donnent lieu à une efflorescence printanière du MPB. La lumière est le facteur le plus limitant annuellement. Cependant, la TSV limite la croissance du MPB 40 % du temps en été. La photoinhibition pourrait se superposer à la thermoinhibition au printemps et en été. Le broutage et la remise en suspension (RES) du MPB façonnent également la dynamique du MPB. La bioturbation par P. ulvae contribue à une RES chronique du MPB du sédiment vers la colonne d’eau au printemps et en été. Les vagues contribuent à la RES du MPB par le biais d’événements de RES massive en hiver, au printemps et en automne. 50 % de la PP annuelle du MPB est exporté vers la colonne d’eau par le biais de RES chroniques et massives. Nous avons également développé une méthode qui combine les données de télédétection et les résultats du modèle couplé physique-biologique en un algorithme capable de prédire la PP à partir de données satellitales. En plus d’apporter de nouvelles perspectives sur la dynamique du MPB, ce travail propose de nouveaux outils numériques pour surveiller et prédire la PP du MPB et son devenir dans les eaux côtières dans un contexte de changement climatiqueThe high primary production (PP) of intertidal mudflats at temperate latitudes is mostly supported by microphytobenthos (MPB), which support both benthic and pelagic food webs. In the present thesis, we use a physical-biological coupled model to investigate the spatial and temporal variability of MPB dynamics on a large temperate intertidal mudflat of the French Atlantic coast. The model explicitly simulates the MPB biomass and the grazer (Peringia ulvae) biomass and density. The outputs provide key findings on MPB dynamics. In winter-spring, optimal light and mud surface temperature (MST) conditions for MPB growth lead to a MPB spring bloom. Light is the most limiting driver over the year. However, a high MST limits the MPB growth 40% of the time during summer. The photoinhibition of MPB photosynthesis can potentially superimpose on thermoinhibition in spring-summer. Grazing and resuspension of MPB biomass also shape the dynamics of the MPB biomass. Bioturbation by P. ulvae contributes to a chronic export of MPB biomass from the sediment to the water column in spring-summer. Waves contribute to the MPB resuspension through massive resuspension events in winter, spring and fall. 50% of the annual MPB PP is exported to the water column through chronic and massive resuspension events. We also developed a new method that combine remote sensing data with outputs of the physical-biological coupled model into a single algorithm that can predict PP from satellite data. In addition to bring new insights on the MPB dynamics, this work proposes new numerical tools to monitor and predict MPB PP and its fate in coastal waters in a context of climate change
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Saint-Béat, Blanche. "Modélisation du rôle du biofilm dans le fonctionnement du réseau trophique de la vasière de Brouage (Bassin de Marennes-Oléron) : influence sur les flux de carbone et conséquences sur la stabilité." Phd thesis, Université de La Rochelle, 2012. http://tel.archives-ouvertes.fr/tel-01065560.
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La vasière intertidale de Brouage, écosystème très étudié localement de longue date, a fait l'objet depuis 5 ans d'analyses plus approfondies notamment sur le devenir du biofilm microbien se formant à la surface des sédiments à marée basse. Ce travail de thèse s'inscrit dans cette optique. Il propose, par le couplage d'outils mathématiques et écologiques, d'analyser le réseau trophique de la vasière de Brouage sous différentes conditions abiotiques à partir de la synthèse des données les plus récentes. La modélisation inverse a permis d'estimer les flux manquants du réseau trophique. Les calculs d'indices d'analyse des réseaux écologiques ou ENA (Ecological Network Analysis) ont caractérisé la structure et le fonctionnement du réseau trophique.Un premier travail méthodologique, basé sur la dégradation-reconstruction d'un jeu de données très complet, a défini la meilleure fonction, la moyenne, pour le choix d'une seule solution pour chaque flux à la sortie de la modélisation inverse. La moyenne est la meilleure fonction puisque son utilisation aboutit à une bonne estimation des flux manquants quel que soit le niveau d'information intégré au modèle. Cette fonction permet aussi une bonne préservation de la structure et du fonctionnement du réseau trophique ainsi reconstruit. Le réseau trophique de la vasière de Brouage à basse mer a été étudié sous un aspect saisonnier par l'opposition de l'été et de l'hiver, l'hiver étant caractérisé par la présence d'oiseaux migrateurs sur la vasière. L'activité limicole des oiseaux est soutenue en hiver par une forte production du microphytobenthos et un fort recyclage de la matière. L'organisation interne et la spécialisation des flux restent cependant semblables pour les deux saisons considérées. Dans un deuxième temps, le réseau trophique à pleine mer en été a été modélisé sous différentes conditions hydrodynamiques permettant ou pas la remise en suspension du biofilm microbien. La comparaison entre ces deux situations met en évidence l'effet de la remise en suspension sur le couplage benthos-pelagos. Le système soumis à la remise en suspension présente un très faible indice de recyclage lié à la faible intégration au réseau trophique pélagique du carbone particulaire benthique remis en suspension. De plus, la remise en suspension provoque une augmentation de l'activité du système couplée à une faible spécialisation des flux, ce qui est supposé déstabiliser le système.
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Luglia, Mathieu. "Caractérisation et facteurs structurants des fonctions microbiennes des sédiments de la zone intertidale en Guyane française : des vasières estuariennes aux mangroves matures." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4340/document.
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En contexte équatorial, les sédiments intertidaux sont colonisés par un continuum écologique allant de vasières en cours de stabilisation à des sols colonisés par divers faciès de mangroves. Les fonctions microbiennes édaphiques de ces écosystèmes sont méconnues. Ces recherches ont donc eu pour objectif de définir les facteurs de contrôle et de variabilité spatio-temporelle des fonctions microbiennes des milieux estuariens et littoraux de Guyane française. Elles ont été conduites sur divers stades de colonisation biologique de ces habitats et à diverses échelles spatio-temporelles en tenant compte du rôle de l'instabilité hydro-sédimentaire et des variabilités induites par les saisons hydro-climatiques. Différents facteurs pouvant influencer les fonctions microbiennes ont été considérés : i) la qualité chimique (RMN solide du 13C) de la MOS en fonction de la composition des formations végétales et de leurs stades de développement ; ii) les caractéristiques physico-chimiques des sédiments et des eaux interstitielles en fonction de la localisation des divers faciès de mangroves. Les résultats ont mis en évidence l'importance des instabilités hydro-sédimentaires dans la mise en place et la structuration des fonctions microbiennes sédimentaires de Guyane. En outre, pour les différents modèles étudiés, les facteurs de structuration sont apparus variables. Néanmoins, la MO, en termes de quantité et de qualité, s'est révélée être un facteur prépondérant pour l'expression de ces fonctions des stades allant de la vasière nue à la jeune mangrove. En revanche, il est apparu plus difficile de discerner des facteurs structurants génériques pour les divers faciès de mangroves maturesUnder equatorial conditions, coastal sediments of intertidal mudflats form an ecological continuum, from bare mud being stabilized to soil settled by various mangrove facies. Edaphic microbial functions of terrestrial ecosystems are extensively documented; on the contrary, this is not the case with regards to sedimentary environment. This study had the main objective defining the drivers of the spatiotemporal variability of microbial functions (aerobic respiration, metabolic diversity, and enzyme activities) in coastal sediments of French Guiana. These researches were carried out according to biological colonization states (mudflats, pioneer and mature mangroves) and using various spatiotemporal scales considering the fundamental role of the hydro-sedimentary instability and potential variability due to hydro-climatic seasons. Different factors which can influence microbial functions were studied: i) the chemical quality (13C solid-state NMR) of OM with respect to vegetation presence and composition, and its development state; ii) the physicochemical characteristics of sediments and porewaters according to localization and topography of the different mangrove facies. Generally, results showed the importance of hydro-sedimentary instability for the establishment and structuring of microbial functions. Moreover, giving the different models, structuring factors were variables. However, OM, in terms of quantity and quality, was overriding for the expression of these functions and this was true for the evolution states from mudflat to young mangrove. By contrast, it appeared much more difficult discerning generalizable drivers for mature mangroves
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Vennin, Arnaud. "Etude de l'interface eau-sédiment dans les géosystèmes estuariens : approche couplée biogéochimie et modélisation par l'évaluation des flux de nutriments (C,N,P)." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR023/document.
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L’estuaire de Seine est un géosystème macrotidal présentant un hydrodynamisme fort lié à la combinaison des courants fluviatiles et tidaux. Ces phénomènes entrainent l’érosion et le dépôt des sédiments au niveau des vasières intertidales. Au sein des vasières, l’interface eau-sédiment est une zone importante car c’est à cet endroit que se réalise les échanges en nutriment (C, N, P) entre le sédiment et la colonne d’eau. L’objectif de cette thèse est d’évaluer l’impact des forçages hydrodynamiques, physiques et thermiques sur les flux de nutriment à cette interface en utilisant une double approche expérimentale de terrain et de modélisation. Dans ce but, une vasière d’embouchure et une vasière amont de l’estuaire sont échantillonnées au cours des mois de mars-avril 2017. Des échantillonneurs passifs ainsi que des instruments de mesure en continu sont implantés dans le sédiment. Les données obtenues sont ensuite intégrées en entrée dans des modèles de diffusion et d’advection afin d’estimer la contribution relative de la diffusion et des mouvements d’eau dans les flux de nutriment. Les résultats expérimentaux obtenus montrent les différences de fonctionnement hydrodynamiques des deux vasières du fait de leur localisation différente dans l’estuaire. Ils mettent aussi en avant l’hétérogénéité des sédiments des deux vasières d’un point de vue hydrodynamique, physique et biogéochimique. Enfin ils permettent de comprendre la dynamique de la température du sédiment en lien avec le cycle diurne et la marée. La partie modélisation de cette étude est divisée en deux parties distinctes : l’étude de la diffusion et de l’advection à l’interface eau-sédiment. La diffusion est étudiée de façon horizontale et verticale. Le facteur prépondérant de la dynamique de diffusion est la température, celle-ci est modulée par plusieurs paramètres. Les flux potentiels de diffusion sont aussi calculés pour les deux vasières. L’étude de l’advection au sein du sédiment est réalisée à l’aide de deux modèles : le modèle VFLUX et le modèle 1DTempPro. Les vitesses d’écoulement de l’eau interstitielle sont fonction du phasage-déphasage du cycle diurne avec celui de la marée. Ces résultats mettent en avant le rôle prédominant de l’advection par rapport à la diffusion dans la dynamique des flux de nutriment et permettent de proposer un modèle conceptuel des échanges thermiques et de l’advection-diffusion au sein des vasières intertidalesThe Seine estuary is a macrotidal geosystem with a strong hydrodynamism linked to the combination of fluvial and tidal currents. These phenomena cause erosion and sediment deposition on the intertidal mudflats. Within the mudflats, the water-sediment interface is an important area because it is there that nutrient exchanges (C, N, P) take place between the sediment and the water column. The objective of this thesis is to evaluate the impact of hydrodynamic, physical and thermal forcing on nutrient fluxes at this interface using a dual experimental field and modelling approach. For this purpose, a mudflat situated at the mouth of the river and an upstream mudflat of the estuary are sampled during the months of March-April 2017. Passive samplers and continuous measuring instruments are implanted in the sediment. The resulting data are then integrated into diffusion and advection models to estimate the relative contribution of water diffusion and movement in nutrient fluxes.The experimental results show differences in the hydrodynamic functioning of the two mudflats due to their different location in the estuary. They also highlight the heterogeneity of the sediments of the two mudflats from the hydrodynamic, physical and biogeochemical points of view. Finally, they allow us to understand the dynamics of sediment temperature in relation to the diurnal cycle and the tide. The modelling part of this study is divided into two distinct parts: the study of diffusion and advection at the water-sediment interface. The diffusion is studied in a horizontal and vertical direction. The main factor of diffusion dynamics is temperature, which is modulated by several parameters. The potential diffusion fluxes are also calculated for the two mudflats. The study of advection within the sediment is performed using two models: the VFLUX model and the 1DTempPro model. Interstitial water flow velocities are a function of the phase-diphase shift of the diurnal cycle with that of the tide. These results highlight the predominant role of advection compared to diffusion in the dynamics of nutrient flows and allow to propose a conceptual model of heat exchange and advection-diffusion within intertidal mudflats
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Chen, Chun-Pin, and 陳俊斌. "A Simulation and Analysis of Maokong Mudflow." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/13260407976075030540.
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碩士國立臺灣科技大學
營建工程系
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The digital topography data and estimated mud flow discharge were used to simulate the hazard of Jangmi typhoon. The information about flow rate, deposited depth and submerged region are reported in this study. This research have two part, first part is to Collect data and experiment, and consult experiment result to determine rheological parameter. Second part is to analysis Some related survey and test data. Then, the two dimensional numerical program FLO-2D, proposed by O’Brien and Julian, was used to simulate the maokong mudflow case. The influence on the flow region of mudflow due to local trivial stream, rheological parameters and estimated discharge were considered. The strength parameters of soils in upper and middle slope areas were adopted to discuss the difference of mudflow. To understand influence of surface roughness, The sensitivity analysis related to coefficient of laminar flow resistance and manning's n roughness values are also been discussed and compared with sediment concentration by volume.
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Wang, Yi-Fu, and 王怡富. "Evaluation on Potential of Mudflow in Chi-Shan Area." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/66459464842678111160.
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Yao, Chun-Huang, and 姚俊煌. "The Study of Basic Rheological Parameters for the Mudflow." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/dz6249.
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碩士國立臺灣科技大學
營建工程系
95
Bingham flow Model is usually adopted to present the rheological behavior of debris flow. Bingham yield stress ( ) and Bingham viscosity (η) are parameters of Bingham Flow Model. The debris-flow starts to flow constantly, when the applied critical stress larger than the Bingham yield stress. A “Flow Development Stage” exists in advance of the “Constant Flow Stage.” So, the “Ultimate Critical Yield Stress ( )” in the Flow Development Stage is recommended to interpret the start of a debris flow. The Moving Ball Test (MBT) and SR-5 Rheometer test were used in this research. Samples with different ratios of sand and clay were tested in small strain rate. The result shows good relationship between water content and with R2 larger than 0.99. It is then possible to calculate Ultimate Critical Yield Stress ( ) by only using fundamental physical soil parameters such as water content and fine particle content through the rheologic equations founded in this study. The Direct Shear Test (DST) was employed to examine the specimen with water content less than liquid limit in this research. Relationships between shear stress and water content are built. From the curves in solid phase and liquid phase, the intersection point was used to define the liquid limit other than the one from Attarburg test. The undrained shear strengths corresponding to liquid limits in this study are in a range between 1.68 and 1.85 kN/m2. Some previous researches from Youssef et. al. (1965); Federico (1983); Wroth and Wood (1978) show ranges from 1.1 to 2.6 kN/m2. Because the agreement in both results, we have confidence on the liquid limits obtained in this research and recommend our test procedures as a new approach to examine the liquid limit.
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Wang, Ching, and 王靖. "The Preliminary Study of Finite Element Analysis of Mudflow and Stony Debris Flow." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/9zevc8.
Full textAbstract:
碩士國立交通大學
土木工程系所
101
This study aims to investigate the behavior of migration and deposition for debris flow using two-phase flow analysis of fluid dynamics. This work made use of “COMSOL Multiphysics” (herein referred to as "COMSOL") as the numerical simulation tool to simulate fluid behavior of two-phase flow. The rheological models of debris flow are assumed to be Non-Newtonian fluid, including yield shear stress, viscous stress, dispersive shear stress from particles collision, and turbulent stress from bed roughness, and so on. Reviewing rheological models and parameters for debris flows from previous studies, debris flow rheological properties vary with the particle size distribution, mineral properties, debris flow’s sediment concentration, and other physical quantities. It should be reasonable to consider the debris flow rheological model and its corresponding rheological properties together. This study deliberately validates the ranges of parameters which are collected in order, and view them as basis for simulation. This study regards COMSOL as an analysis platform to build debris flow migration model and to design debris flow rheological model as well. With the rheological model for mudflow, this study uses effective viscosity from the effective Bingham rheological behavior so that the Navior-Stokes equation originally simulating Newtonian fluid is able to simulate rheological behavior of Bingham fluid. For rheological model of stony debris flow, considering that particles collision force and turbulent force are square proportional to shear rate, this study adds particles collision force and turbulent force as volume forces to the Navior-Stokes equation originally simulating Newtonian fluid. Assuming that the yield shear stress is constant, viscous flow is proportional to the velocity flow gradient; the shear stress due to particle collision is proportional to the square of flow rate of gradient. When the shear stress is neglected, this rheological model is reduced to the Bingham model. This study evaluates whether the behavior of the migration and deposition of debris flow is reasonably simulated. The major role of the Level Set method is to distinguish the interface between debris flow and air. However, the problem of poor mass conservation for debris flow appears. It appears the mesh size and the interface thickness of two phase flow have an influence on the quantity of poor mass conservation.
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Lin, Po-han, and 林伯翰. "The Study of Relationship Between two Feldspar Kaolin of Rheological Parameters for Mudflow." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/66095933673960006871.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
97
The influence of Feldspar to the shear strength and liquid limit of the cohesive soil were studied, since the characteristics of Feldspar is similar to the silt. In order to obtain rheological parameters of the commercial Kaolinite with different water contents, the Moving Ball Test (MBT) was employed under small shear strain rate. The results show that its fluid phase is in a non-Newtonian fluid state. When the applied shear stress exceeded the shear strength ( ), the fluid sample is in the liquid-developing stage and flows very slowly. When the shear stress more than the Bingham Yield Shear Strength ( ), the fluid sample is in a steady state condition. The shear strength ( ) is then recommended as the initial shear strength of a debris flow. The regression equations between water content and the initial shear strength were built in this study with coefficient of R2 larger than 0.98. It shows high reliability. The liquid limits are generally obtained by Atterberg test. However, the artificial errors are obvious in this test. Some previous researches showed that the shear strength corresponding to the liquid limits ranging from 1.1 to 2.6 kN/ m2. The Direct Shear Test (DST) for shear strength test in the solid state and the Moving Ball Test (MBT) for shear strength test in the liquid state were used in this research. The interpolation of these two results could then be obtained to find the critical shear strength in the liquid limit state. The shear strengths corresponding to liquid limit states in this study are in a range between 1.89 and 2.44 kN/m2. Because of the good agreements in both results, it is recommended to use our test procedures as a new approach to examine the liquid limit state of a cohesive soil.
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YuanitaWulandari and 尤妮塔. "Antenatal Care Needs for Pregnant Women in Temporary Shelters Following Volcanic Mudflow in Indonesia." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/04293778039718251745.
Full textAbstract:
碩士國立成功大學
護理學系
102
Background: Volcanic mudflow which categorized as natural disasters has brought the negative impact to the human life and pregnant women as well. Pregnant women required specific antenatal care (ANC) and fulfillment of daily needs when staying in temporary shelter. However, care and attention to pregnant women in temporary shelter after natural disaster is still unknown. Purposes: To explore the ANC needs as well as the satisfaction of the ANC service, and to identify the relationship between the demographic characteristics and ANC service which was received in temporary shelters after volcanic mudflow. Methods: A cross-sectional study was conducted in Magelang district of Indonesia. one hundred eighteen subjects who had pregnant experience when they stayed in temporary shelter were recruited. Self-developed instruments were used to measure ANC service, satisfaction of ANC service, level of needs and fulfillment of the daily needs. Results: Subjects received 59.1% to 96.6% of four domains on the ANC service items. The mean of ANC service satisfaction level was from 1.69 to 1.79. The mean of the level of needs on the daily needs were from 4.21 to 4.41, and the mean of fulfillment level on the daily needs were from 1.74 to 2.16. Moreover, pregnant women who did not prepare money for health care (Ua = 1109.5, p = .001), were housewife (Ua = 401.5, p=.036), shared responsibility with the other family (Ua= 734.5, p〈 .001), and had a husband to share responsibility person (Ua = 190.5, p= .020) received higher percentages of the ANC service. Conclusion: This study indicated that pregnant women stay in temporary shelter had high demand related to pregnancy needs. In order to maintain and monitor the health status of pregnant women and fetus as well as to improve the pregnancy outcome, government and non-government organization as well as health care provider which involved in disaster management should provide specific attention related to the needs regarding pregnancy.
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Widjaja, Budijanto, and 倪金安. "Viscosity Determination of Soil in Plastic and Viscous Liquid States for Elucidating Mudflow Behavior." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/12117608586095841835.
Full textAbstract:
博士國立臺灣科技大學
營建工程系
101
The transformation of soil from a plastic state into a viscous liquid state is primarily caused by changing the water content of the soil mass. As the water content increases, the soil mass gradually starts to behave like a viscous liquid. In spite of viscosity being a key parameter to the behavior of mudflows, there have no datasets of soil viscosity changes successfully measured continuously as they move from plastic to viscous liquid states. The aim of the current research is to design a new device to overcome this difficulty. Based on the trap door principle formulated by Terzaghi (1943) and the Bingham model, a new device called the Flow Box was designed. The governing equation of the Flow Box was derived in this research in order to obtain the relationship between initial viscosity and liquidity index. In this study, the viscosities in both plastic and viscous liquid states were clearly defined by the Flow Box Test. The expected decrease in initial viscosity was followed by an increase in liquidity index, which corroborated with the test results. The initial viscosity readings with the results of other similar research and the case study of the Maokong mudflow was also validated. Hence, the purpose of this research to create a new device to successfully determine viscosity levels as soil changes from plastic to liquid state is completed. The phase concept implies that the state of soil changes from plastic to viscous liquid as a function of water content. This principle could be used to interpret the behavior of mudflow, which is the most dangerous mass movement today. When Typhoon Jangmi hit northern Taiwan in 2008, a mudflow occurred in the Maokong area as the result of a high-intensity rainfall. This case was studied using three case simulations each with different water contents. Based on the mudflow classifications, the primary criteria used were flow velocity and solid concentration by volume. The results show that the mass movement confirms the aforementioned criteria for mudflow especially when the water content reaches or exceeds the liquid limit. The validation using Karanganyar and Ciwidey mudflows has the similar trend to Maokong mudflow. The flow box test can determine the viscosity for both plastic and viscous liquid states, which is advantageous. Viscosity is important in explaining the general characteristics of mudflow movement because it controls flow velocity. Therefore, the present study successfully elucidates the changes in mudflow from its transportation to its deposition via numerical simulation using laboratory rheology parameters.
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Shao, Songdong, and E. Y. M. Lo. "Incompressible SPH method for simulating Newtonian and non-Newtonian flows with a free surface." 2003. http://hdl.handle.net/10454/3258.
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NoAn incompressible smoothed particle hydrodynamics (SPH) method is presented to simulate Newtonian and non-Newtonian flows with free surfaces. The basic equations solved are the incompressible mass conservation and Navier¿Stokes equations. The method uses prediction¿correction fractional steps with the temporal velocity field integrated forward in time without enforcing incompressibility in the prediction step. The resulting deviation of particle density is then implicitly projected onto a divergence-free space to satisfy incompressibility through a pressure Poisson equation derived from an approximate pressure projection. Various SPH formulations are employed in the discretization of the relevant gradient, divergence and Laplacian terms. Free surfaces are identified by the particles whose density is below a set point. Wall boundaries are represented by particles whose positions are fixed. The SPH formulation is also extended to non-Newtonian flows and demonstrated using the Cross rheological model. The incompressible SPH method is tested by typical 2-D dam-break problems in which both water and fluid mud are considered. The computations are in good agreement with available experimental data. The different flow features between Newtonian and non-Newtonian flows after the dam-break are discussed.
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You, Jia-Ying, and 游佳穎. "A Study on the Conditions of Mudflow Simulation in an Example of Foun-Qiu Village under Typhoon Herb." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/9yq3qr.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
103
The main simulation study on the mudflow in Feng Qiu Village, Nan-Tou County, under Typhoon Herb at 1996 is employed in this research. Another mudflow in Shen Mu Village under Typhoon Morakot at 2009 is also used to confirm those influence factors, such as initial viscosity and inflow rate, in a simulation analysis. The arriving time of mudflow obtained through fieldwork and aerial photograph after disaster were adopted to examine the numerical simulation results. It is expected to build up key parameters for simulations of similar mudflows in the future. The viscosity values obtained through Flow Box Test in this study are all compatible to the previous researches. In the Feng Qiu Village case, when LI is 1.0, initial viscosity is 0.25Pa∙s, and in-flow rate is 111.11m^3/s, the arriving time to the accumulation area is 10.2 minutes, which is similar to 10 minutes obtained from fieldwork. In Shen Mu Village case, when LI is 1.0, initial viscosity is 0.018Pa∙s, and in-flow rate is 100m^3/s, the arriving time to the accumulation area is 5.7 minutes, which is also similar to 5 minutes obtained from fieldwork. Therefore, the recommendation in this study is that the viscosity and in-flow rate are two major important influence factors to a mud flow.