Aboveground plant community dynamics in the oligohaline marsh at Big Branch Marsh National Wildlife Refuge, Louisiana, USA, were assessed in response to nutrient loading (3 N x 3 P treatments) and disturbance (both planned lethal disturbance and stochastic tropical storm/hurricane disturbance). Sampling was conducted seasonally from April 2004 to September 2006. Spartina patens and Schoenoplectus americanus are co-dominant plant species in this marsh. Low N-loading additions resulted in increased S. patens cover. However, increased N loading did not result in a shift in plant community composition despite S. americanus consistently having higher leaf tissue N than S. patens. Our results indicate that S. americanus may be more resilient than S. patens to disturbances that do not increase marsh surface elevation. Hurricane Katrina deposited significant amounts of sediment into remaining plots (August 29, 2005). By 2006, this disturbance resulted in a significant increase in both species richness and S. patens cover.

Les missions océanographiques Carambar (2010), Carambar 1.5 (2014) et Carambar 2 (2016-2017) menées au large de la pente nord du Petit Banc des Bahamas (PBB) ont permis d’étudier les processus d’export sédimentaire quaternaires sur ce système carbonaté. Les 24 270 km² de données bathymétriques couplées aux 6398 km de lignes sismiques très haute-résolution et aux 42 carottes sédimentaires reparties entre – 177 m et – 4873 m de profondeur ont permis de caractériser ce système depuis la pente supérieure jusqu’à la plaine abyssale.Le travail présenté ici s’intéresse aux résultats obtenus sur les carottes sédimentaires prélevées sur le haut de pente supérieur du PBB (Carambar 1.5) et celles obtenues sur le bas de pente et dans la zone du canyon du Great connecté à la plaine abyssale (Carambar 2). Ils viennent compléter les résultats obtenus précédemment par Tournadour (2015) et Chabaud (2016) sur les pentes inférieures et moyennes.Un prisme de haut niveau marin se dépose haut de pente supérieure. Actuellement, ce prisme daté de l’holocène s’étend de - 177 m à – 360 m. Les dépôts sédimentaires sont principalement engendrés parle density cascading et le passage d’ouragans. Son alimentation La formation du prisme a débuté il y a13,6 ± 3,5 ka cal BP, après le Meltwater Pulse 1A. Les Meltwater Pulses ont engendré la formation de terrasses qui correspondent alors à des environnements peu profonds et qui induisent une production carbonatée qui peut être exportée vers le prisme. La principale phase de développement du prisme est datée à 6,5 ± 0,9 ka cal BP, quand le niveau marin a finalement atteint le rebord de plate-forme. La sédimentation du bas de pente suggère une alimentation principalement pélagique et liée aux passages des courants plutôt qu’aux apports de plate-forme. Les variations dans les faciès dans ces dépôts sont donc issues de variations climatiques (intensification des courants, apports arctiques). La sédimentation de cette zone semble similaire à celle retrouvé sur la Blake Outer Ridge à 400 km au nord.Entre -1300 et -4800 m, la pente se caractérise par le canyon géant du Great Abaco. L’alimentation peu fréquente de ce canyon contrôlé structuralement a lieu principalement par le biais de tributaires, la tête du canyon ne semble pas être le lieu préférentiel de passage de courants de turbidité fréquents. / Over the past decade, the Little Bahamas Bank (LBB) in the Caribbean has been at the heart of oceanographic cruises Carambar (2010), Caramba 1.5 (2014) and Carambar 2 (2016-2017). These scientific expeditions were carried out with the aim of improving our knowledge of the processes tha controlled sediment export during the Quaternary in this tropical setting. Thus, bathymetric datacovering some 24,270 km² of seabed, high-resolution seismic lines running over 6,398 km and 42sediment cores ranging from 177 to 4,873 m water depth were collected in the upper slope through tothe abyssal plane of the LBB system.This study focusses on those sediment cores retrieved in the upper (Carambar 1.5) and lower slope ofthe LBB and those from the Great Canyon (Carambar 2) which is connected to the abyssal plane. These results are complementary to previous studies led on the middle and lower northern slope of the LBB (Tournadour, 2015; Chabaud, 2016).A highstand accretion wedge, currently dated to the Holocene, expands at water depths of 177-360 m. Sediment deposition in the prism is mainly the result of hurricanes and density cascading. Its initiation is dated at 13. 6 ± 3.5 ka cal BP, following Meltwater Pulse 1A. Melwater Pulses led to the formationof shallow terraces that enhanced carbonate production and ultimately supplied the prism with sediment through the export of said carbonate. The height of the development of the prism occurred at 6.56 ± 0.9ka cal BP when the sea level reached the shelf-break.Sedimentation in the lower slope is indicative of more pelagic processes, since currents play a greater part in the deposition of sediment than the shelf. Variability in the facies of theses deposits are thus the result of climatic variations (e.g strengthening of currents, influxes of Arctic water). Sediments in this are a share similarities with those in Blake Outer Ridge, 400 km north of the LLB. At water depth of1,300-4,800 m, the slope is scored by a giant canyon, namely the Great Abaco. The morphology of this canyon attests to a structural control of sediment supply: rather than the head of the canyon, tributaries appear to supply the majority of sediment within this system.

This is the first longitudinal, retrospective, qualitative, descriptive and multi-case study of hurricanes in Puerto Rico, from 1899 to 1956, researching for planning purposes the key lessons from the disaster management changes that happened during the transition of Puerto Rico from a Spanish colony to a Commonwealth of the United States. The selected time period is crucial to grasp the foundations of modern disaster management, development and planning processes. Disasters are potent lenses through which inspect realpolitik in historical and current times, and grasp legacies that persist today, germane planning tasks. Moreover, Puerto Rico is an exemplary case; it has been an experimental laboratory for policies later promoted by the US abroad, and it embodies key common conditions to develop my research interface between urban planning and design, meteorology, hydrology, sociology, political science, culture and social history. After introducing the dissertation, I present a literature review of the emergence of the secular characterization of disasters and a recent paradigm shift for understanding what a disaster is, its causes and how to respond. Next, I summarize the multidisciplinary research and policy knowledge concerning Puerto Rican hurricanes. Subsequently, I explain my methodological sequential data analysis, beginning with three case studies, followed by cross-case comparisons and assessments, ending in answer, recommendations and conclusions. I implemented a version of Grounded Theory, combining deductive and inductive thinking, with a phenomenologist standpoint that valued people's experiences and interpretations of the world. I aimed to denaturalize so-called ‘natural disasters’, exposing with a political economy lens the political character of public decision-making before, during and after a disaster; and grasp how politics impacted the society under study. My research methods were archival research in the field and online, visual sociology and case study. Based on information-oriented sampling, I chose the destructive hurricanes San Ciriaco (1899), San Felipe (1928) and Santa Clara (1956), which occurred at critical historical junctures. I examined three themes: characterization, causation, and relief. Those themes divided into six sub-questions and thirty-eight variables, summarized later. Answer: Disaster management vastly improved mirroring shifting ideas of God, nature, knowledge and humanity; always influenced by the dependent position of the island. Historically, citizens tried to handle hurricanes through mythological beliefs, empirical observations, rituals and material practices; some of which endured colonization and modernization into the mid 20th century. Disaster management emerged haphazardly; at first it was ineffective and improvised relief, without much preventive or reconstructive policy-making. The official perception of hurricanes changed from being essentially uncontrollable religious or natural events, to natural events that could be tamed with technology, physical changes and policies. Yet, it was a more nuanced confluence of environmental, economic, social, cultural, and political factors that enabled storms to become destructive disasters affecting the Puerto Rican economy, environment and society. The social groups that experienced higher resilience or vulnerability during a disaster respectively corresponded to the groups that were best and least served during relief and who could or could not produce public transcripts and policies. Such division resulted from entrenched social and political arrangements, including citizens’ rights, colonial administrative policies, social hierarchy that merged local and external power dynamics, and notions of habitus . Eventually, the growing understanding of citizens’ rights was critical to reduce hurricane casualties and the worst forms of vulnerability through New Deal and Commonwealth developmental projects. By also including contentious aims though, they created other forms of underdevelopment and dependency from the US; whilst technology and modernity paradigms bolstered new risks that would become rather costly. Simultaneously, disaster management became a federal responsibility, which reached Puerto Rico; but it was the unplanned intersection of a hodge-podge of disciplines, approaches and institutions, centered on physical interventions and neglecting the role of culture and the political economy of disasters with negative lasting impacts. Although improvised, contradictory and controversial; the main factors enabling the rise of disaster management were increased governmental leadership, knowledge construction, public awareness, planning and investment in hard and soft infrastructure, and relief provision. My dissertation contributes to Puerto Rican Studies and to emerging planning discussions about the Circum-Caribbean. Also, it contributes to disaster management, an area of academic and practice-oriented literature relevant for planning, fastly growing given the rising frequency and intensity of multiple disasters; and which is usually focused on contemporary events, prospective forecasting and proposal-making. Contrastingly, my dissertation’s strengths reside in being a critical and exhaustive historical study of hurricanes that proposes an option to the customary deleterious disciplinary fragmentation of disaster studies and management, and to the emphasis on physical change that remain standards in most countries.

<div>A tropical cyclone (TC) vortex is an immense, coherent, organized-convective system. Beneath this large-scale organization, is a litany of azimuthally asymmetric convective motions that exist on a spectrum of scales. These asymmetries are especially dominant during periods when the vortex undergoes critical transitions in its intensity and structure. However, the precise nature of influence of the organization of asymmetries on TC intensity change remains an enigma. The inherent difficulty in predicting their behavior is because asymmetries may arise due to different external or intrinsic sources and occur at different spatial and temporal scales while several complex mechanisms act near-simultaneously to dictate their evolution in time. As a result, multiple pathways are possible for a TC vortex that is influenced by these asymmetries. Our preliminary investigations using numerical models made it apparent that there wasn't a single, unifying way to address this problem. In this thesis, I outline multiple novel techniques of diagnosing and predicting which of the many pathways are likely for a TC vortex that is influenced by azimuthal asymmetries. </div><div> </div><div> First, using three-dimensional numerical simulations of a pair of sheared and non-sheared vortices, I demonstrate the diagnostic potential of the juxtaposition in the azimuthal phasing of: </div><div>(i) the asymmetrically distributed vertical eddy flux of moist-entropy across the top of the boundary layer, and the radial eddy flux of moist-entropy within the boundary layer; and (ii) eddy relative vorticity, eddy moist-entropy, and vertical velocity throughout the depth of the vortex. </div><div> </div><div> Second, I introduce an energetics-based diagnostic framework that computes the energy transactions occurring at asymmetries across various length-scales in the wavenumber domain. By applying it to select cases, this thesis uncovers the relative importance of all the energy pathways that support or disrupt the growth of asymmetries within the vortex. Contrary to the traditional explanations of convective aggregation/disaggregation and axi/asymmetrization through barotropic mean-eddy transactions, my thesis reveals that the growth or disruption of asymmetries are predominantly due to (i) the baroclinic conversion from available potential to kinetic energy at individual scales of asymmetries and (ii) the transactions of kinetic energy across asymmetries of different length scales. </div><div> </div><div>Finally, this thesis introduces two further diagnostic frameworks targeted at tackling the problem of real-time forecasting of TC rapid intensity changes. The first is an empirical framework which examines symmetric and asymmetric convection and other state variables within the vortex, and in the environment across a suite of TCs and identifies a set of `important' variables that are significantly different during time periods that precede a rapid intensification as opposed to a rapid weakening. My framework then ranks the variables identified based on how significantly they influence a rapid intensity change in a TC and the amplification factor of any associated variability. We recommend that future observational, and consequent TC modeling and data assimilation efforts prioritize the highest ranked variables identified here. </div><div><br></div><div>The second is a stochastic model wherein a scale-specific stochastic term is added to the equations describing the energy transactions within the TC vortex. By simulating a stochastic forcing that may arise from any scale, I compute the probability of the vortex transitioning into a rapidly intensifying or a rapidly weakening configuration across an ensemble of scenarios. </div><div><br></div><div>In summary, this thesis introduces and applies a variety of diagnostic techniques that help determine the impact of azimuthal asymmetries on TC intensity evolution.</div>

Risk mitigation decisions for civil infrastructure exposed to rare natural and manmade hazards are often impacted by risk aversion, a behavioral phenomenon in which the decision maker's perception and judgment of risk are systematically distorted, resulting in decisions that might be viewed as excessively conservative when compared to those from a traditional minimum expected cost analysis. This study addresses how decisions regarding structural safety are affected by the attitudes of the decision-maker toward risk using decision models, such as cumulative prospect theory, that allow risk-averse behaviors to be modeled quantitatively. Perspectives on the general characteristics of risk-aversion are first drawn from risk pricing techniques in the insurance industry. These perspectives are then refined for structural engineering applications by investigations of decisions involving seismic retrofit of unreinforced masonry structures in San Francisco, CA and aseismic design of a steel moment frame in Vancouver, BC. Risk attitudes when confronting extreme wind hazards are also assessed using a decision by the North and South Carolina Code Councils to waive a provision in the International Residential Code that would have required additional windborne debris protection in residential construction. An examination of risk attitudes toward competing natural hazards is then introduced by comparing decisions related to wind and seismic effects in areas where both hazards may be significant. These investigations have led to tentative conclusions regarding the role of risk aversion in the assurance of structural safety and in code-related decisions and suggest avenues for future study.

Thesis (M.S.)--Mississippi State University. Forest Products Department. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, December 2009. / Title from PDF title page (viewed on Dec. 11, 2009). "Department of American Studies." Includes bibliographical references (p. 142-157).

Media use of hurricane graphics to apprise populations vulnerable to severe weather provides a persuasive demonstration of the importance and complexity of visual communication. Surprisingly little research, however, has explored how audiences interpret weather graphics. This study examined whether the general public and the National Weather Service share a common understanding of selected weather related terms and meaning of a NWS informational graphic. Using a coorientation model, general public responses to a questionnaire were compared to definitions prescribed by the NWS. Additionally, the public were asked questions to measure trust of the NWS as a credible and reliable source of severe weather information. Selected broadcast meteorologists were surveyed to measure their opinions of the NWS as well as to measure their perceptions of how the general public would respond to questions relating to knowledge of weather terms and graphics. Results revealed discrepancies between the intent of such graphics and audience interpretations. While the vast majority of respondents recognized the Tropical Cyclone Track Watch/Warning Graphic and understood much of the information it conveyed, study respondents did not seem to remember or understand the meaning of the terms Watch and Warning. While these terms or conditions are only one aspect of the graphic they represent critical information for populations at risk. Additionally, the results of this study indicate that weather forecasting professionals' perceptions of the public's understanding of the graphic are inaccurate. Results also show respondents generally rate the NWS as a reliable and competent agency but they do not consistently rate their local weather providers as well. Weather scientists' foremost concern may be the accuracy of their forecasts, but they also must consider the accuracy of the perceptions of those forecasts if they are to be effective in warning populations at risk of severe weather. These results have sobering implications for both governmental and private sources of emergency communication.

Civil infrastructure facilities play a central role in the economic, social and political health of modern society and their safety, integrity and functionality must be maintained at manageable cost over their service lives through design and periodic maintenance. Hurricanes and tropical cyclones, tornadoes, earthquakes and floods are paramount among the potentially devastating and costly natural disasters impacting civil infrastructure. Even larger losses may occur in the future, given the population growth and economic development accompanying urbanization in potentially hazardous areas of the world. Moreover, in recent years, the effects that global climate change might have on both the frequency and severity of extreme events from natural hazards and their effect on civil infrastructure facilities have become a major concern for decision makers. Potential influences of climate change on civil infrastructure are even greater for certain facilities with service periods of 100 years or more, which are substantially longer than those previously considered in life-cycle engineering and may extend across multiple generations. Customary risk-informed decision frameworks may not be applicable to such long-term event horizons, because they tend to devalue the importance of current decisions for future generations, causing an ethical and moral dilemma for current decision-makers. Thus, intergenerational risk-informed decision frameworks that consider facility performance over service periods well in excess of 100 years and extend across multiple generations must be developed. This dissertation addresses risk-informed decision-making for civil infrastructure exposed to natural hazards, with a particular focus on the equitable transfer of risk across multiple generations. Risk-informed decision tools applied to extended service periods require careful modifications to current life-cycle engineering analysis methods to account for values and decision preferences of both current and future generations and to achieve decisions that will be sustainable in the long term. The methodology for supporting equitable and socio-economical sustainable decisions regarding long-term public safety incorporates two essential ingredients of such decisions: global climate change effect on stochastic models of extreme events from natural hazards and intergenerational discounting methods for equitable risk-sharing. Several specific civil infrastructure applications are investigated: a levee situated in a flood-prone city; an existing dam built in a strong earthquake-prone area; and a special moment resisting steel frame building designed to withstand hurricanes in Miami, FL. These investigations have led to the conclusion that risks can and should be shared across multiple generations; that the proposed intergenerational decision methods can achieve goals of intergenerational equity and sustainability in engineering decision-making that are reflective of the welfare and aspirations of both current and future generations; and that intergenerational equity can be achieved at reasonable cost.

This thesis presents hypothetical return plans for hurricane evacuees who have previously evacuated their residence in southern Rhode Island. Using Geographic Information Systems software, appropriate time tables for evacuees to return to their homes are generated. Two case scenarios based on Category 3 and 4 intensity hurricanes making landfall in Westerly, Rhode Island were simulated. Over the last century, population and especially home values in coastal Rhode Island have increased leaving great risk to those in the area. Statistically, hurricanes are less likely to strike Rhode Island than the Gulf Coast or the Southeastern United States. However, within the last century dangerous and damaging hurricanes have affected Rhode Island. This lower frequency of hurricanes decreases awareness and emphasizes the need for further research. Reentry zones for each scenario are defined and ranked by severity of damage using debris, building damage, potential economic loss and population displacements with HAZUS software. Results from both Category 3 and Category 4 test cases show that the downtown census tract experiences the greatest amount of damage and longest return times for evacuees. / Department of Geography