Havsnivåhöjning och kraftigare stormar är två konsekvenser av klimatförändringarna som i sin tur leder till ökad erosion och översvämning. När kustområdena omvandlas, och i värsta fall försvinner, påverkas människors möjligheter att bo och leva där. För att minska risken att sociala, ekonomiska och ekologiska värden går förlorade krävs att vi planerar skyddsåtgärder för havsnivåhöjning, erosion och översvämning samt planerar för hur vi kan anpassa oss efter dessa föränderliga förutsättningar.  Syftet med denna studie är att undersöka hur svenska kommuner planerar för klimatanpassning idag och hur planerad reträtt skulle kunna användas som strategi i Sverige. Flexmark, en idé som tagits fram i ett projekt lett av SGI, inkluderades i studien för att ta reda på om den kan underlätta planeringen för klimatanpassning i Sverige. För att genomföra undersökningen valdes de skånska kommunerna Ystad, Trelleborg och Lomma ut samt Länsstyrelsen Skåne och Region Skåne för djupare studie. I studien undersöktes plandokument rörande klimatanpassning framtagna av kommunerna, regionen och länsstyrelsen. En intervjustudie med informanter från samtliga organisationer kompletterade studien. Resultatet visade att de valda kommunerna jobbar med klimatanpassning men än så länge inte med planerad reträtt. Osäkerhet kring vad som är möjligt enligt PBL, motstånd hos kommuninvånare samt frågan om vem som skulle ansvara för och finansiera reträtten angavs som några av de aspekter som gör strategin svår att införa.  Naturbaserade lösningar och vallar är klimatanpassningsåtgärder som används inom kommunerna idag. Majoriteten av de intervjuade anser att planerad reträtt kommer behövas i svensk planering i framtiden men att det idag inte finns möjlighet eller vilja att utföra en sådan åtgärd. För att ge inspiration till hur reträtt kan planeras och hanteras presenteras tre internationella exempel som en referensram för vad som varit framgångsfaktorer för lyckade reträtter i andra länder. De internationella fallen tillsammans med intervjuerna och dokumentstudien analyseras för att undersöka hur planerad reträtt skulle kunna användas som strategi i Sverige. Idéen om flexmark fick ett generellt positivt mottagande bland informanterna i intervjustudien och skulle med fördel kunna användas som verktyg inom strategin planerad reträtt.  Tillvägagångssätt för planerad reträtt i en svensk kontext analyserades utifrån styrningsmodellerna hierarkisk styrning, samarbetsstyrning samt självstyrning som presenterar olika alternativ för initiativ, styrning och finansiering av planerad reträtt. Samarbetsstyrd planerad reträtt, med initiativtagande och styrning på lokal nivå samt rätt till ekonomisk stöttning från nationell nivå, är enligt forskarna i den här studien, den strategi som lämpar sig bäst inom svensk planering. För att planerad reträtt ska få ett lyckat resultat krävs att berörda parter involveras tidigt och att kontinuerlig dialog förs mellan dem under processen. / Sea level rise and increased intensity of storms are two consequences of climate change which in turn lead to increased erosion and flooding. When coastal areas are transformed, and in the worst case disappear, many people's everyday life will be affected. To reduce the risk of social, economic and ecological values ​​being lost, we need to plan for protection against sea level rise, erosion and flooding and plan for how we can adapt to these changing conditions. The purpose of this study is to investigate how Swedish municipalities plan for climate change adaptation today and how planned retreats could be used as a strategy in Sweden. Flexmark, an idea developed in a project led by SGI, was included in the study to find out if it can facilitate planning for climate change adaptation in Sweden. To carry out the investigation, Skånes’s municipalities Ystad, Trelleborg and Lomma were selected, as well as the County Administrative Board of Skåne and Region Skåne for deeper study. The study examined planning documents concerning climate change adaptation produced by the municipalities, the region and the county administrative board. An interview study with informants from all organizations supplemented the study. The results showed that the selected municipalities are working with climate change adaptation but so far not with planned retreats. Uncertainties regarding what is possible according to the Planning and Building Act, opposition from municipal residents and the matter of who would be responsible for and finance the retreat were stated as some of the aspects that make the strategy difficult to implement. Nature-based solutions and dikes are climate change adaptation measures used in municipalities today. The majority of the interviewees believe that planned retreats will be needed in Swedish planning in the future, but today there is no opportunity or willingness to carry out such a measure. To provide inspiration for how retreats can be planned and managed, three international examples are presented as a reference framework for what have been key factors for successful retreats in other countries. The international cases together with the interviews and the document study are analyzed to investigate how planned retreats could be used as a strategy in Sweden. The responses to ​​flexmark were generally positive among the informants and the idea could be used as a tool within the strategy planned retreat. Approaches of planned retreat in a Swedish context were analyzed based on the governance modes hierarchical governance, co-governance and self-governance, which present various alternatives for initiative, governance and financing of planned retreats. Cooperative planned retreat, initiated and governed at local level with financial support from national level, is according to the researchers of this study, the strategy that is best suited in Swedish planning. In order for a planned retreat to generate a successful result, it is necessary that all affected parties are involved early and that a continuous dialogue is conducted between them during the process.

Este trabalho objetiva investigar a dinâmica geomorfológica glacial das áreas livres de gelo na Península Potter, Ilha Rei George, Antártica, em resposta à recente retração da geleira Polar Club. O mapeamento geomorfológico e a interpretação da evolução dos sistemas lacustres entre 2006 e 2011 das áreas livres de gelo na Península Potter foi realizado através da interpretação visual em uma imagem Quickbird (RGB432), em imagens COSMO-SkyMed polarizações VV e HH em modo spotlight processadas com filtros espaciais e perfis topográficos. Também foram considerados os aspectos morfométricos da península, interpretados através da geração de mapas de hipsometria, declividade, curvas de nível e sombreamento. A variação frontal da geleira Polar Club entre os anos de 1981 a 2015 foi obtida pela análise temporal de imagens Landsat. O mapeamento geomorfológico da Península Potter evidenciou os processos geomorfológicos proglaciais e o padrão de disposição espacial das feições lineares marginais ao gelo, como cordões morâinicos e feições glaciofluviais (relacionadas ao aporte da fusão sazonal da neve e do gelo), bem como terraços marinhos, ravinas e afloramentos rochosos. As imagens COSMO-SkyMed e a aplicação de filtros Passa Alta e Direcionais possibilitaram a delimitação das feições de interesse com maior nitidez. O modelo de evolução da variação frontal da geleira Polar Club indica que condição de último avanço glacial registrado pela geomorfologia proglacial pode estar relacionado à Pequena Idade do Gelo e que houve um contínuo processo de retração desde então. Entre 1981-2015 evidenciou-se a redução de área de 2,95km2 para a geleira Polar Club (perda de área total de 9,4%). Este processo pode estar relacionado com a tendência de aumento das temperaturas médias do ar, a tendência de aumento de dias com precipitação líquida no verão e o número de dias em que a temperatura média ultrapassou os 0°C na região nas últimas décadas. O recuo da geleira Polar Club é pouco expressivo quando comparado a outras geleiras da Ilha Rei George, no entanto, quando se observa as áreas expostas evidenciou-se que houve um aumento significativo (36,9%) no período. Através da análise da evolução dos depósitos morâinicos da Península Potter foi possível identificar três fases principais de formação de morâinas que evidenciam antigas posições da frente da geleira durante períodos de estabilização frontal. A análise da evolução dos sistemas lacustres na área de estudo evidenciou que diversos lagos sofreram alterações de área em resposta à dinâmica de retração glacial registrada para os últimos 34 anos. / This study aimed to investigate the glacial geomorphological dynamics of the ice-free areas in the Peninsula Potter, King George Island, Antarctica, in response to the recent Polar Club Glacier retreat processes. The geomorphological mapping and lacustrine systems evolution modelling between 2006-2011 were obtained with Quickbird (RGB432) image, application of the spatial digital filters in COSMO-SkyMed (cross and co-polarization, spotlight mode) images and topographic profiles visual interpretations. Also considered were the morphometric aspects of the peninsula, interpreted by generating hypsometry, slope, contour and shaded relief maps. The Polar Club Glacier frontal variation between 1981-2015 was obtained with Landsat temporal analysis. The Potter Peninsula geomorphological mapping evidenced the proglacial and geomorphological processes and the spatial distribution pattern of linear marginal to ice features, as morainic ridges and glaciofluvial features, related to the contribution of the seasonal melting of snow and ice, marine terraces, ravines and rocky outcrops. The High Pass and directional filters in COSMO-SkyMed images provided conditions for geomorphological features. The frontal glacier fluctuations modelling indicated that last glacial advance condition recorded by proglacial geomorphologic can be related Little Ice Age and continuous retreat process. Between 1981-2015 the Polar Club glacier lost 2,95km2 of total area (9,4% of total area). The retreat process can be related to the trend of rising average temperatures in recent decades, trend of increase in days with liquid precipitation in summer and the number melting degree days. The Polar Club Glacier retreat is not very significant when compared to other glaciers of King George Island, however, when observing the exposed areas was evident that there was a significant increase (36.9%). The moraine deposits evolution analysis in Peninsula Potter provided conditions for identify three main phases of moraines deposition and that show past glacier front positions during periods of glacier marginal stabilization. The analysis of the evolution of lacustrine systems in the study area evidenced changes in various lakes during last 34 years in response of glacial retreat dynamics.

Este trabalho investiga a dinâmica de retração frontal de duas geleiras de maré, Drummond (66°40'S, 65°43'O) e Widdowson (66°43'S, 65°46'O), na costa ocidental da Península Antártica. O estudo usou fotografias aéreas e imagens satelitais LANDSAT (a partir de 1986) para determinar a variação de área dessas geleiras no período 1957–2015 e analisar a sensibilidade às recentes mudanças ambientais na Península Antártica. O modelo digital de elevação AsterGDEM2 foi usado para caracterizar a morfologia e morfometria da bacia de drenagem dessas massas de gelo. A análise estatística dos dados de temperatura média anual da Estação Vernadsky (65°14’ S, 64°15’ O) mostra tendência ao aquecimento atmosférico no período 1950–2015 (0,047°C ano-1) nesta parte da Península Antártica ocidental. As frentes das duas geleiras retraíram ao longo dos últimos 68 anos, no entanto a geleira Widdowson apresentou uma perda maior (36,03 km2, ou 16,81% da área original) e uma linha de neve mais elevada (200 m a.n.m. em 2016) do que a geleira Drummond (18,84 km2, ou 4,26% da área original; linha de neve a 100 m a.n.m. em 2016) no período. Essa diferença na retração da duas geleiras, lado a lado e com a mesma orientação de fluxo do gelo, são atribuídas as diferentes declividades da superfície e proporção da área de acumulação sobre a área total. A geleira de menor área, Widdowson, somente atingiu um ponto de estabilização (apoiada ao embasamento rochoso lateral) em 2001, enquanto a frente da Drummond estabilizou-se em 1974. Além disso, a geleira Widdowson é mais íngreme no setor frontal, o que pode ter influenciado na taxa de desprendimento de icebergs e gerado um deslizamento basal mais eficiente, aumentando a velocidade de fluxo do gelo e, por consequência, aumentando as taxas de retração. Esses resultados condizem com estudos para outras geleiras de descarga com frentes flutuantes na Península Antártica, as quais são mais sensíveis às mudanças climáticas. A dinâmica dessas geleiras também é influenciada por mudanças nas forçantes oceânicas, taxas de precipitação, derretimento superficial e morfologias diferentes do embasamento rochoso; esses pontos devem ser tratados em trabalhos futuros. Como subproduto desta investigação, foi gerado um banco de dados em SIG para a continuidade do monitoramento das duas geleiras. / This work investigates the ice front retreat dynamics of two tidewater glaciers, Drummond (66°40'S, 65°43'W) and Widdowson (66°43'S, 65°46'W), on the western coast of the Antarctic Peninsula, associated with environmental changes in the last six decades. The study uses aerial photographs and LANDSAT satellite images (from 1986 onwards) to determine these glaciers area variations in the period 1957–2015 and to analyze their sensitivity to recent environmental changes in the Antarctic Peninsula. The digital elevation model ASTERDEM2 was edited by a routine to characterize the morphology and the morphometry of the drainage basins of these ice masses. The statistical analysis of the updated mean annual temperature data from the Faraday/Vernadsky station (65°14’ S, 64°15’ W) shows a trend towards regional atmospheric warming in the period 1950–2015 (0.047°C year-1) in this part of the West Antarctic Peninsula. The ice fronts of these two glaciers have retreated for the last 68 years, however, the Widdowson Glacier had a more significant loss (36.03 km² or 16.81% of the original area) and a higher snow line elevation (200 m a.s.l. in 2016) than the Drummond Glacier (18.84 km2, or 4.26% of the original area; snow line at 90 m a.s.l. in 2016) in the period. This retreat difference of the two glaciers, side by side and with the same ice flow orientation is attributed to different surface slopes and accumulation area proportion over the total area. The smaller area glacier, Widdowson, has shown to be more sensitive to environmental changes and only reached a stabilization point (supported to the lateral bedrock) in 2001, while the Drummond front stabilized in 1974. In addition, the Widdowson glacier is steeper in the frontal sector, which may have influenced on the calving rate and generate a more efficient basal slip, increasing the ice flow rate and, consequently, increasing the retraction rate. These results are consistent with studies for other floating outlet glaciers with calving in the Antarctic Peninsula, which are more sensitive to climate change. The dynamics of these glaciers is also influenced by changes in ocean forcing, precipitation rates, surface melting and bedrock morphology; these points should be investigated in future works. As a by-product of this research, a GIS database wasgenerated for a continuous monitoring of the two glaciers.

On the basis of coastal disaster mitigation and protection, a beach must have sufficient width for preventing the destruction to public facilities, as well as protecting the safety of life and private property during storm events. The requirement of such a horizontal extent from the initial shoreline to the probable erosion landward to safeguard against the onslaught of a storm is referred to as ¡¥storm beach buffer width¡¦. Upon neglecting the effects of global warming and sealevel rise on a beach and berm with profile in equilibrium, numerical calculations are conducted first to validate the range of the most important parameters (K »P £` ) in the SBEACH model using the results of profile changes available from the CERC¡¦s large wave tank (LWT) tests in 1960s. These results are then applied to assess the profile changes for a beach with a vertical seawall and the other without sufficient berm, subject to the normal incidence of storm waves over a specific duration. Finally, a total of 48 cases with sufficient beach width are then investigated, from which a multiple linear regression model is proposed to determine the extent of berm retreat, as well as the location and height of a submerged offshore bar, for the benefit of coastal profession on preliminary design of storm buffer. Our modeling results using SBEACH reveal that: (1) A seawall without or with insufficient fronting beach could result in serious scour at its toe and even the total loss of the entire beach berm; (2) A beach with sufficient berm, natural or artificially nourished, is capable of protecting the back beach, despite the temporary erosion in the early hours of a storm action; (3) Under the same conditions of wave height and period, a wide buffer is necessary for a beach with small mean sand grain, and the berm height should be designed at 1.6 times of the designed storm surge level, in order to effectively absorb storm wave energy and maintain the provision of a storm buffer; and (4) The multiple linear regression model proposed in this study can be used to evaluate the scour depth and retreat of the berm, as well as the width of a storm beach buffer, upon the input of wave conditions and mean beach sand grain etc.

The lower Da-An River in western Taiwan was uplifted ~10 during the 1999 Mw 7.6 Chi-Chi earthquake, resulting in a 20- to 30-m-deep bedrock gorge. However, the amount of coseismic displacement along the channel bed does not fully explain the resulting bedrock channel incision. Using a series of aerial photographs, digital terrain models (DEM), and real-time kinematic global positioning system (RTK GPS) surveys, we characterized knickpoint retreat and fluvial incision in the Da-An River gorge. We also analyzed discharge and precipitation data and collected measurements of rock strength and joint plane orientations to understand the climatic, lithological, and structural influence on the evolution of the actively incising gorge. Two stages of fluvial incision and knickpoint migration are identified in the gorge following surface uplift during the Chi-Chi earthquake. From 1999 to 2004, 3 to 5 m of alluvium was removed from the channel bed, followed by 3 to 4 m of bedrock channel incision. The knickpoint generated immediately after the earthquake stayed where the uplift occurred at this time. Since 2005, the channel bed has lowered rapidly with local incision rate as high as 15 m/yr in terms of knickpoint migration. The average knickpoint migration rate over the period 2005 to 2009 was 238 m/yr; total upstream migration from the location of knickpoint formation was 1190 m. While tectonic uplift formed the knickpoint and set the stage for channel incision, climate played a critical role in accelerating the fluvial response to coseismic displacement. More than 20 m of bedrock channel incision and 1180 m knickpoint migration occurred during the post-2004 typhoon seasons (May-October). Based on repeat surveys of the Da-An River longitudinal profile and analysis of precipitation and discharge data, we suggest that a discharge threshold of 1200 to 2600 m³/s is required to initiate upstream knickpoint migration. However, once the threshold is exceeded, bedding dip becomes the primary control on rates and patterns of knickpoint propagation. Rotation occurred in a hinge zone where the bedding dips change from horizontal to upstream-dipping, while replacement was observed in the strata dipping upstream. The highest knickpoint migration rates (> 300 m/yr) were recorded in flat-lying, horizontal strata (< 10º) where parallel retreat was the dominate process. Overall, the knickpoint propagation followed the process of replacement behavior, in which the height of knickpoint decreases while migrating upstream. Thus, while tectonic processes set the initial conditions for knickpoint propagation in the Da-An River, the response time of the fluvial system to this forcing is strongly dependent on climate and local structure.

Depuis la fin du Petit Age Glaciaire, les glaciers du massif du Mont-Blanc se retirent et libèrent ainsi d’importants volumes de sédiments. La fourniture sédimentaire grossière, qui est l’un des éléments de contrôle principaux de l’activité géomorphologique des torrents proglaciaires, peut être profondément modifiée. Dans le contexte de la vallée de Chamonix, où la pression urbaine est très forte, l’accélération du retrait glaciaire soulève des questionnements de la part à la fois des gestionnaires et des scientifiques sur l’évolution des risques et de la gestion des flux solides.L’objectif de ce travail de thèse est d’étudier le couplage sédimentaire entre les espaces libérés des glaces et les torrents jusqu’en fond de vallée, avec un double niveau de réponse. Le premier niveau permet de comprendre les trajectoires géomorphologiques des systèmes glacio-torrentiels depuis la fin du Petit Age Glaciaire et à l’échelle de la vallée. Il est étayé par une analyse géomorphologique et par l’étude de l’évolution du réseau hydrographique, qui s’appuie sur une modélisation et sur de nombreux documents d’archive. Cette étape souligne la diminution du potentiel du système torrentiel à remobiliser des sources sédimentaires. En conséquence, l’activité des torrents a fortement baissée depuis 150 ans. La seconde approche concerne l’étude des dynamiques récentes basée sur la comparaison diachronique de MNT LiDAR à haute résolution. Elle se focalise sur les trois systèmes glacio-torrentiels les plus grands de la vallée (Argentière, Mer de Glace et Bossons) dont les activités morphogènes ont pu être interprétées sous le prisme de crues d’occurrence décennale survenues en août 2014. Cette partie montre l’efficacité des processus de stockage sédimentaire au sein même des espaces désenglacés, ainsi que l’importance du forçage humain sur la morphogénèse torrentielle qui prime désormais sur l’influence du retrait glaciaire. L’état de la fourniture sédimentaire résulte actuellement de l’impact des différentes infrastructures, telles que les captages sous-glaciaires ou l’autoroute d’accès au Tunnel du Mont Blanc.Nos résultats montrent donc une première phase de diminution de l’activité torrentielle, principalement causée par le retrait des glaciers de 1850 à 1950, puis les conséquences pression des activités humaines sur les évolutions hydromorphologiques. La baisse de la torrentialité est toutefois ponctuée de quelques évènements, comme la crue du septembre 1920 sur l’Arveyron de la Mer de Glace, dont nous avons reconstitué les conséquences géomorphologiques. Malgré leur intensité, les effets de ces crues restent néanmoins relativement limités à l’aval immédiat des glaciers.Contrairement donc aux hypothèses initialement soulevées, le retrait glaciaire n’implique pas une augmentation de la fourniture sédimentaire, mais au contraire une diminution des apports du fait de la déconnexion entre les espaces désenglacés et les systèmes torrentiels. / Since the end of Little Ice Age, glaciers of the Mont blanc massif are retreating and large sediment volume are releasing from the ice. Thus, sediment supply, which is a main control factor of the proglacial stream geomorphic activity, could be deeply modified. Therefore, the consequences on the sediment fluxes and the risk management need to be understanding because of the present acceleration of glacier retreat and urban sprawl in the Chamonix valley. The goal of this thesis is to study the sediment coupling between stream systems and areas released by glaciers. A first approach allows understanding the geomorphic trajectory of proglacial system at the Chamonix scale since the end of the Little Ice Age. Our results supported by modelling and archives analyses, show the decreasing capacity of the hydrographic pattern to be connected with sediment sources. The second approach is lead on the LiDAR DEM multi-temporal comparison. It focuses on the three main proglacial systems: Argentière, Mer de Glace and Bossons, whom occurred a decennal flood during the 2014 summer. This part of our study underlines the storage efficiency into deglaciated areas and the increasing role of anthropic forcing. Present sediment yield to proglacial stream is leaded by facilities such as the Mont Blanc Tunnel substructure or the subglacial harnessing. Our results show that the decreasing geomorphic activity of proglacial stream in the Chamonix valley is mainly caused by glacier retreat from the early 18th Century to the middle 20th century, then it is leaded by the increasing human pressure. Nevertheless, the fall of stream activity is punctuated by extreme events, such as the 1920 flood in the Arveyron of the Mer de Glace that we reconstructed the geomorphic consequences. Despite their intensity, effects of that king of events are limited close to the glacier downstream. Contrary to our initial hypotheses, glacier retreat in the Chamonix Valley, is not follow by a geomorphic crisis of proglacial streams because of the disconnectivity between sediment released from the ice and stream systems.

Este trabalho objetiva investigar a dinâmica geomorfológica glacial das áreas livres de gelo na Península Potter, Ilha Rei George, Antártica, em resposta à recente retração da geleira Polar Club. O mapeamento geomorfológico e a interpretação da evolução dos sistemas lacustres entre 2006 e 2011 das áreas livres de gelo na Península Potter foi realizado através da interpretação visual em uma imagem Quickbird (RGB432), em imagens COSMO-SkyMed polarizações VV e HH em modo spotlight processadas com filtros espaciais e perfis topográficos. Também foram considerados os aspectos morfométricos da península, interpretados através da geração de mapas de hipsometria, declividade, curvas de nível e sombreamento. A variação frontal da geleira Polar Club entre os anos de 1981 a 2015 foi obtida pela análise temporal de imagens Landsat. O mapeamento geomorfológico da Península Potter evidenciou os processos geomorfológicos proglaciais e o padrão de disposição espacial das feições lineares marginais ao gelo, como cordões morâinicos e feições glaciofluviais (relacionadas ao aporte da fusão sazonal da neve e do gelo), bem como terraços marinhos, ravinas e afloramentos rochosos. As imagens COSMO-SkyMed e a aplicação de filtros Passa Alta e Direcionais possibilitaram a delimitação das feições de interesse com maior nitidez. O modelo de evolução da variação frontal da geleira Polar Club indica que condição de último avanço glacial registrado pela geomorfologia proglacial pode estar relacionado à Pequena Idade do Gelo e que houve um contínuo processo de retração desde então. Entre 1981-2015 evidenciou-se a redução de área de 2,95km2 para a geleira Polar Club (perda de área total de 9,4%). Este processo pode estar relacionado com a tendência de aumento das temperaturas médias do ar, a tendência de aumento de dias com precipitação líquida no verão e o número de dias em que a temperatura média ultrapassou os 0°C na região nas últimas décadas. O recuo da geleira Polar Club é pouco expressivo quando comparado a outras geleiras da Ilha Rei George, no entanto, quando se observa as áreas expostas evidenciou-se que houve um aumento significativo (36,9%) no período. Através da análise da evolução dos depósitos morâinicos da Península Potter foi possível identificar três fases principais de formação de morâinas que evidenciam antigas posições da frente da geleira durante períodos de estabilização frontal. A análise da evolução dos sistemas lacustres na área de estudo evidenciou que diversos lagos sofreram alterações de área em resposta à dinâmica de retração glacial registrada para os últimos 34 anos. / This study aimed to investigate the glacial geomorphological dynamics of the ice-free areas in the Peninsula Potter, King George Island, Antarctica, in response to the recent Polar Club Glacier retreat processes. The geomorphological mapping and lacustrine systems evolution modelling between 2006-2011 were obtained with Quickbird (RGB432) image, application of the spatial digital filters in COSMO-SkyMed (cross and co-polarization, spotlight mode) images and topographic profiles visual interpretations. Also considered were the morphometric aspects of the peninsula, interpreted by generating hypsometry, slope, contour and shaded relief maps. The Polar Club Glacier frontal variation between 1981-2015 was obtained with Landsat temporal analysis. The Potter Peninsula geomorphological mapping evidenced the proglacial and geomorphological processes and the spatial distribution pattern of linear marginal to ice features, as morainic ridges and glaciofluvial features, related to the contribution of the seasonal melting of snow and ice, marine terraces, ravines and rocky outcrops. The High Pass and directional filters in COSMO-SkyMed images provided conditions for geomorphological features. The frontal glacier fluctuations modelling indicated that last glacial advance condition recorded by proglacial geomorphologic can be related Little Ice Age and continuous retreat process. Between 1981-2015 the Polar Club glacier lost 2,95km2 of total area (9,4% of total area). The retreat process can be related to the trend of rising average temperatures in recent decades, trend of increase in days with liquid precipitation in summer and the number melting degree days. The Polar Club Glacier retreat is not very significant when compared to other glaciers of King George Island, however, when observing the exposed areas was evident that there was a significant increase (36.9%). The moraine deposits evolution analysis in Peninsula Potter provided conditions for identify three main phases of moraines deposition and that show past glacier front positions during periods of glacier marginal stabilization. The analysis of the evolution of lacustrine systems in the study area evidenced changes in various lakes during last 34 years in response of glacial retreat dynamics.

Este trabalho objetiva investigar a dinâmica geomorfológica glacial das áreas livres de gelo na Península Potter, Ilha Rei George, Antártica, em resposta à recente retração da geleira Polar Club. O mapeamento geomorfológico e a interpretação da evolução dos sistemas lacustres entre 2006 e 2011 das áreas livres de gelo na Península Potter foi realizado através da interpretação visual em uma imagem Quickbird (RGB432), em imagens COSMO-SkyMed polarizações VV e HH em modo spotlight processadas com filtros espaciais e perfis topográficos. Também foram considerados os aspectos morfométricos da península, interpretados através da geração de mapas de hipsometria, declividade, curvas de nível e sombreamento. A variação frontal da geleira Polar Club entre os anos de 1981 a 2015 foi obtida pela análise temporal de imagens Landsat. O mapeamento geomorfológico da Península Potter evidenciou os processos geomorfológicos proglaciais e o padrão de disposição espacial das feições lineares marginais ao gelo, como cordões morâinicos e feições glaciofluviais (relacionadas ao aporte da fusão sazonal da neve e do gelo), bem como terraços marinhos, ravinas e afloramentos rochosos. As imagens COSMO-SkyMed e a aplicação de filtros Passa Alta e Direcionais possibilitaram a delimitação das feições de interesse com maior nitidez. O modelo de evolução da variação frontal da geleira Polar Club indica que condição de último avanço glacial registrado pela geomorfologia proglacial pode estar relacionado à Pequena Idade do Gelo e que houve um contínuo processo de retração desde então. Entre 1981-2015 evidenciou-se a redução de área de 2,95km2 para a geleira Polar Club (perda de área total de 9,4%). Este processo pode estar relacionado com a tendência de aumento das temperaturas médias do ar, a tendência de aumento de dias com precipitação líquida no verão e o número de dias em que a temperatura média ultrapassou os 0°C na região nas últimas décadas. O recuo da geleira Polar Club é pouco expressivo quando comparado a outras geleiras da Ilha Rei George, no entanto, quando se observa as áreas expostas evidenciou-se que houve um aumento significativo (36,9%) no período. Através da análise da evolução dos depósitos morâinicos da Península Potter foi possível identificar três fases principais de formação de morâinas que evidenciam antigas posições da frente da geleira durante períodos de estabilização frontal. A análise da evolução dos sistemas lacustres na área de estudo evidenciou que diversos lagos sofreram alterações de área em resposta à dinâmica de retração glacial registrada para os últimos 34 anos. / This study aimed to investigate the glacial geomorphological dynamics of the ice-free areas in the Peninsula Potter, King George Island, Antarctica, in response to the recent Polar Club Glacier retreat processes. The geomorphological mapping and lacustrine systems evolution modelling between 2006-2011 were obtained with Quickbird (RGB432) image, application of the spatial digital filters in COSMO-SkyMed (cross and co-polarization, spotlight mode) images and topographic profiles visual interpretations. Also considered were the morphometric aspects of the peninsula, interpreted by generating hypsometry, slope, contour and shaded relief maps. The Polar Club Glacier frontal variation between 1981-2015 was obtained with Landsat temporal analysis. The Potter Peninsula geomorphological mapping evidenced the proglacial and geomorphological processes and the spatial distribution pattern of linear marginal to ice features, as morainic ridges and glaciofluvial features, related to the contribution of the seasonal melting of snow and ice, marine terraces, ravines and rocky outcrops. The High Pass and directional filters in COSMO-SkyMed images provided conditions for geomorphological features. The frontal glacier fluctuations modelling indicated that last glacial advance condition recorded by proglacial geomorphologic can be related Little Ice Age and continuous retreat process. Between 1981-2015 the Polar Club glacier lost 2,95km2 of total area (9,4% of total area). The retreat process can be related to the trend of rising average temperatures in recent decades, trend of increase in days with liquid precipitation in summer and the number melting degree days. The Polar Club Glacier retreat is not very significant when compared to other glaciers of King George Island, however, when observing the exposed areas was evident that there was a significant increase (36.9%). The moraine deposits evolution analysis in Peninsula Potter provided conditions for identify three main phases of moraines deposition and that show past glacier front positions during periods of glacier marginal stabilization. The analysis of the evolution of lacustrine systems in the study area evidenced changes in various lakes during last 34 years in response of glacial retreat dynamics.

Este trabalho investiga a dinâmica de retração frontal de duas geleiras de maré, Drummond (66°40'S, 65°43'O) e Widdowson (66°43'S, 65°46'O), na costa ocidental da Península Antártica. O estudo usou fotografias aéreas e imagens satelitais LANDSAT (a partir de 1986) para determinar a variação de área dessas geleiras no período 1957–2015 e analisar a sensibilidade às recentes mudanças ambientais na Península Antártica. O modelo digital de elevação AsterGDEM2 foi usado para caracterizar a morfologia e morfometria da bacia de drenagem dessas massas de gelo. A análise estatística dos dados de temperatura média anual da Estação Vernadsky (65°14’ S, 64°15’ O) mostra tendência ao aquecimento atmosférico no período 1950–2015 (0,047°C ano-1) nesta parte da Península Antártica ocidental. As frentes das duas geleiras retraíram ao longo dos últimos 68 anos, no entanto a geleira Widdowson apresentou uma perda maior (36,03 km2, ou 16,81% da área original) e uma linha de neve mais elevada (200 m a.n.m. em 2016) do que a geleira Drummond (18,84 km2, ou 4,26% da área original; linha de neve a 100 m a.n.m. em 2016) no período. Essa diferença na retração da duas geleiras, lado a lado e com a mesma orientação de fluxo do gelo, são atribuídas as diferentes declividades da superfície e proporção da área de acumulação sobre a área total. A geleira de menor área, Widdowson, somente atingiu um ponto de estabilização (apoiada ao embasamento rochoso lateral) em 2001, enquanto a frente da Drummond estabilizou-se em 1974. Além disso, a geleira Widdowson é mais íngreme no setor frontal, o que pode ter influenciado na taxa de desprendimento de icebergs e gerado um deslizamento basal mais eficiente, aumentando a velocidade de fluxo do gelo e, por consequência, aumentando as taxas de retração. Esses resultados condizem com estudos para outras geleiras de descarga com frentes flutuantes na Península Antártica, as quais são mais sensíveis às mudanças climáticas. A dinâmica dessas geleiras também é influenciada por mudanças nas forçantes oceânicas, taxas de precipitação, derretimento superficial e morfologias diferentes do embasamento rochoso; esses pontos devem ser tratados em trabalhos futuros. Como subproduto desta investigação, foi gerado um banco de dados em SIG para a continuidade do monitoramento das duas geleiras. / This work investigates the ice front retreat dynamics of two tidewater glaciers, Drummond (66°40'S, 65°43'W) and Widdowson (66°43'S, 65°46'W), on the western coast of the Antarctic Peninsula, associated with environmental changes in the last six decades. The study uses aerial photographs and LANDSAT satellite images (from 1986 onwards) to determine these glaciers area variations in the period 1957–2015 and to analyze their sensitivity to recent environmental changes in the Antarctic Peninsula. The digital elevation model ASTERDEM2 was edited by a routine to characterize the morphology and the morphometry of the drainage basins of these ice masses. The statistical analysis of the updated mean annual temperature data from the Faraday/Vernadsky station (65°14’ S, 64°15’ W) shows a trend towards regional atmospheric warming in the period 1950–2015 (0.047°C year-1) in this part of the West Antarctic Peninsula. The ice fronts of these two glaciers have retreated for the last 68 years, however, the Widdowson Glacier had a more significant loss (36.03 km² or 16.81% of the original area) and a higher snow line elevation (200 m a.s.l. in 2016) than the Drummond Glacier (18.84 km2, or 4.26% of the original area; snow line at 90 m a.s.l. in 2016) in the period. This retreat difference of the two glaciers, side by side and with the same ice flow orientation is attributed to different surface slopes and accumulation area proportion over the total area. The smaller area glacier, Widdowson, has shown to be more sensitive to environmental changes and only reached a stabilization point (supported to the lateral bedrock) in 2001, while the Drummond front stabilized in 1974. In addition, the Widdowson glacier is steeper in the frontal sector, which may have influenced on the calving rate and generate a more efficient basal slip, increasing the ice flow rate and, consequently, increasing the retraction rate. These results are consistent with studies for other floating outlet glaciers with calving in the Antarctic Peninsula, which are more sensitive to climate change. The dynamics of these glaciers is also influenced by changes in ocean forcing, precipitation rates, surface melting and bedrock morphology; these points should be investigated in future works. As a by-product of this research, a GIS database wasgenerated for a continuous monitoring of the two glaciers.

Este trabalho investiga a dinâmica de retração frontal de duas geleiras de maré, Drummond (66°40'S, 65°43'O) e Widdowson (66°43'S, 65°46'O), na costa ocidental da Península Antártica. O estudo usou fotografias aéreas e imagens satelitais LANDSAT (a partir de 1986) para determinar a variação de área dessas geleiras no período 1957–2015 e analisar a sensibilidade às recentes mudanças ambientais na Península Antártica. O modelo digital de elevação AsterGDEM2 foi usado para caracterizar a morfologia e morfometria da bacia de drenagem dessas massas de gelo. A análise estatística dos dados de temperatura média anual da Estação Vernadsky (65°14’ S, 64°15’ O) mostra tendência ao aquecimento atmosférico no período 1950–2015 (0,047°C ano-1) nesta parte da Península Antártica ocidental. As frentes das duas geleiras retraíram ao longo dos últimos 68 anos, no entanto a geleira Widdowson apresentou uma perda maior (36,03 km2, ou 16,81% da área original) e uma linha de neve mais elevada (200 m a.n.m. em 2016) do que a geleira Drummond (18,84 km2, ou 4,26% da área original; linha de neve a 100 m a.n.m. em 2016) no período. Essa diferença na retração da duas geleiras, lado a lado e com a mesma orientação de fluxo do gelo, são atribuídas as diferentes declividades da superfície e proporção da área de acumulação sobre a área total. A geleira de menor área, Widdowson, somente atingiu um ponto de estabilização (apoiada ao embasamento rochoso lateral) em 2001, enquanto a frente da Drummond estabilizou-se em 1974. Além disso, a geleira Widdowson é mais íngreme no setor frontal, o que pode ter influenciado na taxa de desprendimento de icebergs e gerado um deslizamento basal mais eficiente, aumentando a velocidade de fluxo do gelo e, por consequência, aumentando as taxas de retração. Esses resultados condizem com estudos para outras geleiras de descarga com frentes flutuantes na Península Antártica, as quais são mais sensíveis às mudanças climáticas. A dinâmica dessas geleiras também é influenciada por mudanças nas forçantes oceânicas, taxas de precipitação, derretimento superficial e morfologias diferentes do embasamento rochoso; esses pontos devem ser tratados em trabalhos futuros. Como subproduto desta investigação, foi gerado um banco de dados em SIG para a continuidade do monitoramento das duas geleiras. / This work investigates the ice front retreat dynamics of two tidewater glaciers, Drummond (66°40'S, 65°43'W) and Widdowson (66°43'S, 65°46'W), on the western coast of the Antarctic Peninsula, associated with environmental changes in the last six decades. The study uses aerial photographs and LANDSAT satellite images (from 1986 onwards) to determine these glaciers area variations in the period 1957–2015 and to analyze their sensitivity to recent environmental changes in the Antarctic Peninsula. The digital elevation model ASTERDEM2 was edited by a routine to characterize the morphology and the morphometry of the drainage basins of these ice masses. The statistical analysis of the updated mean annual temperature data from the Faraday/Vernadsky station (65°14’ S, 64°15’ W) shows a trend towards regional atmospheric warming in the period 1950–2015 (0.047°C year-1) in this part of the West Antarctic Peninsula. The ice fronts of these two glaciers have retreated for the last 68 years, however, the Widdowson Glacier had a more significant loss (36.03 km² or 16.81% of the original area) and a higher snow line elevation (200 m a.s.l. in 2016) than the Drummond Glacier (18.84 km2, or 4.26% of the original area; snow line at 90 m a.s.l. in 2016) in the period. This retreat difference of the two glaciers, side by side and with the same ice flow orientation is attributed to different surface slopes and accumulation area proportion over the total area. The smaller area glacier, Widdowson, has shown to be more sensitive to environmental changes and only reached a stabilization point (supported to the lateral bedrock) in 2001, while the Drummond front stabilized in 1974. In addition, the Widdowson glacier is steeper in the frontal sector, which may have influenced on the calving rate and generate a more efficient basal slip, increasing the ice flow rate and, consequently, increasing the retraction rate. These results are consistent with studies for other floating outlet glaciers with calving in the Antarctic Peninsula, which are more sensitive to climate change. The dynamics of these glaciers is also influenced by changes in ocean forcing, precipitation rates, surface melting and bedrock morphology; these points should be investigated in future works. As a by-product of this research, a GIS database wasgenerated for a continuous monitoring of the two glaciers.