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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Reduction of seawall overtopping at the Strand

Roux, George Bishop 03 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The Strand is located within False Bay and frequently encounters large quantities of wave overtopping over the coastal defences. This results in the damage of property and infrastructure and causes streets to be flooded. Physical modelling tests were done by a consultancy firm to determine a solution by making use of a recurve structure at the back of the beach. This study is an expansion of the previous physical modelling that was done and focuses on several factors that were not tested by the consultancy firm that could have an influence on the overtopping rate and provide additional information on the recurve design. These tests were: (i) the effectiveness of the proposed recurve wall design in reducing overtopping was compared to a vertical wall; (ii) the influence that modifications to the beach profile such as the beach slope, beach width and beach level have on the overtopping rate; and (iii) the sensitivity of overtopping to changes in wave period was tested. The information gathered from these tests was used to propose a possible solution for the Strand. Numerical modelling was done with Delft3D-Wave to determine the wave height at the back of the beach using a nested grid. The waves at the Strand are depth limited and therefore very sensitive to changes in water level. By altering the beach level the model showed how the significant wave height at the back of the beach changes. First estimates of overtopping were determined using the relevant empirical calculations from the EuroTop Manual 2007 for a vertical seawall. No estimate could be made for the recurve wall since it did not fall in the valid range of the equations. From the physical modelling it was found that the overtopping reduced significantly from a vertical to a recurve seawall by a factor of about 50% depending on the wall height. All the prediction methods tested proved to be accurate in estimating the overtopping when the ratio of freeboard to significant wave height was ≤1.83. For non-breaking wave conditions the beach profiles that were gently sloped (1:50) and wide produced more overtopping than the beach profiles that were steep (1:10) and narrow. Increasing the beach level only decreased the overtopping if the water depth was shallow enough to cause the waves to break before they reached the back of the beach. Overtopping was found to increase with longer wave periods until the wave period became too long and the waves broke offshore which resulted in the overtopping decreasing. Possible solutions to overtopping were proposed based on two beach levels and the implementation of a recurve seawall. Revised crest levels for the wall were made along the length of the beach for both the 1:20 and 1:100 year water levels. / AFRIKAANSE OPSOMMING: Die Strand is in Valsbaai geleë en ervaar dikwels baie oorspoeling deur golwe bo-oor kusverdedigingswerke. Dit lei tot skade aan eiendom sowel as aan infrastruktuur en veroorsaak dat strate oorstroom. Fisiese modelleringstoetse is deur ’n konsultasiefirma gedoen om ’n oplossing te probeer vind deur van ’n teruggebuigde struktuur aan die agterkant van die strand gebruik te maak. Hierdie studie is ’n uitbreiding van die vorige fisiese modellering wat gedoen is en fokus op verskeie faktore wat nie deur die konsultasiefirma getoets is nie. Dit kan moontlik ’n invloed op die oorspoelingstempo hê en verskaf bykomende inligting oor die ontwerp van die terugbuiging. Hierdie toetse is: (i) die doeltreffendheid van die voorgestelde ontwerp van die teruggebuigde strandmuur in die vermindering van oorspoeling word vergelyk met ’n vertikale muur; (ii) die invloed wat veranderinge aan die strandprofiel soos die helling van die strand, die wydte van die strand asook die strandvlak op die oorspoelingstempo het; en (iii) die sensitiwiteit van oorspoeling op veranderinge in golfperiode is getoets. Die inligting wat uit hierdie toetse verkry is, word gebruik om ’n moontlike oplossing vir die Strand voor te stel. Numeriese modellering is met Delft3D-Wave gedoen om die golfhoogte aan die agterkant van die strand vas te stel deur van ’n genestelde ruitenet gebruik te maak. Die golwe by die Strand word deur diepte beperk en is dus baie sensitief vir veranderinge in die watervlak. Deur die strandvlakke te verander het die model getoon hoe die betekenisvolle golfhoogte aan die agterkant van die strand verander. Die eerste beramings van oorspoeling is bepaal deur van die relevante empiriese berekenings uit die EuroTop-handleiding 2007 vir ’n vertikale strandmuur gebruik te maak. Daar kon geen beraming vir die teruggebuigde muur gemaak word nie aangesien dit nie binne die geldige bereik van die vergelykings val nie. Uit die fisiese modellering is daar vasgestel dat oorspoeling noemenswaardig met ’n gemiddeld van ongeveer 50% verminder is, afhangend van die muurhoogte. Al die voorspellingmetodes wat getoets is was akkuraat in die beraming van die oorspoeling wanneer die verhouding van vryboord tot betekenisvolle golfhoogte ≤1.83 was. Vir nie-brekende golftoestande het strandprofiele met ’n lae helling (1:50) en wat wyd was meer oorspoeling tot gevolg gehad as strandprofiele wat steil (1:10) en nou was. ’n Verhoging in die strand se vlakke het die oorspoeling slegs verminder indien die diepte van die water vlak genoeg was om die golwe te laat breek voordat hulle die agterkant van die strand bereik het. Oorspoeling is gevind om te vermeeder met verlengde golflengte tot dat die golflengte só lank geword het dat die golwe in dieper water begin breek wat aanlieding tot verminderde oorspoeling gegee het. Daar word moontlike oplossings vir oorspoeling voorgestel gebaseer op twee strandvlakke en die implementering van ’n teruggebuigde strandmuur. Voorgestelde golfkruinvlakke vir die muur is al langs die lengte van die strand gemaak vir beide die 1:20- en 1:100-jaar watervlakke.
192

Perceived risk versus actual risk to sea-level rise: a case study in Broward County, Florida

Unknown Date (has links)
Global climate change stressors downscale to specific local vulnerabilities, requiring customized adaptation strategies. Southeast Florida has a high likelihood of sealevel rise impact to due to the low-lying porous limestone geology. High risk is coupled with high exposure due to high-valued coastal properties, productive ecosystems, and dense populations. Coastal populations are particularly at risk due to erosion, inundation and storm surge, but interior populations are also susceptible to rising water tables and extended periods of inundation. All of these impacts are amplified by sea-level rise. Robust sea-level rise adaptation options require significant economic costs. If perceived risk does not adequately line up with actual risk, lack of funds and preparation will prevent implementation of the most effective strategies. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
193

Mechanisms Controlling Distribution of Cosmopolitan Submerged Aquatic Vegetation: A Model Study of Ruppia maritima L. (widgeongrass) at the Everglades-Florida Bay Ecotone

Unknown Date (has links)
Aquatic plants and submerged aquatic vegetation (SAV) are some of the most wide-ranging species and create important habitat for fish and wildlife in many ecosystems, including highly variable coastal ecotones. Mechanistically understanding factors controlling current distributions of these species is critical to project future distribution and abundance under increasing variability and climate change. I used a population-based approach to quantify the effects of spatial and temporal variability on life history transitions of the SAV Ruppia maritima L. (widgeongrass) in the highly dynamic Everglades-Florida Bay ecotone as a model to (1) examine which life history stages were most constrained by these conditions and (2) determine how management can promote life history development to enhance its distribution, an Everglades restoration target. Ruppia maritima life history transitions were quantified in a series of laboratory and field experiments encompassing a ra nge of abiotic and biotic factors known to affect seagrass and SAV (salinity, salinity variability, temperature, light and nutrients and seed bank recruitment and competition). These studies revealed that R. maritima life history varied east to west across the Everglades ecotone, driven by multiple gradients in abiotic factors that constrained different life history transitions in distinct ways. Based on this examination, persistence of SAV populations from dynamic coastal environments is highly dependent on large reproductive events that produce high propagule densities for recruitment. Large productive meadows of SAV also depend on high rates of clonal reproduction where vegetation completely regenerates in a short amount of time. Therefore, in hydrologically variable systems, maintenance or increases in SAV reproduction is required for population persistence through recruitment. However, SAV communities that do not experience high rates of sexual reproduction are dependent on successful seed germination, seedling and adult survival and clonal reproduction for biomass production and maintenance. Seedling survival and to a lesser extent, adult survival, are bottlenecks that can limit life history transitions under highly variable hydrological conditions. To ensure long-term survival in these communities, management activities that increase survival and successful life history development through these critical stages will be beneficial. If not, SAV populations may become highly reduced and ephemeral, providing less productive habitat. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection
194

Conflits d'usage environnementaux sur les rives de la lagune de Bizerte (Tunisie) : une mise en perspective méditerranéenne / Environmental conflicts of use on the lagoon of Bizerte (Tunisia) : one put in perspective mediterranean

Yahyaoui, Ahlem 24 October 2018 (has links)
La thèse cherche à comprendre les significations socio-spatiales des dynamiques conflictuelles relatives à l'environnement en territoire lagunaire pour apprécier ses effets en termes de gouvernance environnementale. L'analyse porte sur les raisons et la genèse des oppositions d'acteurs à l'œuvre autour de la lagune de Bizerte (Tunisie) et de l’étang de Berre (Marseille). Mettre l’accent sur les conflits représente un enjeu pour la mise en place d’une gestion intégrée des zones humides. Ce sujet a été travaillé par d’autres chercheurs, cependant, il reste d’un intérêt majeur, d’une part, parce qu’il renforce la connaissance en la matière, et d’autre part, parce que le territoire étudié est original. La recherche pose plus particulièrement la question des éventuelles incidences que les conflits peuvent avoir sur les organisations et les institutions en place. L’action publique est-elle renouvelée suite à l’émergence ou à la régulation des conflits ? Ces questionnements se réfèrent à des enjeux de sociétés, actuels et majeurs, sur un territoire en mutation extrêmement rapide : la lagune de Bizerte, sur la rive Sud de la Méditerranée, dans un pays où le régime est en pleine transition. Cette recherche ouvre des perspectives dans l'étude du potentiel d'émergence de la démarche participative et de l'intégration sociale de la question environnementale sur des territoires littoraux, urbains ou ruraux. / The dissertation seeks to recognize the socio-spatial meanings of dynamic conflicts related to the environment in the lagoon and to assess its effects in terms of environmental governance as well. The analysis concentrates on the reasons and the genesis of the actors’ oppositions at work around the lagoon of Bizerte (Tunisia) and the pond of Berre (Marseille). Putting the light on these conflicts represents an issue for the integrated wetland management. This topic has been tackled on by other researchers. However, it remains a major interest due to the knowledge and the originality of the territory. Particularly, the thesis raises the question of the potential impacts that conflicts can have on organizations and institutions in place. In fact, is it possible that public action will be renewed to follow the emergence or conflicts regulation? This question is tied to the challenges of the current and major companies and to an extreme rapidity of territory changing: Bizerte’s lagoon is situated on the southern shore of the Mediterranean and in a country where the regime is in continuous transition. This research covers the ground to study the potential emergence of the participative approach and the social integration of environmental issues in coastal, urban and rural territory.
195

Restructuring and adjustment in resource-dependent coastal communities : a case study of the Western rock lobster fleet hosting communities

Huddleston, Veronica January 2009 (has links)
In an attempt to address the seeming imbalance within studies of rural communities in Australia linked to primary industries, this study examines the broader aspects of policy changes and bio-economic imperatives in the Western Rock Lobster Fishery and the effects of the restructuring of the fishery on communities that host the rock lobster fleet. It is an innovative study in that it is one of the first comprehensive studies of industry restructuring in the fisheries sector; a study of the linkages and implications of restructuring on the social, economic and cultural facets of coastal communities in Western Australia. Globalisation in the fishery sector, aided by technological advances, has resulted in a greater exploitation of high-value fisheries for export. Intensified globalisation has also brought about environmental and social standards that ensure the survival of by-catch species and promote responsible codes of fishing practice. In Australia, the active support of the government for globalisation, led to the adoption of export-oriented policies emphasising competitiveness and efficiency. Consideration of market principles thus govern fisheries regulators when deciding on the management arrangements to adopt for a particular fishery. In considering a number of policy instruments and management measures, government regulators also consider the conservation of marine resources alongside the production of significant economic and social benefits. The Western Rock Lobster Fishery is the most valuable single species fishery in Western Australia with a sizeable financial and employment contribution to coastal communities along the Western Australian coast. Any management scheme adopted for this fishery, as such, not only has to take into account biological and environmental imperatives but also economic and social objectives. The analysis of the fishery undertaken in this thesis underlines the need for a holistic view of fishery management that takes into consideration not only biological sustainability, but also promotes an understanding of fishers' behaviours and fishing patterns and the consequent effects on specific communities. The demographic and social changes that affect rural communities further complicate the economic restructuring at the fishery level, with fishers' responses differing based on their circumstances and preferences. This thesis presents a snapshot of a fishery deliberating changes in management arrangements and its effects on coastal communities whose socio-demographic and economic development historically has depended, and to a great extent is still dependent, upon rock lobster fishing. It provides empirical evidence that lends support to the view that the pro-market policies promoting competition and entrepreneurialism have resulted in a spatially uneven development in regional Australia. Specific localities can deal with the changes brought about by globalisation and policy change. However, the manner in which these communities deal and cope with these changes depends on a number of factors, among others, the level of diversification of the local economy, demographic and social structures, and other factors such as the level of resilience and the social capital base within the community.
196

The Oregon Nearshore Research Inventory Project : the importance of science and the scientific research community in marine spatial planning

Sherman, Kate (Katherine Joanna Hav) 31 May 2012 (has links)
The purpose of Oregon's Nearshore Research Inventory (NRI) project was to inventory and map the current and future use of Oregon's nearshore environment by the scientific research community for use in Oregon's marine spatial planning process. Spatial and qualitative data on the use of Oregon's ocean and coast by the scientific research community was collected using ethnographic research methods, including the geographic distribution of research, the people who are conducting scientific research, timeline for scientific research, and more. Through the NRI project, Oregon's Territorial Sea amendment process became the first marine spatial planning process in the world, other than through ocean zoning (e.g. Australia's Great Barrier Reef and China), to comprehensively recognize the scientific community as a stakeholder. This thesis contains the methods used to create the NRI database, interview the scientific community, and includes future recommendations for managers and the scientific community based on the results of the NRI. As new uses, such as wave energy extraction, get proposed along coastlines and in the ocean, marine spatial planning (MSP) can be a tool to reduce conflict and find compatible uses of ocean and coastal space. Sound science needs to be used to understand social, ecological, and economic components to ocean and coastal resources and make tradeoff decisions about ocean and coastal space use in the MSP process. The results of the NRI project demonstrate the need to recognize that the scientific research community as a stakeholder in the MSP process. Their use of ocean and coastal space helps provide the sound scientific information that is needed to make ecosystem-based management decisions. Interruptions in long-term scientific research and monitoring could limit the availability of scientific information for use in future management decisions. There are also other values to comprehensively inventorying use of the ocean and coast by the scientific community. Spatial data about where people conduct scientific research provides information for potential collaboration amongst the scientific community and between scientists and non-scientists. It also identifies data gaps, which can then be filled to help have a more comprehensive understanding of ocean and coastal issues. The NRI can act as a template for other states to include the scientific community as a stakeholder in a MSP process, and as a template for a regional inventory of scientific research which can be useful for ecosystem based approaches to management. Overall, there should be value placed on sound scientific information for management decisions and the scientific community as a stakeholder in the marine spatial planning process, as demonstrated through the NRI. / Graduation date: 2013
197

Saltwater Intrusion in Coastal Aquifers

Park, Chan-Hee 21 November 2004 (has links)
Utilizing the analytical solution of the steady state sharp interface saltwater intrusion model in coastal aquifers, a multi-objective optimization formulation of pumping rates and well locations in a coastal aquifer is formulated to solve problems in water management practice. The proposed optimization problem uses progressive genetic algorithm technique and the method developed is applied to the previous work of Cheng et al. [2000]. Through this analysis, several other applications are provided to demonstrate the use of the model in practical applications. This work is the first to optimize pumping rates as well as well locations simultaneously in coastal aquifer management. Known the limitation of the analytical solution, the work is expanded to cover the physics of saltwater intrusion in a more realistic way. This is variable density flow in a variably saturated porous medium. In this method, mixing between two fluids such as saltwater and freshwater can be described and the porous medium is also expanded to cover saturated and unsaturated zones together. One of the objectives is to develop a three dimensional physical model, verify the model, and apply to various applications in coastal aquifers. The developed model, TechFlow, is used to investigate instability issues associated with the numerical solution of the Elder problem in the perspective that includes physical instability issues associated with density differences used in numerical solutions, sensitivity of the solution to idealization irregularity, and the importance of accurate estimation of the velocity field and its association to the grid density levels that is necessary to solve the problem accurately. Saltwater intrusion hydrodynamics in a beach under the influence of tidal effects is also investigated using TechFlow. Based on the results of TechFlow with the use of various boundary conditions for the transport equation, the saltwater intrusion hydrodynamics in a beach under the influence of tidal effects shows unique dynamics. These solutions are primarily affected by density differences, tidal effects on a mild slope, variably saturated porous medium and finite domain solution condition. TechFlow is also used to investigate saltwater upconing beneath pumping wells both two- and three-dimensional applications.
198

Urban Coastal Settlements: Implementation Of A Coastal Area Assessment Model In Iskenderun Case

Cakir, Bilge 01 August 2010 (has links) (PDF)
Coastal urban settlements require a special planning approach since they bring the concepts of &ldquo / urban&rdquo / and &ldquo / coastal&rdquo / together. In relation to the specific contents of these concepts, there are also different models of management plans. &ldquo / Urban Disaster Risk Management&rdquo / and &ldquo / Integrated Coastal Zone Management&rdquo / are two of them. Urban Disaster Risk Management model deals with the planning and management problems of urban settlements in the case of disaster risk conditions. Likewise, Integrated Coastal Zone Management model focuses on the whole coastal area and deals with the sustainable use and protection of all types of coastal resources. However, in case of urban coastal settlements, these models of management plans can be valid together, can overlap, and they can even conflict with each other. In this thesis study, these two models of management plan and their coexistence are considered. A Coastal Area Assessment Model is set up and applied for Iskenderun case. This model provides a detailed spatial analysis opportunity in planning and management of coastal urban settlement. Therefore the model offers a significant input for the planning process through determining urban and coastal risks at the same time. Coastal Area Assessment Model is a tool which takes both Urban Disaster Risk Management and Integrated Coastal Zone Management models&rsquo / concerns into account and evaluates the coastal settlement in terms of urban risk sectors and coastal management issues. This study also introduces an approach on classification of the coastal areas and coastal urban settlements while setting up the Coastal Area Assessment Model. Coastal Area Assessment Model becomes an advantageous tool since it has significant contributions to the planning process by making a simple risk analysis and guiding the proper utilization and protection of the population, built environment, and resources of the coastal areas. Risk sectors, coastal management issues, critical and prior intervention areas of a coastal urban settlement are easily determined, and preparation of development plans of a coastal settlement is guided by the implementation of Coastal Area Assessment Model. In addition to these, general principles on planning and management of coastal settlements are determined by the implementation of the model for the implementation conditions of Urban Disaster Risk Management model, Integrated Coastal Zone Management model, and the Coastal Area Assessment Model in Turkey are also discussed and presented.
199

Local people's perceptions of marine protected areas : a case study of Ponta do Ouro, Mozambique.

Gaspar, Anselmo Cesar. January 2008 (has links)
Marine protected areas (MPAs) cannot be managed outside the context of human societies that are dependent on their associated ecosystems and resources. This means that local people’s perceptions need to be considered in the establishment of MPAs as well as their subsequent management, planning and decision making processes. Accordingly, this study investigated respondents’ perceptions of the Ponta do Ouro – Kosi Bay MPA. The MPA is part of the now proclaimed Lubombo Trans-frontier Conservation Area (TFCA). An interviewer - administered questionnaire was used to obtain primary data from 35 respondents, all resident in the study area and who are involved in various activities based on the coastal area and its marine resources. The focus of the study was on awareness regarding the establishment, impacts of the MPA, the setting of priorities for the MPA and lastly, respondents’ roles and responsibilities The findings from the study reveal low levels of awareness of the establishment of the MPA among respondents, although there was acknowledgement of its potential contribution to biodiversity conservation. Various types of impacts of the establishment of the MPA were noted. The establishment of the MPA was perceived to negatively impact on the access to, and use of, marine resources. It was also felt that the MPA would impact on the exercise of traditional authority. Concerning the setting of future priorities for the MPA, socio-economic considerations, particularly job creation rated highest. Biodiversity conservation ranked highest in terms of factors that should shape the current priorities of the MPA. Overall, tourism and related job creation and biodiversity conservation were identified as the main opportunities associated with the establishment of the MPA. Controlling access to the area, curbing inappropriate resource use, controlling development and ensuring that local people benefit were highlighted as major opportunity benefits. Constraints were mainly considered in relation to the exercise of traditional leadership, access to the area and restrictions in selling of harvested marine resources. Regarding how to collaborate in the MPA, various skills among the respondents were mentioned, with respect to the following areas: enforcement (control, patrols and security) and community relations and awareness (including communication and the translation of documents). Lastly, while the respondents displayed both supportive and unsupportive attitudes as results of perceptions of the intended MPA, in an overall sense, the MPA was considered as a positive development. This was in spite of the perceived weak communications that exist at present between the authorities and local people. Enhanced, communication between authorities in charge of the MPA and local people could help to provide a more positive sentiment towards the MPA. This is particularly true of the local people who, if they understood the rationale for the MPA more fully and how it would impact on their use of the resources of the MPA, would be more likely to support its establishment and existence. / Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.
200

A GIS assessment of development and land use change in the coastal zone of the Ndlambe and Ngqushwa local municipalities, Eastern Cape, South Africa

Palmer, Bronwyn Jane January 2009 (has links)
The coastal zone accommodates some of the most diverse ecosystems in the world and offers a wide range of ecosystem goods and services; consequently it has become a focal point of human development. People are attracted to the coast because of access to resources, favourable climate, aesthetic appeal and potential for recreational activities. As pressure for utilisation and development increases, so does the need to manage the coastal system more effectively. This research focuses on the coastal zone of the Ndlambe and Ngqushwa local municipalities in the Eastern Cape, South Africa, which are physically and environmentally similar, yet have distinct demographic and socio-economic differences. The research integrates information using GIS, from three time epochs, to determine where development and land use change is occurring. The Ndlambe Local Municipality displays high levels of formal development, while the Ngqushwa Local Municipality exhibits little formal development. These differences in development and land use are related to economic, social and legislative ‘drivers’ based on an adapted Driver-Pressure-State- Impact-Response model. The model identifies that development and land use changes lead to increased pressure on the natural system, which in turn leads to shifts in the natural state of the coastal zone, resulting in adverse impacts on the coastal zone. Changes in the natural functioning of the coastal zone highlight the need for a response in terms of changes in legislation governing coastal management and spatial planning. This research concludes that pressure for development in the coastal zone within the research site is beginning to increase and will adversely affect the coastal zone if not managed effectively. These two local municipalities have the opportunity to move forward and develop in such a way that allows for conservation and sound management of the coastal zone, which will ensure long-term sustainability within the coastal zones of the Ndlambe and Ngqushwa local municipalities

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