Browsing by Author "Costas, Susana"
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- Âmago II: the creative process of an underwater vietnamese self-portraitPublication . Costas, Susana; Mendes da Silva, BrunoThis short paper explores the legacy of video art, challenging conventions of representation and perception while blurring boundaries between physical and virtual realities. It focuses on the digital creation process of the video artwork Amago II, which delves into themes of self-representation, self-narratives, and cultural symbolism of spaces and objects. The video art employs visual metaphors to guide the viewer through a diachronic experience, reflecting deliberate technical and aesthetic choices. The culmination of these choices results in the presentation of the artwork and its reception by the audience.
- Assessing stakeholders’ risk perceptions in a vulnerable coastal tourism destination (Faro beach, Southern Portugal)Publication . Domingues, Rita B.; Costas, Susana; Jesus, Saúl; Ferreira, OscarEffective coastal management is essential in regions where tourism is a main economic activity. However, poor communication and disagreement between stakeholders hamper the way decisions are conveyed to residents and home/business owners, potentially affecting economic development. We analysed managers and scientists' views regarding risk perceptions of Faro Beach (Algarve) residents, contributing to the identification of differences and similarities towards a sustainable management. We used a qualitative content analysis of managers and scientists' discourses. Managers and scientists recognize that residents, particularly fishermen, are quite knowledgeable about the risks they face by living at the beach. However, scientists and managers believe that residents easily forget about the problems due to an optimism bias and positive previous experience with hazards, that never caused fatalities or serious consequences, leading to an underestimation of the severity of the risks. Managers think that residents are not concerned about the environmental problems of Faro Beach, and both scientists and managers see education as the best solution to increase risk perception and concern of residents. We suggest that truly collaborative approaches to coastal management should be promoted, including an active involvement of residents in the decision process, thus increasing their self-efficacy and behavioural control.
- Barrier island resilience assessment: Applying the ecological principles to geomorphological dataPublication . Kombiadou, Katerina; Matias, Ana; Costas, Susana; Carrasco, A. Rita; Plomaritis, Theocharis A.; Ferreira, ÓscarApplying the ecological resilience principles to barrier island geomorphological evolution requires approaches that perceive and interpret resilience far from predefined barrier characteristics and static views. Accepting that barrier islands, like all natural systems, are dynamic and adaptively changing in response to external disturbances is fundamental to the formulated approach. To this aim, geomorphological units and dimensions were used to describe barrier island stability landscape as an actively shifting ‘topography’, reshaping in response to exogenous events and in relation to intrinsic properties. The structure of the subaerial barrier was characterised using the environmental units of Beach, Dune and Marsh (or BDM), where different combinations of BDM structure define distinct barrier stable states, under a simplified framework that is applicable over a wide range of barrier structures. The methodology is based on reconstructing resilience trajectories of barrier islands through identifying the distinct BDM states and related shifts (thresholds crossed) and assessing resilience dimensions (latitude, resistance and precariousness defined as barrier width and height and proximity to mainland, respectively) that, jointly, define the shape of the stability domain. The approach was applied to the Ria Formosa barrier island system (S. Portugal), using multi-decadal geomorphological data and gradually decreasing spatial discretisation, passing from individual barrier transects to sectors and to entire barriers. The joint evolution of two inland-migrating barriers (Cabanas Island and Cacela Peninsula) was used as an exemplar of adaptive capacity in barrier geomorphic change and, therefore, of resilient response to external pressures. Resilience pathways showed that the Ria Formosa barriers have been resilient over the studied timeframe, with a tendency for maintaining or increasing BDM structural complexity. In general, the stability domain tends to shift from low latitude and high resistance forms (narrow-deep basins of attraction) in the west part of the barrier chain, to higher latitudes and lower resistance ones (wide-shallow basins) towards the east. Precariousness peaks near the edges of the system (low lagoon width) and minimises towards the central part (most detached barriers). Scaling issues regarding smoothing of longshore variability and potential consequences on masking thresholds and critical dimensions are highlighted and discussed, along with the key role of the meaning of specified resilience (of what?) in the assessment. The methodology is a novel approach, easily transferable to different systems and spatiotemporal scales of analysis, representing a step forward in interpreting and assessing barrier island resilience.
- Benchmarks and sediment source(s) of the 1755 Lisbon tsunami deposit at Boca do Rio EstuaryPublication . Font, Eric; Veiga-Pires, C.; Pozo, Manuel; Nave, Silvia; Costas, Susana; Ruiz, F.; Abad, Manuel; Simões, Nuno; Duarte, Sílvia; Rodriguez-Vidal, J.Standardizing the signature of tsunami deposits has been identified as a major limitation for the identification of paleo-tsunami deposits. This limitation mostly arises from the strongly source-dependent nature of these deposits, which in turn determines their composition and depositional architecture, and from the effect of the local morphology of the corresponding depositional environment. Here, we provide new highresolution mineralogical, geochemical and micro/macrofauna data of the 1755 tsunami layer of Boca do Rio estuary (Algarve, Portugal) with the aim of unraveling the signatures of estuarine tsunami deposits and linking them to possible sediment sources. We also apply for the first time diffuse reflectance spectrophotometry (DRS) analysis. Our results show that the 1755 tsunami deposit of the Boca do Rio estuary is featured by an enhancement in Sr and Ca, which are linked to the input of biogenic and detrital carbonates (shell fragments and limestone clasts) from the beach foreshore and a strong depletion in most terrestrial- and marine-sensitive indicators. The latter is interpreted as resulting from the reworking of the estuarine clays and subsequent dilution within a huge volume of sand eroded from the coastal barrier. It confirms that in the case of the Boca do Rio estuary, the sediment source is essentially proximal and coastal. Textural and mineralogical features between the base and the top of the tsunami layer suggest the imprint of run-up and backwash currents derived from a unique wave. Micro and macrofauna analysis and DRS data of the siliciclastic fraction show slight but significant environmental changes occurring just after the tsunami, which could be provoked by an eventual closure of the estuary mouth.
- Benchmarks and sediment source(s) of the 1755 Lisbon tsunami deposit at Boca do Rio EstuaryPublication . Font, Eric; Veiga-Pires, C.; Pozo, Manuel; Nave, Silvia; Costas, Susana; Muñoz, Francisco Ruiz; Abad, Manuel; Simões, Nuno; Duarte, SílviaStandardizing tite signature of tsunami deposits has been pointed as a major limitation on the identification paleo-tsunaml deposits. This limitation majorly arises from the strongly source-dependent nature of these deposits, which in turn determines their composition and Structure, and from the effect of the local morphology of the corresponding depositional environmemt. Here, we provide new high-resolution mineralogical, geochemical and paleontological data of the 1755 tsunami layer of Boca do Rio estuary (Algarve-Portugal.
- Benchmarks, sediment source and hydrodynamics of the 1755 Lisbon tsunami deposit at Boca do Rio EstuaryPublication . Font, Eric; Veiga-Pires, C.; Pozo, Manuel; Nave, Silvia; Costas, Susana; Muñoz, Francisco Ruiz; Abad, Manuel; Simões, Nuno; Duarte, SílviaStandardizing the signature of tsunami deposits has been pointed as a major limitation on the identification of paleo-tsunami deposits. This limitation majorly arises from the strongly source-dependent nature of these deposits, which in turn determines their composition and structure, and from the effect of the local morphology of the corresponding depositional environment. Here, we provide new high-resolution mineralogical, geochemical and paleontological data of the 1755 tsunami layer of Boca do Rio estuary (Algarve, Portugal) with the aim of unraveling the signatures of estuarine tsunami deposit and link them to sediment source.
- Biotic and abiotic factors governing dune response to storm eventsPublication . Garzon, Juan L.; Costas, Susana; Ferreira, OscarThe alongshore response of dunes to storm events can be extremely variable and,consequently, their capacity to maintain their services, including the protection ofhinterland communities. In this study, the role of biotic and abiotic factors determin-ing the magnitude of dune retreat driven by a severe storm along a 60 km barrierisland system was investigated. Data from high-resolution satellite imagery, digitalterrain models, and wave propagation models were used in this assessment. Theassessed abiotic factors included the backshore volume, dune height, downdrift inletdistance, and incident wave power. The evaluated biotic factor was the vegetationcover, characterized by a vegetation index retrieved from the multispectral imagery.The results revealed large alongshore variability on dune retreat, ranging from negli-gible impact to ca. 40 m of retreat. All combined factors allowed us to explain up to70% of the dune retreat variability through a multi-regression analysis. Among allinvestigated factors, the major contributor controlling the magnitude of dune retreatwas the backshore volume (more robust berms reduced the retreat) followed by thewave power (normal and longitudinal components). Moreover, the removal of localsalient features in the dune line caused the straightening of the coastline, highly con-tributing to the development of dune retreat hotspots. The other evaluated factorshad a smaller influence on reducing coastal retreat, including the vegetation, whosecontribution to dune protection was around one order of magnitude lower than thatprovided by the backshore volume. The results highlight the importance of regionalassessments to understand the causes behind the large alongshore variability ofstorm impacts at dunes. They also state the relatively low influence of the vegetationfrom this climatic region to enhance dune resistance to storms.
- Bridging the gap between resilience and geomorphology of complex coastal systemsPublication . Kombiadou, Katerina; Costas, Susana; Carrasco, A. Rita; Plomaritis, Theocharis; Ferreira, Oscar; Matias, AnaResilience has been used over a wide range of scientific fields and often ambiguously, causing confusion over terminology and concepts and giving rise to distinct interpretations and misconceptions, even within the same scientific discipline. Starting by providing clarifications and definitions of the main terminology and key principles of ecological resilience theory, we pass on to expressing them through geomorphic dimensions of barrier islands. Three distinct environments (beach, dune, marsh) are proposed as the panarchical levels of analysis, along with potential feedbacks between them and geomorphic dimensions that can express the changes of the stability landscape. Morphological changes induced by storms and subsequent recovery are transferred to stability landscapes, over a range of storm impacts and recovery. We postulate that postperturbation recovery should not be restricted to regaining pre-disturbance barrier dimensions, but should be viewed in terms of reorganisation and adaptation, accounting for maintaining the existence of functions, or the ability of the system to regain them. The proposed scheme and dimensions are tested using geomorphological data from barrier response to distinct disturbances, over different temporal scales that range from event to multi-decadal ones. The case of a barrier island migrating landwards is conceptualised in terms of alternative states and thresholds arising during the process and related phases and changes to the adaptive cycle. The methodology and approach presented is a step towards more holistic views of geomorphic systems’ resilience that we hope will contribute to furthering interdisciplinary understanding and cooperation in the area of sustainability and resilience of natural systems.
- Climate variability across the last deglaciation in NW Iberia and its marginPublication . Naughton, F.; Goni, Maria F. Sanchez; Rodrigues, T.; Salgueiro, Emilia; Costas, Susana; Desprat, S.; Duprat, J.; Michel, E.; Rossignol, L.; Zaragosi, S.; Voelker, Antje; Abrantes, FatimaThe direct comparison between marine and terrestrial data from the NW Iberian margin, core MD03-2697, allows us to accurately evaluate, without chronological ambiguity, the vegetation response to North Atlantic climate events across the last deglaciation. Comparison of MD03-2697 data with other marine and terrestrial records from a vast area stretching from the Azores to western (W) France, Iberia and its margin, the W Mediterranean and NW Africa reveals the importance of enhanced winter North Atlantic westerlies episodes in driving a heterogeneous regional climatic signal during particular events of the last deglaciation. Heinrich Stadial 1 (HS1)/Oldest Dryas is a complex event marked by three synchronous main phases (a: extremely cold/relatively wet; b: cool/dry; c: relatively warmer/increasing moisture availability) in regions directly influenced by the North Atlantic while it is characterized by a single phase (cold and dry) in most inland and high altitude areas. Changes in the strength and position of North Atlantic westerlies could explain the variability in moisture during HS1 from W Pyrenees to W Mediterranean. The Bolling-Allerod (B-A) event is marked by a synchronous progressive increase of ocean and atmospheric temperatures and precipitation from the Bolling to the Allerod in W Iberia and W Pyrenees contrasting with the Greenland temperature pattern. Mid-to high latitudes thermal contrast and the gradual strengthening of the Atlantic Meridional Overturning Circulation (AMOC) triggered the continuing enhancement of westerlies, and moisture, along this period.Finally, the Younger Dryas (YD) Stadial is characterized by a land-ocean synchronous returning cold conditions (but not so cold as HS1) and, although dry conditions persisted during this period, extreme winter precipitation occurrences might have affected the most coastal areas of north and central W Iberia and Pyrenees. In contrast, dry conditions persisted during the YD in the western Mediterranean regions. The westerlies migrated further north following the displacement of the Polar Front during the deglaciation precluding the input of moisture in the W Mediterranean region, which persisted very dry during the YD Stadial. (C) 2016 Published by Elsevier Ltd.
- Coastal barrier stratigraphy for Holocene high-resolution sea-level reconstructionPublication . Costas, Susana; Ferreira, Óscar; Plomaritis, Theocharis; Leorri, EduardoThe uncertainties surrounding present and future sea-level rise have revived the debate around sea-level changes through the deglaciation and mid-to late Holocene, from which arises a need for high-quality reconstructions of regional sea level. Here, we explore the stratigraphy of a sandy barrier to identify the best sea-level indicators and provide a new sea-level reconstruction for the central Portuguese coast over the past 6.5 ka. The selected indicators represent morphological features extracted from coastal barrier stratigraphy, beach berm and dune-beach contact. These features were mapped from high-resolution ground penetrating radar images of the subsurface and transformed into sea-level indicators through comparison with modern analogs and a chronology based on optically stimulated luminescence ages. Our reconstructions document a continuous but slow sea-level rise after 6.5 ka with an accumulated change in elevation of about 2 m. In the context of SW Europe, our results show good agreement with previous studies, including the Tagus isostatic model, with minor discrepancies that demand further improvement of regional models. This work reinforces the potential of barrier indicators to accurately reconstruct high-resolution mid-to late Holocene sea-level changes through simple approaches.