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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.
11

Dinâmica morfo-sedimentar ao longo do sistema praial da Ilha Comprida - SP / Morpho-sedimentological dynamics along the beach system of Ilha Comprida - SP

Silva, Filipe Galiforni 06 October 2014 (has links)
O objetivo deste trabalho é avaliar as variações espaço-temporais da dinâmica morfo-sedimentar do sistema praial de Ilha Comprida-SP. Assim, para reconhecer os padrões de onda encontrados na região, resultados do modelo global de ondas WAVEWATCH III foram utilizados. Da mesma forma, levantamentos de campo periódicos foram realizados em cinco diferentes setores com obtenção de dados morfológicos e sedimentares. Simulações com o modelo numérico MIKE21 SW foram realizadas para reconhecer as tendências de transporte e distribuição de força de onda. Os resultados mostraram uma tendência geral de transporte para NE, com maiores valores para a região sul em relação a norte, com dois setores principais de divergência residual: centro-sul e norte. A divergência centro-sul apresenta um aumento e uma migração para sul nos meses mais energéticos, enquanto que a divergência norte apresenta uma manutenção espacial ao longo das estações. A distribuição de força de onda mostrou-se mais elevada nos setores centro-sul e norte, coincidindo com os pontos de divergência. Dados granulométricos mostraram baixa variabilidade temporal, mas possuem diferenças espaciais que refletem a hidrodinâmica local. Os dados volumétricos apresentam maiores valores médios nos setores centro-norte e menores no centro-sul e norte. De modo geral, os resultados mostram que ao longo de uma linha de costa exposta a um mesmo padrão de ondas, sua variabilidade é um reflexo de alterações hidrodinâmicas locais. Tais conclusões são importantes para o conhecimento do estado atual das praias e de sua evolução. / The aim of this study is to evaluate the spatial-time variations on the beach system of Ilha Comprida-SP. Therefore, the wave reanalysis database from the global wave generation model WAVEWATCH III was used to recognize the wave pattern for the region. Furthermore, periodic field works at five different sectors have been conducted to collect morphological and sedimentological data. The numerical model MIKE 21 SW has been applied to propagate waves onshore and recognize the transport tendency and the nearshore wave power distribution. Results show a transport trend to the NE, with the southern sector being larger than the northern sector in magnitude, with two main residual longshore drift divergence spots: in the central-southern and northern regions. Moreover, the central-southern divergence spot become larger and migrated to the south during the most energetic months, while the northern divergence spot kept its position throughout the year. Wave power results show two main areas with higher values that coincide with the observed longshore divergence spots. Sediment data presents low temporal variability, although spatial variations have been found reflecting the hydrodynamic conditions. The volumetric data shows largest values in the central-northern sector, being smaller in the central-southern and northern regions. In summary, the findings show that along this wide open stretch of coastline, exposed to the same offshore wave regime, its variability is a result of local hydrodynamic conditions. These results help in further understanding the island\'s long term evolution and current state of its beaches.
12

Análise espacial da vulnerabilidade das praias do Estado de Santa Catarina a ondas por meio de um índice multicritério / Coastal vulnerability assessment of Santa Catarina´s beaches to waves using a multicriteria index

Mirela Barros Serafim 26 June 2017 (has links)
A manifestação de danos em infraestruturas costeiras decorrente da ação de ondas tem estimulado avaliações de vulnerabilidade para fins de gestão integrada da costa. Os municípios costeiros do Estado de Santa Catarina concentram 28% de sua população e sua interface com o oceano é predominantemente composta por praias arenosas dominadas por ondas. Impactos costeiros relacionados a processos dominados por ondas, sobretudo às escalas local e regional, podem ser ainda mais danosos do que os ocasionados por processos naturais de larga escala (p. ex., a subida do nível do mar). A abordagem utilizada neste estudo consiste na definição de um índice multicritério de vulnerabilidade a ondas de maior frequência de ocorrência e de tempestade para o litoral de Santa Catarina. O índice de vulnerabilidade (IVC) foi obtido a partir da integração entre o índice de capacidade adaptativa, composto por variáveis socioeconômicas e de ocupação (área ocupada, distância entre a ocupação e a linha de costa, número de residentes, renda por residente e número de domicílios de uso ocasional), e o índice de suscetibilidade - composto por variáveis do meio físico (altura significativa de onda, gradiente de deriva litorânea potencial, largura de praia, elevação e declividade). A dinâmica costeira resultante da incidência de ondas sobre as manchas urbanas na área em perigo é analisada através de produtos de modelagem numérica, integrados às demais variáveis em ambiente de Sistema de Informação Geográfica (SIG). A relevância das variáveis na composição do índice foi avaliada pelo método de decisão multicritério AHP (analytic hierarchy process). As variáveis e os índices foram representados em cinco classes de vulnerabilidade (muito baixa, baixa, média, alta e muito alta) nos setores do Plano Estadual de Gerenciamento Costeiro (GERCO/SC). Com base na opinião de especialistas, as variáveis físicas foram consideradas mais relevantes do que as socioeconômicas. Os setores mais suscetíveis e vulneráveis são: centro-sul, sul, norte, centro-norte e centro, respectivamente. Já os setores de menor capacidade adaptativa são: centro-norte, centro, norte, centro-sul e sul, respectivamente. A baixa presença de residentes e ocupações na área em perigo, bem como as maiores distâncias entre a ocupação e a linha de costa - variáveis utilizadas na determinação da capacidade adaptativa e que favorecem a redução da vulnerabilidade - apresentaram um papel secundário na determinação do IVC para os setores centro-sul e sul. Os setores ao norte do Estado são menos suscetíveis e vulneráveis, todavia se encontram intensamente ocupados em praias com menores larguras de faixa de areia, terrenos planos e com baixa declividade (segmentos de maior suscetibilidade). A maior ocorrência de danos por erosão e inundação, atualmente observada ao norte do Estado, pode ser facilmente revertida caso haja a expansão de áreas ocupadas próximo às linhas de costa dos setores centro-sul e sul, tendo em vista a alta suscetibilidade e os baixos valores de renda e de segunda-moradia encontrados ao sul do Estado. / The occurrence of coastal infrastructure damage due to wave action has been promoting vulnerability assessments for integrated coastal management. Santa Catarina\'s coastal municipalities concentrate 28% of the state\'s population and the interface between the coastline and the ocean is predominantly composed by wave-dominated sandy beaches. Coastal impacts related to wave-dominated processes, especially at local and regional scales, can produce more damaging effects than large-scale natural processes (e. g., sea level rise). The approach suggested in this study consists of defining a vulnerability multicriteria index, for Santa Catarina\'s coastline, to waves with higher frequency of occurrence and to storm wave events. The coastal vulnerability index (IVC) was obtained by integrating the adaptive capacity index, composed by socioeconomic and occupational variables (constructed area, distance between human settlements and shoreline, number of residents, income per capita and number of households for occasional use), and the susceptibility index - consisting of environmental variables (significant wave height, potential longshore drift gradient, beach width, coastal elevation and slope). The resulting coastal dynamics from nearshore wave incidence is analyzed through the application of a numerical model, integrated with the other variables by geoprocessing techniques in a Geographic Information System (GIS) environment. The variables\' relevance in the index formula was obtained by the analytic hierarchy process (AHP). Variables and indices were hierarchized in five vulnerability classes (very low, low, medium, high and very high) and represented in the sectors from the State Coastal Management Plan (GERCO/SC): north, center-north, center, center-south and south. Based on specialists\' opinion on the determination of vulnerability, physical/environmental variables were considered more relevant than socioeconomic variables. The most susceptible and vulnerable sectors are: center-south, south, north, center-north and center, respectively. Sectors with the lowest adaptive capacity are: center-north, center, north, center-south and south, respectively. The low number of residents and settlements in the endangered area, as well as the greater distances between occupied area and the shoreline - variables used to determine adaptive capacity and that contribute to reduction of vulnerability - played a secondary role in the CVI\'s determination for the center-south and south sectors. The northern sectors of the state are less susceptible and vulnerable; however, they are intensely occupied in beaches with smaller beach width, lower elevation and slope (segments with higher susceptibility degrees). The highest occurrence of erosion and flood damage, currently observed at the north of the state, can easily be reversed in case of expansion of settlements near the center-south and south sectors, as a function of the higher susceptibility degrees and lower income per capita and number of households of occasional use found at the south of the state.
13

EVALUATION OF LOCAL OFFSHORE SEDIMENTS FOR COASTAL RESTORATION PROJECTS IN PALM BEACH COUNTY, FL, USA

Unknown Date (has links)
Open-coast beach-dune environments are vulnerable to erosion, such as from storms or interruption of littoral drift. Although protected from event-driven wave energy, backbarrier shorelines are also susceptible to erosion, due to tidal currents and boat wakes. A common response to mitigate erosion is to place sediment and restore the environment. For placement on beaches, a significant effort has been made to identify offshore resources available; however, offshore resources have seldom been considered for dune or backbarrier shoreline restoration. This study evaluates the geotechnical sediment properties of offshore sediments in proven borrow areas for beach nourishment and reclassifies them for placement in dunes and along the backbarrier in Palm Beach County, Florida. Two different methods calculate volume of offshore resources available for dune or backbarrier projects, including numerical calculations and interpolation of volume through SURFER. Because existing proven borrow areas are delineated for beach nourishment, less volume of sediment available in these areas for other coastal environments. The results of this study suggest that identifying offshore sediment sources for lower-energy environments would not adversely impact sediment needed for beach nourishment. As coastal environments are increasingly threatened by climate change and sea level rise, sediment resources become scarcer, the need to efficiently and effectively use sediments will be of utmost importance for scientists, engineers, and managers in their efforts to protect coastal habitat and communities. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection
14

Spatial Analysis of Archaeological Assemblages from the Late Ceramic Age (AD 400-1400) Site of Grand Bay, Carriacou, West Indies

Casto, Kara I. 25 March 2015 (has links)
The present study utilizes a geographic information system (GIS) to examine the spatial relationships between the assemblages of major artifact and ecofact categories at the Late Ceramic Age (AD 400-1400) site of Grand Bay, Carriacou. In addition, the study examines how these assemblages formed through various cultural and natural formation processes and have been affected by recent episodes of coastal erosion. Previous archaeological research for this region of the Caribbean is lacking, but with the determined efforts of the Carriacou Archaeological Field Project, Grand Bay's role has been brought to the forefront of current investigations answering questions about pre-Columbian migration and colonization of the Lesser Antilles, inter-island exchange systems, maritime adaptations, and subsistence economies. With the rapid destruction of Grand Bay's archaeological resources through coastal erosion exacerbated by illegal sand mining, the site also has the potential to provide information on site management and preservation practices of coastal and island archaeological and historical sites that has created open and continuous discourse between archaeologists, lawmakers, landowners, and other key stakeholders. As Grand Bay is one of the most intensively occupied sites in the southern Lesser Antilles, its value to Caribbean archaeology is undeniable. Thus, its immediate study and preservation are imperative before what information can be gleaned from the site is lost forever. Using data gathered from four field seasons at Grand Bay and spatial autocorrelation and cluster analysis, the present study aims to identify spatial patterns within the distributions of major archaeological materials categories. These two forms of spatial analysis focus on identifying clusters and individual outliers within the assemblages that are then used to examine site formation processes, identify potential activity areas, and interpret the overall spatial organization and distribution of archaeological materials at Grand Bay. Analysis of Grand Bay's archaeological assemblage shows that three main material categories - ceramics, vertebrate remains, and shell - are, in general, spatially correlated and form the majority of the midden deposits at Grand Bay. Clustering of these materials shows that different areas of the site were used more intensively over time resulting in patterns of higher artifact concentration in these areas. The possible clustering of coral artifacts can likely be explained by the storage of this resource for use in tool manufacture. Areas of clustering and outliers among shell and vertebrate assemblages can be explained by differing excavation techniques and the effectiveness of wet-screening to recover smaller constituents vital to understanding Grand Bay's subsistence economies. Within the assemblages recovered in the habitation area at Grand Bay, clustering of the three main material categories may indicate the primary deposition of refuse or the spread of the midden deposits into this space. Further analysis of diagnostic ceramics is required to fully understand this clustering pattern. The separate cluster of stone artifacts may represent a lapidary and or tool manufacture activity area. Although some inconsistencies were revealed in the data, and a lack of data for deeper midden deposits did not allow for further analysis, overall this study provides evidence to support basic inferences about the formation of the midden deposits at Grand Bay through cultural processes and the effect coastal erosion has on these interpretations. A final purpose of the study is to demonstrate how spatial analysis of the data supports and/or refutes these interpretations. Results from the analyses in this study should not be viewed as definitive, but as a stepping stone for future research at Grand Bay.
15

The modification of arctic permafrost coastlines

Lantuit, Hugues January 2008 (has links)
The arctic region is undergoing the most rapid environmental change experienced on Earth, and the rate of change is expected to increase over the coming decades. Arctic coasts are particularly vulnerable because they lie at the interface between terrestrial systems dominated by permafrost and marine systems dominated by sea ice. An increased rise in sea level and degradation of sea-ice as predicted by the Intergovernmental Panel on Climate Change in its most recent report and as observed recently in the Arctic will likely result in greater rates of coastal retreat. An increase in coastal erosion would result in dramatic increases in the volume of sediment, organic carbon and contaminants to the Arctic Ocean. These in turn have the potential to create dramatic changes in the geochemistry and biodiversity of the nearshore zone and affect the Arctic Ocean carbon cycle. To calculate estimates of organic carbon input from coastal erosion to the Arctic Ocean, current methods rely on the length of the coastline in the form of non self-similar line datasets. This thesis however emphasizes that using shorelines drawn at different scales can induce changes in the amount of sediment released by 30% in some cases. It proposes a substitute method of computations of erosion based on areas instead of lengths (i.e. buffers instead of shoreline lengths) which can be easily implemented at the circum-Arctic scale. Using this method, variations in quantities of eroded sediment are, on average, 70% less affected by scale changes and are therefore a more reliable method of calculation. Current estimates of coastal erosion rates in the Arctic are scarce and long-term datasets are a handful, which complicates assessment and prognosis of coastal processes, in particular the occurrence of coastal hazards. This thesis aims at filling the gap by providing the first long-term dataset (1951-2006) of coastal erosion on the Bykovsky Peninsula, North-East Siberia. This study shows that the coastline, which is made of ice-rich permafrost, retreated at a mean annual rate of 0.59 m/yr between 1951and 2006. Rates were highly variable: 97.0 % of the rates observed were less than 2 m/yr and 81.6% were less than 1m/yr. However, no significant trend in erosion could be recorded despite the study of five temporal subperiods within 1951-2006. The juxtaposition of wind records could not help to explain erosion records either and this thesis emphasizes the local controls on erosion, in particular the cryostratigraphy, the proximity of the Peninsula to the Lena River Delta freshwater plume and the local topographical constraints on swell development. On ice-rich coastal stretches of the Artic, the interaction of coastal dynamics and permafrost leads to the occurrence of spectacular “C-shaped” depressions termed retrogressive thaw slumps which can reach lengths of up to 650 m. On Herschel Island and at King Point (Yukon Coastal Plain, northern Canada), topographical, sedimentological and biogeochemical surveys were conducted to investigate the present and past activity of these landforms. In particular, undisturbed tundra areas were compared with zones of former slump activity, now stabilized and re-vegetated. This thesis shows that stabilized areas are drier and less prone to plant growth than undisturbed areas and feature fundamentally different geotechnical properties. Radiocarbon dating and topographical surveys indicated until up to 300 BP a likely period of dramatic slump activity on Herschel Island, similar to the one currently observed, which led to the creation of these surfaces. This thesis hypothesizes the occurrence of a ~250 years cycle of slump activity on the Herschel Island shoreline based on the surveyed topography and cryostratigraphy and anticipates higher frequency of slump activity in the future. The variety of processes described in this thesis highlights the changing nature of the intensity and frequency of physical processes acting upon the arctic coast. It also challenges current perceptions of the threats to existing industry and community infrastructure in the Arctic. The increasing presence of humans on Artic coasts coupled with the expected development of shipping will drive an increase in economical and industrial activity on these coasts which remains to be addressed scientifically. / In der Arktis sind die derzeit stärksten Umweltänderungen weltweit zu beobachten, und es wird angenommen, dass sich deren Ausmaß sogar noch verstärken wird. Aufgrund ihrer Lage zwischen terrestrischen, von Permafrost geprägten Systemen und marinen, von Meereis geprägten Systemen, sind arktische Küstenregionen im Zuge dieses Wandels besonders sensibel. Ein verstärkter Meeresspiegelanstieg und der Rückgang des Meereises, wie vom letzten Bericht des Intergovernmental Panel on Climate Change (IPCC) vorhergesagt und in letzter Zeit in der Arktis beobachtet, werden zu erhöhten Küstenrückzugsraten führen. Ein Anstieg der Küstenerosion würde zu einer drastischen Erhöhung von Sedimentfracht, organischem Kohlenstoff und von Schadstoffen im Arktischen Ozean führen. Durch diese wiederum drohen dramatische Änderungen in der Geochemie und Biodiversität der küstennahen Zone sowie Veränderungen im Kohlenstoffkreislauf des Arktischen Ozeans. Modelle zur Berechnung des Eintrags organischen Kohlenstoffs in den Arktischen Ozean infolge von Küstenerosion basieren auf der Länge der Küstenlinie in Form von „non self-similar“ Datensätzen. Die vorliegende Arbeit zeigt jedoch, dass die Nutzung von Küstenlinien unterschiedlicher Maßstäbe Abweichungen in der berechneten Sedimentfracht von bis zu 30 % zur Folge haben kann. Es wird daher eine alternative Methode zur Berechnung von Erosionsraten vorgeschlagen, die auf Flächen, nicht auf Längenangaben basiert (z.B. Pufferzonen anstelle von Küstenlinien) und die auf einfache Art und Weise für die Zirkum-Arktis angewandt werden kann. Durch diese Methode ist die Variation der berechneten Erosionsmengen um durchschnittlich 70 % weniger von Maßstabsänderungen betroffen. Damit kann eine deutlich höhere Zuverlässigkeit in den Prognosen erreicht werden. Aktuelle Abschätzungen von Küstenerosionsraten in der Arktis sind spärlich und es gibt nur sehr wenige Langzeitdatensätze, so dass Einschätzungen und Prognosen zu Prozessen im Küstenbereich, insbesondere von dessen Gefährdung, schwierig sind. Die vorliegende Arbeit soll dazu beigetragen, diese Lücke zu schließen, indem der erste Langzeitdatensatz (1951-2006) zu Küstenerosionsraten auf der Bykovsky Halbinsel in Nordost-Sibirien bereitgestellt wird. Die Arbeit zeigt, dass die Küstenlinie auf der Bykovsky Halbinsel, die durch eisreichen Permafrost geprägt ist, im Zeitraum 1951-2006 um durchschnittlich 0,59 m pro Jahr zurückging. Die Rückzugsraten waren dabei äußerst variabel: 97 % aller ermittelten Raten betrugen weniger als 2 m und 81,6 % weniger als 1 m pro Jahr. Ein signifikanter Trend in den Erosionsraten konnte dabei jedoch trotz Analyse von fünf verschiedenen zeitlichen Epochen nicht festgestellt werden. Auch die Gegenüberstellung von Winddatensätzen kann die Erosionsraten nicht erklären. Deshalb stellt diese Arbeit die Bedeutung lokaler Kontrollmechanismen wie Kryostratigraphie, die Nähe der Bykovsky Halbinsel zum Lena-Delta und seinen Süßwasservorkommen sowie die lokale Topographie und deren Einfluss auf Wellengang und Wellenbildung heraus. Innerhalb eisreicher arktischer Küstenabschnitte führt die Interaktion zwischen Küstendynamik und Permafrost zur Ausprägung eindrucksvoller, „C-förmiger“ Depressionen, sogenannten regressiven auftaubedingten Rutschungen, die Längen von bis zu 650 m erreichen können. Auf Herschel Island und am King Point (Yukon Küste, Nordkanada) wurden topographische, sedimentologische und biogeochemische Aufnahmen durchgeführt, um die rezente und vergangene Dynamik dieser Landschaftsformen nachvollziehen zu können. Insbesondere wurden ungestörte Tundrenareale mit ehemals aktiven Rutschungszonen, die heute stabil und wiederbewachsen sind, verglichen. Die vorliegende Arbeit zeigt, dass diese ehemaligen, heute stabilisierten Rutschungszonen trockenere und für Pflanzenwachstum weniger geeignete Standorte darstellen als ungestörte Bereiche und überdies fundamental andere geotechnische Eigenschaften aufweisen. Radiocarbon-Datierungen und topographische Aufnahmen weisen darauf hin, dass es auf Herschel Island und am King Point bis vor 300 Jahren eine Periode ausgeprägter, auftaubedingter Rutschungsaktivitäten ähnlich denen, die derzeit auf der Insel beobachtet werden können, gegeben haben muss, die zur Ausbildung dieser Oberflächenstrukturen geführt haben. Diese Arbeit stellt auf Grundlage der untersuchten Topographie und Kryostratigraphie die Hypothese auf, dass an der Küstenlinie von Herschel Island ein etwa 250-jähriger Zyklus von Rutschungsaktivitäten existiert und antizipiert eine höhere Frequenz im Auftreten dieser Rutschungsaktivitäten für die Zukunft. Die Vielfalt an Faktoren, die in dieser Arbeit beschrieben wurden, hebt die veränderte Intensität und Frequenz der auf arktische Küsten einwirkenden physikalischen Prozesse hervor. Dadurch werden auch aktuelle Auffassungen zur Bedrohung bestehender Industrie und Infrastruktur in der Arktis hinterfragt. Im Zusammenhang mit dem erwarteten Ausbau der Schifffahrt treibt der zunehmende anthropogene Einfluss die ökonomische und industrielle Entwicklung in arktischen Küstenregionen an, die Gegenstand einer wissenschaftlichen Betrachtung sein sollten.
16

Antecedent and anthropogenic influences on the Galveston Island shoreface

Pitkewicz, Jennifer Lynn 15 May 2009 (has links)
Galveston Island, Texas has been experiencing high rates of erosion in recent years, spawning an interest in developing complex beach management programs. However, before any effective management project can be implemented we must understand all of the processes that control the shoreface. It is only recently that scientists have begun to recognize the importance of the role that the geologic framework plays on the coastal evolution of the shoreline. In this region, it is the antecedent geology as well as the anthropogenic obstructions which are the key factors controlling the formation of the modern shoreface. This study defines the extents to which these antecedent and anthropogenic factors influence the shoreface as well as refines the geologic interpretations offshore of Galveston Island. Using sidescan sonar, CHIRP seismic sonar, multibeam bathymetry data and sediment cores, the shoreface and subsurface geology were modeled. It was determined that the thickness, extent and slope of the modern sediment in the nearshore environment is controlled by the topography of the Beaumont Clay, a consolidated clay deposited during the Pleistocene. Anthropogenic obstructions, including the Galveston Seawall, groin and jetty system, have changed the sediment transport patterns in the region and have created a system of erosion and accretion not only along the shoreline, but for the entire length of the shoreface.
17

Radar interferometry for monitoring land subsidence and coastal change in the Nile Delta, Egypt

Aly, Mohamed Hassan 15 May 2009 (has links)
Land subsidence and coastal erosion are worldwide problems, particularly in densely populated deltas. The Nile Delta is no exception. Currently, it is undergoing land subsidence and is simultaneously experiencing retreat of its coastline. The impacts of these long-term interrelated geomorphic problems are heightened by the economic, social and historical importance of the delta to Egypt. Unfortunately, the current measures of the rates of subsidence and coastal erosion in the delta are rough estimates at best. Sustainable development of the delta requires accurate and detailed spatial and temporal measures of subsidence and coastal retreat rates. Radar interferometry is a unique remote sensing approach that can be used to map topography with 1 m vertical accuracy and measure surface deformation with 1 mm level accuracy. Radar interferometry has been employed in this dissertation to measure urban subsidence and coastal change in the Nile Delta. Synthetic Aperture Radar (SAR) data of 5.66 cm wavelength acquired by the European Radar Satellites (ERS-1 and ERS- 2) spanning eight years (1993-2000) have been used in this investigation. The ERS data have been selected because the spatial and temporal coverage, as well as the short wavelength, are appropriate to measure the slow rate of subsidence in the delta. The ERS tandem coherence images are also appropriate for coastal change detection. The magnitude and pattern of subsidence are detected and measured using Permanent Scatterer interferometry. The measured rates of subsidence in greater Cairo, Mansura, and Mahala are 7, 9, and 5 mm yr-1, respectively. Areas of erosion and accretion in the eastern side of the delta are detected using the ERS tandem coherence and the ERS amplitude images. The average measured rates of erosion and accretion are -9.57 and +5.44 m yr-1, respectively. These measured rates pose an urgent need of regular monitoring of subsidence and coastline retreat in the delta. This study highlighted the feasibility of applying Permanent Scatterer interferometry in inappropriate environment for conventional SAR interferometry. The study addressed possibilities and limitations for successful use of SAR interferometry within the densely vegetated delta and introduced alternative strategies for further improvement of SAR interferometric measurements in the delta.
18

Morphodynamics of beach-dune systems laden with large woody debris: Haida Gwaii (Queen Charlotte Islands), British Columbia

Anderson, Jeffrey 22 February 2010 (has links)
This thesis explores the geomorphic implications of large woody debris (LWD) residing in the backshore of beach-dune systems along the northeastern coasts of Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada. Detailed topographic surveys were employed to quantify seasonal mass balance of the beach-dune systems along two distinctly different coastlines. Erosion and accretion potential models were applied to characterize sediment transport conditions. Holman’s (1986) R2% wave runup model was superimposed on total water levels, to model wave runup exceedence of the beach-dune junction elevation (6.5 m aCD). Modelled ‘erosion potential’ hours were demonstrated to correspond with observed erosion including removal of the LWD zone, resulting in decreased mass balance. Similarly, Fryberger and Dean’s (1979) Drift Potential model was used to model accretion potential hours. Modelled accretion potential hours were also able to effectively describe conditions when actual accretion occurred. The presence of LWD in the backshore offered two functions to the above processes: it acted effectively as an ‘accretion anchor’, promoting increased mass balance and rebuilding of the incipient foredune; and, it offered a mass of sediment fronting the foredune to protect the beach-dune system from storm wave attack and subsequent erosion.
19

Evolução da paisagem da praia da Caueira no município de Itaporanga d’Ajuda-Sergipe

Ribeiro, Emerson Alves 28 February 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Brazilian coast has come to be valued and transformed into a landscape of consumption from the combination of socioeconomic factors occurred mainly after the war. The use and occupation of land held in an unplanned way become the main human influences responsible for the dismantling of the morphological structures important in the maintenance and protection of coastal environments. This dissertation aimed to analyze the transformations of the landscape through the use and occupation of land between the years 1965 to 2003, and to identify changes in the beach Caueira by monitoring the morphodynamic beach profile and the line coast carried out between January 2010 and January 2011. The methodological procedures used in the study told with literature relevant to the subject of cartographic documents and data collection in the field. From the knowledge of the geo-environmental conditions and mapping of the processes use and land cover of Holocene coastal plain of the city of Itaporanga D Ajuda four different times, it was found many changes resulting from the combination of natural phenomena and / or anthropogenic interference contributing to transformation and evolution of the landscape over five decades. Through the monitoring system praial in five sectors of the coast for a year, it was possible to identify the morphodynamic beach stage, the occurrence of periods of erosion and sediment deposition and morphological features of these successful processes. These indicators were associated with natural climatic conditions and the degree of anthropogenic interference. The crossing of this information points to know more susceptible to destruction unleashed by the combination of natural and anthopogenic factors. / O litoral brasileiro passou a ser valorizado e transformado como paisagem de consumo a partir da combinação de fatores socioeconômicos ocorridos principalmente no pós-guerra. A apropriação da zona costeira de forma não planejada, transformou-se no principal fator responsável pelo desmonte das estruturas morfológicas importantes na manutenção e proteção dos ambientes costeiros. A presente dissertação teve como principal objetivo analisar as transformações da paisagem do litoral de Itaporanga D Ajuda a partir da ocupação e entre os anos de 1965 a 2004, além de verificar as mudanças ocorridas na praia da Caueira através do monitoramento da morfodinâmica do sistema praial e da linha de costa realizado entre os meses de janeiro de 2010 e 2011. Os procedimentos metodológicos utilizados na pesquisa contaram com o levantamento bibliográfico e documentos cartográficos, atividade de gabinete e levantamento de dados em campo. A partir do conhecimento sobre o comportamento do sistema praial e das intervenções humanas, bem como, dos condicionantes geoambientais e do mapeamento dos processos de uso e ocupação do solo na zona costeira do referido município, constatou-se inúmeras alterações resultantes da combinação de fenômenos naturais e/ou das interferências antrópicas que contribuíram para a caracterização da paisagem ao longo de cinco décadas. O cruzamento dessas informações permitiu conhecer os pontos mais susceptíveis a erosão e a frequência com que estes fenômenos ocorrem. O modelo de ocupação utilizado na zona costeira ratificou a degradação ambiental evidenciada ao longo de meio século. Diante dos resultados obtidos concluiu-se que a zona costeira e o litoral de Itaporanga D Ajuda, estão vulneráveis ao mau uso e aos propósitos da exploração e especulação imobiliária.
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Evolução da paisagem da praia da Caueira no município de Itaporanga d’Ajuda-Sergipe

Ribeiro, Emerson Alves 28 February 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Brazilian coast has come to be valued and transformed into a landscape of consumption from the combination of socioeconomic factors occurred mainly after the war. The use and occupation of land held in an unplanned way become the main human influences responsible for the dismantling of the morphological structures important in the maintenance and protection of coastal environments. This dissertation aimed to analyze the transformations of the landscape through the use and occupation of land between the years 1965 to 2003, and to identify changes in the beach Caueira by monitoring the morphodynamic beach profile and the line coast carried out between January 2010 and January 2011. The methodological procedures used in the study told with literature relevant to the subject of cartographic documents and data collection in the field. From the knowledge of the geo-environmental conditions and mapping of the processes use and land cover of Holocene coastal plain of the city of Itaporanga D Ajuda four different times, it was found many changes resulting from the combination of natural phenomena and / or anthropogenic interference contributing to transformation and evolution of the landscape over five decades. Through the monitoring system praial in five sectors of the coast for a year, it was possible to identify the morphodynamic beach stage, the occurrence of periods of erosion and sediment deposition and morphological features of these successful processes. These indicators were associated with natural climatic conditions and the degree of anthropogenic interference. The crossing of this information points to know more susceptible to destruction unleashed by the combination of natural and anthopogenic factors. / O litoral brasileiro passou a ser valorizado e transformado como paisagem de consumo a partir da combinação de fatores socioeconômicos ocorridos principalmente no pós-guerra. A apropriação da zona costeira de forma não planejada, transformou-se no principal fator responsável pelo desmonte das estruturas morfológicas importantes na manutenção e proteção dos ambientes costeiros. A presente dissertação teve como principal objetivo analisar as transformações da paisagem do litoral de Itaporanga D Ajuda a partir da ocupação e entre os anos de 1965 a 2004, além de verificar as mudanças ocorridas na praia da Caueira através do monitoramento da morfodinâmica do sistema praial e da linha de costa realizado entre os meses de janeiro de 2010 e 2011. Os procedimentos metodológicos utilizados na pesquisa contaram com o levantamento bibliográfico e documentos cartográficos, atividade de gabinete e levantamento de dados em campo. A partir do conhecimento sobre o comportamento do sistema praial e das intervenções humanas, bem como, dos condicionantes geoambientais e do mapeamento dos processos de uso e ocupação do solo na zona costeira do referido município, constatou-se inúmeras alterações resultantes da combinação de fenômenos naturais e/ou das interferências antrópicas que contribuíram para a caracterização da paisagem ao longo de cinco décadas. O cruzamento dessas informações permitiu conhecer os pontos mais susceptíveis a erosão e a frequência com que estes fenômenos ocorrem. O modelo de ocupação utilizado na zona costeira ratificou a degradação ambiental evidenciada ao longo de meio século. Diante dos resultados obtidos concluiu-se que a zona costeira e o litoral de Itaporanga D Ajuda, estão vulneráveis ao mau uso e aos propósitos da exploração e especulação imobiliária.

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