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1
Mendoza, Ponce Ernesto Tonatiuh. „Coastal Vulnerability to Storms in the Catalan Coast“. Doctoral thesis, Universitat Politècnica de Catalunya, 2008. http://hdl.handle.net/10803/6402.
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Este trabajo presenta un marco metodológico para la estimación de la vulnerabilidad costera al impacto de tormentas a dos escalas, regional y local. Se hace una evaluación de la vulnerabilidad costera física mediante la cuantificación de dos componentes: erosión e inundación. Posteriormente, ambos elementos son integrados en un Índice de Vulnerabilidad Costera. La metodología desarrollada cubre los siguientes pasos: (i) clasificación de tormentas, (ii) evaluación de la respuesta inducida en la playa -inundación y erosión- (iii) caracterización de las playas en la zona de estudio (iv) definición del índice de vulnerabilidad costera y (v) evaluación de la vulnerabilidad costera. Estos pasos han sido derivados y aplicados a la costa catalana (Mediterráneo Noroccidental español) y pueden ser adaptados a otras costas. Los resultados obtenidos pueden ser fácilmente utilizados por los gestores costeros para identificar zonas costeras sensibles a una clase de tormenta dada y sus procesos inducidos (inundación, erosión o la combinación de ambos) para decidir donde tomar acciones para mitigar estos impactos.This work presents a methodological framework for the estimation of coastal vulnerability to storm impacts at two scales, regional and local. It estimates the physical coastal vulnerability through the quantification of two components: erosion and flooding. Afterwards the two elements are integrated into the so called Coastal Vulnerability Index. The methodological process covers the following steps: (i) storm classification, (ii) evaluation of the induced beach response -flood and erosion-, (iii) coastal zone characterization, (iv) definition of a coastal vulnerability index to storms and (v) assessment of the coastal vulnerability. These steps have been derived and applied to the Catalan coast (NW Spanish Mediterranean) and can be adapted to other coasts. The obtained results can be used by coastal managers in an easy manner to identify sensitive coastal stretches for a given storm class and the induced processes (flooding, erosion or combination of both) with the purpose to take actions and mitigate these impacts.
2
Lin, Ye Jue. „Multivariate characterization of wave storms in coastal areas“. Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/619809.
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Wave-storms are the responsible of the main changes in the Coast. Their detailed characterization results in a better design of any marine structure. The most common approach to describe wave-storms is to simplify the event by taking the significant wave-height (Hp), peak period (Tp) and direction (0p) at the peak of the storm and treating these variables independently. However, it is well accepted that some relationship should exist between them. What is more, the development of sophisticated numerical models in Coastal Engineering are demanding additional variables such as the duration of the wave-storm (D), the amount of associated energy (E), temporary evolution of the variables and their relationship to atmospheric climate-indices, to better reproduce the simulated processes.
The main objectives and results of this thesis are as follows. First, wave-storms in the present wave climate of the Catalan Coast are characterized, assuming stationarity. The wave-storm variables modelled are: the energy at the peak of the wave-storm (Eu ), Tp , E, D, 0p and the proportions of time from the start to the storm peak and from the storm peak to the end (growth-decay rates). E, Eu , Tp and D are fit by generalized Pareto distributions (GPD). Their joint probability structure is characterized by a hierarchical Archimedean copula (HAC). 0p is characterized through a mixture of von Mises-Fisher probability distribution functions and related to E, T p and D through a multinomial logistic model. The growth-decay rates are related to D through third degree polynomials. A triangle and an irregular-trapezoid are proposed to model the wave-storm shape.
In the present climate of the Catalan Coast, the constructed statistical model can serve to generate synthetic wave-storms. The most predominant 0p are north and east. The most appropriate geometric figure to describe the evolution of the wave-height is a irregular-trapezoid. For D over 100h, the peak of the wave-storm is generally closer to the end of the wave-storm than to the start.
After establishing a stationary model, non-stationarity is incorporated into the characterization of wave-storms in the Catalan Coast. E, Hp , T p and D are characterized through non-stationary GPDs. The wave-storm threshold, the wave-storminess and the parameters of the GPDs are related to North Atlantic Oscillation (NAO), East Atlantic pattern (EA) and Scandinavian pattern (SC) and their first two time-derivatives, through Vectorial generalized additive models. The joint probability structure is characterized by a pseudo-time-dependent HAC. A severe greenhouse gas emission scenario is considered.
The mean values of all wave-storm variables decrease in the 21st century, except for D in the northern part of the coast. A negative NAO may cause an increase in wave-storminess; the wave-storm threshold and the GPD parameters are most influenced by the dynamics of the climate-patterns, rather than by the climate-patterns themselves.
The non-stationary methodology is repeated in the northwestern Black Sea, considering both a mild and a severe emission scenarios. Here, wave-storminess is not affected by the proposed climate-patterns, whereas the wave-storm threshold is strongly influenced by SC and EA. The average value of the wave-storm variables seem to have a more positive trend than in the Catalan Coast, and it is observed that an increase in mean values is related to an increase in variance. SC and EA also strongly influence the parameters of the GPDs.
In the two study areas, the dependence between E and D is high, while the general dependence among the wave-storm variables is medium. In the Catalan Coast, it is expected that the dependence between E and D should increase with time. In the northwestern Black Sea, it is the dependence among all the wave-storm variables that increases with time, in both emission scenarios; the severe emission scenario presents less dependence among wave-storm variables.El enfoque más común para describir los temporales de mar es simplificar este suceso tomando la altura de ola significante (Hp), el periodo pico (Tp) y la dirección (0p) en el pico de la tormenta y tratándolas de forma independiente. Sin embargo, está ampliamente aceptado que exista al menos alguna relación entre ellas. Es más, el desarrollo de sofisticados modelos numéricos en la ingeniería de costas pide variables adicionales como la duración de tormenta (D), la cantidad de energía asociada (E), la evolución temporal de las variables y su relación con índices climáticos atmosféricos, todo para una mejor reproducción de los procesos simulados. Los objetivos y resultados principales de esta tesis son los siguientes: Primero, se caracteriza tormentas de mar en el clima de oleaje presente, de la costa catalana, suponiendo estacionalidad. Las variables modeladas son: la energía unitaria en el pico del temporal (Eu), Tp, E, D, 0p y la proporción de tiempo desde el inicio hasta el pico y desde el pico al final del temporal (ratios de crecimiento-decrecimiento). Se caracteriza E, E u, T p y D con distribuciones generalizadas de Pareto (GPD), y se caracteriza la estructura de probabilidades conjunta de estas variables vía una cópula jerárquica arquimedeana (HAC). Se caracteriza 0p con una combinación de distribución de probabilidad de von Mises-Fisher y se le relaciona con E, T p y D a través de un modelo logístico multinomial. Se propone una forma triangular o trapezoide-irregular para modelar la forma del temporal. En el clima presente de la costa catalana, el modelo estadístico construido puede generar temporales sintéticos. Las 0p principales son el norte y el este. La figura geométrica que mejor describe la evolución de la altura de ola es un trapezoide irregular. Para D mayor que 100h, el pico del temporal está generalmente más cerca del final que del principio. La media de cada variable decrece en el siglo XXI, excepto la de D, en el norte de la costa. Una NAO negativa puede causar una subida de la tormentosidad. Además, el umbral de tormenta y los parámetros de GPD están influenciados principalmente por la dinámica de los patrones climáticos, en vez de serlo por los propios patrones climáticos. Después de establecer un modelo estacionario, se incorpora la no estacionalidad a la caracterización de temporales de mar en la costa catalana. Se caracteriza E, Hp, Tp y D con GPDs no estacionarios. El umbral de temporal, la tormentosidad y los parámetros de los GPDs están relacionados con la Oscilación de Atlántico norte (NAO), el Patrón de Atántico oriental (EA) y el Patrón escandinavo (SC) y sus primeras dos derivadas temporales, a través de Modelos aditivos generalizados vectoriales. Se caracteriza la estructura de probabilidades conjunta con un HAC pseudo-dependiente del tiempo. Se considera un escenario grave de cambio climático. Se repite la metodología no estacionaria en el noroeste del Mar Negro, considerando tanto un escenario suave de cambio climático como otro grave. En el noroeste del Mar Negro, la tormentosidad de mar no está afectada por los patrones climáticos propuestos, todo y que el umbral de temporal está fuertemente influenciado por SC y EA. Los valores medios de las variables de temporal parecen tener una tendencia más positiva que en la costa catalana, y se observa que una subida de los valores medios se relaciona con otra subida de las varianzas. SC y EA afectan fuertemente a los parámetros de los GPDs. En las dos zonas de estudio, la dependencia entre E y D es alta, mientras que la dependencia general entre las variables de temporal es media. En la costa catalana, se espera que la dependencia entre E y D crezca con el tiempo. En el noroeste del Mar Negro, es la dependencia entre todas las variables de temporal la que crece con el tiempo, en ambos escenarios de cambio climático: el escenario grave presenta menos dependencia entre las variables.
3
Kortekaas, Stella. „Tsunamis, storms and earthquakes : distinguishing coastal flooding events“. Thesis, Coventry University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491429.
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Bosom, García Eva. „Coastal vulnerability to storms at different time scales: application to the Catalan coast“. Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/277381.
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Storm-induced impacts are known to cause important economic and environmental damages to coastal systems worldwide. Consequently, the relevance of including hazards and vulnerability assessments in coastal policies has been highlighted during the last years, so that coastal managers can make informed decision to apply mitigation and/or adaptation plans.
The main purpose of this thesis is to develop a methodology to quantitatively assess coastal vulnerability to storms at different time scales, considering the two main storm-induced hazards separately (inundation and erosion). In this work, vulnerability is defined as the potential of a coastal system to be harmed by the impact of a storm. Thus, it has been quantified by comparing the magnitude of the hazards with the adaptation ability of the coast.
The proposed methodology is based on a probabilistic approach where hazard time series are fitted to an extreme value distribution. Consequently, hazard magnitudes and vulnerability are related to a probability of occurrence instead of to a determined storm event. The coastal manager has to decide the probability of occurrence to be accepted in the analysis, which will determine the return period (Tr) to be considered. Vulnerability indicators that compare the magnitude of each hazard to the response capability of the beach are built for erosion and inundation independently. Final vulnerability is formulated in terms of these two intermediate variables by means of a linear function that ranges from a minimum value of 0 (optimum state) to a maximum of 1 (failure state), defining 5 qualitative categories. In this particular case, these thresholds have been defined for each hazard in terms of the protection function provided by the beach.
In order to evaluate changes in vulnerability at different time scales, variations in the adaptation ability of the coast due to the effects of other medium and long-term processes have also been considered. Taking into account the characteristics of the study area, erosion due to longshore sediment transport (LST) gradients and erosion and inundation caused by relative sea-level rise (RSLR) have been selected as the main medium and long-term coastal processes, respectively, to be analysed. In this sense, shoreline evolution rates have been used as representative of accretion/erosion due to LST, whereas different combinations of sea-level and subsidence scenarios have been used to determine erosion and inundation due to RSLR.
The developed methodology has been applied to most of the sedimentary coastline (219 km) of Catalonia (NW Mediterranean). The results obtained for a Tr=50-yr show similar percentages of high and very high vulnerable coastline for erosion and inundation. However, the increase in vulnerability due to the contribution of LST and RSLR is slightly higher in the case of erosion. Results also indicate that changes in vulnerability due to RSLR are generally lower than those obtained when only LST is accounted. RSLR contribution is detected at longer time scales and is significantly higher in the southern part of the Catalan coast. This is mainly due to the presence of dissipative beaches with very mild slope together with the potentially significant subsidence of the Ebre delta. On the opposite, LST contribution does not seem to target any specific beach type.
To conclude, the proposed method permits to identify the most vulnerable spots of a coastal area considering the dynamic response of the system at different time scales. This information is relevant for coastal managers when it comes to efficiently allocate the available resources. Moreover, the versatility of this method allows, not only to update the results according to the available information on hazards magnitude and beach geomorphology, but also to easily apply it to other coastal zones.Los temporales pueden causar daños importantes en la costa, tanto a nivel económico como ambiental. En consecuencia, durante los últimos años se ha destacado la importancia de incluir estimaciones de la magnitud de los procesos y de la vulnerabilidad en las políticas costeras, de forma que los gestores puedan tomar decisiones informadas para aplicar planes de mitigación y/o adaptación. El principal objetivo de esta tesis es desarrollar una metodología que permita evaluar, cuantitativamente, la vulnerabilidad de la costa al impacto de temporales para diferentes escalas de tiempo, considerando por separado los principales procesos implicados (inundación y erosión). En este trabajo, la vulnerabilidad se define como el potencial de un sistema costero a ser dañado, por lo que se ha cuantificado comparando la magnitud de los procesos con la capacidad de adaptación de la costa. La metodología propuesta se basa en una aproximación probabilística en la que las series temporales de intensidad de los procesos se ajustan a una distribución de valores extremos. En consecuencia, tanto la magnitud de los procesos como la vulnerabilidad se asocian a una probabilidad de ocurrencia en vez de a un evento determinado. El gestor debe decidir la probabilidad de ocurrencia a tener en cuenta en el análisis, la cual determinará el periodo de retorno (Tr). Una vez seleccionado el periodo de retorno, se crean indicadores de vulnerabilidad que comparan la magnitud del proceso con la capacidad de respuesta de la playa de forma independiente para erosión e inundación. La vulnerabilidad final se formula en términos de estas dos variables intermedias por medio de una función lineal que va desde un valor mínimo de 0 (estado óptimo) a un máximo de 1 (estado de fallida), definiendo 5 categorías cualitativas. En este caso, estos umbrales se han definido considerando la función de protección de la playa. Para evaluar las variaciones temporales de la vulnerabilidad, se han analizado los cambios en la capacidad de adaptación de la costa frente al impacto de temporales inducidos por los efectos de otros procesos costeros. Considerando las características de la zona de estudio, la erosión debida a los gradientes en el transporte longitudinal de sedimentos (LST) y la erosión y e inundación causadas por la subida relativa del nivel del mar (RSLR) han sido seleccionados como los principales procesos que actúan a medio y largo plazo respectivamente. La erosión/acreción debida al LST se ha determinado mediante tasas de evolución costera, mientras que para caracterizar la erosión e inundación debidas a la RSLR se ha utilizado una combinación de distintos escenarios de nivel del mar y subsidencia. La metodología se ha aplicado a la mayor parte de la costa sedimentaria (219 km) de Cataluña (Mediterráneo noroeste). Los resultados obtenidos para un Tr= 50 años muestran porcentajes similares de costa sujeta a alta o muy alta vulnerabilidad a los dos procesos. Sin embargo, el incremento de vulnerabilidad debido a la contribución del LST y la RSLR es ligeramente mayor en el caso de la erosión. En general, los cambios inducidos por la RSLR son menores que los obtenidos considerando solo el LST. La contribución de la RSLR se detecta a escalas de tiempo mayores y es mayor en la parte sur de la costa catalana. Esto se debe a la presencia de playas disipativas con pendientes muy suaves y a la potencialmente significativa subsidencia del delta del Ebro. La contribución del LST no parece afectar a ningún tipo concreto de playa. Finalmente, este método permite identificar los puntos más vulnerables de la costa considerando la respuesta dinámica del sistema a lo largo del tiempo. Esta información es relevante para los gestores en cuanto a la organización de los recursos disponibles. Además, su versatilidad permite tanto actualizar los resultados en función de la información disponible sobre los procesos y la geomorfología costera, como aplicarlo fácilmente a otras regiones.
5
Doe, Robert K. „An investigation into the physical impacts of coastal storms on the Dorset coast“. Thesis, University of Portsmouth, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439190.
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Coastal storms affecting Dorset are investigated with the aid of a new metadata repository, The Dorset Coastal Storms Database. This customised database has been designed to facilitate extensive secondary data collection and provide a medium with which to analyse fundamental relationships between these data. The database presents the only county-based digital archive of coastal storm forcing and associated physical impacts. A wide range of impacts, vulnerable coastal environments and specific coastal storms have been identified and analysed for the period 1865 to present. A new intensity grading scale for coastal storm impacts has been developed in order to facilitate the identification of coastal storm types. An increase in intensity of coastal storms producing physical impacts on the Dorset coast has been identified. A thorough examination of local and regional storminess has been performed to determine baseline conditions, identify trends, and postulate future trends. A reduction in the average annual number of days with gale along the Dorset coast is highlighted, along with a shift in the number of coastal storms with physical impacts from October-December, to that of January-March. A regional field monitoring programme between 1999 and 2004 facilitated the collection of primary data during, and following, extreme events along the Dorset coast. These Rapid Response Surveys identified Studland beach and dunes, between Middle and Knoll beach, as one of the most vulnerable zones to future storm climates.
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Hickey, Kieran Richard. „Documentary records of coastal storms in Scotland 1500-1991 A.D“. Thesis, Coventry University, 1997. http://curve.coventry.ac.uk/open/items/aa6dfd04-d53f-4741-1bb7-bdf99fb153be/1.
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This study is concerned with the preparation of a research datum line in historical climatology and will provide a valuable data set for a wide variety of researchers in the future who are interested in the relationship between aspects of the coastal and climate systems and the human-coastal environment interface. The principal objective was to create and prepare an original historical data base on the storms, floods, erosion events and sand movements in Scotland 1500-1991 A.D.
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Franck, Travis Read. „Coastal communities and climate change : a dynamic model of risk perception, storms, and adaptation“. Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54846.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 303-311).
Climate change impacts, including sea-level rise and changes in tropical storm frequency and intensity, will pose signicant challenges to city planners and coastal zone managers trying to make wise investment and protection decisions. Meanwhile, policymakers are working to mitigate impacts by regulating greenhouse gas emissions. To design effective policies, policymakers need more accurate information than is currently available to understand how coastal communities will be affected by climate change. My research aims to improve coastal impact and adaptation assessments, which inform climate and adaptation policies. I relax previous assumptions of probabilistic annual storm damage and rational economic expectations-variables in previous studies that are suspect, given the stochastic nature of storm events and the real-world behavior of people. I develop a dynamic stochastic adaptation model that includes explicit storm events and boundedly rational storm perception. I also include endogenous economic growth, population growth, public adaptation measures, and relative sea-level rise. The frequency and intensity of stochastic storm events can change a region's long- term economic growth pattern and introduce the possibility of community decline. Previous studies using likely annual storm damage are unable to show this result. Additionally, I consider three decision makers (coastal managers, infrastructure investors, and residents) who differ regarding their perception of storm risk. The decision makers' perception of risk varies depending on their rationality assumptions.
(cont.) Boundedly rational investors and residents perceive storm risk to be higher immediately after a storm event, which can drive down investment, decrease economic 3 growth, and increase economic recovery time, proving that previous studies provide overly optimistic economic predictions. Rationality assumptions are shown to change economic growth and recovery time estimates. Including stochastic storms and variable rationality assumptions will improve adaptation research and, therefore, coastal adaptation and climate change policies.
by Travis Read Franck.
Ph.D.
8
Mulvaney, Heidi Sarah. „An investigation into sandy beach stabilisation through controlled drainage“. Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342713.
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Switzer, Adam D. „Depositional characteristics of recent and late Holocene overwash sandsheets in coastal embayments from southeast Australia“. Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20051202.112948/index.html.
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Lee, Hyerin M. ArchMassachusetts Institute of Technology. „Weathering the storms : new suburban typology for coastal cities through a case study on Winthrop, MA“. Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127849.
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Thesis: M. Arch., Massachusetts Institute of Technology, Department of Architecture, May, 2020Cataloged from PDF version of thesis.
Includes bibliographical references (pages 61-62).
Climate change is intensifying natural events around the world. As the sea level rises, coastal cities are becoming more vulnerable to storm surges and flooding. This is especially problematic in the U.S. where the population is concentrated and is on the rise along the coasts. Properties of high total value are also at risk. Various flood mitigation strategies have been implemented domestically and internationally. Hard solutions such as seawalls and levees can be effective but they are expensive and potentially catastrophic in the event of failure. Soft solutions like dunes and living shorelines have stabilizing effects but they are moderate in their effectiveness and will not protect against significant sea level rise or major storms. Strategies involving retreat is a sure way to remove people and properties from harm's way. If the sea level continues to rise, retreating will become inevitable. Currently, there are many challenges with this method. In the U.S., flood insurance policy is structured in a way to incentivize people to stay in flood-prone areas as opposed to moving. Relocation can be disorienting for people involved and costly for tax payers. Economic and political pressure often sides with building more than building less. This thesis aims at providing a design solution for coastal suburbs that can enable retreat in a sustainable way. Winthrop, Massachusetts, which is a dense suburb lying six miles to the east of Boston and is experiencing frequent flooding was selected as a case-study site. The thesis proposes a new building typology that can appeal to suburban life style, be implemented incrementally, and, most importantly, protect people and properties from the dangers of coastal flooding.
by Hyerin Lee.
M. Arch.
M.Arch. Massachusetts Institute of Technology, Department of Architecture
11
Etri, Talal [Verfasser]. „Effects of storms on short and medium-term morphodynamics of a tide-dominated coastal region / Talal Etri“. Kiel : Universitätsbibliothek Kiel, 2008. http://d-nb.info/1019541881/34.
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Beigzadeh, Shima. „System Dynamics and Statistical Modeling of Severe Storms: The Case of Charlottetown, P.E.I., Canada“. Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31420.
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Scientific evidence points to a changing global climate. The most vital and visible impacts of this phenomenon for sea-level communities are sea-level rise, coastal erosion, and more frequent severe coastal storms. However, limited research has been conducted to date to project the damage from rising maximum water levels and corresponding storm surges, and their impacts on the sustainability of coastal communities. This research focuses on the urban coastal community of Charlottetown, Prince Edward Island (P.E.I.), Canada as part of the C-Change International Community University research Alliance (ICURA), “Managing Adaptation to Environmental Change in Coastal Communities: Canada and the Caribbean.” The stochastic process that underlies, maximum observed water levels in Charlottetown, is modeled using historical data. Maximum observed water levels and storm surges are represented by fitted conditional and marginal univariate probability density functions. The statistical package “Easy-Fit” is used as a tool for analyzing goodness of fit to the historical data for maximum observed water levels in Charlottetown. A System Dynamics (SD) model, using STELLA, is developed to simulate the projected impacts of maximum observed water levels on the City of Charlottetown. The SD model captures the dynamics of the four pillars of community sustainability, namely Environmental, Economic, Social-Cultural and Human sectors identified for the City of Charlottetown. The model defines and evaluates the robustness of alternative adaptation strategies for various model scenarios to projected storms over a long-term planning period. The results quantify the vulnerability of Charlottetown. The analysis of the results from implementing 3 main adaptation strategies for protection, accommodation, and retreat scenarios as well as the ones from the most common current response of “doing nothing”, provide information on the dynamic and pillar-related impacts of storms on Charlottetown. Analysis of these strategy options clearly indicates that doing nothing in the face of more frequent severe storms is an inefficient strategy. Model results show that the protect strategy is unlikely to deliver complete protection, and the retreat option is costly and not well received. The accommodation strategy including a combination of protection options and controlled retreat will provide the most robust option for the coastal City of Charlottetown. The SD model and analysis provides a framework for the evaluation of adaptation strategies for alternative coastal communities.
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Paudel, Shishir. „CLIMATE CHANGE, SHIFTS IN TROPICAL STORM REGIMES AND TRIADICA SEBIFERA INVASION IN COASTAL MISSISSIPPI, UNITED STATES“. OpenSIUC, 2013. https://opensiuc.lib.siu.edu/dissertations/694.
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Global climate change is predicted to affect timing and severity of disturbance events (e.g., fire, drought, hurricanes, wind storms, and inundation), but the extent of these disturbance events and their impacts on natural ecosystems may vary regionally. Rising sea level, increased frequency and intensity of tropical storms, and altered inundation regimes are likely to create changing environmental conditions in low-lying coastal ecosystems. These large scale disturbances may increase resource availability and regeneration spaces, reduce competition, and possibly increase community vulnerability to invasion. Shifting disturbance regimes and invasion together are predicted to drive long-term shifts in coastal plant community structure and ecosystem processes. However, impacts of altered environmental conditions on native and invasive plant species and the species responses to changed environmental conditions are poorly understood. The aims of this study were: (i) to assess the probability of occurrence of juveniles of the invasive exotic Triadica sebifera and co-occurring native species, Baccharis halimifolia, Ilex vomitoria, and Morella cerifera in the field in relation to surrounding environmental factors, (ii) to assess the effects of elevated salinity across a typical coastal transition on germination of T. sebifera, B. halimifolia and M. cerifera, using controlled growth chamber and greenhouse experiments, (iii) to assess the effects of climate change and shifting inundation and tropical storms regimes on T. sebifera, B. halimifolia and M. cerifera, and (iv) to evaluate the role of vesicular arbuscular mycorrhizae (VAM) on spread of invasive T. sebifera in coastal transition ecosystems at the Grand Bay National Estuarine Research Reserve (GBNERR), Coastal Mississippi, southeastern USA. Results from assessing the probability of occurrence of juveniles of invasive and co-occurring native species showed that soil water conductivity (i.e., salinity) was the major factor related to the occurrence of invasive T. sebifera and native B. halimifolia, I. vomitoria and M. cerifera along the coastal transitions. Probability of occurrence of the invasive T. sebifera was significantly related to landscape factors and occurrence was highest in close proximity to roads, trails, power lines, and recreational sites, and water bodies. These results imply that future increases in salinity will negatively impact I. vomitoria, M. cerifera, and T. sebifera, leading to range contraction of these species away from the coast. However, natural and anthropogenic disturbances that often increase resource pulses and reduce competition, likely increase the dominance of T. sebifera in already invaded areas. Positive effects of landscape structures on T. sebifera occupancy highlight the role of landscape variables in promoting new invasions in coastal forests of the southeastern USA. Controlled growth chamber and greenhouse germination experiments demonstrated that germination of all species (i.e., T. sebifera, B. halimifolia, and M. cerifera) decreased with elevated salinity and that the reduction was most pronounced in soils from the most seaward zones along the coastal transition. Although native B. halimifolia was least sensitive to elevated salinity, invasive T. sebifera displayed plasticity of germination trait across different salinity levels in most inland soils. These results suggest that the phenotypic plasticity may facilitate spread of Triadica sebifera under some degree of salinity stress in more inland section of the coastal transition. A manipulative greenhouse experiment demonstrated that simulated canopy damage from intense hurricane winds and associated storm surge produced differential effects on survival and growth of native (B. halimifolia and M. cerifera) and invasive (T. sebifera) species at simulated different forest conditions common in the GBNERR. Invasive T. sebifera was by far the most shade tolerant of the three species and seedling survival under highly shaded conditions may provide it with a competitive edge over native species during community reassembly following tropical storms. T. sebifera may better utilize post-hurricane conditions (e.g., resource-rich empty spaces) and potentially increase its dominance in coastal forested ecosystems. The last experimental study revealed that invasive T. sebifera had higher VAM colonization compared to co-occurring native species both in controlled greenhouse and field experiments, and that the higher colonization leads to significant increases in aboveground biomass, supporting the hypothesis that VAM fungi strongly benefit the invasive species. These results suggest that the VAM colonization may be necessary for the initial establishment of T. sebifera along the coastal transitions. Furthermore, my research also suggested that T. sebifera was not allelopathic and did not interfere with growth of native species. Overall, the findings of this research provide insight into the impacts of climate change related shifts on performance of invasive and co-occurring native species across coastal transitions of the southeastern USA. Variation in invasive and co-occurring native species' performances under changed environmental conditions (e.g., elevated salinity and increased light availability) and improved mutualistic association between invasive T. sebifera and VAM fungi may drive increased invasion with frequent community reassembly of low-lying coastal ecosystems undergoing rapid climate change.
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Borchers, Eric K. „Uncovering the Progress of Planning for Vulnerability to Sea-Level Rise & Coastal Storms: A Plan Evaluation of Norfolk, VA & New York City“. VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4785.
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In response to recent storms like Superstorm Sandy and sea-level rise influenced by climate change, cities, particularly those located at the coast, have taken initiative to combat these growing threats with adaptive urban planning. Although civilians residing in susceptible neighborhoods are often the most vulnerable socioeconomically, there has been minimal evidence that planning has accounted for the characteristics of vulnerability. This thesis evaluates the recent planning efforts and vulnerability of Norfolk, VA and New York City to gauge the progress being made toward reducing citizen vulnerability and raising adaptability and preparedness. The most recent peer-reviewed research is consulted to forge the evaluation framework and also to recognize breakthroughs and conformity. After analyzing the performance of the sets of planning documents in both cities, it is evident that the ability to effectively plan for the public’s vulnerability is contingent in part on inter-governmental capacity, but more specifically on disaster experience.
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Baumann, Juliette. „Signature sédimentaire des submersions de tempête dans le domaine rétrolittoral : application à la Charente Maritime“. Thesis, La Rochelle, 2017. http://www.theses.fr/2017LAROS038/document.
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Cette thèse présente l’étude de la signature sédimentaire des submersions marines de tempête, dans le domaine rétrolittoral. Cette signature peut être extrêmement variable principalement en fonction des paramètres météo-océaniques menant à la submersion, de la morphologie de l’avant-côte et du domaine rétrolittoral et du disponible sédimentaire. Premièrement, l’étude de dépôts de washover mis en place lors de l’hiver 2013-2014, au sud de l’île d’Oléron, particulièrement énergétique en terme de climat de vagues, via une approche couplant processus hydrodynamiques et sédimentologie, a permis (1) de mettre en évidence l’importance des ondes infragravitaires, sur une côte dissipative à caractère macrotidal, dans le déclenchement de l’overwash de la barrière et la mise en place de washovers ; et de (2) proposer un nouveau modèle de faciès des dépôts de washover mis en place par des ondes infragravitaires combinées à la marée haute. Deuxièmement, la caractérisation de la signature sédimentaire des submersions marines en domaine rétrolittoral plus distal a montré que dans le contexte morphologique des marais de Charente-Maritime, les apports extrêmement faibles de sédiments en provenance du domaine continental, entre deux évènements de submersion marine, empêche la distinction des différents niveaux de submersion. Cependant cette étude a permis de valider des proxies tels que la microfaune ou l’isotopie de la matière organique pour l’identification de niveaux de submersion marine, permettant en partie de pallier aux limites inhérentes à l’anomalie granulométrique généralement utilisée. Cette étude a aussi permis la mise en évidence d’une variabilité dans la signature sédimentaire des submersions marines entre deux marais géomorphologiquement contrastés et plus ou moins exposés aux houles en provenance de l’océanThis thesis presents the study of the sedimentary signature of marine submersions triggered by storms, in the back barrier area. This signature can be extremely variable mainly according to the meteo-oceanic parameters leading to the submersion of the back barrier area, the morphology of the nearshore, shore and back barrier area, and sediment availability. Firstly, the study of washover deposits emplaced during the winter of 2013-2014 on the southern end of the Oléron Island, characterized by an exceptional wave climate, via a coupled hydrodynamical and sedimentological approach, allowed us to (1) highlight the importance of infragravity waves, on macrotidal and dissipative coasts, in triggering the overwash and emplace washover deposits ; and (2) to suggest a new facies model of washover deposits emplaced by infragravity waves combined to high tides. Secondly, the characterization of the sedimentary signature of marine submersions in the distal part of the back barrier area showed that in the morphological context of the Charente-Maritime coastal marshes, the extremely limited amounts of sediments in provenance from the continent, between two submersion events, prevent the distinction of the different marine submersion sedimentary layers. Nevertheless, this study allowed validating new proxies as microfauna and organic matter isotopy for the identification of marine submersion sedimentary signature, allowing to work independently of the granulometric anomaly proxy and its known limits. This study also allowed evidencing the variability in the sedimentary signature of marine submersions in geomorphologically contrasted marshes and that this variability was linked to the ocean waves exposure
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Lopez, Solano Carlos. „Cοupling stοchastic and numerical apprοaches fοr investigating the dynamics οf cοastal extreme events : Case οf the English Channel and the Νοrmandy cοasts“. Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMR043.
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Les zones côtières sont de plus en plus vulnérables en raison du changement climatique, ce qui entraîne des risques tels que les submersions côtières ou l'érosion des plages, exacerbés par les activités anthropiques et le réchauffement climatique. Une gestion côtière efficace et des stratégies d'adaptation sont cruciales. Les modèles numériques avancés et la surveillance des tempêtes extrêmes sont essentiels pour une évaluation précise des risques et des systèmes d'alerte précoce. Cette thèse examine les houles extrêmes et les surcotes en Manche, mer située entre la France et l’Angleterre), en intégrant les oscillations climatiques globales et les facteurs hydrodynamiques locaux. Les plages de Normandie, avec leurs morphologies diverses, sont étudiées en utilisant des modèles numériques et des systèmes de surveillance pour comprendre les hydrodynamiques et les risques côtiers.Les facteurs stochastiques de l’hydrodynamique marin sont explorés en se concentrant sur les variations de la hauteur des houles et du niveau de la mer, analysées à travers des méthodes statistiques et spectrales. Une variabilité significative des surcotes a été identifiée, alimentée par les tendances à long terme du niveau de la mer et les interactions marée-surcote, les hauteurs des houles étant influencées par les interactions océan-atmosphère, révélant des dépendances à la température de surface de la mer, à la pression atmosphérique et aux indices climatiques. Une classification des événements extrêmes typiques dans la Manche est récemment réalisée.Une simulation de 40 ans de données avec une validation par rapport aux mesures de bouées et de marégraphes en Angleterre et en France a été réalisée. L'étude classe les tempêtes, en évaluant leur impact sur la côte de Normandie, montrant des variations significatives de la hauteur des houles, principalement en fonction de leur origine et de leur direction de propagation, principalement l'océan Atlantique. Les simulations détaillées soulignent le rôle de la morphologie côtière dans la dissipation de l'énergie et le comportement des houles.La modélisation numérique pour simuler les dynamiques des houles de tempête sur trois sites côtiers normands, est détaillée et validée en comparant les simulations avec les mesures des bouées, les formulations théoriques et les données de run-up de houles mesurées par les Systèmes de Surveillance Vidéo (VMS). Les résultats montrent que la hauteur de run-up est influencée par les niveaux d'eau et la hauteur des houles, avec des variations spécifiques pour chaque site en raison des caractéristiques des plages, principalement la porosité des différents sédiments.Les méthodologies stochastiques et numériques ainsi que les bases de données des études précédentes sont enfin appliquées pour lier l’hydrodynamisme avec la morphodynamique des plages dans des conditions extrêmes, en étudiant les composantes d’inondation sur la baie de Seine et l'impact des structures côtières et de la perméabilité sur l'érosion des plagesCoastal zones face increasing vulnerability due to climate change, leading to hazards like coastal flooding or beach erosion, exacerbated by anthropogenic activities and global warming. Effective coastal management and adaptation strategies are crucial. Advanced numerical models and monitoring of extreme storms are essential for accurate risk assessment and early warning systems. The DYNSEEC project aims to enhance understanding of storm dynamics, focusing on coastal flooding to improve risk assessment and mitigation efforts. This dissertation examines extreme waves and storm surges along the English Channel, integrating global climate oscillations and local hydrodynamic factors. Normandy’s beaches, with diverse morphologies, are studied using numerical modelling and monitoring systems to understand hydrodynamics and coastal risks.The stochastic drivers of maritime hydrodynamics are explored, focusing on wave height and sea level variations, analyzed through statistical and spectral methods. The research identifies significant variability in surges driven by long-term sea level trends and tide-surge interactions, with wave heights influenced by ocean-atmosphere interactions, and revealing dependencies on sea surface temperature, sea level pressure, and climate indexes. A classification of typical extreme events on the English Channel is lastly performed.A simulation of 40 years of data, with validation against buoy and tide gauge measurements in England and France has been carried out. The study classifies storms, assessing their impact on Normandy’s coast, showing significant wave height variations, dependent mostly on their origin and direction of propagation, primarily the Atlantic Ocean. Detailed simulations emphasize coastal morphology’s role in energy dissipation and wave behavior.The numerical modeling to simulate storm wave dynamics at three Norman coastal sites is detailed, validated by comparing simulations with buoy measurements, theoretical formulations, and wave run-up data measured by Video Monitoring Systems. Results show that run-up height is influenced by water levels and wave height, with site-specific variations due to beach characteristics, mainly the porosity of gravels and pebbles.The stochastic and the numerical methodologies and databases from previous studies are finally applied to link hydrodynamics with beach morphodynamics under extreme conditions, studying compound flooding on the Seine Bay and the impact of coastal structures and beach permeability on beach erosion
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Aouiche, Ismail. „Dynamique morphosédimentaire de la baie d’Agadir : approche multi-méthodes et préconisations pour une gestion intégrée de la zone côtière“. Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM3017/document.
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Les systèmes côtiers, où le transport sédimentaire est perturbé par les aménagements côtiers sur la côte et l’avant côte, fournissent généralement d'excellents exemples permettant de mettre en lumière ces liens. Cela est faisable lorsque l’ensemble des données bathymétriques d’avant-côte, qui ne sont pas toujours disponibles, sont recueillies au fil du temps. La baie et la ville d'Agadir forment ensemble un des pôles de développement économique le plus important de la côte atlantique du Maroc. En utilisant une approche méthodologique basée sur la modélisation de la houle et des courants, le différentiel de levées topo-bathymétriques, la détermination de l’évolution du trait de côte et le suivi topographique de la zone intertidale, nous mettons en évidence les liens étroits entre les variations des petits fonds et la ligne du trait de côte. Ces liens impliquent à la fois les voies de transport cross-shore et longshore, les variations du budget sédimentaire et la détermination de cellules sédimentaires. Nous avons également suivi l’évolution morphologique de la zone intertidale de la baie en réponse à huit tempêtes qui ont lieu entre Janvier 2014 et Mars 2014. Les résultats obtenus par les simulations numériques montrent que les deux premières tempêtes sont responsables des changements morphologiques majeurs au niveau de la zone intertidaleCoastal systems where sediment transport is perturbed by engineering interventions on the shoreline and shoreface commonly provide fine examples liable to throw light on these links. This is especially so where shoreface bathymetric datasets, which are generally lacking, are collected over time, enabling more or less fine resolution of the meso-scale coastal sediment budget. Agadir Bay and the city of Agadir together form one of the two most important economic development poles on the Atlantic coast of Morocco. Using a combined methodological approach based on wave–current modelling, bathymetric chart-differencing, determination of shoreline fluctuations, and beach topographic surveying, we highlight the close links between variations in the bed of the inner shoreface and the bay shoreline involving both cross-shore and longshore sand transport pathways, sediment budget variations and new sediment cell patterns. This work discusses also the morphological changes and evolution of Agadir Bay beach (Morocco) in response to eight storms between January 2014 and March 2014. A comparison is carried out of the evolution and variability of the beach in a sector of the bay protected by the commercial harbour of Agadir relative to a sector down drift of the harbour that is more exposed to waves, and changes affecting the beach following these storms are examined. Wave influence is evaluated using numerical simulations. The results show that despite being of relatively low intensity, the two first storm events, and especially storm 1, are responsible for major beach morphological changes
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Poulose, Jismy. „Interaction of storm tides with wind waves : coastal inundation along the west coast of India“. Thesis, IIT Delhi, 2019. http://eprint.iitd.ac.in:80//handle/2074/8117.
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Burvingt, Olivier Jean-Patrick. „Storm impact and recovery along the south west coast of England“. Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/12830.
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Extreme storms are responsible for rapid changes to coastlines worldwide. During the 2013/14 winter, the west coast of Europe experienced a sequence of large, storm-induced wave events, representing the most energetic period of waves in the last 60 years. The southwest coast of England underwent significant geomorphological change during that period, but exhibited a range of spatially variable and complex morphological responses, despite being subjected to the same storm sequence. The 2013/14 storm response along the southwest coast of England was first used as a natural field laboratory to explain the variability in storm response through the introduction and evaluation of a new classification of how sandy and gravel beaches respond to extreme storms. Cluster analysis was conducted using an unique data set of pre- and post-storm airborne Light Detection and Ranging (LiDAR) data from 157 beach sites and the calculation of volumetric beach changes and a novel parameter, the longshore variation index which quantifies the alongshore morphological variability in beach response. The method used can be applied to any sandy and gravel beaches where topographic data with sufficient spatial resolution is available. Four main beach response types were identified that ranged from large and alongshore uniform offshore sediment losses up to 170 m3 m-1 (at exposed, cross-shore dominated sites) to considerable alongshore sediment redistribution but limited net sediment change (at more sheltered sites with oblique waves). The key factors in determining the type of beach response are: exposure to the storm waves, angle of storm wave approach and the degree to which the beach is embayed. These findings provide crucial information for the development of coastal studies at regional scale, especially along coastal areas where abrupt changes in coastline orientation can be observed. A 10-year time series (2007-2017) of supra- and intertidal beach volume from exposed and cross-shore transport-dominated sites was used to examine the extent to which beach behaviour is coherent over a relatively large region (100-km stretch of coast) and predictably coupled to incident wave forcing. Over the study period, 10 beaches, exposed to similar wave/tide conditions, but having different sediment characteristics, beach lengths and degrees of embaymentisation, showed coherent and synchronous variations in sediment volumes, albeit at different magnitudes. This result is crucial for studying coastal changes in remote coastal areas or in areas where only few topographic data are available. The sequence of extreme storms of the 2013/14 winter, which represents the most erosive event over at least a decade along most of the Atlantic coast of Europe, is included in the data set, and three years after this winter, beach recovery is still on-going for some of the 10 beaches. Post-storm beach recovery was shown to be mainly controlled by post-storm winter wave conditions, while summer conditions consistently contributed to modest beach recovery. Skilful hindcasts of regional changes in beach volume were obtained using an equilibrium-type shoreline model, demonstrating that beach changes are coherently linked to changes in the offshore wave climate and are sensitive to the antecedent conditions. Furthermore, a good correlation was found between the beach volume changes and the new climate index WEPA (West Europe Pressure Anomaly), which offers new perspectives for the role and the use of climatic variations proxies to forecast coastline evolution. A process based model, XBeach, was used to model storm response at one macrotidal beach characterized by the largest sediment losses during the 2013/14 sequence of extreme storms. Beach volume changes were modelled over hypothetical scenarios with varying hydrodynamics conditions and beach states to investigate the relative roles of hydrodynamic forcing (i.e., waves and tides), beach antecedent state and beach-dune morphology in beach response to extreme storms. This modelling approach is applicable to any beach system where process based models have been implemented. Beside significant wave height and peak wave period, the beach antecedent state was shown to be the dominant factor in controlling the volumes of sediment erosion and accretion along this cross-shore dominated beach. Modelled volumes of erosion were, on average, up to three times higher along an accreted beach compared to an eroded beach for the same wave conditions. The presence of a dune, being only significantly active during spring tides and storm conditions along this macrotidal beach, was shown to reduce erosion or even cause accretion along the intertidal beach. This work provides a detailed, quantitative insight of the hydrodynamic and morphological processes involved in storm response and beach recovery on a number of spatial and temporal scales. This improved understanding of the potential impact of extreme events will hopefully aid future research efforts and ensure effective management of sedimentary coastlines.
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Coggin, David. „LIDAR IN COASTAL STORM SURGE MODELING: MODELING LINEAR RAISED FEATURES“. Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3362.
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A method for extracting linear raised features from laser scanned altimetry (LiDAR) datasets is presented. The objective is to automate the method so that elements in a coastal storm surge simulation finite element mesh might have their edges aligned along vertical terrain features. Terrain features of interest are those that are high and long enough to form a hydrodynamic impediment while being narrow enough that the features might be straddled and not modeled if element edges are not purposely aligned. These features are commonly raised roadbeds but may occur due to other manmade alterations to the terrain or natural terrain. The implementation uses the TauDEM watershed delineation software included in the MapWindow open source Geographic Information System to initially extract watershed boundaries. The watershed boundaries are then examined computationally to determine which sections warrant inclusion in the storm surge mesh. Introductory work towards applying image analysis techniques as an alternate means of vertical feature extraction is presented as well. Vertical feature lines extracted from a LiDAR dataset for Manatee County, Florida are included in a limited storm surge finite element mesh for the county and Tampa Bay. Storm surge simulations using the ADCIRC-2DDI model with two meshes, one which includes linear raised features as element edges and one which does not, verify the usefulness of the method.M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering MS
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García, León Manuel. „Coastal risk forecast system : fostering proactive management at the Catalan coast“. Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/669662.
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The action of sea storms is one of the most complex littoral processes with deep management implications. Along the Catalan shoreline which is about 700 km long, 190 km are subject to erosion and/or flooding. Around one million people live in areas potentially affected. Sea Level Rise could exacerbate this problem in the near future. Reactive interventions have been the norm in coastal engineering and management. This dissertation proposes a pre-storm strategy that foster cost-effective eco-compatible measures, termed Quick Defence Measures (QDM). Pre-storm intervention requires to forecast the future post-storm state. Hence, the main objective of this thesis is to assess present coastal risk through a Coastal Early Warning System (CEWS), termed LIM-COPAS, that forecasts the more relevant episodic coastal hazards at the area.
LIM-COPAS consists of four modules: (i) meteorological model; (ii) wave generation/propagation code; (iii) coupled morpho-hydrodynamic model and (iv) risk module via non-stationary multivariate probabilistic models. The performance of this suite of models has been tested with (i) a set of hindcast events and (ii) synthetic storm conditions. The hindcasted events have been: December 2008 (D-08); October-2015 (O-15); November 2015 (N-15); January 2016 (J-16); February 2016 (F-16); December 2016 (D-16) and January 2017 (J-17).
In D-08, errors in nearshore spectral wave parameters have been about twice than those in the offshore area. The error was around 20% in hydrodynamics and 50% in morphodynamics. The post-storm response has been acceptably reproduced, with a Brier Skill Score near 0.4.
LIM-COPAS has shown good accuracy with high return period events (i.e. Tr,waves > 10 yrs, D-16 and J-17), but lower agreement was found for milder storms (i.e. O-15 and F-16).
The meteorological module provided wind fields that were systematically overestimated. The integrated Mean Bias (MB) was -1.52 ± 0.78 m/s. Tarragona (Coefficient of Efficiency, COE = 0.27 ± 0.13) and Begur (COE = 0.29 ± 0.17) had metrics above the average value (COE = 0.24 ± 0.14); but lower agreement was found at Mahón (COE = 0.13 ± 0.16) and Dragonera.
Wave metrics were more accurate than for the wind fields. The integrated Hs COE was 0.52±0.12 and Tm02 COE was 0.36±0.14. At the central coast, Hs has presented good metrics: low MB (-0.06 ± 0.08 m) and high COE (0.58 ± 0.11). The northern coast metrics were the most stable.
The newly developed risk module has been implemented at 79 beaches. Erosion has been estimated as a bounded cost, whereas flooding as a high upside cost. Dissipative beaches tend to exhibit higher costs than reflective beaches under high sea levels. Tr,waves < 10 yrs events joint with storm-surges can lead to significant damage costs. The estimated losses for the N-15 event (2510·10^3 euros) do not differ excessively from J-17 (3200·10^3 euros).
Two types of QDM have been numerically tested: (i) sand dunes and (ii) geotextile detached breakwaters. The benefits from maintaining the sand volumes outperform the flooding cost reduction. In general terms, the detached breakwater can be a suitable option for beaches in an intermediate morphodynamic state against low to moderate sea levels and high wave return periods. At dissipative beaches, dunes are the best option, but they require a minimum beach width (around 30 m) that ensures their lifetime.
QDM functionality can be enhanced with compatible long-term actions (nourishments, sand bypasses, submerged vegetation, etc.). A healthy beach state is paramount for the QDM effectiveness. A higher sustainable management under present and future climate can be reached with the joint combination of (i) CEWS as a short-term forecasting tool; (ii) QDM that mitigate storm impacts and (iii) long-term interventions that improves the beach health.La acción de los temporales de mar es uno de los procesos litorales más complejos, con profundas implicaciones en la gestión del litoral. A lo largo de la línea de costa catalana, 190 km están sometidos a erosión y/o inundación. Cerca de un millón de personas viven en áreas potencialmente afectadas. La tradición en ingeniería y gestión costera han sido intervenciones reactivas. Esta tesis propone una estrategia pre-tormenta que fomente una serie de medidas eco-compatibles, denominadas Medidas de Acción Rápida (MAR). Las intervenciones pre-tormenta requieren predecir el estado post-temporal de la costa. Por tanto, el principal objetivo de esta tesis es evaluar el riesgo costero episódico mediante un Sistema de Alarma Temprana Costero (CEWS), denominado LIM-COPAS, que predice las peligrosidades costeras más relevantes en dicha área. LIM-COPAS consiste de cuatro módulos: (i) modelo meteorológico; (ii) código de generación/propagación del oleaje; (iii) modelo acoplado morfo-hidrodinámico y (iv) un módulo de riesgo vía modelos probabilísticos multivariantes y no-estacionarios. El comportamiento de estos módulos ha sido analizado mediante (i) una serie de eventos pasados y (ii) temporales sintéticos. Los eventos pasados han sido: Diciembre 2008 (D-08); Octubre 2015 (O-15); Noviembre 2015 (N-15); Enero 2016 (J-16); Febrero 2016 (F-16); Diciembre 2016 (D-16) y Enero 2017 (J-17). En D-08, los errores en los parámetros espectrales de oleaje costero han sido casi el doble que en mar abierto. El error ha sido del 20% en la hidrodinámica y del 50% en la morfodinámica. La respuesta post-temporal ha sido reproducida aceptablemente, con Brier Skill Score cercanos a 0.4. LIM-COPAS ha demostrado buena precisión con tormentas de alto período de retorno (i.e. Tr,waves _ 10 yrs, D-16 y J-17), pero menor concordancia fue encontrada para las tormentas moderadas (i.e. O-15 y F-16). El módulo meteorológico estimó campos de viento que fueron sistemáticamente sobreestimados. El Sesgo Medio (MB) integrado fue de −1,52 ± 0,78 m/s. Tarragona (Coeficiente de Eficiencia, COE = 0,27±0,13) y Begur (COE = 0,29±0,17) tuvieron métricas por encima de la media (COE = 0,24±0,14); no obstante, peor ajuste se encontró en Mahón (COE = 0,13 ± 0,16) y Dragonera. Las métricas de oleaje fueron más precisas que las del viento. Hs COE integrada fue 0,52±0,12 y Tm02 COE fue 0,36±0,14. En la costa central, Hs presentó buenas métricas: bajo MB (−0,06 ± 0,08 m) y alto COE (0,58 ± 0,11). Las métricas en la costa norte fueron las más estables. El módulo de riesgo ha sido implementado en 79 playas. La erosión se ha estimado como un coste acotado, mientras que la inundación como un coste con alta cota superior. Las playas disipativas tienden a exhibir mayores costes que las playas reflejantes bajo altos niveles del mar. Episodios con Tr,waves _ 10yrs, concomitantes a mareas meteorológicas pueden conllevar costes significantes. Las pérdidas estimadas para N-15 (2510 · 103euros) no difieren en exceso de J-17 (3200 · 103 euros). Dos tipos de MAR han sido testeadas numéricamente: (i) dunas y (ii) diques exentos constituídos por geotextiles llenos de arena. Los beneficios de mantener estables los volúmenes de arena superan la reducción de los costes por inundación. En términos generales, los diques exentos pueden ser una opción adecuada para playas de estado morfodinámico intermedio frente a oleaje de alto período de retorno y niveles del mar bajos a moderados. En playas disipativas, las dunas son la mejor opción, pero requieren un ancho mínimo de playa (cerca de 30 m) que garantice su vida útil. La funcionalidad de las MAR puede mejorarse mediante acciones compatibles a largo-plazo (alimentaciones, bypass de arena, vegetación sumergida, etc.). Un estado de playa saludable es esencial para la efectividad de las MAR. Una gestión más sostenible bajo clima presente y futuro puede ser alcanzada mediante (i) CEWS como herramienta de predicción a corto plazo; (ii) MAR que mitiguen los impactos de los temporales y (iii) intervenciones a largo-plazo que mejoren la salud de la costa.
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Lavaud, Laura. „The contributions of short waves to storm surges in coastal zones“. Thesis, La Rochelle, 2022. http://www.theses.fr/2022LAROS007.
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Les surcotes et submersions marines associées aux tempêtes peuvent entraîner des catastrophes majeures. Les surcotes correspondent à une élévation temporaire du niveau moyen de la mer, induite par les gradients de pression atmosphérique, le vent et les vagues. La dissipation des vagues en zone littorale génère une augmentation du niveau moyen à la côte, le wave setup, qui contribue aux surcotes. Cette thèse de doctorat examine les contributions des vagues aux surcotes, notamment le wave setup, dans différents milieux littoraux en combinant l’analyse de données in-situ et la modélisation numérique à haute résolution. En premier lieu, la contribution du déferlement de vagues de tempête à l’embouchure de deux environnements abrités des vagues est étudiée. Les résultats montrent que le wave setup généré représente 40% du pic de la surcote dans l'Estuaire de l'Adour et 23% dans le Bassin d'Arcachon. La dissipation des vagues et la circulation moyenne induite sont ensuite analysées sur un estran rocheux. La forte rugosité de l’estran a deux effets antagonistes sur le wave setup : (1) les vagues sont fortement dissipées par frottement au fond, ce qui réduit le wave setup par rapport à un fond sableux ; (2) la circulation induite par les vagues sur un fond rugueux augmente le wave setup. Enfin, la dissipation des vagues et le wave setup sont examinés sur un pré salé. Lors de l’épisode de mer de vent étudié, la végétation halophyte du pré salé explique 65% de la dissipation des vagues, ce qui réduit le wave setup par rapport à un cas sans végétation. De nouvelles mesures sont nécessaires pour analyser l'effet sur le wave setup des non-linéarités des vagues sur un fond végétaliséStorm surges and associated coastal flooding can result in major catastrophes. Storm surges correspond to a temporary rise in sea level driven by atmospheric pressure gradients, wind and short waves. In particular, the dissipation of short waves in the nearshore drives a mean water level increase, the wave setup, which contributes to storm surges. This PhD thesis examines the contributions of short waves to storm surges, notably the wave setup, in contrasting coastal environments. To that end, the analysis of field data is combined with high-resolution numerical modelling. First, this work investigates the contribution to storm surges of very large storm waves breaking at the inlet of two wave-sheltered environments. The results indicate that the resulting wave setup contributes up to 40% and 23% to the storm surge peak in the Adour Estuary and the Arcachon Lagoon respectively. Second, the dissipation of storm waves and the resulting depth-varying circulation are analysed at a rock shore platform. Two counteracting effects of the high bottom roughness on the wave setup are identified: (1) waves suffer a strong dissipation by bottom friction, which reduces the wave setup compared to a smooth bottom; (2) the wave-induced circulation over a rough bottom enhances the wave setup. Lastly, waves and wave setup dynamics are investigated on a salt marsh. During the studied wind sea event, the halophytic vegetation of the salt marsh accounts for 65% of the wave dissipation, which reduces the wave setup compared to a case without vegetation. New field measurements on salt marshes are needed to explore the effect of wave non-linearities on the wave setup in vegetation fields
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Hepworth, Daniel Ary. „Response of a Partially Mixed Coastal Plain Estuary to Storm Events“. W&M ScholarWorks, 1988. https://scholarworks.wm.edu/etd/1539617584.
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Shah-Hosseini, Majid. „Geomorphic evolution and coastal hazards along the Iranian coast of Makran“. Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM3010.
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Cette thèse a deux objectifs principaux: (i) la reconstruction de l'évolution des plaines côtières autour des baies de Chabahar et de Pozm et (ii) L'évaluation des risques côtiers (tsunamis et tempêtes extrêmes) par l'étude des dépôts de haute énergie. Vastes plaines côtières et paleo-rivages protégées par des terrasses marines soulevées sont présents autour des baies de Chabahar et Pozm. Nous avons mise en évidence des changements du niveau marin relatif le long de quatre profils. L'architecture interne des paleo-rivages a été imagée en utilisant le géoradar (GPR). Des analyses sédimentologiques et stratigraphiques des séquences côtières ont été examinées par carottages et tranchées. Les paleo-rivages sont datées entre 4800 et 270 ans BP à des distances respectives de 5 km et de 670 m du rivage actuel. La position spatiale des paléo-rivages montre une chute du niveau relatif de la mer de 15 m au cours des 4800 derniers années. Nous insistons aussi sur le rôle de contrôle des structures géologiques. Les dépôts d'événements (tsunami et tempêtes) ont été étudiés en contexte de côte meuble par Les sédiments sableux et coquilliers d'origine marine, et sur les côtes rocheuses par les dépôt des blocs déplacés. Nous avons appliqué des modèles hydrologiques pour évaluer et comparer la hauteur des vagues et la distance d'inondation. Nos résultats montrent qu'aucun événement de tempête, connu ou potentiel, n'est capable de transporter les blocs observés. Des vagues de tsunamis de l'ordre de 4 m de hauteur sont suffisantes pour transporter les blocs. La côte de Makran a enregistré des indices de paléo-tsunamis probablement générés par de grands séismes dans la zone de subductionIn this thesis we have two main goals: (i) to reconstruct the Holocene coastal evolution and relative sea-level changes using strandplains around the Chabahar and Pozm bays; and (ii) to evaluate coastal hazards (tsunami and extreme storms) along the Iranian coast of Makran using high-energy deposits. Since the mid-Holocene, the shoreline rimming the bays of Chabahar and Pozm has prograded ~5 km and formed extensive strandplains. We documented relative sea-level changes along four coast-normal profiles. Internal architecture of strandplain imaged using Ground Penetrating Radar (GPR). The sedimentology and stratigraphy of the coastal sequence were studied by coring and trenching. The highest paleo-coastline is located about 5 km inland and stands approximately 15 m above present sea level. Paleo-shorelines date back between 4800 and 270 years BP at respective distances of 5 km to 670 m from the active shoreline. The spatial position of the palaeo-coastlines demonstrates a fall in local sea level of around 15 m during the last ~4800 years. Event deposits attesting to high-energy waves have been studied in low-lying coast by study of Over-washed sandy and shelly marine sediment and on the rocky shore by study of displaced boulder deposits. We applied hydrologic models to estimate the height and inundation distance of exceptional waves. Our results demonstrate that no known or probable storm is capable of detaching and transporting the boulders. Tsunami waves 4 m in height are enough to transport the boulders. We conclude the Makran coast has archived evidence of palaeo-tsunami events generated in the Makran subduction zone
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Ratcliff, Jay. „Abrupt Climate Change and Storm Surge Impacts in Coastal Louisiana in 2050“. ScholarWorks@UNO, 2008. http://scholarworks.uno.edu/td/879.
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The most critical hazards impacting the world today are the affects of climate change and global warming. Scientists have been studying the Earth's climate for centuries and have come to agreement that our climate is changing, and has changed, many times abruptly over the history of our planet. This research focuses on the impacts of global warming related to increased hurricane intensities and their surge responses along the coast of the State of Louisiana. Surge responses are quantified for storms that could potentially occur under present climate but 50 years into the future on a coast subjected to current erosion and local subsidence effects. Analyses of projected hurricane intensities influenced by an increase in sea surface temperatures (SSTs) are performed. Intensities of these storms are projected to increase by 5% per degree of increase in SSTs. A small suite of these storms influenced by global warming and potentially realized by abrupt climate changes are modeled. Simulations of these storms are executed using a storm surge model. The surges produced by these storms are significantly higher than surges produced by presentday storms. These surges are then compared to existing surge frequency distributions along the Louisiana coast.
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André, Camille. „Analyse des dommages liés aux submersions marines et évaluation des coûts induits aux habitations à partir de données d'assurance : perspectives apportées par les tempêtes Johanna (2008) et Xynthia (2010)“. Phd thesis, Université de Bretagne occidentale - Brest, 2013. http://tel.archives-ouvertes.fr/tel-00961315.
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Cette thèse de doctorat porte sur l'analyse des dommages et sur l'évaluation des coûts induits sur les habitations par les submersions marines. L'étude se base sur les données d'assurance de deux évènements récents ayant touché la France et causé des submersions sur les côtes bretonnes et atlantiques : les tempêtes Johanna (mars 2008) et Xynthia (février 2010).Dans un premier temps, l'analyse des données d'expertise et d'indemnisation d'assurance, en lien avec celle des paramètres de l'aléa et des enjeux exposés, a eu pour but la meilleure compréhension des différents types de dommages, et l'explication des coûts observés. En parallèle, un travail de modélisation de l'aléa a été réalisé à une échelle régionale, afin de déterminer des indicateurs des forçages météo-marins, et à une échelle locale, afin de préciser les processus d'endommagement sur les sites étudiés pour les deux tempêtes. La caractérisation de la vulnérabilité et de la valeur des enjeux (coûts de construction) a été menée à l'aide de différents paramètres issus de bases de données nationales (INSEE et IGN) et de campagnes de terrain.Dans un second temps, les informations recueillies ont permis la construction de modèles empiriques de prédiction du coût des dommages aux habitations spécifiques à l'aléa submersion marine, outils aujourd'hui inexistants en France. Les différents types de modèles testés sont basés sur des approches statistiques univariées (fonctions d'endommagement) et multivariées. L'apport des données d'assurance à la réalisation de tels modèles est discuté, et des recommandations ainsi que des perspectives de recherche sont évoquées, afin de rendre ces modèles opérationnels et d'augmenter leur capacité de prédiction des coûts d'évènements catastrophiques futurs.
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Brownell, Andrew. „Morphological Changes Associated with Tropical Storm Debby in the Vicinity of Two Tidal Inlets, John's Pass and Blind Pass, West-Central Florida“. Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4869.
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Tropical Storm Debby affected the Gulf coast of Florida in late June, 2012. The storm's southerly approach temporarily reversed the annual net southward longshore sediment transport. The energetic conditions associated with Tropical Storm Debby can be seen in the wind, wave and tidal measurements taken from both onshore and offshore weather stations around the dual tidal inlets system of John's Pass and Blind Pass, approximately 25 kilometers north of the mouth of Tampa Bay. The energetic and persistent southerly forcing, in addition to higher storm induced water levels and wave heights, resulted in atypical beach erosion and sediment deposition on the ebb tidal deltas of the two inlets and the surrounding beaches. The John's Pass ebb delta gained 60,000 cubic meters of sediment and the Blind Pass ebb delta gained 9,000 cubic meters as a result of the storm. Shoreline position, beach profile and offshore bathymetric surveys conducted before and after Tropical Storm Debby illustrate the changes in the coastal morphology such as the development of an offshore bar south of Blind Pass and erosion of the dry beach north and south of John's Pass. The Coastal Modeling System (CMS) was used to simulate wave and tide-driven current fields during the passage of the storm. The modeled wave field qualitatively illustrated the shadowing effect of the Tampa Bay ebb delta in reducing the southerly approaching storm wave energy arriving at the study area during the storm. The tidal flow patterns through the inlets and over the ebb tidal deltas were considerably different during the storm, as compared to normal tidal cycles.
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Restrepo, Ana Catalina. „Analysis of storm surge impacts on transportation systems in the Georgia coastal area“. Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42897.
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Many Climate Scientists believe that global warming will produce more extreme weather events such as tropical storms, hurricanes, intense rainfall, and flooding. These events are considered to be the most catastrophic natural events for transportation systems especially in coastal areas. Due to the severe damage from storm surge and flooding. Evaluating the magnitude of possible storm surges and their impacts on transportation systems in coastal areas is fundamental to developing adaptation plans and impact assessments to mitigate the damage.
This thesis focuses on existing transportation systems in the Georgia coastal area that could be affected by several storm surges. An existing storm surge model is used to estimate the storm surges and the surge heights based on the category, direction, and forward speed of a storm. The ground elevation of the ports, interstates, state roads, railroads, and the principal airports on the Georgia coast are identified through a GIS analysis using the national elevation data set. Having the storm surge elevation and the elevation of the existing infrastructure, a GIS study is performed to identify those parts of the transportation system that will be affected by each type of storm giving results such as the length or sections of transportation assets under or above the surge elevation. A literature review of storm surge, rising sea levels, and their impacts on coastal bridges, roads, airports, ports, and railroads is presented in the thesis. Also, a description of the software used to analyze and estimate the impacts of climate change on transportation systems is described.
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Xiao, Hong. „Numerical simulation of dynamic wave force on coastal structures under extreme storm surge conditions“. Tallahassee, Florida : Florida State University, 2009. http://etd.lib.fsu.edu/theses/available/etd-07142009-130212/.
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Thesis (Ph. D.)--Florida State University, 2009.Advisor: Wenrui Huang, Florida State University, College of Engineering, Dept. of Civil and Environmental Engineering. Title and description from dissertation home page (viewed on Oct. 20, 2009). Document formatted into pages; contains xv, 134 pages. Includes bibliographical references.
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McCall, Robert Timothy. „Process-based modelling of storm impacts on gravel coasts“. Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3929.
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Gravel beaches and barriers occur on many high-latitude, wave-dominated coasts across the world. Due to their natural ability to dissipate large amounts of wave energy, gravel coasts are widely regarded as an effective and sustainable form of coastal defence. However, during extreme events waves may overtop, overwash, and even lower, the crest of the gravel beach, flooding the hinterland. In the evaluation of the safety of gravel coasts against flooding, coastal managers currently rely on models that have been shown in previous studies to be inaccurate. The research in this thesis attempts to improve the current predictive capacity of gravel beach storm response by developing a new process-based model to simulate storm impacts on gravel coasts. The numerical model developed in this thesis, called XBeach-G, is a morphodynamic, depth-averaged, cross-shore profile model, based on the XBeach model for sandy coasts (Roelvink et al., 2009). The model simulates the morphological response of gravel beaches and barriers to storms by solving: (1) intra-wave flow and surface elevation variations using a non-hydrostatic extension of the non-linear shallow water equations; (2) groundwater processes, including infiltration and exfiltration, using a Darcy-Forchheimer-type model; and (3) bed load transport of gravel using a modification of the Van Rijn (2007a) bed load transport equation to include flow acceleration effects, which are shown to be significant on coarse-grained beaches. The model is extensively validated for hydrodynamics, groundwater dynamics and morphodynamics using detailed data collected in physical model experiments, as well as data collected in the field on four natural gravel beaches in the UK and one in France. Validation results show that the model has high quantitative skill in simulating observed hydrodynamics on gravel beaches across a wide range of forcing conditions, in particular with regard to wave transformation, wave run-up and wave overtopping. Spatial and temporal variations in groundwater head are shown to be well represented in the model through comparison to data recorded in a physical model experiment. Validation of the morphodynamic component of XBeach-G shows that the model has high model skill (median BSS 0.75) in simulating storm impacts on five gravel beaches during ten storm events, with observed morphodynamic response ranging from berm-building to barrier rollover. The model is used to investigate hydrodynamic processes on gravel beaches during storms, where it is found that incident-band variance is elemental in the generation of wave run-up on gravel beaches. Furthermore, simulations of wave run-up during high-energy wave events show a distinct disparity between run-up predicted by empirical relations based on the Iribarren parameter and wave steepness, and run-up predicted by XBeach-G, where predictions by the empirical relations substantially underestimate observed wave run-up. Groundwater processes are shown, by means of sensitivity simulations, to strongly affect the morphodynamic response of gravel beaches and barriers to storms. The research in this thesis supports the hypothesis that infiltration in the swash is a key driver for the berm-building response of gravel beaches and helps to reduce erosion of the upper beach during storms. Through model simulations on a schematic gravel barrier it is shown that groundwater processes effectively increases the capacity of gravel barriers to withstand storms with 1-3 m higher surge levels than if groundwater processes did not occur. Reducing the width of a barrier leads to a lowering of this capacity, thereby reducing the resilience of the barrier to extreme storm events. Despite its strong influence on gravel beach morphodynamics, it is found that infiltration plays a relatively small role on wave run-up levels on most natural gravel beaches (median R 2% run-up level reduction of 8%). Application of the model in validation simulations and sensitivity simulations in this thesis, as well as in storm hindcast simulations discussed by McCall et al. (2013) shows the value of using the process-based XBeach-G model in coastal flooding analysis over the use of empirical tools. While no model can be considered entirely accurate, application of XBeach-G in all hindcast overwash simulations has lead to reasonable estimates of overtopping discharge and of morphological change, which is a significant improvement over the frequently substantial errors of the empirical tool designed for this purpose.
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Hartt, Maxwell. „Geographic Information Systems and System Dynamics - Modelling the Impacts of Storm Damage on Coastal Communities“. Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19817.
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A spatial-temporal model is developed for modelling the impacts of simulated coastal zone storm surge and flooding using a combined spatial mapping and system dynamics approach. By coupling geographic information systems (GIS) and system dynamics, the interconnecting components of the spatial-temporal model are used with limited historical data to evaluate storm damage. Overlapping cumulative effects layers in GIS (ArcMap) are used for describing the coastal community’s profile, and a system dynamics feedback model (STELLA) is developed to define the interconnecting component relationships of the community. The component-wise changes to the physical environment, community infrastructure, and socioeconomic resources from the storm surge and seal level rise are examined. These changes are used to assess the impacts of the community system as a whole. For the purpose of illustrating this model, the research is applied specifically to the case of Charlottetown, Prince Edward Island, Canada, a vulnerable coastal city subject to considerable impacts from pending sea level rise and more frequent severe storm surge attributed to the changing climate in the coastal zone.
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Kim, Soo-Youl. „Effect of large tidal variation on storm surge in the western coastal sea of Korea“. 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/77799.
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Carpenter, Carl A. „Mathematical model and computer algorithm for tracking coastal storm cells for short term tactical forecasts“. Thesis, Monterey, California : Naval Postgraduate School, 1992. http://handle.dtic.mil/100.2/ADA257110.
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Thesis (M.S. in Applied Science)--Naval Postgraduate School, Sept. 1992.Thesis Advisors: Wash, Carlyle H. ; Pastore, Michael J. "September, 1992." Description based on title screen as viewed on April 16, 2009. Includes bibliographical references (p. 90-92). Also available in print.
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Lee, Michael. „Rapid Prediction of Tsunamis and Storm Surges Using Machine Learning“. Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103154.
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Tsunami and storm surge are two of the main destructive and costly natural hazards faced by coastal communities around the world. To enhance coastal resilience and to develop effective risk management strategies, accurate and efficient tsunami and storm surge prediction models are needed. However, existing physics-based numerical models have the disadvantage of being difficult to satisfy both accuracy and efficiency at the same time. In this dissertation, several surrogate models are developed using statistical and machine learning techniques that can rapidly predict a tsunami and storm surge without substantial loss of accuracy, with respect to high-fidelity physics-based models. First, a tsunami run-up response function (TRRF) model is developed that can rapidly predict a tsunami run-up distribution from earthquake fault parameters. This new surrogate modeling approach reduces the number of simulations required to build a surrogate model by separately modeling the leading order contribution and the residual part of the tsunami run-up distribution. Secondly, a TRRF-based inversion (TRRF-INV) model is developed that can infer a tsunami source and its impact from tsunami run-up records. Since this new tsunami inversion model is based on the TRRF model, it can perform a large number of tsunami forward simulations in tsunami inversion modeling, which is impossible with physics-based models. And lastly, a one-dimensional convolutional neural network combined with principal component analysis and k-means clustering (C1PKNet) model is developed that can rapidly predict the peak storm surge from tropical cyclone track time series. Because the C1PKNet model uses the tropical cyclone track time series, it has the advantage of being able to predict more diverse tropical cyclone scenarios than the existing surrogate models that rely on a tropical cyclone condition at one moment (usually at or near landfall). The surrogate models developed in this dissertation have the potential to save lives, mitigate coastal hazard damage, and promote resilient coastal communities.Doctor of Philosophy
Tsunami and storm surge can cause extensive damage to coastal communities; to reduce this damage, accurate and fast computer models are needed that can predict the water level change caused by these coastal hazards. The problem is that existing physics-based computer models are either accurate but slow or less accurate but fast. In this dissertation, three new computer models are developed using statistical and machine learning techniques that can rapidly predict a tsunami and storm surge without substantial loss of accuracy compared to the accurate physics-based computer models. Three computer models are as follows: (1) A computer model that can rapidly predict the maximum ground elevation wetted by the tsunami along the coastline from earthquake information, (2) A computer model that can reversely predict a tsunami source and its impact from the observations of the maximum ground elevation wetted by the tsunami, (3) A computer model that can rapidly predict peak storm surges across a wide range of coastal areas from the tropical cyclone's track position over time. These new computer models have the potential to improve forecasting capabilities, advance understanding of historical tsunami and storm surge events, and lead to better preparedness plans for possible future tsunamis and storm surges.
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Michaud, Héloïse. „Impacts des vagues sur les courants marins : Modélisation multi-échelle de la plage au plateau continental“. Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2011. http://tel.archives-ouvertes.fr/tel-00680405.
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Le littoral sableux du Languedoc-Roussillon est un système vulnérable aux risques d'érosion et de submersion. Ces aléas sont liés à la conjonction des facteurs naturels que sont les vagues, vent, élévation du niveau de la mer et apports sédimentaires et sont donc aggravés en période de tempête. En vue d'une gestion des risques, une meilleure connaissance des phénomènes hydrodynamiques de l'échelle littorale à l'échelle côtière est essentielle. Ce travail a conduit à la réalisation d'une plateforme de modélisation numérique composée du modèle de circulation océanique 3D Symphonie, traditionnellement dédié aux échelles régionales et côtières, qui a été modifié pour inclure le forçage par les vagues, modélisées par les modèles Wavewatch III ou Swan, et ainsi étendre sa validité au littoral. Le modèle a été testé sur des cas académiques littoraux. Des mesures sur la plage à double barres de Sète pendant l'hiver 2008-2009, ont également servi à parfaire le modèle qui reproduit ainsi avec succès les caractéristiques des courants en zone littorale : la dérive, les courants sagittaux sur des bathymétries plus complexes et les profils verticaux des courants. Pour valider le modèle à des échelles plus côtières, nous avons confronté ses résultats à des mesures réalisées pendant une tempête hivernale en 2004 aux alentours de l'embouchure de la Têt, mais également sur des tempêtes de 2007 et 2008 dans le Golfe d'Aigues-Mortes. Les courants sont globalement bien reproduits. Les zones d'action des vagues semblent limitées aux zones de profondeur inférieure à 30 m. Notre modèle autorise une reproduction correcte des courants à toutes les échelles et sa nature 3D permet un calcul plus précis de la tension de cisaillement de fond et du courant près du fond, responsables respectivement de la mise en suspension et de l'advection des sédiments.
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Denlinger, Emily E. „Contribution of Hurricane Ike Storm Surge Sedimentation to Long-term Aggradation of Coastal Marshes in Southeastern Texas and Southwestern Louisiana“. Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc500114/.
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Coastal marshes and wetlands are vital natural resources that offer habitats for plants and animals, serve as ecological filtration for soil and water pollutants, and act as protection for coastlines. Fishing, both commercial and sport, has a large economic impact in the study area – the Gulf Coast between Galveston Bay, TX and Oak Grove, LA. The objective of this research was to determine the contribution of Hurricane Ike storm surge sedimentation to long-term marsh aggradation in Texas and Louisiana coastal marshes. The research hypothesized that Hurricane Ike’s storm surge deposit would be equal to decades and possibly even a century’s worth of the average annual non-storm sedimentation. A quantitative field study was performed. The storm surge deposit was examined in a series of 15 transects covering approximately 180 km east of Hurricane Ike’s landfall. Nine of the 15 transects were re-surveyed a year after the initial measurement to assess preservation of the deposit. The results demonstrate that Hurricane Ike contributed between 10 to 135 years’ worth of sediment to coastal marshes along the coasts of Texas and Louisiana, and the sediment deposits have been preserved for over two years.
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Wolff, Victoria H. „Storm smart planning for adaptation to sea level rise : addressing coastal flood risk in East Boston“. Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50122.
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Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2009.Includes bibliographical references (p. 67-69).
Regardless of how well we implement sustainability plans, now and in the future, the weight of scientific evidence indicates that mean sea level will continue to rise at an increasing rate over the next century. Thus, coastal lands and development lie in a precarious position, increasingly vulnerable to flood damage brought by storm surges and extreme weather events. In order to avoid disastrous losses of property, life, ecological health and social wellbeing, our cities and regions must quickly implement adaptation plans that consider plausible climate models. Coastal risk can be managed through rigid protections, soft landscape solutions, and land use decisions and regulations. In developing and implementing adaptation plans, it is important to understand the options and their applicability to different site contexts. Experts warn that today's once-in-a century flood will likely occur every two or three years by 2050!' However, Boston, like many other U.S. coastal cities, is in the early stages of devising adaptation plans that seek to reduce coastal flood risk from sea level rise. As implementation of adaptation plans may take several years or decades, Boston should act quickly to strategically consider its options. This thesis examines the effectiveness of different planning approaches to hazard mitigation in urban coastal areas and applies them to at-risk sites in East Boston under coastal flood scenarios for the years 2050 and 2100. Two sites in East Boston, one with a soft edge and one with a hard edge, create two distinct urban landscapes for design solutions.
(cont.) A menu of planning solutions that has been collected from a review of the literature and best practices is then used to inform design solutions to these problems. By applying contemporary predictions for sea level rise and the problem-specific expertise of coastal management to the site-specific realm of land use planning, I hope to provide a precedent and method for planners, particularly in the Boston area, to seriously incorporate sea level rise predictions into community discussions, regulations, and comprehensive plan making.
by Victoria H. Wolff.
M.C.P.
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Hodge, Joshua B. „Hurricane Storm Surge Sedimentation on the McFaddin National Wildlife Refuge, Texas: Implications for Coastal Marsh Aggradation“. Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849751/.
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This study uses the storm surge sediment beds deposited by Hurricanes Audrey (1957), Carla (1961), Rita (2005) and Ike (2008) to investigate spatial and temporal changes in sedimentation rates on the McFaddin National Wildlife Refuge in Southeast Texas. Fourteen sediment cores were collected along a transect extending from 90 to 1230 meters inland from the Gulf Coast. Storm-surge-deposited sediment beds were identified by texture, organic content, carbonate content, the presence of marine microfossils, and Cesium-137 dating. The hurricane-derived sediment beds are marker horizons that facilitate assessment of marsh sedimentation rates from nearshore to inland locations as well as over decadal to annual timescales. Near the shore, on a Hurricane Ike washover fan, where hurricane-derived sedimentation has increased elevation by up to 0.68 m since 2005, there was no measurable marsh sedimentation in the period 2008-2014. Farther inland, at lower elevations, sedimentation for the period 2008-2014 averaged 0.36 cm per year. The reduction in sedimentation in the period 2008-2014 on the nearshore part of the marsh is likely due to reduced flooding in response to increased elevation from hurricane storm surge sediment deposition. These results provide valuable knowledge about the sedimentary response of coastal marshes subject to storm surge deposition and useful guidance to public policy aimed at combating the effects of sea level rise on coastal marshes along the Gulf of Mexico.
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Tate, Anthony Scott. „Short-term response of coastal vegetation in northwestern Florida to experimental storm surge and wrack application“. OpenSIUC, 2010. https://opensiuc.lib.siu.edu/theses/375.
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Climate change with concomitant increases in global sea temperatures, rising sea levels, and shifts in weather patterns may affect the frequency and intensity of tropical storms. Disturbances associated with hurricanes, such as storm surge and wrack deposition, may play crucial roles in allowing coastal species to migrate inland in response to rising sea levels. An experiment was conducted to examine changes in plant community structure in relation to simulated storm surge and wrack deposition. Vegetation plots were established in four community types (brackish marsh, freshwater marsh, wetland forest, and pine savanna) along an estuarine gradient in northwest Florida. Soil conductivity (µS) was assessed pre- and post-treatment application, as well as light attenuation (PAR) at ground level. Percent cover of each species per plot was determined prior to and after treatment applications. Post-treatment soil conductivity was significantly higher than pre-treatment values in the wetland forest and pine savanna; however, pre- and post- soil conductivity did not differ in brackish and freshwater marshes. The semi-saline conditions of the brackish marsh and frequent flooding in the freshwater marsh likely contributed to non-significant differences in soil conductivity. In brackish marsh, freshwater marsh, and pine savanna communities, light at ground level was highest for the storm surge treatment, while control and wrack plots had intermediate and low light at ground levels, respectively. The storm surge treatment reduced cover of some species, causing browning and eventual loss of leaves, particularly in pine savanna species. Wrack deposition resulted in substantial mortality to underlying vegetation and reduced species richness in all communities. New recruits into plots with wrack deposits, such as saw palmetto, suggest that these disturbances may facilitate community reassembly. This research should provide insight into how coastal plant communities respond to climate change-related shifts in tropical storm regimes.
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Liu, Zhuo. „Development of Large-Scale Unstructured Grid Storm Surge and Sub-Grid Inundation Models for Coastal Applications“. W&M ScholarWorks, 2018. https://scholarworks.wm.edu/etd/1550153651.
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Storm surge and inundation induced by hurricanes and nor'easters pose a profound threat to coastal communities and ecosystems. These storm events with powerful winds, heavy precipitation, and strong wind waves can lead to major flooding for cities along U.S. Coasts. Recent examples of Hurricane Irene (2011) in North Carolina and Virginia and Hurricane Sandy (2012) in New York City not only demonstrated the immense destructive power by the storms, but also revealed the obvious, crucial need for improved forecasting of storm tide and inundation. in part I, a large-scale unstructured-grid 3-D barotropic storm tide model SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model) is developed with open ocean boundary aligning along the 60-degree West longitude to catch most Atlantic hurricanes that may make landfall along U.S. East and Gulf Coasts. The model, driven by high-resolution NAM (North America Mesoscale) and ECMWF (European Centre for Medium-Range Weather Forecasts) atmospheric fields, was coupled with Wind Wave Model (WWMIII) to account for wave effects, and used to simulate storm surge in 3-D barotropic mode rather than the traditional 2-D vertical average mode. For Hurricane Sandy, the fully coupled wave-current interaction 3-D model using ECMWF atmospheric forcing performs the best. The storm tide results match well with observation at all nine NOAA tidal gauges along the East Coast. The maximum total water level in New York City, is accurately simulated with absolute error of amplitude less than 8 cm, and timing difference within 10 minutes. The scenarios of "2-D" versus "3-D" and "with" versus "without" wind wave model were compared and discussed in details. Overall, the wave contribution amounts to 5-10% of surge elevation during the event. Also, the large-scale model with similar setup is applied to hindcasting storm tide during Hurricane Irene and the results are excellent when compared with observed water level along Southeast Coast and inside Chesapeake Bay. in part II, a high-resolution sub-grid inundation model ELCIRC-sub (Eulerian-Lagrangian CIRCulation) was developed from the original finite-volume-based ELCIRC model. It utilized the sub-grid method for imbedding high-resolution topography/bathymetry data into the traditional model grid and delivering the inundation simulation on the street level scale. The ELCIRC-sub contains an efficient non-linear solver to increase the accuracy and was executed in the MPI (Message Passing Interface) parallel computing platform to vastly enlarge the water shed coverage, and to expand the numbers of sub-grids allowed. The ELCIRC-sub is first validated with a wetting/drying analytic solution and then applied in New York City for Hurricane Sandy (2012). Temporal comparisons with NOAA and USGS water level gauges showed excellent performance with an average error on the order of 10 cm. It accurately captured the highest surge (during Hurricane Sandy) at Kings Point on both maximum surge height and the explosive surge profile. Spatial comparisons of the modeled peak water level at 80 locations around New York City showed an average error less than 13 cm. The modeled maximum modeled inundation extent also matched well with 80% of the FEMA flooding map. in terms of robustness and efficiency for practical application, ELCIRC-sub surpasses the prototype model UnTRIM2.
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Autret, Ronan. „Etude zonale des dynamiques des dépôts de tempête de sommet de falaise : de la Bretagne à l'Islande“. Thesis, Brest, 2018. http://www.theses.fr/2018BRES0014/document.
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Les blocs supratidaux de tempête que l’on trouve au sommet des falaises vont à l’encontre du schéma classique qui décrit l’érosion des falaises. Généralement, le recul des escarpements rocheux se fait au rythme des écroulements gravitaires dont les éléments s’accumulent en pied de falaise, la mer intervenant surtout dans le déblaiement des matériaux accumulés à la base des versants. Dans le cadre de cette thèse, nous étudions les processus d’érosion qui se traduisent par l’accumulation de dépôts grossiers en sommet de falaise. Nous montrons qu’au cours des événements météo-océaniques extrêmes, les effets combinés d’un niveau d’eau à la côte particulièrement élevé et du déferlement de vagues de haute énergie peuvent se manifester localement par l’arrachement et le transport de blocs littoraux supratidaux. Leur masse peut dépasser plusieurs dizaines de tonnes, et leur remaniement peut se faire à plusieurs mètres au-dessus du niveau des hautes mers. De même, leur déplacement peut atteindre plusieurs dizaines à centaines de mètres à l’intérieur des terres. A l’heure où l’on s’interroge sur une possible intensification et/ou augmentation de la fréquence des événements météoocéaniques extrêmes, la dynamique morphosédimentaire de ces blocs littoraux apparait comme un indicateur géomorphologique pertinent pour l’évaluation de ces changements. Un suivi topo-morphologique, sédimentaire et hydrodynamique pluriannuel a été réalisé sur plusieurs sites bretons (Finistère) et islandais (presqu’île de Reykjanes). Les résultats de ce suivi ont montré des schémas de circulation hydro-sédimentaire bien distincts suivant le contexte morphodynamique. Si dans certains cas, les processus transversaux prédominent dans l’édification et le remaniement de ces accumulations, dans d’autres cas, la composante longitudinale contrôle une partie des transferts à la côte. Les processus d’arrachement et de transport de blocs sont concomitants, et peuvent se produire à plusieurs reprises au cours d’un même événement et/ou hiver, y compris pendant les tempêtes d’intensité modérée. L’étude rétrospective des conditions météo-océaniques favorables au déclenchement de ces processus sur les 70 dernières années montre une forte variabilité interannuelle, sans périodicité ni tendance particulière. Cette variabilité est commandée par la dynamique atmosphérique WEPA aux latitudes tempérées de la Bretagne, et par l’ONA aux latitudes sub-polaires de l’IslandeCliff-top storm deposits (CTSDs) corresponding to boulder accumulations are locally identified along the North–Atlantic coasts (Iceland, Scotland, Ireland, France), where they are defined as one of the most remarkable morphosedimentary storm signature. Their study aims to understand the effects of high energy storm waves on these specific rocky cliffed coasts facing deep–water and exposed to energetic wave–climates. Recent works demonstrated the role of high energy storm waves (instead of tsunami waves) in transporting and supplying in boulders these deposits. In the context of climate change, and the possible intensification and/or increase in frequency of extreme meteo-oceanic events, CTSDs appears as a potential geomorphological indicator for the monitoring of these changes on high-energy rocky coasts. This thesis propose an analysis of their morphosedimentary dynamics based on field observations realized at high (64°N) and medium (48°N) latitude of the Northeast Atlantic basin. In the present work, their morphosedimentary dynamics have been annually surveyed using low altitude aerial photographs. Results shows two different hydrosedimentary circulation patterns of CTSDs. The first one concerns inland boulder transport, corresponding the directions of the incident waves. This pattern confirms the contemporary edification of ridges. The second one concerns longshore or seaward boulder transport, describing a longitudinal drift of this sedimentary material.The processes of quarrying and transport of CTSDs are concomitant and can repeatedly occur during one single event and/or winter, including during regular storms. The retrospective analysis of sea weather forecast favorable to these processes during the last 70 years showed an infraannual frequency with no particular periodicity nor tendency
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Grime, David. „The effect of storms on chenier plains : the Shoal Bay chenier plain“. Thesis, The University of Wollongong, 1991. http://hdl.handle.net/1885/281556.
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The southern coast of Shoal Bay, near Darwin, Northern Territory is a
small, well vegetated chenier plain. Chenier plains are prograded coastal
mudflats that support a number of long narrow ridges formed from sand and
shell debris, that run parallel to the coast. Mangrove communities on the
mudflat occur in zones, also parallel to the coastline, indicating species
preference for protection, depth and duration of tidal inundation and level of
salinity.
Chenier plains are thought to be formed through fluctuations in
sediment supply resulting in, episodic coastal progradation, and coastal
erosion and ridge deposition above the level of high tide. Some of the
literature suggests that progradation may be aided by the seaward
mangrove zones trapping sediments, while erosion of the mudflats and
subsequent ridge formation can be attributed to high energy storm activity,
such as that of a tropical cyclone.
This study is involved with examining the recent history of the chenier
plain at Shoal Bay, in regard to the effects of cyclone Tracy, which struck the
area on December 25, 1974. The storm devastated large areas of the central
mangrove zones, those of Bruguiera, Ceriops and Rhizophora, mostly by
windthrow. The seaward mangrove zones, such as that of Avicennia, and
the landforms were mostly unaffected by the storm winds, and the storm
surge associated with the cyclone was relatively small, as it occurred in
conjunction with a neap high tide.
The overall effects of cyclone Tracy on the chenier plain were much
less than those described for other storms in the literature. All of the changes
that have occurred on the Shoal Bay chenier plain over the period examined
can be explained by normal wave and tide action, and do not require a high
energy event.
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Bedington, Michael. „Drift modelling of marine mammal carcases in coastal waters“. Thesis, University of the Highlands and Islands, 2015. https://pure.uhi.ac.uk/portal/en/studentthesis/drift-modelling-of-marine-mammal-carcases-in-coastal-waters(c1165a29-6c4c-4b6f-b079-e39d4ff164e5).html.
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A floating object's drift is governed by its buoyancy, shape, and the wind, waves and currents it experiences. Here, I develop a drift modelling framework for marine mammal carcases in coastal waters. The resulting models were run forwards and backwards in time to provide insights into strategies for environmental monitoring under two scenarios. The first explored the beach search options for carcases resulting from potentially fatal collisions between tidal-stream turbines and marine mammals. The second applied the reverse problem for known-location mass strandings to highlight potential at-sea mortality sites. The drift properties of carcase-like objects were assessed in at-sea experiments. Wave transport was found to be greater than Stokes drift alone and in a complex coastal area could not be represented by a downwind multiplier as many previous models have assumed. A high resolution unstructured grid wave model was set up to complement existing wind and current models for the West Coast of Scotland, and these components were combined to build a carcase drift model. In the forward case, from tidal turbine locations, the drift model showed a wide spread of potential stranding sites, suggesting monitoring a limited number of beaches is unlikely to be fruitful. However, selecting beaches in response to immediate wind direction would improve efficiency. Stranding locations alone can only provide evidence of turbine interactions if the number of animals affected is large. In the reverse case, when applied to a mass stranding in Chile, the drift model showed the ability to exclude areas of origin, even though it could not pinpoint an exact mortality site. This work advances understanding of wave transport of surface floating objects, of carcase drift modelling, and of the feasibility of strandings monitoring. The decomposition rate of carcases is a source of uncertainty in the model where further work should be undertaken.
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Boudreau, Danielle L. „Fifty Years of Weathering the Storm: Are the Louisiana Gulf Coastal Parishes Prepared for Another Major Hurricane?“ ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1902.
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This study examines ten major storms that have affected Louisiana in the last fifty years, beginning with Hurricane Betsy in 1965. The goal is to determine if the nine coastal parishes are prepared adequately for another major hurricane impact. It examines storms that have affected the state physically, in terms of property and ecological damages. It also considers storms that provided non-physical influences, by way of mitigation policy changes and social, economical, ecological, and political policy alterations. The main focus is on the transformations, if any, of social vulnerability in light of emergency preparedness in the areas impacted, particularly along the Louisiana coast. I argue that, while the State has come a long way, Louisiana is not currently prepared adequately to handle another major storm by 2015. Furthermore, I offer recommendations for improvement in preparedness measures for the future.
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Chu, Tai-wai David. „Oceanic hazard risk in low-lying areas of Hong Kong“. Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38849355.
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Chan, Yuen-man, und 陳苑雯. „Field and laboratory studies of E. coli decay rate at a coastal beach with reference to storm events“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B4598864X.
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Doughty, S. David. „The influence of inlet modifications, geologic framework, and storms on the recent evolution of Masonboro Island, NC /“. Electronic version (PDF), 2006. http://dl.uncw.edu/etd/2006/doughtys/sdaviddoughty.pdf.
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Fallon, Kathleen Michelle. „Rip Current Formation and Beach Safety Implications for Several U.S. Atlantic Coast Beach Areas“. FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3382.
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This dissertation combines seemingly different studies, which work together to describe the physical characteristics of rip current development and associated social implications at several locations. These fast-moving, concentrated flows of water travel offshore and can be found on any beach with sufficient wave action. Any event of increased wave steepness will erode a large quantity of sediment from the beach. The material deposited offshore eventually makes its way back; during this process, ocean water becomes trapped behind a shore-attached bar resulting in a ridge-and-runnel. These formations are seen at East Hampton, where rip-like currents form as concentrated water drains from the runnel through a breach in the ridge. Camera images from 2010-2016 captured ridge-and-runnel formations and the ensuing currents. These newly described rips behave similarly to bar-gaps; however, they are not directly related to wave action. Coastal scientists consider rip currents to be the number one hazard at most beaches. In Palm Beach County, two traditional rip types were studied: bar-gap and structurally-controlled. Lifeguard incident reports from 2011-2016 were used to correlate wind speeds and wave heights to rip related rescues at three beaches. This research was undertaken in an effort to determine under what conditions most beachgoers become caught in this hazard. Rip currents were seen to be the most dangerous to bathers on days with moderate wind and wave activity. The same beach states that lead to the strongest rips also tend to keep beachgoers from entering the ocean. A social survey at Miami Beach, from 2011 to 2012, quantified beachgoer’s rip knowledge and their recognition of hazards. A significant portion of the respondents showed insufficient knowledge, which indicated they are at-risk of being caught or drowning in a rip current. Frequent exposure to the beach, maturation, and residency were identified as the main contributors to one’s literacy whereas education was the only variable that influenced a beachgoer’s visual recognition of hazard. The information gathered by these surveys can aid in creating better rip current awareness campaigns targeted to demographics that were determined as the most at-risk. An understanding of the physical and social science of rip currents can mitigate the impact of these beach hazards.
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Elko, Nicole A. „Storm-influenced sediment transport gradients on a nourished beach“. [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001576.
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KARUZA, ANA. „BIOGEOCHEMICAL CYCLE OF ORGANIC MATTER IN COASTAL MARINE ENVIRONMENT: THE ROLE OF VIRUSES IN CONTROLLING BACTERIAL PROLIFERATION“. Doctoral thesis, Università degli studi di Trieste, 2006. http://thesis2.sba.units.it/store/handle/item/13296.
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2003/2004Il principale obiettivo della ricerca è stato quello di acquisire le conoscenze relative al ruolo del virioplancton nelle catene trofiche e nei flussi biogeochimici. La prima parte dello studio è stata dedicata alla distribuzione spazio-temporale del virioplankton nella parte più settentrionale del Mare Adriatico. In una stazione costiera del Golfo di Trieste sono stati effettuati dei campionamenti a frequenza bisettimanale/mensile a diverse quote lungo la colonna d'acqua, per implementare la serie temporale dei dati storici di abbondanza virale disponibili presso il Laboratorio di Biologia Marina relativi ad un monitoraggio iniziato nel 1998 nella stessa stazione. L'acquisizione della serie storica del virioplancton è stata necessaria per poter definire lo stato di 'normalità' del sistema relativo a questa componente allo scopo di poter rilevare eventuali 'alterazioni, tra le quali anche la formazione di aggregati mucillaginosi che, con intensità particolarmente forte sporadicamente interessa il bacino, con gravi conseguenze sul turismo ed attività di pesca. L'analisi della distribuzione del virioplancton su un reticolo spaziale più ampio, effettuata durante 3 campagne oceanografiche stagionali nel 2004 nel bacino adriatico settentrionale, in collaborazione con il progetto Interreg Veneto, ha consentito di valutare l'effetto della presenza di forti gradienti chimico-fisici determinati dall'input del fiume Po, sulla componente virale e sul funzionamento del circuito microbico. In questo studio, il bacino settentrionale dell'Adriatico, con le sue caratteristiche geografiche ed idrologiche ha giocato da ottimo laboratorio naturale, in cui l'introduzione di una forzante ha fortemente condizionato la distribuzione delle componenti microbiche ed la loro interazione, per cui si è confermato molto adatto agli studi 'causa-effetto'. I risultati ottenuti hanno evidenziato come le informazioni ottenute da queste diverse strategie di campionamento non si sovrappongono, ma si implementano, consentendo di acquisire nuove conoscenze relative al funzionamento del circuito microbico nell'Adriatico settentrionale, ed in particolare sulle interazioni tra i virus ed i loro ospiti più comuni. L'uso dei principali indici utilizzati in ecologia microbica per valutare il rapporto tra i virus ed i loro ospiti quali il VBR (Virus-to-Bacterium Ratio) ed il VBP (Virus-to- Bacterium Product), ha messo in evidenza una alterazione delle interazioni virus-batteri nel periodo di comparsa delle mucillagini (primavera-estate 2000) che ha confermato come una spinta lisi virale abbia condizionato lo sviluppo delle poche specie batteriche presenti. Sperimentalmente, invece, è stata valutata l'entità del processo di lisi virale che oltre a determinare mortalità batterica influenza in modo significativo il flusso di carbonio all'interno del sistema pelagico e condiziona il trasferimento di energia lungo la rete alimentare. Per valutare quanto l'azione virale sia condizionata dal metabolismo della cellula ospite, sono stati allestiti esperimenti in cui il popolamento batterico era sostenuto da una disponibilità di substrato diversa sia per composizione che per peso molecolare. Esperimenti in mesocosmo hanno permesso, inoltre, di valutare il ruolo dei virus in condizioni di diversa disponibilità di fosforo inorganico. Questo sale nutritivo rappresenta, infatti un fattore limitante per i popolamenti planctonici dell'Adriatico. I risultati ottenuti, confortati da quelli provenienti dall'analisi in campo che ha confermato come l'abbondanza dei virus in mare rimanga relativamente costante nel tempo hanno sottolineato la necessità di valutare quanto il processo di produzione di una nuova progenie virale sia bilanciato dal processo di distruzione o danneggiamento provocato da fattori come gli U.V., ecc. Poiché non esiste ancora un metodo standardizzato per valutare la produzione virale è stato allestito un esperimento per confrontare i 3 protocolli disponibili. Il primo protocollo prevede la stima della produzione virale attraverso l'incorporazione diretta di un tracciante radioattivo nell'acido nucleico dei virus prodotti e quindi rilasciati, durante il periodo d'incubazione. Il secondo protocollo si basa sulla produzione di virus da parte di cellule batteriche infette a priori,mentre il terzo protocollo stima la produzione virale attraverso la stima della mortalità batterica con il metodo delle diluizioni seriali. Questo quadro sperimentale ha consentito, da un lato, di ottenere una stima della mortalità batterica e, più specificatamente, di quella della frazione metabolicamente più attiva, e dall'altro di valutare l'entità dei processi di produzione virale in diverse condizioni ambientali. Le tecniche di biologia molecolare quali PCR (Polymerase Chain Reaction) e DOGE (Denaturant Gradient Gel Electrophoresis) sono state utilizzate per la verifica dell'influenza dei virus sulla struttura della comunità batterica.
The main goal of the present study was to extend the knowledge relatively to the role of virioplankton in microbial food webs and biogeochemical fluxes. The first section of the study describes spatial and temporal virioplankton distribution in the Northern Adriatic Sea. Samplings were carried in a coastal station of the Gulf of Trieste at different depths. In the first period samplings were carried out on a monthly basis and were subsequently intensified to a twice a month sampling frequency. The obtained data implemented the time series of virioplankton abundances present in data base of Marine Biology Laboratory (Trieste), which were monitored from 1998 at the same sampling station. The obtaining of the time series was necessary to define the 'normality' state of the system regarding viral component of marine plankton in order to detect eventual 'alterations', such as mucilage formation, known to sporadically interest in its particularly massive form the northern basin of the Adriatic Sea, seriously affecting turism and fishery. The analysis of spatial virioplankton distribution on extended sampling area, conducted over 3 seasonal oceanographic cruises during 2004 in the Northern Adriatic basin, in collaboration with Veneto Interreg Project, provided the opportunity to explore the functioning of 'microbial circuit' and significance of viruses under contrasting environmental conditions, since the Northern Adriatic Sea displays highly evident trophic gradient due to the Po River inflow. In fact, the study area played a role of natural laboratory since the introduction of hydrological parameters strongly affected the distribution of microbial components and their interactions, highlighting the adaptability of the basin in 'cause-effect' studies. The results obtained by spatial sampling strategy did not overlap with those obtained by long-term temporal study in a coastal station of the Northern Adriatic, but extended the information amount: different methodological strategies allowed us to acquire precious findings regarding viral population's dynamics, since viral interaction with their hosts is particularly difficult to define because of the variety of interaction types. The investigation of most common viral ecology indexes, largely used to evaluate virus-host interaction, such as VBR (Virus-to-Bacterium Ratio) and phage-host density product ( analogically named VBP from Virus-to-Bacterium Product ), evidenced the alteration of virus and bacteria interactions before, during and after mucilage formation relatively to spring-summer period of 2000. The obtained results evidenced the presence of particularly enhanced viral lysis that strongly affected bacterial community, which, moreover, in that period was characterized by low species diversity. The experimental approach allowed the evaluation of the entity of viral lysis, which not only provoke bacterial mortality but also strongly affects carbon flux in the pelagic system and influences the energy transfer in the food web. Several experiments were performed in order to evaluate the depending of viral activity upon host cell metabolism and organic substrate availability of microbial community. Moreover, mesocosm experiments allowed evaluating the role of viruses in the presence of different availability of inorganic phosphorous, particularly important since representing the limiting factor for plankton community in the Adriatic Sea. The results obtained both by field studies and experimental approach confirmed the temporal stability of virioplankton abundance in marine system and highlighted the need of informations relatively to virioplankton balance between its production and decay rates. Since there is no standard method for the estimate of viral production, three different experimental protocols were set up in order to compare the accuracy of the obtained results and to establish the usefulness of a single technique. The first technique provides an estimate of virus production rates by radiotracer incorporation method that measures production of DNA-containing viral progeny over incubation period. Another method provides the rates of virus production of the bacteria infected prior to the beginning of the experiment, while the serial dilution technique designed originally for the estimate of grazing activity was adopted and modified to determine virus production in natural phage-host assemblage. This experimental framework, together with the experiment set up to evaluate virus-mediated mortality of different bacterial groups ( distinguished according to their metabolism), provided new findings relatively to viral impact on bacterioplankton and allowed the estimate of viral production in different environmental conditions. Molecular biology techniques, such as PCR (Polymerase Chain Reaction) e DGGE (Denaturant Gradient Gel Electrophoresis) were used to verify the influence of virus-mediated mortality on the bacterial community structure.
XVII Ciclo
1976
Versione digitalizzata della tesi di dottorato cartacea.