Shorelines are a primary source of attraction for the nearly two million tourists who visit Palm Beach County annually. Many of Palm Beach County beaches are located on barrier islands, separated by a series of inlets which serve as access points to the Intracoastal Waterway. However, inlets are often cited as a source of erosion, through interruption of littoral drift and interaction with nearshore hydrodynamics (e.g., causing wave diffraction or refraction). In an effort to mitigate potential negative impacts of the economically important tidal inlets, Palm Beach County has installed a sand transfer plant (STP) at two inlet locations, the Lake Worth Inlet and the South Lake Worth Inlet. Through analysis of annual aerial photography and beach profile surveys taken between 2000 and 2009, this study will determine what effect, if any, these sand transfer plants are having on the inlet-adjacent shorelines north and south of the two inlets with STP, as well as an inlet without an STP (Boca Inlet). This study hopes to increase the understanding of shoreline dynamics in Palm Beach County, which could recognize important alongshore patterns, such as the occurrence of erosional hot spots, to assist in future mitigation efforts. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

This study investigates young Gambians’ social and economic aspirations. It considers how young Gambians’ aspirations are shaped and negotiated, and the strategies they employ to achieve their objectives. Whilst existing research tends to view young Gambians’ social and economic advancement through a lens of international migration, this study focuses on the aspirations and strategies of those who find themselves in a state of ‘involuntary immobility’ – that is, an aspiration to migrate but the inability to do so. The study looks at how two groups of young urban Gambians from low socio-economic backgrounds pursue local livelihoods. Known as ‘beach hustlers’ and ‘chanters’, these youths take advantage of the resources of the tourism sector and of opportunities provided by information and communication technologies (ICT) in an attempt to fulfil their aspirations. Drawing on data collected from multi-sited ethnographic fieldwork conducted between 2013 and 2014 in Kololi, the country’s main tourism hotspot on the shore of the Atlantic Ocean, and Brikama, where internet use in cybercafés has rapidly grown over the past two decades, I use the cases of ‘beach hustlers’ and ‘chanters’ (cyber hustlers) to shed light on the life-trajectories of young Gambians. I discuss how ‘beach hustlers’ take advantage of the Gambia’s booming tourism industry by engaging in diverse informal economic activities. I then consider how ‘chanters’ accumulate wealth by employing various methods and ruses in their interactions with toubabs (white westerners) through internet-mediated encounters. This study shows that the majority of young Gambians who find it increasingly difficult to migrate to the West pursue local livelihoods to fulfil their aspirations of social and economic advancement. The aspirations and strategies of the hustlers in this study are shaped and influenced by intervening social, cultural and religious obligations and expectations. The study argues that the formation of Gambian hustlers’ aspirations is the result of an interplay between familial and societal dynamics; such as generational and gender relations and reciprocal social exchange, and personal desires of upward social mobility. The study further shows that the strategies young Gambians employ are influenced by the structural constraints and opportunities that appear in specific space–time conditions. By doing so, this study contributes to the literature on the aspirations of urban youths in developing countries and the strategies they employ to achieve them, and how young people experience and respond to conditions of ‘involuntary immobility’.

A principal contribuição para a exposição externa aos seres humanos provem da radioatividade natural presente em solos, principalmente do 40K e das séries do 238U e 232Th. No presente trabalho foram determinadas as concentrações de atividade de 226Ra (série do 238U) , 232Th e 40K em amostras superficiais de areia coletadas mensalmente em 11 locais ao longo da Praia de Camburi durante o ano de 2011, selecionados para cobrir toda a extensão da praia. As amostras seladas foram medidas por espectrometria gama, após um tempo de espera de aproximadamente 30 dias, para que fosse atingido o equilíbrio radioativo nas séries do 238U e 232Th. A concentração de atividade do 226Ra foi determinada pela média ponderada das concentrações do 214Pb e do 214Bi, a concentração de atividade do 232Th pela média ponderada das concentrações do 212Pb, do 212Bi e do 228Ac. A atividade do 40K foi determinada pela sua única transição gama de 1460,8 keV. Para todas as amostras, as concentrações foram corrigidas pelos fatores de autoatenuação gama. A partir destas concentrações foram avaliados os índices radiológicos, atividade equivalente em rádio (Raeq), índice de concentração de atividade (Iγ), índice de risco à exposição gama externo (Hext), índice de risco à exposição gama interno (Hint), taxa de dose gama absorvida no ar (D) em nGy.h-1 e dose efetiva anual (E) em mSv.a-1. No local estudado foi realizada uma avaliação da correlação das concentrações de atividade de 226Ra, 232Th e 40K com os fatores geológicos, geográficos, climatológicos (precipitação pluviométrica e temperatura) e oceanográficos (variação da altura das marés). Devido à presença forte de monazita, a concentração de 232Th é mais elevada do que a concentração de 226Ra e 40K. As concentrações de atividade encontradas variaram de 4 Bq.kg-1 a 1380 Bq.kg-1 para o 226Ra, de 9 Bq.kg-1 a 7453 Bq.kg-1 para o 232Th e de 6 Bq.kg-1 a 504 Bq.kg-1 para o 40K. A variação encontrada para o Raeq foi de 20 Bq.kg-1 a 12077 Bq.kg-1 , para o Iγ foi de 0,07 a 42,08, para o Hext foi de 0,05 a 32,61, para o Hint foi de 0,06 a 36,34 e para a taxa de dose absorvida no ar foi de 9 nGy.h-1 a 5160 nGy.h-1. As baixas concentrações de atividade de 226Ra,232Th e 40K em todos os pontos no mês de abril estão possivelmente relacionadas aos valores máximos da variação da altura das marés e da precipitação pluviométrica. A temperatura média de Vitória durante o ano de 2011 não interfere diretamente nas variações observadas nas concentrações de atividade de 226Ra,232Th e 40K das areias. Foi realizada uma avaliação da dose efetiva anual para um indivíduo do público que frequenta a Praia de Camburi durante 8 horas diárias em 1 mês, em janeiro ou em julho, e todas as doses encontradas estão abaixo do limite de 1 mSv.a-1, recomendado pela ICRP 60 para público em geral. / The main contribution to the external exposure to humans comes from gamma emitting radionuclides in soils, especially the 40K and 238U and 232Th series. In this work, the activity concentrations of 226Ra (238U serie), 232Th and 40K in surface sand monthly collected at 11 sites along the Camburi beach during the year 2011, selected to cover the entire length of the beach, were determined. The samples were hermetically sealed and measured by high resolution gamma spectrometry, after a resting time of approximately 30 days, in order to attain the radioactive equilibrium in the 238U and 232Th series. The activity concentration of 226Ra was determined by the weighted average concentrations of 214Pb and 214Bi, the activity concentration of 232Th by the weighted average concentrations of 212Pb, 212Bi and 228Ac. The activity of 40K was determined by its single transition of 1460,8 keV. For all samples the concentrations were corrected by self attenuation factors. From these concentrations, radiological indices like radium equivalent activity (Raeq), activity concentration index (Iγ), external exposure risk index (Hext), internal exposure risk index (Hint), absorbed gamma dose rate in air (D) in nGy.h-1 and annual effective dose (E) in mSv.y-1 were evaluated. In the studied area it was realized an assessment of the correlation of the activity concentrations of 226Ra, 232Th and 40K with the geological, geographical, climatological (rainfall and temperature) and oceanographic (tidal height variation) factors. Due to the strong presence of monazite, the concentration of 232Th is higher than the concentration of 226Ra and 40K. The activity concentrations found ranged from 4 Bq.kg-1 to 1380 Bq.kg-1 for 226Ra, from 9 Bq.kg-1 to 7453 Bq.kg-1 for 232Th and 6 Bq.kg-1 to 504 Bq.kg-1 for 40K. The variation of Raeq from 20 Bq.kg-1 to 12077 Bq.kg-1, of Iγ from 0,07 to 42,08, of Hext from 0,05 to 32,61, of Hint from 0,06 to 36,34 and of absorbed gamma dose rate in air from 9 nGy.h-1 to 5160 nGy.h-1. The low activity concentrations of 226Ra, 232Th and 40K in all points in April , are possibly related to the maxima of the variation of the height of the tides and rainfall. The average temperature of Vitória during the year 2011 does not directly interfere in the observed variations in the activity concentrations of 226Ra, 232Th and 40K sands. The assessment of the annual effective dose to an individual from the public who attends the Camburi Beach throughout 8 hours per day in a month, in January or July, showed that all values are below the limit of 1 mSv.y-1 , recommended by the ICRP 60 for the general public.

Entender os processos morfodinâmicos de uma determinada região costeira frente a ações naturais e antrópicas é de grande importância para o uso, manutenção e conservação destes ambientes. A Ponta da Praia (Santos, SP) vem sofrendo modificações significativas após a urbanização da Baixada Santista e a construção do Porto de Santos, e vem apresentando aceleração no processo de erosão, sendo necessária a sua manutenção. Para isso, o monitoramento e compreensão dos processos responsáveis pelo comportamento morfodinâmico da praia são de fundamental importância. Neste trabalho buscou-se a melhor compreensão dos processos erosivos da região e, para alcançar os objetivos foram feitos estudos, de forma contínua, da variabilidade da topografia praial em conjunto com a caracterização dos sedimentos superficiais no setor emerso, combinados com o monitoramento meteorológico e do regime de frentes frias da região. Os resultados fornecem informações sobre o comportamento morfo-sedimentar da praia, sua taxa de erosão e suas relações com as forçantes e manutenções realizadas durante o período de estudo, mostrando que mesmo em curto prazo a alimentação artificial não é eficaz. / To understand the morphodynamic processes in a given coastal region facing natural and human actions have great importance for the use, maintenance and conservation of these environments. The Ponta da Praia (Santos, SP) has undergone significant changes after urbanization of Santos and the construction of the Port of Santos, and has shown acceleration in the erosion process, so their maintenance is required. For this, the monitoring and understanding of the processes responsible for the behavior of morphodynamic beach are of fundamental importance. In this study we sought to better understand the erosion processes in the region and to achieve the objective studies were made continuously, of the variability of praial topography together with the characterization of surface sediments in the emerged sector, combined with meteorological monitoring and the system of cold fronts in the region. The results provide information about the morpho-sedimentary behavior of the beach, its rate of erosion and its relations with the forcings and maintenance performed during the study period, showing that even in a short term perspective, the artificial load isn\'t effective.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-12-18T15:52:54Z No. of bitstreams: 1 Camila Eberhardt_.pdf: 56257631 bytes, checksum: 6af6d8b097ca2109b0e89a2f9798ed0a (MD5) / Made available in DSpace on 2018-12-18T15:52:54Z (GMT). No. of bitstreams: 1 Camila Eberhardt_.pdf: 56257631 bytes, checksum: 6af6d8b097ca2109b0e89a2f9798ed0a (MD5) Previous issue date: 2018-10-05 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / A tese “Um Mar de Imagens: Representações Imagéticas do município de Torres (1930-1960)” procura identificar as diferentes imagens que foram produzidas sobre Torres, além da tradicional representação de que Torres significa praia e, dessa forma, conhecer a história e a memória do município durante esse período entre 1930 a 1960. Para tanto a presente tese analisa dois acervos iconográficos: o acervo Banco de Imagens e Sons desenvolvido pela Ulbra, Campus Torres, que possui 2.647 fotografias; e o acervo da Casa de Cultura, organizado pelo município de Torres, que conta com 1.100 fotografias. Deste modo, trabalhamos com temáticas visuais que foram criadas para atender à complexidade dos acervos, não restringimos a análise somente à cidade, mas também adentramos nos territórios pertencentes ao interior do município. O trabalho realizado pelo estúdio fotográfico Feltes foi observado no decorrer da pesquisa pois compreendeu um importante estúdio fotográfico no município de Torres entre os anos de 1930 a 1960. Ao mesmo tempo, analisamos a Revista do Globo que atuou entre os anos de 1929 a 1967. Por meio da revista, podemos compreender as representações sobre praia e alegria que em inúmeras reportagens foram adjetivos destinados à praia de Torres. As imagens realizadas no município de Torres entre os anos de 1930 a 1960 e preservadas por meio dos acervos analisados, juntamente com as reportagens da Revista do Globo, permitiram a compreensão da história e da memória do município em que diferentes aspectos socioculturais estiveram presentes. / The thesis "A Sea of Images: Imaginary Representations of the municipality of Torres (1930-1960)" seeks to identify the different images that were produced about Torres, besides the traditional representation of what Torres means beach and, thus, to know the history and the memory of the municipality during this period between 1930 and 1960. For this purpose, the present thesis analyzes two collections of images: the Collection of Images and Sounds developed by Ulbra, Campus Torres, which has 2,647 photographs; and the collection of the House of Culture, organized by the municipality of Torres, which has 1,100 photographs. In this way, we work with visual themes that were created to meet the complexity of the collections, do not restrict the analysis to the city only, but also enter the territories belonging to the interior of the municipality. The work carried out by the photographic studio Feltes was observed in the course of the research because it comprised an important photographic studio in the municipality of Torres between the years of 1930 to 1960. At the same time, we analyzed the Globe Magazine that acted between the years of 1929 to 1967. Through the magazine, we can understand the representations about beach and joy that in numerous reports were adjectives destined to Torres beach. The images made in the municipality of Torres between the years 1930 and 1960 and preserved through the analyzed collections, together with the reports of the Globe Magazine, allowed the understanding of the history and memory of the municipality in which different socio-cultural aspects were present.

Entender os processos morfodinâmicos de uma determinada região costeira frente a ações naturais e antrópicas é de grande importância para o uso, manutenção e conservação destes ambientes. A Ponta da Praia (Santos, SP) vem sofrendo modificações significativas após a urbanização da Baixada Santista e a construção do Porto de Santos, e vem apresentando aceleração no processo de erosão, sendo necessária a sua manutenção. Para isso, o monitoramento e compreensão dos processos responsáveis pelo comportamento morfodinâmico da praia são de fundamental importância. Neste trabalho buscou-se a melhor compreensão dos processos erosivos da região e, para alcançar os objetivos foram feitos estudos, de forma contínua, da variabilidade da topografia praial em conjunto com a caracterização dos sedimentos superficiais no setor emerso, combinados com o monitoramento meteorológico e do regime de frentes frias da região. Os resultados fornecem informações sobre o comportamento morfo-sedimentar da praia, sua taxa de erosão e suas relações com as forçantes e manutenções realizadas durante o período de estudo, mostrando que mesmo em curto prazo a alimentação artificial não é eficaz. / To understand the morphodynamic processes in a given coastal region facing natural and human actions have great importance for the use, maintenance and conservation of these environments. The Ponta da Praia (Santos, SP) has undergone significant changes after urbanization of Santos and the construction of the Port of Santos, and has shown acceleration in the erosion process, so their maintenance is required. For this, the monitoring and understanding of the processes responsible for the behavior of morphodynamic beach are of fundamental importance. In this study we sought to better understand the erosion processes in the region and to achieve the objective studies were made continuously, of the variability of praial topography together with the characterization of surface sediments in the emerged sector, combined with meteorological monitoring and the system of cold fronts in the region. The results provide information about the morpho-sedimentary behavior of the beach, its rate of erosion and its relations with the forcings and maintenance performed during the study period, showing that even in a short term perspective, the artificial load isn\'t effective.

A análise dos parâmetros morfométricos publicados buscou relacionar o comportamento morfodinâmico praial com o da barreira costeira holocênica no estado do Rio Grande do Sul (RS), para estabelecer de que maneira estes ambientes estão relacionados. Foram analisados os dados de 31 praias, de Torres ao Chuí, possibilitando uma revisão e reavaliação dos estágios morfodinâmicos, com a compartimentação destes locais em cinco grupos, baseados em sua morfodinâmica e mobilidade praial. O grupo 1 é composto pelas praias intermediárias de mobilidade moderada à alta, que estão em sua maioria localizadas no litoral médio do RS correspondente a barreira agradacional, com alto desenvolvimento de campos de dunas transgressivas e dunas frontais, e estão também associadas às praias com característica retrogradante da barreira, porção sul da barreira agradacional. O grupo 2 compõe as praias dissipativas, com estágio intermediário ocorrendo de maneira secundária, de moderada à alta mobilidade, associadas a barreira progradante do litoral norte. Este setor apesar de apresentar alto potencial de transporte sedimentar por ventos e por ondas não apresenta campos de dunas bem desenvolvidos, onde o aporte sedimentar favorece a progradação costeira. O grupo 3 é formado por praias intermediárias de baixa mobilidade, associadas à porção norte da barreira agradacional e às praias do litoral sul que representam a transição entre a barreira progradante e retrogradante. No litoral médio a associação da baixa mobilidade praial com a alta capacidade de transporte e disponibilidade sedimentar, resultante do transporte sedimentar pelo vento no sentido continental, permitiu o desenvolvimento de grandes campos de dunas transgressivos e de dunas frontais. O grupo 4 é constituído por praias dissipativas e secundariamente intermediárias, de baixa mobilidade, da barreira progradante do litoral sul, que não desenvolveu vastos campos de dunas, semelhante ao que ocorre na barreira progradante ao norte. O grupo 5 é formado por duas praias diferenciadas, onde o estágio intermediário predomina e o refletivo ocorre eventualmente no verão, e estão localizadas em barreiras retrogradantes. As praias dissipativas são responsáveis por remobilizar o maior volume sedimentar da antepraia ao ambiente praial, onde integra o processo de progradação costeira. A porção da barreira agradacional, responsável pelas maiores dunas frontais, apresenta a menor mobilidade, sendo que conforme sua mobilidade é aumentada em direção ao sul, os maiores campos de dunas transgressivas ocorrem. Os estágios intermediários possuem energia suficiente para transportar sedimentos da antepraia para a praia, enquanto que a formação ou não das dunas é influenciada pelo potencial de transporte do vento NE e pela orientação da linha de costa com relação a este vento. As barreiras retrogradantes estão associadas a estágios intermediários de mobilidade variável, sendo que os dois focos erosivos do estado estão associados à alta mobilidade, o qual deixa estes ambientes susceptíveis aos episódios de erosão durante a passagem de eventos de tempestades. Assim, o caráter erosivo da barreira pode estar associado tanto com a energia de ondas, quanto com uma antepraia irregular e um déficit sedimentar, que acarreta em variações na morfodinâmica praial. / The analysis of the morphometric parameters of the published works about beach morphodynamics in the State of Rio Grande do Sul had the objective to relate the morphodynamic behavior of the beach with the holocene coastal barrier, in order to establish how these environments are related. The data of 31 beaches were analyzed, allowing a review and reevaluation of the morphodynamic stages, with the compartmentalization of these sites in five groups, based on their morphodynamics and beach mobility. Group 1 is composed of intermediate beaches with moderate to high mobility, which are located in the middle coast corresponding to the aggradational barrier, with high development of transgressive dunes and foredunes, and, associated too with the beaches with retrogradational characteristics of the barrier. Group 2 consists of dissipative beaches, with intermediate stage occurring in a secondary way, being these from moderate to high mobility, associated with the progradational barrier of the north coast. This sector, despite to present a high potential for sediment transport by winds and waves, does not have well development dunefields, where the sediment budget supports coastal progradation. Group 3 is formed by intermediate beaches of low mobility, associated with the northern portion of the aggradational barrier and the beaches of the south coast that represent the transition between the prograded and retrograded barrier. In the middle coast, the association of low beach mobility with high transport capacity and sedimentary availability, and the resulting of the sedimentary transport by wind onshore, allowed the development of large transgressive dunefields and foredunes. Group 4 consists of dissipative and secondarily intermediate beaches, with low mobility, of the progradational barrier of the south coast, which, similar to what occurs in the progradational barrier of the north, did not develop largest dune fields. Group 5 is formed by two beaches with peculiar characteristics, where the intermediate stage predominates and the reflective occurs eventually in the summer, associated with the retrograded barrier. The dissipative beaches are responsible for remobilizing highs sediments volumes of the shoreface and provide to the beach environment, where, in this case, it is converted into coastal progradation. The portion of the aggradational barrier responsible for the largest frontal dunes presents the smaller mobility, and as its mobility is increased towards the south, the largest transgressive dunefields in the state occurs. The intermediate stages have enough energy to carry sediments from the shoreface to the beach, while the formation of the dunes is influenced by the transport potential of the NE wind and by the orientation of the coastline in relation to this wind. Retrograded barriers are associated to intermediary stages of variable mobility, and the two erosive hotspots of the state are associated with high mobility, which turns these environments susceptible to erosion episodes during the passing of storm events. Thus, the erosive character of the barrier may be associated with both wave energy and an irregular shoreface and a negative sediment budget, which leads to variations in beach morphodynamics.

Orientador: José Carlos Casagrande / Banca: Márcio Roberto Soares / Banca: Rose Mary Reis Duarte / Banca: João Antonio Galbiatti / Banca: Reinaldo Monteiro / Resumo: Este trabalho abrangeu o Litoral do Estado de São Paulo, desde Ubatuba - litoral norte (Parque Estadual da Serra do Mar - Núcleo de Picinguaba e Parque Estadual da Ilha Anchieta) até a Ilha do Cardoso - litoral sul (Estação Ecológica Juréia-Itatins, Vila de Pedrinhas no município de Ilha Comprida e Parque Estadual da Ilha do Cardoso). Os objetivos foram: correlacionar a floresta baixa e alta de restinga com os parâmetros químicos e físicos do solo, caracterizar o estrato arbóreo de florestas de restinga alta e baixa do litoral do estado de São Paulo, verificar se há similaridade florística entre as áreas e analisar se a similaridade está associada ao solo. A amostragem do solo foi realizada nas profundidades 0 - 5, 5 - 10, 10 - 15, 15 - 20, 0 - 20, 20 - 40 e 40 - 60 cm. Para cada profundidade foram analisados pH, M.O., P, K, Ca, Mg, Al, H+Al, m, SB, CTC e V e análises granulométricas. A amostragem das espécies arbóreas foi feita por meio do "método de quadrantes". O critério para inclusão amostral considerou todos os indivíduos arbóreos com diâmetro à altura do peito (DAP) maior ou igual a 1,6 cm, inclusive aqueles que apresentavam duas ou mais ramificações do caule abaixo de 1,30 m, cuja soma dos DAPs fosse igual ou maior do que 1,6 cm. Para as análises multivariadas, foram utilizadas amostras de solo na profundidade 0 - 10 cm. Os resultados foram: Independentemente dos processos geológicos, os solos de restinga são semelhantes entre si, quanto a sua fertilidade e textura; Nas áreas em que ocorreram solos espódicos (floresta alta e baixa de restinga da Ilha Anchieta e floresta alta da Juréia - Itatins), ocorre valores mais elevados, em profundidade, de matéria orgânica, CTC e alumínio; Os solos de floresta de restinga alta... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work covered the coast of São Paulo, from Ubatuba - north coast (Serra do Mar State Park - Picinguaba core and Ilha Anchieta State Park) to Ilha do Cardoso - south coast (Juréia Ecological Station - Itatins, Vila de Pedrinhas in the city of Ilha Comprida and the Cardoso Island State Park). The objectives were: to correlate low and high restinga forest with the soil's chemical and physical parameters, characterize the tree layer of high and low restinga forest of São Paulo Coast, verify if there is any vegetation similarity among the areas and to analyze if similarity is associated to the soil. Soil sampling was made at 0 - 5, 5 - 10, 10 - 15, 15 - 20, 0 - 20, 20 - 40 e 40 - 60 cm depth. For each depth pH, M.O., P, K, Ca, Mg, S, Al, H+Al, Na, B, Cu, Fe, Mn, Zn, m, SB, CTC e V and granulometric analysis were carried. Tree species sampling was done through the "quarter method". For multivariate analysis, soil samples used were of 0 - 10 cm depth. The criterion for inclusion in the sample considered all trees with diameter at chest height (DCH) greater than or equal to 1.6 cm, including those who had two or more branches below 1.30 m, whose sum of DCHs were equal to or greater than 1.6 cm. The results showed that regardless of the geological processes, the resting soils are similar to each other about their fertility and texture; In areas where spodic soils occurred (high and low restinga forest at Ilha Anchieta and high forest at Juréia - Itatins) higher values in depth, organic matter, CTC and aluminum are presented; high and low resting forest soils are naturally low in nutrients, with the largest reserves concentrated in the depths 0 - 5, 5 - 10 and 0 - 20 cm; Sand fraction is dominant for all high and low restinga forest areas studied, always... (Complete abstract click electronic access below) / Doutor

Nas últimas décadas, a praia de Massaguaçu vem sofrendo processos erosivos intensos, cujos segmentos possuem taxas de recuo acentuadas, denominadas Zonas de Erosão Acentuada (ZEAs). Partindo deste problema este trabalho se propôs a entender a dinâmica sedimentar do arco praial de Massaguaçu e das possíveis causas de formação e manutenção das ZEAs. A coleta de dados se baseou no levantamento batimétrico e do clima de ondas, bem como no levantamento sonográfico de varredura lateral e na coleta de amostras de sedimento de superfície da antepraia de Massaguaçu. Para processar os dados se optou pela aplicação da modelagem numérica utilizando o modelo SWAN (propagação de ondas em águas profundas) e o modelo SMC (módulos OLUCA, COPLA e EROS, que trabalham, respectivamente, com propagação de ondas em águas rasas, simulação de correntes e simulação de transporte sedimentar). Para a formulação da discussão foram selecionados os 6 (seis) casos que apresentaram as condições de ondas mais representativas. Tais casos mostraram que a dinâmica sedimentar e os processos costeiros responsáveis pela formação e manutenção das ZEAs são controlados por dois padrões distintos de ondas incidentes. O primeiro padrão está relacionado às ondas vindas de NE - E, que geram correntes longitudinais para o sul. Suas correntes longitudinais e transversais à costa são de baixa intensidade resultando em um transporte sedimentar e em variações da morfologia praial menos intensos, além de formar células de circulação em vórtices. O segundo padrão, por sua vez, está relacionado às ondas oriundas SSE - SE - ESSE, cujas correntes litorâneas longitudinais rumam ao norte. Tais correntes longitudinais e transversais à costa, apresentam uma intensidade maior, portanto o transporte sedimentar e as variações da morfologia ao longo do arco praial são maiores bem como as células de circulação em vórtices. Partindo desses resultados, percebeu-se que as ZEAs em Massaguaçu estão ligadas a um possível aumento na frequência e na intensidade das tempestades ao longo das últimas décadas e até o presente momento, não há mecanismos naturais que revertam esta retração da linha de costa. / Over the past decades in Massaguaçu beach has happening a strong erosion process with segments that have higher retreat rates, commonly termed as Erosional Hot Spots (EHSs). This research aims the understanding of the sedimentary dynamics along the Massaguaçu embayment and also the possible causes of the formation and maintenance of the EHSs. The methodology was separately on two steps. At first we collected bathymetry, wave and side-scan sonar data, and samples of the surface sediments from the shoreface of Massaguaçu beach. Later, to analyze majority data, we chose to use numerical modeling based on the SWAN model (propagation of waves in deep water) and SMC model (modules OLUCA, COPLA and EROS, that work respectively with the propagation of waves in shallow water, the simulation of currents and finally the simulation of sediment transport). After modeling, we were able to select the 6 (six) most representative wave conditions cases. Those results show that the control of the sediment dynamics and the coastal processes responsible for the formation and the maintenance of ZEA are based on the characteristics of the incident waves. On trying to explain that process, it was possible to recognize two distinct patterns. The first pattern observed is associated with the NE - E waves, generating longshore currents to the south. In this case, both the longshore and the crosshore currents are less intense, forming cells circulation in vortex, resulting in minor variations in sediment transport and beach morphology. The second pattern is related with the SSE - SE - ESE waves, generating longshore currents to the north. In this case both the longshore and the crosshore currents are more intense, although still with occurrence of forming cells circulation in vortex, resulting in a larger sediment transport and morphological changes along the beach. Finally, what we have seem was that the ZEAs in Massaguaçu are possibly linked to a potential increment on storms frequency and intensity over the past decades and unfortunately, at present, there is still no mechanism to recover this natural retreat of the coastline.

Understanding the behaviour of waves and their interaction with the coast is vital for marine engineers and maritime planners. As sea levels rise due to climate change, low-lying coastal areas and existing sea defences will become increasingly vulnerable to run-up and overtopping by large wave events. Accurate and effcient numerical models are essential tools for the assessment of such events and the impact they have on the coast so that effective coastal protection can be designed. This thesis presents a depth-integrated numerical solver with two horizontal dimensions for modelling waves in the coastal zone from intermediate depth to zero depth. Pre-breaking, the evolution of the water surface is calculated using the enhanced Boussinesq equation set of Madsen and Sorensen (1992). This equation set has improved dispersion characteristics over the classical Boussinesq equations, but with relatively few terms compared to models based on the Navier-Stokes equations, allowing for more effcient numerical modelling while maintaining suffcient accuracy. The equations are discretised using second-order finite differences and solved using the conjugate gradient method with fourth-order Runge-Kutta time stepping. Switching from the Boussinesq equation set to the shallow water equations allows shoaling waves to break, with the broken waves then propagating as bores. The shallow water equations are solved using a finite volume MUSCL-Hancock scheme with an HLLC approximate Riemann solver in order to resolve the behaviour of steep-fronted bores at the shore. The model incorporates a wetting and drying algorithm that models the moving wet/dry front. Waves are generated by a line of independently moving piston paddles, allowing full replication of laboratory experiments. A mapping technique is used in the region of the paddles to map the moving physical domain onto a fixed computational domain to facilitate the solution of the governing equations. Different aspects of the model are verified using standard benchmark tests. The complete model is then validated by comparing the numerical simulation of laboratory experiments with high quality experimental data from the UK Coastal Research Facility (UKCRF). The laboratory experiments simulated include the interaction of regular waves with sinusoidal and tri-cuspate beaches, and the interaction of both uni-directional and multi-directional focused wave groups with a plane beach. It is found that the model provides satisfactory wave phase resolution and reproduces most of the flow features of waves and currents in the shallow nearshore environment.