A investigação dos movimentos morfológicos da embocadura de canais e de linhas de praia pode ser instrumental para a descrição da influência de processos costeiros de curto prazo. A Lagoa do Peixe (LP) encontra-se dentro do Parque Nacional da Lagoa do Peixe (PNLP), 344 km², litoral médio da Planície Costeira do Rio Grande do Sul. O objetivo desse trabalho foi descrever o comportamento morfodinâmico da embocadura do canal, sua instabilidade, geometria, caracterização geomorfológica e a análise da variabilidade da posição da linha de praia adjacente, entre 1987 e 2009. A partir do conjunto de imagens LANDSAT (1973 a 2009) e de técnicas de geoprocessamento, foram analisadas as características morfológicas e a dinâmica do canal. O movimento de curto prazo na linha de praia foi avaliado a partir de imagens LANDSAT TM vetorizadas (1987 e 2009) pelo método dos pontos extremos. Os resultados foram comparados a modelos numéricos, possibilitando a descrição de um canal de maré com um mecanismo de assoreamento morfodinâmico. A região do PNLP sofre a influência da variabilidade do seu regime de precipitação sazonal, onde o maior volume de chuvas ocorre no inverno. Esse regime pluviométrico é associado às correntes litorâneas de SW, que tem de maior capacidade de deriva que as correntes de NE, mais frequentes no verão. A abertura natural do canal ocorreu no biênio: 1997-1998, onde os totais de precipitação anual foram de 400 mm acima da média para a região do PNLP (1265 mm). O assoreamento do canal da LP esta relacionado à diminuição do volume de chuvas. Com a aproximação do verão, o transporte de sedimentos, promovido pelos ventos e correntes de NE, é menos competente, porem de maior frequência, contribuindo para a formação de pontais que se desenvolvem no sentindo das correntes. A análise da variabilidade da posição da linha de praia adjacente ao PNLP acusou um processo progradante ao norte do canal (até 40 m) e retrogradante ao sul (máximo 80 m). Esses resultados são compatíveis com outros resultados oferecidos pela literatura respectiva. / The investigation of morphological change in lagoonal inlets and shorelines can be instrumental to describe the influence of short term coastal processes. The Lagoa do Peixe (LP) is set within the Parque Nacional da Lagoa do Peixe (PNLP), 344 km², located on the mid-section of the Rio Grande do Sul coastal plain. The objective of this work was to describe the morphodynamic behavior of inlet, its instability, geometry and geomorphologic characteristics, as well as an analysis of the variability of the adjacent shoreline position, between 1987 e 2009. A set of LANDSAT images (from 1973 to 2009) and geoprocessing techniques were employed to analyze the morphologic characteristics and dynamics of the LP channel. Short term movements of the shoreline were evaluated from the vectorized LANDSAT TM imagery (1987 and 2009), using the extreme points method. The results were compared to numerical models, which made it possible to describe a tidal inlet with a morphodynamic sedimentation mechanism. The PNLP region is influenced by the variability of its precipitation regime, in which larger precipitation volumes occur in winter. This pluviometric regime is associated to the longshore SW currents which have a greater drifting capacity than the NW currents, more frequent in summer. The natural opening of the channel occurred in the two-year periods of 1997-1998, where total annual precipitation was 400 mm above the average for the PNLP region (1265 mm). LP channel sedimentation is related to the lowering of rain volumes. With the progression of summer, sediment transport promoted by wind and NE currents, is less competent, although more frequent, contributing to the formation of spits that develop siding the currents. Analyses of the variability of PNLP adjacent coastline position indicated a progradation process to the north of the channel (up to 40 m) and a retrogradation process to the south (maximum of 80 m). These results are compatible with other assessments offered by the respective literature.

A investigação dos movimentos morfológicos da embocadura de canais e de linhas de praia pode ser instrumental para a descrição da influência de processos costeiros de curto prazo. A Lagoa do Peixe (LP) encontra-se dentro do Parque Nacional da Lagoa do Peixe (PNLP), 344 km², litoral médio da Planície Costeira do Rio Grande do Sul. O objetivo desse trabalho foi descrever o comportamento morfodinâmico da embocadura do canal, sua instabilidade, geometria, caracterização geomorfológica e a análise da variabilidade da posição da linha de praia adjacente, entre 1987 e 2009. A partir do conjunto de imagens LANDSAT (1973 a 2009) e de técnicas de geoprocessamento, foram analisadas as características morfológicas e a dinâmica do canal. O movimento de curto prazo na linha de praia foi avaliado a partir de imagens LANDSAT TM vetorizadas (1987 e 2009) pelo método dos pontos extremos. Os resultados foram comparados a modelos numéricos, possibilitando a descrição de um canal de maré com um mecanismo de assoreamento morfodinâmico. A região do PNLP sofre a influência da variabilidade do seu regime de precipitação sazonal, onde o maior volume de chuvas ocorre no inverno. Esse regime pluviométrico é associado às correntes litorâneas de SW, que tem de maior capacidade de deriva que as correntes de NE, mais frequentes no verão. A abertura natural do canal ocorreu no biênio: 1997-1998, onde os totais de precipitação anual foram de 400 mm acima da média para a região do PNLP (1265 mm). O assoreamento do canal da LP esta relacionado à diminuição do volume de chuvas. Com a aproximação do verão, o transporte de sedimentos, promovido pelos ventos e correntes de NE, é menos competente, porem de maior frequência, contribuindo para a formação de pontais que se desenvolvem no sentindo das correntes. A análise da variabilidade da posição da linha de praia adjacente ao PNLP acusou um processo progradante ao norte do canal (até 40 m) e retrogradante ao sul (máximo 80 m). Esses resultados são compatíveis com outros resultados oferecidos pela literatura respectiva. / The investigation of morphological change in lagoonal inlets and shorelines can be instrumental to describe the influence of short term coastal processes. The Lagoa do Peixe (LP) is set within the Parque Nacional da Lagoa do Peixe (PNLP), 344 km², located on the mid-section of the Rio Grande do Sul coastal plain. The objective of this work was to describe the morphodynamic behavior of inlet, its instability, geometry and geomorphologic characteristics, as well as an analysis of the variability of the adjacent shoreline position, between 1987 e 2009. A set of LANDSAT images (from 1973 to 2009) and geoprocessing techniques were employed to analyze the morphologic characteristics and dynamics of the LP channel. Short term movements of the shoreline were evaluated from the vectorized LANDSAT TM imagery (1987 and 2009), using the extreme points method. The results were compared to numerical models, which made it possible to describe a tidal inlet with a morphodynamic sedimentation mechanism. The PNLP region is influenced by the variability of its precipitation regime, in which larger precipitation volumes occur in winter. This pluviometric regime is associated to the longshore SW currents which have a greater drifting capacity than the NW currents, more frequent in summer. The natural opening of the channel occurred in the two-year periods of 1997-1998, where total annual precipitation was 400 mm above the average for the PNLP region (1265 mm). LP channel sedimentation is related to the lowering of rain volumes. With the progression of summer, sediment transport promoted by wind and NE currents, is less competent, although more frequent, contributing to the formation of spits that develop siding the currents. Analyses of the variability of PNLP adjacent coastline position indicated a progradation process to the north of the channel (up to 40 m) and a retrogradation process to the south (maximum of 80 m). These results are compatible with other assessments offered by the respective literature.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2017-02-01T18:49:55Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DIssertação Marcelo Menezes.pdf: 4580515 bytes, checksum: ac44866119de747b2c71f8f144475144 (MD5) / Made available in DSpace on 2017-02-01T18:49:55Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DIssertação Marcelo Menezes.pdf: 4580515 bytes, checksum: ac44866119de747b2c71f8f144475144 (MD5) Previous issue date: 2016-08-01 / Esta pesquisa foi realizada no munícipio de Goiana, litoral Norte do Estado de Pernambuco (Bacia da Paraíba), entre as praias de Ponta do Funil e Carne de Vaca. O trabalho teve intuito de levantar informações sobre o sistema costeiro, com base na caracterização morfodinâmica e geoambiental, quantificando o balanço sedimentar e a vulnerabilidade das praias. Para isto fez-se um monitoramento bimestral com levantamento de perfis topográficos e coletas de sedimentos no estirâncio entre os meses de novembro/2014 e setembro/2015. Na correlação dos perfis topográficos associados à sedimentologia das amostras, os resultados indicaram que o balanço sedimentar foi positivo (deposicional) em seis pontos, sendo o perfil praial P5, na praia de Ponta de Pedras, onde houve a maior variação com +281,5m³/m. No perfil praial P1, na praia de Ponta do Funil, foi o único que obteve variação do volume negativa (retrogradacional). No levantamento da linha de preamar máxima, constatou-se a retrogradação no litoral sul e progradação no litoral norte. Os indicadores utilizados revelaram um litoral moderadamente preservado com 69% estabilizado apresentando feições geomorfológicas típicas do ambiente praial, como as escarpas de berma e 31% com obras de proteção costeira, na maioria dos casos sem fundamentação técnica adequada. A porção mais vulnerável da área encontra-se na praia de Catuama, local onde há grande número de casas construídas na pós-praia e até mesmo no estirâncio. / This research was conducted in an area in the municipality of Goiana, northern coast of the state of Pernambuco (Paraíba Basin), located between the Ponta do Funil and Carne de Vaca beaches. The main goal of the work was to obtain information concerning the coastal system, based upon the morphodynamic and environmental quantification of the sedimentary balance and the vulnerability of these beaches. To accomplish that, topographic profiles were conducted with intervals of two months and samples of sediments were collected in the foreshore during the period from November/2014 and September/2015. The correlation of the topographic profiles with the sedimentary characteristics of the collected samples, it was clear that the sedimentary balance was positive (depositional) for six points, with the P5 beach profile, located in the Ponta de Pedras beach, showing the larger variation +281,5m³/m. The P1 beach profile, located in the Ponta do Funil, was the only one to show negative variation of volume (retrogression). During the definition of the line of maximum high tide, it was observed a retrogression on the south coast and progradation on the north coast. The parameters used revealed a moderately preserved coast, with 69% of stabilization showing morphologic features typical of environment with berm scarps and 31% with civil engineering construction to protect the coast; most of them without technical support. The most vulnerable section of the coast was located in the Catuama beach, due to the large number of houses constructed in the post-beach and some involving the foreshore.

The coastal landscape of the named area Zona de Expansão (Expansion Zone) located in the city of Aracaju, the capital of the state of Sergipe, in the Northeast of Brazil, can be characterized by its genetic features and, by anthropic and natural dynamics. Thus, this study, based on the landscape analytical category, aimed to analyze the short, medium and long terms evolution of the physical and anthropic structurings. For this, the vectors and axes of occupation, the landscape units and shoreline evolution were analyzed. The method used was based on literature review, field work and, shoreline and landscape units mapping for a range of different time (1965, 1971, 1978, 1986, 2003 and 2008). It was established as occupation vectors: the state policies; the real estate action; the 2nd residences s and; the tourism. Moreover, the occupation axes were determined by the urban infra-structures such as Náufragos´s road, José Sarney´s road and Joel Silveira´s bridge, as well as the installation of urban equipment dedicated to human occupancy and tourism. The landscape units identified were: Marine Terrace, Dune/Interdune, Tidal Plain, Beach/Foredune and Anthropogenic Intervention. The combination of occupation and development variables has directly influenced the landscape which experimented an increasing of occupancy over the natural units, specially from the 1980´s on. Nevertheless, the natural landscape units still predominate in the landscape. Concerning the evolutionary studies of the shoreline, the data obtained from this research show that most of the investigated shoreline has remained relatively stable over the last 40 years. Only short shoreline variations caused by erosion or progradation have been verified. The only exception of the stable status aforementioned was observed in the shoreline of the southernmost section, as well at Vaza-Barris river mouth, where a high variability of sedimentation determined by the ebb-tidal delta dynamics has been found. This study has also verified the formation of a sandy spit on the left margin of the Vaza-Barris river which has influenced the configuration of the shoreline and landscape of that area. Based on the occupancy level verified in the vicinity of the studied shoreline , there are few areas that pose risks to occupation. However, the coastal zone may suffer due to a potential risk related to the population increase. Finally, the result of this study has emphasized the importance of human occupation planning over the natural landscape units as well as the nearby shorelines, in order to avoid potentially irreversible urban and environmental damages. / A paisagem costeira da Zona de Expansão de Aracaju, Sergipe, NE do Brasil, distingue-se por suas características genéticas e sua dinâmica natural e antrópica. Assim, o presente estudo, o qual se baseou na categoria analítica paisagem, teve por objetivo analisar a evolução dos estruturantes físicos e antrópicos a longo, médio e curto prazos, a partir da determinação: dos vetores e eixos estruturantes da ocupação; dos estudos evolutivos das unidades de paisagem e, do posicionamento da linha de costa e da ocupação antrópica. Os procedimentos metodológicos utilizados foram: levantamento bibliográfico, trabalho de campo e mapeamento das unidades de paisagem e da linha de costa para diferentes anos (1965, 1971, 1978, 1986, 2003 e 2008). Foram estabelecidos como vetores de ocupação da Zona de Expansão: a ação estatal, a ação imobiliária, as segundas residências e o turismo. Os eixos de ocupação foram definidos pelas rodovias dos Náufragos e José Sarney, ponte Joel Silveira, assim como, de aparatos destinados à ocupação e ao turismo. As unidades de paisagem individualizadas foram individualizadas em: Terraço Marinho, Duna/Interduna, Planície de Maré, Praia/Duna Frontal e Intervenção Antrópica. A ação dos vetores de ocupação materializou-se na paisagem, em que foi verificado o aumento de áreas ocupadas e parcialmente ocupadas sobre as unidades de paisagem natural, principalmente após a década de 80. Apesar do crescente aumento da Unidade de Intervenção Antrópica, as unidades de paisagem natural ainda preponderam na paisagem. No que se refere ao estudo evolutivo da linha de costa, os resultados obtidos evidenciam que a maior parte da linha de costa da área investigada apresentou-se estável nos últimos 40 anos, com pequenas variações decorrentes da erosão ou progradação. A exceção desta tendência foi verificada na linha de costa do setor sul, nas adjacências da desembocadura do rio Vaza-Barris, em que se constatou alta variabilidade em função da dinâmica do delta de maré-vazante. Destaca-se, ainda, a formação de um pontal arenoso na margem esquerda do rio Vaza-Barris, que influenciou na configuração da linha de costa e da paisagem desta área. Com base no nível de ocupação verificado nas proximidades da linha de costa estudada, evidenciou-se que poucas áreas apresentam riscos à ocupação. Esse fato não exclui a presença de risco em potencial em grande parte da frente litorânea em função do aumento populacional. Com base nos resultados obtidos nesta pesquisa, enfatiza-se a importância do planejamento da ocupação sobre as unidades de paisagem natural e nas proximidades da linha de costa, a fim de evitar e minimizar futuros problemas urbano-ambientais.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study is to understand the coastal landscape dynamics of the Coroa do Meio e Atalaia in Aracaju-SE. The methodological approach used was: literature review; landscape units and shoreline mapping for a range of different time (1955, 1965, 1978, 1984, 2003 e 2008); shoreline monitoring using beach profiles done between 2008 and 2010; work field and Gis-based environmental data integration. The following landscape units were identified: Beach, Dune/Interdune, Fluviomarine Terrace, Tidal Plain and Human Occupation. The results showed that the landscape changes were primarily due to the expansion of the Human Occupancy, which contributed to the reduction of other landscape units. The remaining units in 2008 were: Tidal Plain, Beach and Human Occupation. The shoreline analysis showed that between 1955 and 2008 progradation occurred at the Atalaia beach and high variability occurred at Artistas beach. The Atalaia beach progradation has been identified since 1984, after stabilization of the right bank of the Sergipe river mouth. The great shoreline variability was not directly influenced by the occupation expansion area; before occupation, shoreline retreat episodes have been recorded. However, the occupation expansion area contributed to make evident the erosion episodes at the Artistas beach. In the short-term analysis of the Artistas beach, the sediment budget was positive between 2008 and 2009 and negative between 2009 to 2010. This analysis confirms the great variability of the shoreline due to the Sergipe river mouth dynamics. Finally, this study concluded that human occupation was the predominant landscape modeller agent, assuming two behaviors: i transformant agent: its expansion contributed to the decrease of the Dune / Interdune, Tidal Plain and Fluviomarine Terrace unit areas and, ii - transformant agent that suffer with its actions: shoreline progradation favored the occupation expansion over the accretional area and the shoreline retreat caused economic losses. Thus, this study provides subsidies for environmental planning of the study area. / O objetivo do presente trabalho é compreender a dinâmica da paisagem costeira da Coroa do Meio e Atalaia em Aracaju-SE. Os procedimentos metodológicos consistiram em: levantamento bibliográfico, mapeamento das unidades de paisagem e da linha de costa para diferentes anos (1955, 1965, 1978, 1984, 2003 e 2008); monitoramento da linha de costa através de perfis de praia realizados no período de 2008 a 2010; trabalho de campo; e integração dos dados ambientais. As seguintes unidades de paisagem foram identificadas: Praia, Duna/Interduna, Terraço Flúviomarinho, Planície de Maré e Ocupação Humana. Os resultados obtidos mostraram que as transformações ocorridas na paisagem ocorreram, predominantemente, em função da expansão da Ocupação Humana, que contribuiu para a redução das demais unidades de paisagem. Em 2008, restaram apenas as seguintes unidades: Planície de Maré, Praia e Ocupação Humana. A análise multitemporal da linha de costa mostrou que entre 1955 e 2008 ocorreu progradação na praia de Atalaia e grande variabilidade na praia dos Artistas. A progradação da praia de Atalaia foi identificada a partir de 1984, após a estabilização da margem direita da desembocadura do rio Sergipe. A grande variabilidade da linha de costa não foi influenciada diretamente pela expansão da ocupação; antes de existir ocupação, já haviam sido registrados episódios de recuo de linha de costa. Contudo, a expansão da ocupação humana contribuiu para tornar evidentes os episódios erosivos na praia dos Artistas. Na análise de curto prazo da praia dos Artistas, o balanço sedimentar foi positivo no período entre 2008 e 2009 e negativo no período de 2009 a 2010. Essa análise corrobora à grande variabilidade da linha de costa decorrente da dinâmica da desembocadura do rio Sergipe. Por fim, concluiu-se que a ocupação humana predominou como agente modelador da paisagem, assumindo dois comportamentos: i transformando: a sua expansão contribuiu para a redução da área das unidades Duna/Interduna, Planície de Maré e Terraço Flúviomarinho e; ii transformando e sofrendo com suas ações: a progradação da linha de costa favoreceu a expansão da ocupação sobre a área acrescida e o recuo da linha de costa causou prejuízos econômicos. Dessa forma, esse trabalho fornece subsídios ao planejamento ambiental da área estudada.

Egmont Key, located at the mouth of Tampa Bay, is part of a dynamic system with many interrelated natural and anthropogenic factors influencing its morphodynamics. This study started in August 2012. During the 3-year period until August 2015, 28 beach profile transects were established and surveyed 10 times. Seventeen historical aerial images from 1942 to 2013 were geo-rectified and analyzed. Three hundred and fourteen sediment samples were procured from the navigation channel dredge area and the beach nourishment area and analyzed for grain size. A numerical wave model was established to simulate the nearshore wave field. The overall goals of this study are to understand the complex morphodynamics of Egmont Key and to evaluate the shore-protection efforts. The overall area of the Egmont Key has reduced 52% from 2.1 km2 in 1942 to 1.o km2 in 2002. The area loss was mostly caused by beach erosion along the Gulf-facing beach. The island-area reduction from 1942 to 2002 was largely linear. Two periods of accelerated area loss from 1978-1984 and 1999-2002 can be related to dredging of the Egmont Channel and the disposal of dredged materials along the channel. Concerning the relatively high mud content in the borrow area for the 2014 nourishment, a large amount of the fine sediment was lost at a temporal scale of hours to days during the dredging and beach nourishment construction processes. Some of the mud was deposited outside the surf zone at water depths of 2 m or greater. This mud became eroded naturally by energetic conditions at a temporal scale of months. Beach erosion and accretion along the Gulf-facing beach can be related qualitatively to tidal flow patterns. Numerical wave modeling shows that the transverse bars offshore Egmont Key have a moderate influence on the wave field, leading to slightly different wave heights along the shoreline. However, there is no clear relationship between the nearshore wave conditions and the erosion/accretion patterns. The severe shoreline erosion has exposed various fort structures at the shoreline and in the nearshore zone. These structures function as detached breakwaters or groins and have localized influence on the beach state.

Muscovy ducks are native only to Central and South America, Mexico, and parts of southern Texas and are considered invasive in some areas outside of their native range. Although they have been introduced worldwide, they remain largely unstudied. The primary focus of this study was to relate Muscovy duck abundance to habitat characteristics of wetlands in Tampa, Florida. Muscovy abundance was measured using point count methods at 21 wetland sites that occur within an eight km radius of the University of South Florida’s main campus. Habitat features at these sites were assessed using field methods and Geographic Information Systems (GIS) (Arc 10.1v). Mann-Whitney U tests and Chi-squared tests were performed to identify significant differences between quantitative data groups. A Chi-squared test determined that there was not a positive correlation between Muscovy abundance and fountains or water regime, yet identified a significant relationship between Muscovy abundance and fencing, in which Muscovies did not frequently occupy ponds with fencing. Mann-Whitney U tests did not identify significances between Muscovy abundance and other habitat groups. Since Muscovy ducks are listed as an invasive species, identifying habitat preferences and deterrents will assist land managers and property owners with habitat modifications in preventing or controlling nuisance Muscovy populations.

Le but de cette étude était de développer une méthodologie pour évaluer la résilience des littoraux aux évènements de tempêtes, à des échelles de temps différentes pour une plage située à une latitude moyenne (Biscarrosse, France). Un site pilote des tropiques, la plage de Jamestown (Ghana), non soumis aux tempêtes, a également été analysé. 6 ans (2007-2012) de données sur la position du trait de côte,obtenues quotidiennement par imagerie vidéo, ainsi que les prévisions hydrodynamiques (ECMWF EraInterim) ont été analysées. Le climat de vagues est dominé par les tempêtes (Hs> 5% de seuil de dépassement) et leurs fluctuations saisonnières; 75% des tempêtes se produisent en hiver, et plus de 60tempêtes ont été identifiées au cours de la période d'étude. Une régression multiple, montre qu’alors que les intensités des tempêtes actuelle et précédente ont un rôle majeur sur l'impact de la tempête, la marée et les barres sableuses jouent un rôle majeur sur la récupération de plage. La position moyenne du trait de côte calculée sur la période de récupération post-tempête montre que la plage de Biscarrosse se reconstruit rapidement (9 jours) après un évènement isolé et que les séries de tempêtes (clusters) ont un effet cumulatif diminué. Les résultats indiquent que le récurrence individuelle des tempêtes est clé. Si l'intervalle entre deux tempêtes est faible par rapport à la période de récupération, la plage devient plus résistante aux tempêtes suivantes; par conséquent, la première tempête d’une série a un impact plus important que les suivantes. Le trait de côte répond, par ordre décroissant, aux évènements saisonniers,à la fréquence des tempête et aux d’échelle annuelle. La méthode EOF montre de bonnes capacité à séparer la dynamique « uniforme » et « non-uniforme » du littoral et décrit différentes variabilités temporelles: les échelles saisonnières et à court terme dominent, respectivement, la première EOF (2D)et le second mode (3D). Le littoral de Jamestown a été étudié comme base d’un projet pilote entre 2013-2014. Les fluctuations du niveau de l'eau jouent un rôle prédominant sur l’évolution de la position du trait de côte. Les vagues et les estimations des marées obtenues par l’exploitation d’images vidéo sont corrélées avec les données de prévisions. Cette étude pionnière montre que cette technique peut être généralisée à toute l’Afrique de l'Ouest en tenant compte des multiples diversités et de la variabilité du climat régional, à travers un réseau d'observations. / The aim of this study was to develop a methodology to statistically assess the shorelineresilience to storms at different time scales for a storm-dominated mid-latitude beach(Biscarrosse, France). On a pilot base, storm-free tropical Jamestown beach (Ghana) was alsoanalysed. 6-years (2007-2012) of continuous video-derived shoreline data and hindcastedhydrodynamics were analysed. Wave climate is dominated by storms (Hs>5% exceedancelimit) and their seasonal fluctuations; 75% of storms occur in winter with more than 60identified storms during the study period. A multiple regression on 36 storms shows thatwhereas current and previous storm intensity have predominant role on current storm impact,tide and sandbar play a major role on the post-storm recovery. An ensemble average on poststormrecovery period shows that Biscarrosse beach recovers rapidly (9 days) to individualstorms, and sequences of storms (clusters) have a weak cumulative effect. The results point outthat individual storm recurrence frequency is key. If the interval between two storms is lowcompared to the recovery period, the beach becomes more resilient to the next storms; and thefirst storm in clusters has larger impact than following ones. Shoreline responds in decreasingorder at seasonal, storm frequency and annual timescales at Biscarrosse. The EOF methodshows good skills in separating uniform and non-uniform shoreline dynamics, showing theirdifferent temporal variability: seasonal and short-term scales dominate first EOF (2D) andsecond (3D) modes, respectively.The shoreline at Jamestown was studied on pilot base from 2013-2014. Water level channgesplay a major role on shoreline changes. Waves estimates from video are in good agreement withhindcasts. This study shows the potential of the technique, to be replicated elsewhere in WestAfrica with all its diversity and regional climate variability through a coastal observationnetwork.

Ce travail de recherche s’inscrit dans le contexte actuel d’accroissement de la vulnérabilité de l’Homme et des activités humaines face aux risques littoraux (aléas érosion et submersion marine), en lien avec les changements environnementaux globaux (élévation du niveau moyen relatif des océans et augmentation de la fréquence et de la virulence des tempêtes) et à la concentration de la population sur le littoral. Suite à la tempête Xynthia du mois de février 2010, l’Etat français s’est doté d’une Stratégie Nationale de Gestion Intégrée du Trait de Côte visant à mettre en place de nouvelles approches en matière de gestion du trait de côte, et notamment, favoriser le repli stratégique contre la défense côtière à tout prix. La mise en place de cette stratégie doit avant tout s’appuyer sur la mise en place d’un réseau d’observation et de suivi de l’évolution du trait de côte à l’échelle de la France. Ce travail s’inscrit dans cette problématique. Il a eu pour objectif d’étudier les dynamiques du trait de côte des plages sableuses et des cordons de galets (formes d’accumulation) de la Bretagne, à différentes échelles spatio-temporelles. Sur le long terme, l’analyse a consisté dans un premier temps à établir une typologie des côtes d’accumulation suivant différents critères morphosédimentaires ; la cinématique du trait de côte a ensuite été analysée à l’échelle des soixante dernières années (1950-2010) à partir d’une étude diachronique par photogrammétrie. Sur le moyen terme, l’analyse s’est faite dans le cadre des suivis topomorphologiques réalisés à l’échelle pluriannuelle à pluridécennale, de plusieurs sites ateliers de l’ODC (IUEM) et/ou du SNO Dynalitt. L’étude des changements morphosédimentaires s’est accompagnée d’une analyse de données de houle, de marée, de vent, et de pression atmosphérique, dans le but d’expliquer la part de ces forçages dans l’alternance de phases d’érosion et de périodes de régénération. Enfin sur le court terme, cette analyse s’est basée sur des levés topomorphologiques à haute fréquence réalisés au cours de l’hiver tempétueux 2013-2014. A cela, s’est ajoutée une étude expérimentale visant à quantifier le runup, dans le but d’analyser l’impact des niveaux d’eau extrêmes à la côte sur l’érosion du trait de côte. De manière globale, la quantification des variations du trait de côte sur le long terme a mis en évidence une tendance à l’érosion (27 % de linéaire étudié), une progradation du trait de côte non négligeable (20,5 % de linéaire) ainsi qu’une importante artificialisation du trait de côte (34,5 % de linéaire). La similitude des réponses morphosédimentaires des cordons littoraux étudiés aux conditions météomarines a permis d’identifier cinq phases distinctes. Trois phases morphogènes (de 1998 à 2003 ; de l’hiver 2006/07 au printemps 2008 ; de l’hiver 2012/13 à aujourd’hui), caractérisées par une érosion importante du trait de côte combinée à une haute fréquence des épisodes tempétueux ; et deux phases au cours desquelles les conditions météomarines ont été plus clémentes (de 2003 à l’hiver 2006/07 ; du printemps 2008 à l’hiver 2012/13), permettant la régénération des cordons littoraux. Au cours de l’hiver 2013-2014, trois tempêtes ont été particulièrement morphogènes en matière d’érosion du trait de côte car elles ont été combinées à de fortes marées de vive-eau : la tempête du 4 et 5 janvier, celle du 1 au 3 février, ainsi que celle du 2 au 3 mars. Durant cet hiver, le recul moyen pour tous les sites étudiés a atteint -6,3 m, avec un maximum d’environ -30,1 m et un minimum de -0,2 m. / This research is part of current context of increasing of human beings and human activities vulnerability face to coastal risks (erosion hazards and marine submersion), linked to global environmental changes (global relative sea level rise and growth of storms’ frequency and intensity) and the current concentration of the population on the coastline. Following the storm Xynthia (February 2010), France has adopted a national strategy dealing with coastal erosion and shoreline retreat, in order to define a new integrated national strategy of coastline management, promoting the relocation of stakes and properties. This strategy focuses on the monitoring of shoreline changes and the identification of coastal risks due to erosion.This work fall within this issue. The main objective was to study sedimentary coasts dynamics (sand dunes and gravel barriers) of Brittany, following different spatial and temporal scales. In the long term, the analysis consisted, first of all, in establishing a typology of sedimentary coasts according to several morpho-sedimentary criteria; then, coastline kinematic has been analyzed over the last sixty years (1950-2010) through a diachronic study using photogrammetry. In the medium term, analysis was carried out as part of topographic surveys performed at multi-annual to multi-decadal scale, on several Observatoire du Domaine Côtier (IUEM) and/or Service National d’Observation - Dynalitt survey sites. The morpho-sedimentary study was combined with a wave, tide, wind and atmospheric pressure analysis, in order to explain the role of these forcing in the erosion and recovery successive phases. Finally, in the short term, analysis was based on high frequency of topomorphological surveys carried out during the 2013-2014 stormy winter. Additionally, an experimental study to quantify runup process, in order to analyze extreme water levels impact on shoreline erosion.Overall, the quantification of coastline variations over the long term revealed an erosion tendency on 27% of the studied linear, a non-negligible progression of the shoreline on 20.5% of the studied linear, and a significant shoreline anthropogenic impact (34.5% of the studied linear). The similarity of the morpho-sedimentary responses of the littoral strands studied to the meteorological conditions allowed to identify five distinct phases. Three morphogenetic phases (1998 to 2003; winter 2006/07 to spring 2008; winter 2012/13 to the present), characterized by severe shoreline erosion combined with a high frequency of storm episodes, and two phases (2003 to winter 2006/07 ; spring 2008 to winter 2012/13) characterized by milder weather conditions, allowing shoreline recovery. During 2013-2014 winter, three storms were particularly morphogenetic for sedimentary coasts, because they were combined with high spring tides: January 4-5, February 1-3, and March 2-3. During this winter, the average retreat for all studied sites reached -6,3 m, with a maximum of -30,1 m and a minimum of -0,2 m.

The Nature Conservancy of Texas (TNC) is concerned with the amount of shoreline erosion taking place at its Mad Island Marsh Preserve (MIMP), located in Matagorda Bay, Texas. The MIMP is a 7,100 acre nature preserve that borders the Gulf Intracoastal Waterway and is eroded by waves generated by barge traffic. TNC is concerned that erosion will shorten Mad Island Bayou which may increase the salinity of Mad Island Lake; with detrimental effects on lake and marsh habitats. This study uses GPS technology to map the current shoreline and GIS to determine ten year erosion rates (1995 - 2005). Results show that erosion is occurring at various rates along the shoreline as well as along the oxbow bend in Mad Island Bayou.