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- Sand bypass and updrift beach evolution after jetty construction at an ebb-tidal deltaPublication . Garel, Erwan; Mendes da Silva de Sousa, Carlos A; Ferreira, ÓscarThe evolution of an ebb-tidal delta (Guadiana, South Portugal) and its updrift beach after jetty construction (in 1972e1974) is analysed based on 24 ortho-rectified aerial photographs (1940e2012) and 13 bathymetric maps (1969e2014). The objectives are to evaluate the re-establishment of the sand bypassing process and if the disruption of the historical delta may affect the updrift beach evolution. Post-jetty progradation of the updrift beach resulted from two large accretion events. The second (largest) event (110 m progradation in 1985e1994) was due to beach attachment of a shoal produced by the erosion of a broad shallow area relict of the historical delta. The reworking of sand from this relict area also enables the individualisation of a lateral updrift bar simultaneously with the new ebb shoal proper formation. Both morphological features were close to (volume) equilibrium in 1995, indicating that most of the sand was transported towards the downdrift side of the inlet at that time. This study shows that erosion of the historical delta may enhance significantly the updrift shoreline progradation and may promote the re-establishment of sand bypassing after jetty construction.
- Aplicação multimédia sobre a Ria Formosa e seus fins educacionais (ForDid)Publication . Oliveira, Sónia; Boski, T.; Moura, Delminda; Mendes da Silva de Sousa, Carlos A; Gomes, Ana; Pereira, LauraNa atualidade torna-se inquestionável a necessidade de integrar a aprendizagem com as novas tecnologias de modo a cativar e facilitar a compreensão dos temas abordados através de aplicações didáticas. Durante a última década o Centro de Investigação Marinha e Ambiental (CIMA) assumiu a responsabilidade de criar meios eficazes de comunicação entre o público em geral e a comunidade científica, através de plataformas multimédia interativas. Foram objecto destas aplicações didáticas as várias vertentes do património natural do Algarve. Após o sucesso das primeiras aplicações GuaDid e MonDid visando o Estuário do Rio Guadiana e a Serra de Monchique respectivamente, o desafio de criar e inovar foi acrescido, resultando numa nova aplicação – ForDid, visando a divulgação do importante sistema lagunar Ria Formosa.
- Decadal morphological response of an ebb-tidal delta and down-drift beach to artificial breaching and inlet stabilisationPublication . Garel, Erwan; Mendes da Silva de Sousa, Carlos A; Ferreira, Óscar; Morales, J. A.The morphodynamic response of a mixed-energy ebb-tidal delta (Guadiana estuary, southern Portugal) and its down-drift barrier island (Canela Island) to channel relocation and stabilisation by jetties is examined using a series of sequential bathymetric maps and vertical aerial photographs spanning five decades. Morphological analysis indicates that the ebb delta is in an immature state, characterised by weak sediment bypassing. Landward-migrating shoals on the swash platform have been produced by the jetty-induced artificial bankbreaching and by the collapse of the eastern portion of the delta. The welding of these shoals has largely controlled the evolution of the coast, with local accretion and erosion lasting for years, and large amounts of regional accretion occurring over decades due to sand accumulation against jetties located further down-drift. These observations provide insights into the potential response of a coast to very large, locally concentrated sand nourishment in the form of shoals. The main effects of the jetties on the coast are observed at the centre of Canela Island, with the production of an erosion hot-spot associated with a temporally persistent and divergent longshore transport providing sand to the adjacent areas. Significant accretion is anticipated for the next decade along the entire island due to the ongoing attachment of the presently observed shoals. After the depletion of this sediment source, and in the context of weak sediment bypassing, the most severe down-drift erosion induced by the jetties is predicted to occur some decades after their construction. This study demonstrates that the geomorphic response of an ebb-tidal delta to jetty construction must be considered at multiple temporal and spatial scales when assessing the impacts of jetties on the down-drift coast
- The workaholism as an obstacle to safety and well-being in the workplacePublication . Maria Ramos Gonçalves, Gabriela; Néné, D.; Mendes da Silva de Sousa, Carlos A; Santos, Joana Conduto Vieira dos; Sousa, António Oliveira eThe work aholism, defined as addiction at work, increase burnout and negatively affects the psychological well-being. It was developed a quantitative study using self-reported measures. This study aims to evaluate the variables: passion for work, work engagement, engagement for life and job satisfaction as predictors of workaholism and the effects of workaholism on the psychological well-being and burnout. With a sample of 199 workers, the results of multiple linear regression analysis allowed to identify that some of the variables and their dimensions have significant effects on the workaholism and on psychological well-being and burnout.
- Deriva sedimentar na franja litoral do estuário do Guadiana: integração de ciência e gestão transfronteiriçaPublication . Mendes da Silva de Sousa, Carlos A; Boski, TomaszA implementação da Gestão Integrada de Zonas Costeiras no estuário do Guadiana exige perspectivar a evolução do sistema natural a longo prazo, considerando as especificidades locais e envolver todas as partes interessadas munidas do mesmo conhecimento. As modificações de origem antrópica impostas à dinâmica natural do estuário do Guadiana, fronteira natural entre Portugal e Espanha, tiveram como consequência a rápida transformação da evolução geomorfológica da orla costeira, afectando hoje bens e propriedades localizadas muito perto da linha de costa. Em particular, a intensificação da regulação do caudal do rio e a interrupção da deriva sedimentar longilitoral pela construção de um conjunto de estruturas de protecção costeira rígida na embocadura, conduziram a uma situação de intensa erosão costeira na margem espanhola. O presente trabalho desenvolveu um Sistema de Suporte à Decisão baseado em duas ferramentas: um Sistema de Informação Geográfica e um modelo analítico integrado de simulação construído com o software ExtendSim®. Os resultados obtidos demonstram que o processo de evolução da linha de costa pode, a longo prazo, afectar seriamente bens e propriedades, com custos pecuniários elevados. Uma resposta exequível reside nos projectos de realimentação de praias, revelando no entanto um ciclo de vida curto e custos crescentes. Respeitar as linhas de recuo, limitando a construção de edificações estáticas perto da linha de costa parece ser a alternativa viável. Resolver problemas de governação costeira, em particular em locais transfronteiriços, requer decisões informadas e eficientes por parte dos gestores costeiros. Estes por sua vez necessitam de avaliar soluções alternativas que considerem diferentes cenários futuros. Sistemas de Suporte à Decisão como o apresentado podem fornecer meios de estruturar e explorar esses problemas, e, em simultâneo, gerar informação qualitativa e quantitativa que facilite a criação de uma base de conhecimento comum.
- Mudança do nível do mar no golfo de Cádiz durante o Plistocénico tardio e HolocénicoPublication . Boski, T.; Moura, Delminda; Mendes da Silva de Sousa, Carlos A; Gomes, Ana; Pereira, Laura; Oliveira, Sónia; Santana, PauloThe multiproxy information data set obtained from borehole sequences permitted to establish a robust chronology of events, which led to the post glacial infilling of the terminal stretches of regional river palleovaleys. The paleoecological reconstructions combined with 14C age model of Guadiana Estuary sedimentary record revealed the fast sea level rise period since ca 13.5 kyr cal BP, halted during the Younger Dryas and resuming at ca 11500 yr cal BP. The Holocene history of coastal evolution is also well documented in the Estuary of Arade and in Ria Formoza, pointing to the sea level stabilization at ca 7500 cal BP after a last jump of up to 8 meters in 700 years which corresponds to the Meltwater pulse 1c. Since then, the upwards movement of the sea surface continued at much slower pace, ie with the 1.2 mm yr-1 rate. The integration of the data embracing the period from since ca 13.5 ka cal BP, to the actuality enabled us to propose the sea-level rise curve for the SW Iberian Atlantic margin. When confronted with the current altimetric data from TOPEX/POSEIDON, Jason I and Jason II satellites, the millennial time-scale natural trend enables to estimate the anthropogenic forcing of SLR to be in order of 1.2 – 1.8 mm year.
- Sea-level rise and anthropogenic activities recorded in the late Pleistocene/Holocene sedimentary infill of the Guadiana Estuary (SW Iberia)Publication . Delgado, J.; Boski, T.; Nieto, J. M.; Pereira, L.; Moura, Delminda; Gomes, A.I.; Mendes da Silva de Sousa, Carlos A; García-Tenorio, R.This study reviews data on sea-level rise during the last 13000 yr cal. BP (13 kyr) as recorded in the estuarine sediments of the Guadiana River (SE Portugal, SW Spain). We combined new data from a 63 m-long borehole, drilled through the entire postglacial sedimentary sequence, with information on five previously studied cores. By integrating sedimentological, geochemical and palaeontological proxies, we were able to make a palaeoenvironmental reconstruction of the Guadiana terminal palaeovalley during the last 13 kyr and propose a curve of sea-level rise for the SW Iberian Atlantic margin. Our foraminifera-based palaeoecological reconstruction, anchored to a 14C age model, reveals rapid sea-level rise from 13 kyr, interrupted during the Younger Dryas and resuming ca 11.5 kyr. The pace of marine transgression slackened ca. 7.5 kyr and since then has progressed upwards at a rate of 1.2 mm yr 1. HoloceneeAnthropocene sediments from two boreholes were also analysed to assess the timing, levels and sources of trace metals produced by acid mine drainage from the Iberian Pyrite Belt. Study of metal/aluminium ratios through the profiles allowed background metal concentrations to be estimated from lithostratigraphic units older than ca. 5 kyr (i.e. unaffected by anthropogenic activities). Human activities are especially evident from 4.5 kyr (the beginning of the Copper Age), with anthropogenic sources of metal fluxes prevailing over natural sources (especially Pb, Co, Ni, and Mn, and, to a lesser extent, Zn, Cu, and Ni). Mining activities became particularly intensive between the late Bronze Age and the Roman period (3e1.5 kyr), when the highest metal enrichment factors were recorded: EFPb z 2, EFCd > 10, EFCr z 2, EFCu z 3, EFZn ¼ 1.4.This study reveals the utility of postglacial sedimentary records for reconstructing historical changes in regional water-sediment quality and separating natural and anthropogenic sources of geochemical contaminants.
- Holocene history of Ria Formosa coastal lagoon system (Southern Portugal): borehole evidence and threedimensional paleotopographyPublication . Mendes da Silva de Sousa, Carlos A; Boski, T.; Gomes, Ana; Pereira, Laura; Lampreia, João; Oliveira, SóniaA paleotopographic model of Ria Formosa is presented based on two borehole campaigns and a systematic comparison with previous works, revealing the existence of a complex network of fluvial valleys. Vertical sediment profiles showed a mosaic of changing depositional environments, resulting from local hydrodynamics, sedimentary sources and, to an extent, by the structurally inherited accommodation space. Sedimentological, geochemical and micropaleontological data were put in the context of an age model obtained from 14C datings, pointing to the existence of an estuarine environment subjected to a rapid coastal flooding from ca. 10000 to 7500 cal. years B.P., followed by a period of infilling in an increasingly confined coastal lagoon environment.
- Modelling of estuarine response to sea-level rise during the Holocene: Application to the Guadiana Estuary-SW IberiaPublication . Sampath, DMR; Boski, T.; Loureiro, Carlos; Sousa, Carlos A. Mendes da Silva deThis paper focuses on simulations of the morphological evolution of an estuary during sedimentary infilling that accompanied Holocene sea-level rise. The simulations were conducted using the Estuarine Sedimentation Model, which uses a behaviour-oriented approach, supported by the chronostratigraphy of the estuary's sedimentary sequence. Behaviour curves were computed to represent the relationship between the estuarine channel depth below maximum high tide and the net accretion at a given location relative to the average sedimentation rate of the estuary during the Holocene. The model was validated by comparing the observed present-day bathymetry of the Guadiana River Estuary, southeastern Portugal, with the corresponding simulated bathymetries for nine control sections across the estuary. The best fit between simulated and actual sediment surface elevations was obtained along the cross-sections in the sheltered, low-energy environments of the estuary. The accuracy of the sedimentary stratigraphy of the best-fit model was further established using 16 radiocarbon ages obtained from five boreholes in the estuary. The present approach is particularly suitable for simulating long-term morphological evolution in sheltered estuarine environments where tidally driven vertical aggradation dominates at centennial to millennium timescales. However, the accuracy of simulated sediment surface elevations and consequently the robustness of behaviour-type models based on Geographical Information System platforms can be enhanced by incorporating (i) the impacts of nearshore hydrodynamic processes and episodic flood events in highly energetic channels, and (ii) the impacts of cross-currents in meandering channel sections. (C) 2015 Elsevier B.V. All rights reserved.
- Holocene background concentrations and actual enrichment factors of metals in sediments from Ria Formosa, PortugalPublication . Mendes da Silva de Sousa, Carlos A; Delgado, Joaquin; Szalaj, Dorota; Boski, T.Metal history in a natural system was described since the early Holocene by analysing the preserved subsurface sediment record and present-day surface sediments. Normalized geochemical data from six sediment cores (129 samples) was compared with 28 surface samples. Pre-anthropic sedimentary environments allowed the definition of local natural Background Values. Enrichment Factors were then used for elements discrimination in terms of natural and anthropogenic inputs to the system. While subsurface results displayed a similar behaviour in all cores, pointing to largely undisturbed system, surface sediments show significant contamination, with high enrichment factors for As, Cu, Pb, and Zn. Other metal pollutants have generally low enrichment values, suggesting natural conditions. Surface results were reproduced as metal enrichment maps which evidenced anthropogenic sources in specific locations. This work reveals the importance of combining subsurface and surface geochemical data with mapping techniques in order to better evaluate the environmental quality of a natural system.