Papers
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Development of an oil spill hazard scenarios database for risk assessment
The occurrence of oil spills in coastal regions may have catastrophic consequences on the environment and severesocio-economic impacts. This work presents a new methodology to evaluate the risk associated with oil spills in coastalzones and estuaries, and illustrates its application in a coastal lagoon (Ria de Aveiro, Portugal). A ranked list of thehydrodynamic scenarios under which oil spills are most likely generated through the analysis of 33 years of wave andwind data, retrieved from the ERA-INTERIM project database, and from the analysis of oil spills that occurred in theAtlantic Iberian shelf. Considering six spill locations and a single oil type spill inside the Aveiro harbor, the databaseresulted in approximately 3500 simulations. Hydrodynamic simulations were made with the MORSYS2D modelingsystem, a soft coupling of the hydrodynamic model ELCIRC and the wave model SWAN. The high-accuracy,unstructured grid, oil fate model VOILS was used in 2D mode to simulate the transport and the oil weathering processesat the surface and in the intertidal areas. The hazard assessment analysis included the determination of the trajectory ofthe plumes, the shoreline retention areas affected by the oil and their oil exposure time. Time evolution of the oilproperties, such as the oil evaporation rate and emulsification processes of the mixture, are provided to support clean-upoperations, as well as robustness controls such as oil mass balance.
Year: 2014
Number Pages:
p6.
Author(s): Boer, S.; Azevedo, A.; Vaz, L.; Costa, R.; Fortunato, A. B.; Oliveira, A.; Tomas, L.; Dias, J. M.; Rodrigues, M.
: Journal of Coastal Research
Keywords: Risk assessment; Oil spill modeling; Climatology
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Metodologia para o traçado da Linha de Máxima Preia-Mar de Águas Vivas Equi - nociais em ambientes de transição: aplicação ao estuário do Tejo (Portugal)
Os trabalhos desenvolvidos por equipas de investigação sobre a zona costeira bem como as ferramentas de gestão e ordenamento dasregiões hidrográficas, como, por exemplo, os Planos de Gestão de Bacia Hidrográfica e os Planos de Ordenamento de Estuários, necessitamda definição de margem e de leito e, por conseguinte, do traçado da Linha de Máxima Preia-Mar de Águas Vivas Equinociais (LMPMAVE)que corresponde ao seu limite. Muito embora a definição destas áreas e respetivo limite esteja descrita na lei que estabelece a titularidadedos recursos hídricos, existe uma dificuldade prática em transpor para a realidade do terreno as conceções legais, particularmente emsistemas de transição, como os estuários. Assim, revela-se prioritário o desenvolvimento de uma metodologia abrangente e objetiva capazde responder a este desafio.No presente trabalho, apresenta-se uma abordagem metodológica interdisciplinar e integrada, baseada na recolha e análise deinformação bibliográfica, cartográfica e de campo sobre a área de estudo (estuário do Tejo), bem como a experiência adquirida notraçado deste limite noutros locais do país. Deste modo, foi possível desenvolver um conjunto de critérios para o traçado da LMPMAVEem ambientes de transição, que podem ser divididos em quatro tipologias: a)biofísica, estabelecida através da presença ou ausência devegetação halófita; b)tipo de estrutura/altimétrica, que se prende com as características intrínsecas da estrutura e sua elevação; c) de usodo solo; d) de índole legal, baseada na Lei 54/2005 de 15 de novembro.O desenvolvimento e aplicação desta metodologia ao estuário do Tejo permitiu dispor pela primeira vez do traçado deste limite nesteimportante sistema de transição e, simultaneamente, ultrapassar a dificuldade de implementar os conceitos legais de LMPMAVE noterreno, ao criar critérios objetivos de suporte à sua marcaçã
Year: 2014
Number Pages:
96-107pp.
Author(s): Rilo, Ana; Freire, P.; Mendes, R.; Ceia , R.; Catalão, J.; Taborda, R.; Melo , Ricardo .; Caçador, M.; Freitas, M. C.; Fortunato, A. B.; Alves, E.
: Revista da Gestão Costeira Integrada
Editor: Revista da Gestão Costeira Integrada
Keywords: Costeira; Metodologia integrada; Margem; Leito
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Morphological evolution of an ephemeral tidal inlet from opening to closure: The Albufeira inlet, Portugal
Like othersimilarcoastalsystems,theAlbufeiralagoonisartificially openedeveryyeartopromotewaterrenewalandclosesnaturallywithinafewmonths.TheevolutionoftheAlbufeiraLagoonInletfromitsopening inApril2010toitsclosure8monthslaterisqualitativelyandquantitativelyanalyzedthroughacombination ofmonthly field surveysandtheapplicationofaprocess-basedmorphodynamicmodel.Field dataalonewouldnotcoverthewholespace
Year: 2014
Number Pages:
49-63pp.
Author(s): Fortunato, A. B.; Nahon, A.; Dodet, G.; Pires, A. R.; Freitas, M.Conceição; Bruneau, N.; Azevedo, A.; Bertin, X.; Benevides, P; Andrade, C.; Oliveira, A.
: Continental Shelf Research, 73
Editor: Elsevier
Keywords: Tidal asymmetry; Nudging; Intermittenttidalinlet; Morphodynamic model; Parelationship
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Salinity modelling accuracy of a coastal lagoon: a comparative river flow analysis of basin model vs. traditional approaches
The main purpose of this study is to investigate the uncertainties in the modelling of salinity fields in the Ria de Aveiro lagoon associated with the estimation of river flow discharges. The prediction of fresh water inputs is necessary to properly implement forcing conditions and consequently to provide accurate forecasts of baroclinic circulation in coastal lagoons. Located in the north-western Portuguese coast, the Ria de Aveiro is a shallow vertically homogeneous mesotidal coastal lagoon with a complex geometry. Although it is tidally dominated, it receives freshwater from five rivers, the Vouga, Antuã, Cáster, Boco and Ribeira dos Moínhos, whose contributions are responsible for the salinity variation within the system. This research concerns the accurate prediction of river flow to be used in the operational forecast system of the lagoon. Given the lack of observed data for river discharges, as there are only two real time measuring stations located in the Vouga and Antuã river basins, but far from the lagoon, alternative estimation approaches are needed. In order to estimate the river discharges for all five rivers, two different approaches were considered: the first estimates the Vouga river flow, the major fresh water source, based on the nearest real time measuring station and estimates the other river flows based on river basin areas proportionality; the second establishes river flows based on the precipitation/river flow relationships for the Vouga and Antuã rivers and on the areas of the other river basins using the SWAT model. The methodology comprises the exploitation of the 3D unstructured-grid hydrodynamic model SELFE, required to adequately simulate the flow and transport of salt in very complex domains such as the Ria de Aveiro. The model is forced by water elevations at the ocean boundary and river flows at the river boundaries, and atmospheric drivers at the surface (wind stress, atmospheric pressure and heat fluxes). The salinity model predictions were compared with data from seven stations, and its accuracy was assessed through Root Mean Square Error (RMSE). The river flows estimated by the first method led to the best fit between observed and predicted salinity.
Year: 2014
Number Pages:
pag 586-591.
Author(s): Tomas, L.; Rodrigues, M.; Fortunato, A. B.; Azevedo, A.; Leitão, J. P.; Oliveira, A.; Rocha , A .; Lopes, N.; Dias, J. M.
: Journal of Coastal Research
Keywords: Circulation forecasts; Selfe 3d; Ria de aveiro; River flow estimation; Alinity field
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Aeolian microtextures in silica spheres induced in a wind tunnel experiment: Comparison with aeolian quartz
Microtextures in quartz attributed to aeolian transport, principally bulbous edges and abrasion fatigue haveseldom been tested in the laboratory under controlled conditions. A wind tunnel experiment was conducted,using glass spheres (>70% SiO2) as a proxy for quartz, with the objective of determining the extent of mechanicaldamage to silica/glass transported in a mixture with quartz beach sand. The microspheres were microscopicallyimaged prior to transport in a wind tunnel, subjected at velocities ranging from 4 to 13 m/s insequential runs of 10 min. The range in velocity is capable of lifting grains into the air column or saltatingquartz grains and silica/glass spheres to produce mechanical impact, i.e. abrasion commonly experiencedin aeolian transport. With increasing velocity silica/glass spheres, which displayed minor imperfectionsprior to transport, began to show significant grain damage exhibiting increasing depth into the silica/glassfabric
Year: 2013
Number Pages:
120-129pp.
Author(s): Costa, P.; Andrade, C.; Mahaney, W.; Marques da Silva, F.; Freire, P.; Freitas, M. C.; Janardo, C.; Oliveira, M.Alexandra; Silva, A.; Lopes, V.
: Geomorphology
Editor: Elsevier
Keywords: Microtextural imprints; Aeolian transport; Sem; Quartz; Silica spheres; Wind tunnel
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Bed shear stress under skewed and asymmetric oscillatory flows
We present a new formulation to predict the bed shear stress under skewed/asymmetric oscillatory flows(with or without a co-linear mean current), extending the work of Nielsen (1992). The nonlinearity of theoscillatory flow is incorporated through the use of two parameters: the index of skewness or nonlinearity,and the waveform parameter. The new formulation is tested against the bed shear stress estimated fromthe log-fit and momentum-integral methods, using oscillatory data from oscillating water tunnel experiments.The new formulation and the momentum-integral method agree well, but differ from those withthe log-fit method, possibly because both methodologies lead to different results for the phase lead betweenthe bed shear stress and the free-stream velocity. The new bed shear stress formulation is incorporated in aquasi-steady bedload formula, and accurately reproduces net transport rates under non-linear, nonbreakingwaves with and without an opposing current.
Year: 2013
Number Pages:
1-10pp.
Author(s): Abreu, T.; Michallet, H.; Silva, P. A.; Sancho, F. E.; Van der A, D. A.; Ruessink, B. G.
: Coastal Engineering
Editor: Elsevier
Volume:
73.
Keywords: Sand transport; Velocity skewness; Acceleration skewness; Oscillatory flow tunnel; Mobile bed; Bed shear stress
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Defining beaches and their evolutionary states in estuaries
Projected rates of global sea level rise and human pressures have increased attention to the potential for landformchange in estuaries. This paper assesses the status of the fetch-limited beaches in the Tagus estuary, one of the largestestuaries in Europe, with a focus on distinguishing active beaches from inactive vegetated banks and identifyingconditions under which they change state. A total of 26 beaches were identified in the inner estuary and 49 in thetributary basins on 2007 aerial photographs and compared with conditions on older photographs (1944-1958). Lengths,widths and maximum fetch distances for beaches were measured and site visits were made to determine their originsand present conditions. Beaches occur at eroding uplands or marshes or on spits extending from eroding uplands.Human-created beaches occur on spoil areas, within niches formed by structures and where vegetation is eliminated orprevented from colonizing (e.g. boat launches and recreational surfaces). Basin infilling, with increase in the elevationof low tide terraces and the formation of bars, is reducing wave energies, and some beaches are reverting to vegetatedbanks. Beaches that become vegetated banks because of human actions occur where use for boating or recreation isabandoned and where spits that form off spoil deposits reduce fetch distances upwind.
Year: 2013
Number Pages:
482-487pp.
Author(s): Freire, P.; Jackson , N.; Nordstrom , K.
Editor: Journal of Coastal Research
Keywords: Fetch distances; Tagus estuary; Human interventions; Sedimentation rates; Wave energy
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Effect of salinity on the settling velocity of fine sediments of a harbour basin
Salinity is known to increase the cohesion of clay minerals, and thus the flocculation of fine-grained sediments insuspension. However, the influence of salinity on the settling velocity of natural particles is often unclear, due toorganic and biological aggregation and other controlling factors. This paper examines the effect of salinity on thesettling velocity of fine sediments collected in a harbour basin in the Tagus estuary. The sediment sample consists ofsilt- and clay-sized particles (D10 = 2
Year: 2013
Number Pages:
1188-1193pp.
Author(s): Portela, L. I.; Ramos, S.; Teixeira, A.
Editor: Journal of Coastal Research
Keywords: Settling column; Harbour siltation; Cohesive sediment
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Estuarine margins vulnerability to floods for different sea level rise and human occupation scenarios
Sea level rise (SLR) is increasing the risk of flooding in marginal low-lying estuarine areas. High water levels inestuaries are associated with the simultaneous occurrence of various phenomena ranging from high tidal levels to largefresh-water discharges. The intense and diverse human occupation of some of these marginal areas increases the floodvulnerability, endangering human lives and causing heavy economic and environmental losses. This issue becomeseven more relevant since the European Floods Directive establishes mandatory guidelines to all member statesregarding flood risk assessment, integrating flood maps with territorial characteristics. The present study aims to assessthe vulnerability to floods of a specific area in Tagus estuary, by integrating hydrodynamic modelling results with landuse cartography. Results suggest that about 16.1% of the estuarine marginal fringe could be flooded for the 2050scenario, rising up to 23.7% for the 2100 scenario. Moreover, industrial and urban areas will be the most affected sites.Considering future development scenarios planned for that site, the results point to an increasing vulnerability of urbanareas and therefore to the relevance of this knowledge in future planning and management guidelines as well asmeasures to adapt to SLR. The uncertainties and implications of the study are also discussed, and future research topicsare indicated.
Year: 2013
Number Pages:
820-825pp.
Author(s): Rilo, Ana; Freire, P.; Guerreiro, M.; Fortunato, A. B.; Taborda, R.
Editor: Journal of Coastal Research
Keywords: Tagus estuary; Climate change; Land use; Future development scenarios
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Experimental and numerical study of the hydrodynamics of the western sector of Ria Formosa
The western sector of Ria Formosa, a lagoon system in the south of Portugal, represents approximately 90% of the total tidal prism of the lagoon and includes three inlets. Two sets of field campaigns to characterize the hydrodynamics of this sector in neap and spring tide conditions were conducted in the autumn of 2011 and spring 2012. The main findings related to the inlets hydrodynamics and water exchanges between the lagoon and the ocean along semi-diurnal tidal cycles are presented. To estimate the relative contribution of the three inlets to the water exchanges between Ria Formosa and the ocean, discharges were evaluated hourly along complete neap and spring semi-diurnal tidal cycles and the tidal prisms computed. In addition, two sea level time series measured in Faro-Olhão inlet and Faro commercial pier were harmonically analyzed. The results were compared with previous studies and used to validate the ELCIRC hydrodynamic model. This model provided additional information about the circulation and tidal prisms and distortion inside the western Ria Formosa. This study confirmed the Faro-Olhão inlet as the main inlet in terms of contribution for the total tidal prism. It is shown that the Ancão inlet lost hydraulic efficiency, contributing less than 6% to the total tidal prism in all situations and the Armona inlet gained efficiency in spring tide and lost efficiency in neap tide. Moreover, the Faro-Olhão inlet exhibits flood prisms higher than ebb prisms under neap and spring tides, suggesting a residual circulation towards the Ancão and Armona inlets.
Year: 2013
Number Pages:
2011-2016pp.
Author(s): Jacob, J.; Cardeira, A.; Rodrigues, M.; Bruneau, N.; Azevedo, A.; Fortunato, A. B.; Rosa, M.; Cravo, A.
: Journal of Coastal Research
Editor: Coastal Education Research Foundation
Volume:
SI 65.
Keywords: Hydrodynamic model; Field campaign; Residual circulation; Tidal prism; Tidal inlet; Lagoon system
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Comunicação
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The Tagus estuary
The estuary of the Tagus river is one of the largest estuaries in Europe covering an area of about 320 km2. It is located in the Portuguese west coast, in the metropolitan area of Lisbon, and due to its social and economic context and environmental characteristics it is the Portuguese most relevant estuary. The estuary comprises along its margins 11 municipalities with about 1.6million inhabitants (Tavares et al., 2015). It hosts the Port of Lisbon, the national leader in the movement of vessels (in number and in GT), and the Tagus Estuary Natural Reserve considered one of the most important sanctuaries for birds in Europe.
Year: 2019
Number Pages:
54-56pp..
Author(s): Freire, P.
: Collection of Papers. 6th Biennal Conference Particles in Europe, PiE-2018. Lisbon, Portugal, 14-17 October 2018
Editor: -
Keywords: Tagus; Estuary
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Tidal influence on the phytoplankton community of Tagus estuary
Estuaries are highly variable systems and the most productive ecosystems in the world.Phytoplankton is a major contributor to the high productivity, rapidly responding to changes inthe environment
Year: 2019
Number Pages:
1p.
Author(s): Cereja, R.; Cruz, J.; Brito, A.; Rodrigues, M.; Brotas, V.
Editor: EEF 2019
Keywords: Tagus; Tidal influence
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Topo-bathymetric monitoring south of the Mondego river mouth after the extension of the north jetty
This work evaluates the morphological evolution of the coastal frontage south of Figueira da Foz (west coast of Portugal) after the extension of the north jetty based on the analysis of topo-bathymetric surveys located in twelve equidistant transepts in the study site. The results show that the study site has large inter-annual morphological variations and the complex morphological behaviour shows an erosive tendency of the beach face downdrift of the structures.
Year: 2019
Number Pages:
19-20pp.
Author(s): Oliveira, J. N.; Oliveira , F.; Teixeira, A.
: 5ª Conferência sobre Morfodinâmica Estuarina e Costeira - Livro de Resumos
Editor: Faculdade de Ciências da Universidade de Lisboa
Keywords: Figueira da Foz.; Erosion; Beach morphodynamics; Hydro-topographic profiles; Nearshore monitoring
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Towards an operational hydrodynamics and biogeochemical model of the Tagus estuary
Climate change and the predicted increase of human activities in estuaries may increase the hazards inthese systems. Water observatories can support both the daily and the long-term management of estuarineecosystems. Although in the past water observatories were mostly based on observations, these tools haveevolved to account for forecasts, scenarios analysis and indicators
Year: 2019
Number Pages:
1p.
Author(s): Rodrigues, M.; Santos, D.; Rogeiro, J.; Fortunato, A. B.; Teixeira, J.; Oliveira, A.; Martins, R.
Editor: International Society for Ecological Modelling / Elsevier
Keywords: Estuary; Tagus
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Using HPC to enable coastal waters observatories
Coastal systems are among the most productive ecosystems in the world, providing multipleresources and guaranteeing the resilience of the coastal communities. Climate change (e.g.,sea level rise) represents a major threat to the world
Year: 2019
Number Pages:
1p.
Author(s): Rodrigues, M.; Oliveira, A.; Martins, R.; Rogeiro, J.; Santos, D.; Fortunato, A. B.; Azevedo, A.
Editor: Ibergrid 2019
Keywords: Waters; HPC
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Water observatories as supporting tools to climate change adaptation in coastal ecosystems
Climate change, such as sea level rise, represents a major threat to the world
Year: 2019
Number Pages:
1p.
Author(s): Rodrigues, M.; Cravo, A.; Fortunato, A. B.; Oliveira, A.; Martins, R.; Jacob, J.; Rogeiro, J.; Rosa, A.; Santos, D.; Freire, P.; Azevedo, A.
Editor: ECCA 2019
Keywords: Coastal; Water
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Bound and free infragravity waves over a bar
This study aims to investigate the changes in the infragravity wave energy under partialshort-wave breaking conditions induced by a longshore bar. Field observations of near-bottompressure records on a cross-shore array were analysed for such purpose. The bispectrum wasemployed to detect the phase-coupling between short and infragravity wave frequencies. This allowedto separate the infragravity wave energy in bound and free energy components.The bar crest induced a decrease on the short-wave energy due to depth-induced breaking. At thesame location, a damping on the bound infragravity wave energy was observed. This dampingcoincides with a negative value of the short-wave radiation stress cross-shore gradient. This providesevidence that bound infragravity wave energy decreases with a reduction in the forcing.
Year: 2018
Number Pages:
198-201pp..
Author(s): Mendes, D.; Pires Silva, A.; Pinto, J.; Fortunato, A. B.
Editor: Instituto Hidrogrâfico
Keywords: S. Jacinto; Field observations; Bispectral analysis; Infragravity waves
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Dinâmica sedimentar e evolução a longo prazo do porto da Praia, ilha de Santiago, Cabo Verde
Resumo: Os processos de evolução costeira em Cabo Verde, resultantes de fatores naturais e deatividades humanas, são ainda pouco conhecidos. Analisa-se neste trabalho a evolução morfológica dabaía do porto da Praia, na ilha de Santiago, com base em levantamentos hidrográficos de 1882 a 2016,fotografia aérea, imagens de satélite e cartografia histórica. Recorre-se também à modelaçãomatemática de processos hidrodinâmicos e morfodinâmicos, considerando a interação ondascorrentes,para interpretar as condições locais. Os elementos analisados sugerem uma tendência deacumulação sedimentar, com uma taxa média de avanço da praia, a longo prazo, da ordem de 1 m/ano.Estima-se que o caudal sólido transportado episodicamente pelas ribeiras afluentes seja uma fontesedimentar importante. Embora a recente expansão do porto tenha diminuído a influência da ação dasondas, as condições mais favoráveis à remobilização e à circulação sedimentar no interior da baíapermanecem associadas aos períodos de agitação marítima mais energética
Year: 2018
Number Pages:
245-248pp..
Author(s): Portela, L. I.
Editor: Instituto Hidrogrâfico
Keywords: Morfodinâmica; Modelação; Cartografia hidrográfica; Acreção; Cabo Verde
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Evolução da praia da Nazaré após a construção do porto de pesca
Evolution of Nazaré beach after the construction of the fishing harbour
Year: 2018
Number Pages:
321-322pp..
Author(s): Portela, L. I.; Teixeira, S.; Sancho, F. E.
Editor: Departamento de Ciências da Terra da Universidade de Coimbr
Keywords: Morphodynamics; Linear regression; Beach; Accretion; Nazaré; GIS; EPR
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Monitoring the implementation of a dredging plan in the Óbidos Lagoon (Portugal)
The Óbidos lagoon (central west coast of Portugal) is a small coastal system exposed tointense wave action. Because its inlet is highly dynamic and closes occasionally, frequent interventionshave been carried out by local and national authorities. However, their results have been ephemeral, andthe interventions
Year: 2018
Number Pages:
273-276pp..
Author(s): Freire, P.; Fortunato, A. B.; Portela, L. I.; Azevedo, A.
Editor: Instituto Hidrogrâfico
Keywords: Dredging; Monitoring; Hydrodynamics; Morphologic evolution; Tidal inlet
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Books
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MEC2011 - Conferência sobre Morfodinâmica Estuarina e Costeira
N/A
Year: 2011
Author(s): Fortunato, A. B.; Freire, P.; Oliveira, A.
Editor: Laboratório Nacional de Engenharia Civil
Volume:
CD Room.
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Capítulo de Livro
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Evaluating the geomorphologic stability of an estuarine sandy beach. Integrated Coastal Zone Management
The hydrodynamics and sediment dynamics of a low energy estuarine beach was analysed. The beach is subjected to local wind waves generated in an area of restricted fetch, wake waves generated by catamarans and a semi diurnal meso-tidal regime. Only storm events of short duration modify the beach profile, which, once the normal hydrodynamic conditions are restored, naturally recovers its initial shape. The beach is characterised by having a steep upper slope until mean sea level, followed, seaward, by a low gradient terrace, and a bimodal sediment distribution. To investigate the hydro sedimentologic beach behaviour, wind, topo-hydrographic and sedimentologic data were used as input and validation of process based numerical modelling. Wave generation and transformation in an area of restricted fetch, nearshore circulation, sediment transport and morphological evolution were simulated for average annual conditions and storm conditions. The statistical analysis of a six-year wind data series allowed to derive the average wind regime, based on which, the average annual wave regime and the average annual longshore sediment budget, 14.5x103 m3year-1, were calculated. The contribution of the individual components of the representative wave regime, discretised by directional sector and height class of incidence, was evaluated as well as the spatial distribution of the longshore sediment transport in the active part of the beach profile. The characteristics of the wave groups generated by the passage of catamarans at different speeds were estimated and their action on the beach morphology was simulated. Although when the catamarans travel at 20 knots speed the average annual wake wave energy dissipated at the beach is 2.5 times higher than the average annual wind wave energy, the erosion effect on the beach profile is still not relevant for the present traffic. In opposition, short duration storm events generate the formation of an erosion scarp at the upper part of the beach face. The numerical modelling of this phenomenon allowed to acknowledge on the protective effect that the low gradient terrace has on the beach face.
Year: 2009
Number Pages:
pp. 35-49.
Author(s): Oliveira, F. S. B. F.; Vargas, C.
Editor: Wiley-Blackwell Publishing
Volume:
Integrated Coastal Zone Management.
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Tese de Doutoramento
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Three-dimensional modelling of cohesive sediment transport in estuarine environments
N/A
Year: 1995
Author(s): Costa, R.
Editor: ******
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A Two-Dimensional Hydrodynamic Model Using a Finite-Volume Approach
A two-dimensional model of wind-driven circulation in a closed basin was developed using a finite-volume technique for generalized curvilinear grids and applying some of the recent developments in hydrodynamic modeling. The terms in the Navier¬Stokes equations were treated separately according to the fractional step method and the propagation step, including the continuity equation and the pressure and stress terms in the momentum equations, was solved using a conjugate gradient method.The model was then applied to a number of test cases to examine the feasibility of the approach used by comparing with results obtained with the two-dimensional version of the three-dimensional model CH3D. These included a square basin with constant slope and with a V-shaped bottom and Lake Okeechobee, in South Florida. To evaluate the long-term numerical stability of the model, a ten-day model simu¬lation with varying wind was also run for Lake Okeechobee.
Year: 1989
Author(s): Capitao, J.
Editor: ******
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Flow-Fine Sediment Hysteresis in Sediment-Stratified Coastal Waters
An examination of the causes for generation and dynamics of turbidity maxima in estuaries reveals the critical role of sediment tidal pumping phenomenon and, to a lesser extent, of the well-known effect of residual gravitational circulation due to salt water penetration. Both phenomena depend on the vertical sediment concentration profile and, consequently, on the magnitude of the vertical mass transport fluxes. Where high concentration suspensions occur regularly, the erosion/deposition fluxes can be drastically modified by sediment stratification, consequently influencing sus¬pended sediment response to currents and wave action. This influence is inherent in flow-sediment hysteresis, which therefore reflects the role of vertical mass transport in the estuarine and coastal suspended fine sediment regime.A vertical transport numerical model was used to investigate the influence of several key parameters describing sediment settling, bed properties and stabilized diffusion on the concentration profile. The model was also applied to simulate the influence of the same parameters on the time-lagged sediment response to flow variations, reflected in the characteristics of flow-sediment hysteresis loops.Field data obtained in Hangzhou Bay (People´s Republic of China), a high concentration environment, showed typical features of flow-sediment hysteresis and confirmed the importance of the vertical mass fluxes in contributing to sediment transport in the bay. A qualitative simulation provided by the numerical model, using settling parameters corresponding to local sediment, while confirming the importance of the hysteresis phenomenon, also revealed the critical need to use algorithms describing adequately stabilized diffusion and bed fluxes.Additional evidence of hysteresis was obtained through analysis of microscale variables, such as the Reynolds stresses and the variances of the velocity components resulting from combined effects of wave action and turbulence. Spectral analysis of the measured random variations did not support the commonly accepted hypothesis of similarity between the responses to turbulent flow of sediment concentration and temperature. The normalized turbulent intensities for all the measured veloc¬ity components showed their highest values during the period of lowest sediment concentration; this result is consistent with the hypothesis of turbulent intensity damping by suspended sediment.
Year: 1989
Author(s): Costa, R.
Editor: ******
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Alimentação artificial de praias
A contribution to increased use and development of the method of artificial nourishment of beaches is the main objective of this thesis. It also aims at being a guide for the design of the reconsctrution or outright creation of beaches.In the first chapter, the subject is introduced and the objectives of the thesis are outlined. The second chapter cover´s some general considerations on littoral dynamics, beach equilibrium and sediment budget.Since the theoretical foundations of the artificial nourishment of beaches still leave much to be desired, a description of this method and its principles are presented in the third chapter. Important technical and economic aspects are included, such as: sampling, analysis and characterization of native and borrow material; selection Of nourishment sources; extraction and transport of borrow sand; and characteristics of the theoretical final beach profile. Such problems as the integration of ecological aspects, and cost-benefit analysis are also treated.in the fourth chapter, the Portuguese experience in this domain is described. The experience of such countries as France and the U.S., where this method has frequently been used is also mentioned. In this way a considerable amount of hitherto scattered information is presented in a unified way.The fifth chapter, treats briefly the problem of coastal model similitude, both as a support for the experimental work: which was carried out and to help engineers in the design of a coastal physical model or in merely assessing the possibilities of such a model.In the sixth chapter, an experimental study is described of the influence of both the grain size of borrow material and the nourishment method on the redistribution of sediments after the nourishment. The obtained results are compared with existing theoretical methods and some prototype results.Finally, in the last chapter the main conclusions and recomendations of the thesis are presented.
Year: 1987
Author(s): Clímaco, M.
Editor: ******
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Solution of Advection-Dominated Transport by Eulerian-Lagrangian Methods Using Backwards Method of Characteristics
We provide a systematic analysis of the consistency, stability, convergence and accuracy of the numerical solution of the transport equation by a general Eulerian-Lagrangian Method (ELM). The method involvesthree basic steps: the backwards tracking of characteristic lines following the flow, the interpolation of concentrations at the feet of these lines, and the solution of dispersion taking such concentrations as initial conditions. The first two steps constitute the Backwards Method of Characteristics (BMC); the third step involves a time-discretization along the characteristic lines, and a spatial discretization of the dispersion operator, both based on conventional techniques (e.g.. Euler or Crank¬Nicholson for time; finite-elements or finite-differences for space).The choice of the spatial interpolator is shown to impact the consistency, stability and convergence, as well as the accuracy of the BMC. Most interpolators ensure consistency, but only a few ensure stability, hence convergence; stability criteria are derived from a newly developed generalized Fourier analysis, which can account for non-linearities introduced by quadratic grids. The comparison of formally derived propagation and truncation errors, complemented by numerical experimentation, provides a reference for the choice of the interpolator, given a specific transport problem characterized by prevailing concentration gradients.The BMC potentiates the use of large time-steps, well above Courant number of order one. In the limiting case of pure advection, optimal accuracy would be obtained for a At close to the total time of interest; the presence of dispersion constrains, however, the size of At, especially in the case of non-uniform flows. The comparison of the truncation errors for the three basic steps of ELM provides a reference to select At. as a function of Ax, of the spatial interpolators and time-discretization schemes, and of the gradients of flow and concentrations.
Year: 1987
Author(s): Melo Baptista, A.
Editor: ******
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Accurate Numerical Modeling of Advection-Dominated Transport of Passive Scalars. A Contribution
Apresenta-se um estudo sistemático, baseado simultaneamente em análises formais e em experimentação numérica, da precisão e estabilidade da solução da equação de transporte por um método Euleriana-Lagrangeana (MEL). 0 método decompõe a equação de transporte em equações separadas de advecção e de difusão, resolvendo a primeira pelo método das características regressivas no tempo (MCR), e a segundo por um método de elementos finitos, do tipo Galerkin.Mostra-se que as interpolações no espaço requeridas pelo MCR são um factor limitativo da precisão global do MEL, e comparam-se diversas técnicas alternativas de interpolação, algumas das quais originais. A combinação de esquemas compactos e não-compactos de interpolação, baseados em polinómios de Lagrange, é apontada como uma potencial solução óptima.Demonstra-se que, para uma adequada escolha do esquema de interpolação, o MCR é consistente, estável e convergente e tem boas características de precisão. Escolhas inadequadas do esquema de interpolação podem, no entanto, causar instabilidade e inconsistência.Estabelece-se a dependência da precisão do MCR no passo de cálculo, mostrando-se que essa precisão aumenta, em geral (para um tempo total fixo), quando se reduz o número de passos de cálculo, isto é, quando se aumenta o passo de cálculo (uma propriedade simultaneamente pouco habitual e muito conveniente). No entanto, na gama de valores muito pequenos do Número de Courant, a precisão é praticamente independente do passo de cálculo, o que evita que o método se torne divergente.Analisa-se brevemente o efeito de malhas irregulares e pluridimensionais sobre a aplicabilidade e precisão do MCR. Apesar de sensível à irregularidade da malha, o método mantém boas características de precisão desde que as distorções geométricas não sejam excessivas. Malhas pluri-dimensionais, quando simultaneamente irregulares, levantam problemas específicos de aplicabilidade de esquemas não-compactos de interpolação; esses problemas poderão se resolvidos através da utilização conjugada de esquemas compactos e não-compactos, para um mesmo problema. Investigação adicional a ainda requerida nestas áreas.Mostra-se ainda que a presença de mecanismos físicos de difusão beneficia tanta a precisão da solução da equação de advecção como a precisão global do MEL.Finalmente, demonstra-se a eficácia da aplicação do MEL (numa forma particular, restricta a esquemas de interpolação compactos) à simulação do transporte de poluentes em águas costeiras. 0 método permite, em particular, realizar simulações longas (várias marés) a custos moderados, mesma para malhas irregulares com elevado número de nós, e, também, evitar a necessidade do uso de difusividades artificiais como garante de estabilidade; em geral, e nestes dois aspectos em particular, o método revela-se superior a métodos Eulerianos, mais convencionais (por exemplo, métodos de elementos finitos, do tipo Galrkin ou Petrov-Galerkin, aplicados à equação de transporte indivisa).
Year: 1986
Author(s): Melo Baptista, A.
Editor: ******
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Sobre a Avaliação de Parâmetros de Qualidade de Água por Detecção Remota: Suspensões
No âmbito de um projecto de investigação intitulado caracterizarão de Formações Estuárias e do Meio Marítimo Litoral Por Técnicas de Detecção Remota , insere-se o estu¬do da avaliação de suspensões na água do mar com recurso à aplicação de técnicas de detecção remota como meio de caracterização de parâmetros de qualidade de água. 0 trabalho que se apresenta foi desenvolvido com os seguintes objectivos:1- Desenvolvimento de metodologias de análise e quantificação de suspensões na água do mar a partir de dados de satélite;2- Implementação sob forma de programas para computador de modelos de quantificação de suspensões orgânicas e inorgânicas na água do mar, a aplicar aos dados do radiómetro CZCS do satélite NIMBUS-7;3- Aplicação e verificação do modelo ao litoral português.Corn vista à consecussão destes objectivos, começa-se por apresentar uma extensa análise das formas de abordagem do problema, enumerando-se os diversos métodos actualmente seguidos, nomeadamente o Empírico, o Teórico e, neste, os métodos microscópico e macroscópico.Com base nesta análise, propõe-se um modelo numérico de quantificção das suspensões a partir dos dados do radiómetro CZCS do satélite NIMBUS-7, o qual, embora empírico na sua formulação como a maioria dos actualmente existentes, se apoia no comportamento radiomótrico da água do mar e dos seus constituintes típicos, cujas características se apresentam também.A implementação prática do modelo exige a filtragem da componente atmosférica presente nos dados rediométricos. Com este objectivo, apresenta-se um modelo baseado na metodo¬logia correntemente utilizada. Consiste na consideração da difusão simples, causada pelos constituintes básicos da atmosfera (moléculas gasosas, aerosóis e ozono) na gama de comprimentos de onda considerada (440, 520, 550 e 670nm). Esta metodologia conduz, porém, a um sistema de equações indeterminado e que é resolvido pela consideração de uma equação ´exterior´ ao processo de transferência radiativa que tem lugar na atmasfera. Para este efeito, utilizou-se a equação de Smith e Wilson por ser a mais divulgada, ressalvando-se, contudo, a necessidade de verificação da sua efectiva aplicação às águas do litoral português, o oqe não foi possível concretizar dada a inexistência de dados.
Year: 1986
Author(s): Oliveira, E. M.
Editor: ******
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Eulerian-Lagrangian Analysis of Pollutant Transport in Shallow Water
A numerical method for the solution of the two-dimensional, unsteady, transport equation is formulated, and its accuracy is tested.The method uses a Eulerian-Lagrangian approach, in which the transport equation is divided into a diffusion equation (solved by a finite element method) and a convection equation (solved by the method of characteristics). This approach leads to results that are free of spurious oscillations and excessive numerical damping, even in the case where advection strongly dominates diffusion. For pure diffusion problems, optimal accuracy is approached as the time-step, At, goes to zero; conversely, for pure-convection problems, accuracy improves with increasing At; for convection-diffusion problems the At leading to optimal accuracy depends on the characteristics of the spatial discretization and on the relative importance of convection and diffusion.The method is cost-effective in modeling pollutant transport in coastal waters, as demonstrated by an illustrative application to a case study (sludge dumping in Massachusetts Bay). Numerical diffusion is eliminated or greatly reduced, raising the need for realistic estimation of dispersion coefficients. Costs (based on CPU time) should not exceed those of conventional Eulerian methods and, in some cases (e.g., problems involving predictions over several tidal cycles), considerable savings may even be achieved.
Year: 1984
Author(s): Melo Baptista, A.
Editor: ******
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Sobre a Propagação de Ondas do Mar em Regiões Costeiras. Análise pelo Método dos Elementos Finitos
0 principal objectivo desta tese é mostrar a habilidade do métodos dos elementos finitos e do método dos elementos de fronteira na modelação das ondas gravíticas de superfície.Na análise linear, as equações reduzidas do movimento ondulatório são resolvidas pelo método dos elementos finitos, levando em linha de conta a reflexão parcial, a radiação e o atrito de fundo. A modelação da radiação é feita com elementos infinitos ou com elementos de radiação, sendo estes encarados como um caso particular dos elementos de reflexão. 0 atrito de fundo é introduzido após a discretização e é levado a efeito através de um coeficiente empírico que se pode relacionar com o coeficiente de Chezy.Quer o modelo determinístico quer o modelo estocástico, obtido do primeiro com base na noção do estimador natural, permitem a realização de ensaios de ressonância ou de agitação. Nos ensaios de ressonância de uma bacia portuária tem particular interesse o conhecimento do espectro de resposta ao ruído bran¬co de banda limitada.A título de exemplo de aplicação mostram-se alguns aspectos do estudo das condições de ressonância do porto de Leixões.Logo que não sejam válidas as hipóteses simplificativas que permitem uma abordagem linear das ondas gravíticas de superfície, são resolvidas as equações não lineares do movimento ondulatório com superfície livre, pelo método dos elementos de fronteira. As suas peculiaridades permitem, sem qualquer dúvida, considerar o método dos elementos de fronteira como o mais vocacionado para este tipo de análise.Os programas de cálculo automático para o estudo da análise não linear estão ainda em fase de teste, pelo que não se apresentam exemplos de aplicação.
Year: 1982
Author(s): Portela, A.
Editor: ******
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Numerical simulation of the tidal flow in homogeneous estuaries
Este trabalho é dirigido principalmente para o uso da simulação numérica dos escoamentos em estuários como uma ferramenta pa¬ra estudos de engenharia. Fazem-se algumas considerações gerais sobre a definição e classificação de estuários seguidas por uma descrição sumária da hidrodinâmica dos estuários. Descrevem-se e comparam-se as várias técnicas utilizadas na solução de problemas de hidradinâmica de stuários.Faz-se a dedução formal de um modelo matemático do escoamento em estuários homogéneos e integram-se verticalmente as suas e¬quações, obtendo-se as conhecidas equações do escoamento em águas pouco profundas ("shallow water equations"). Estas equações são discretizadas utilizando os métodos dos elementos finitos e das diferenças finitas, respectivamente no espaço e no tempo.Faz-se a descrição de um sistema de cálculo para determinar a solução do modelo matemático discretizado e tecem-se várias considerações acerca do seu desenvolvimento e uso.Finalmente apresentam-se os resultados de alguns testes utilizados para verificar o funcionamento do sistema de cálculo.
Year: 1981
Author(s): Figueira, P.
Editor: ******
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Relatório Científico
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Project UBEST: Understanding the biogeochemical buffering capacity of estuaries relative to climate change and anthropogenic inputs - Final Report
The final technical report of the project
Year: 2020
Author(s): Rodrigues, M.; Fortunato, A. B.; Martins, R.; Rogeiro, J.; Oliveira, A.; Azevedo, A.; Freire, P.; Cravo, A.; Jacob, J.; Rosa, A.
Keywords: Ria Formosa; UBEST coastal observatory; Tagus estuary; Water quality; Hydrodynamics
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MOSAIC.PT field campaigns - Cova-Gala, Vieira and São Pedro de Moel beaches, January-March 2019
The present report summarizes the field campaigns of the project MOSAIC.pt, performed between January and March 2019 in the Cova-Gala, Vieira and São Pedro de Moel beaches, located in the Portuguese west coast. The campaigns aimed to characterize the response of the beaches, with diverse typology, to the hydrodynamic forcing and included topographic surveys by GNSS-RTK, drone surveys, superficial sediment sampling and the report of the territorial elements affected.
Year: 2019
Author(s): Freire, P.; Oliveira, F. S. B. F.; Oliveira, J. N.; Henriques, M. J.
Keywords: Sediment sampling; Territorial elements; Photogrammetric survey; Topographic survey
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UBEST field campaigns - 6th Campaign: Tagus Estuary, November 6, 2018
The present report summarizes the 6th field campaign of the project UBEST, performed in the Tagus estuary on November 6, 2018. This campaign was the third in the Tagus estuary and was representative of autumn conditions. Seven stations were chosen along the estuary. In situ measurements of temperature, salinity, pH and dissolved oxygen were carried out and water samples were collected to determine in laboratory the concentration of nutrients, chlorophyll a, total suspended solids, and confirm dissolved oxygen and pH on samples where pH sensors were not available. The data acquired will contribute to a better understanding of the biogeochemical functioning of the Tagus estuary and to calibrate and validate numerical models (hydrodynamic and biogeochemical), that will attempt to predict the response of the estuary to future scenarios of climate change and anthropogenic inputs.
Year: 2019
Author(s): Santos, D.; Rodrigues, M.; Freire, P.; Cravo, A.
Keywords: Physico-chemical parameters; Water samples; Field campaign; Tagus estuary
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UBEST field Campaigns - 4th Campaign: Tagus Estuary, May 10, 2018
The present report summarizes the 4th field campaign of the project UBEST, performed in the Tagus estuary on May 10, 2018. This campaign was the first in the Tagus estuary and was representative of spring conditions. Seven stations were chosen along the estuary where in situ measurements of temperature, salinity, pH and dissolved oxygen (% and mg/L) were carried out and water samples were collected to determine in laboratory the concentration of nutrients, chlorophyll a, total suspended solids, and confirm dissolved oxygen and pH on samples where pH sensors were not available. The data acquired will contribute to better understanding the biogeochemical functioning of the Tagus estuary and to calibrate and validate numerical models (hydrodynamic and biogeochemical), that will attempt to predict the response of the estuary to future scenarios of climate change and anthropogenic inputs.
Year: 2018
Author(s): Santos, D.; Freire, P.; Fortunato, A. B.; Cravo, A.
Keywords: Physico-chemical parameters; Water samples; Field campaign; Tagus estuary
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UBEST field campaigns - 5th Campaign: Tagus Estuary, September 27, 2018
The present report summarizes the 5th field campaign of the project UBEST, performed in the Tagus estuary on September 27, 2018. This campaign was the second in the Tagus estuary and was representative of summer conditions. Seven stations were chosen along the estuary. In situ measurements of temperature, salinity, pH and dissolved oxygen (% and mg/L) were carried out and water samples were collected to determine in laboratory the concentration of nutrients, chlorophyll a, total suspended solids, and confirm dissolved oxygen and pH on samples where pH sensors were not available. The data acquired will contribute to a better understanding of the biogeochemical functioning of the Tagus estuary and to calibrate and validate numerical models (hydrodynamic and biogeochemical), that will attempt to predict the response of the estuary to future scenarios of climate change and anthropogenic inputs.
Year: 2018
Author(s): Santos, D.; Freire, P.; Rodrigues, M.; Cravo, A.
Keywords: Physico-chemical parameters; Water samples; Field campaign; Tagus estuary
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Online monitoring in the Tagus estuary: Parque das Nações station - Installation and operation between January 2016 and February 2017
This report describes the design and installation of the Parque das Nações online monitoring station and the procedures relative to its maintenance and data verification undertaken between January 2016 and February 2017. This station is equipped with a SEBA MPS D3 multiparameter probe, which measures water levels, conductivity and water temperature, and a SEBA Slimcom2 data logger, for data acquisition and transmission. The data acquired during the period to which this report refers are also briefly presented. This monitoring station is under operation in the scope of the projects H2020 BINGO and FCT UBEST.
Year: 2017
Author(s): Rodrigues, M.; Freire, P.; Rogeiro, J.; Fortunato, A. B.
Keywords: Temperature; Tagus estuary; Conductivity; Water levels; Monitoring
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Agitação marítima a sul da embocadura do rio Mondego
O presente estudo tem como objetivo caracterizar o regime de agitação marítima na zona costeira entre as embocaduras dos rios Mondego e Lis no período 1952-2010. Enquadra-se no âmbito de um estudo mais alargado, cujo objetivo é o estudo da dinâmica sedimentar costeira e a previsão da evolução futura da linha de costa do mesmo trecho.A série cronológica compreende 59 anos de dados, de 1952 a 2010, resultando num total de 86200 trios de valores para os parâmetros Hs, Tp e Dir, indissociáveis na caracterização do regime de agitação marítima. Numa primeira fase, estimam-se as frequências de ocorrência relativas destes parâmetros por classes de intervalos semiabertos no limite superior e com amplitudes 0.50 m, 2 s e 10º, respetivamente, sendo consideradas para as direções escalões de 5º quando se justifica maior pormenor. São analisados os parâmetros estatísticos média, desvio-padrão, mínimo e máximo, e 1º, 2º e 3º quartis das séries temporais destes três parâmetros, correspondentes aos regimes geral e sazonais. A sazonalidade considerada tem por base o inverno marítimo, de outubro a março, e o verão marítimo, de abril a setembro, e a mensalidade, na qual a análise incide sobre cada mês individualmente e na inter mensalidade.Concluiu-se que a zona de estudo está sujeita a um regime geral de agitação marítima de elevada energia caracterizado por uma forte sazonalidade. Com características médias Hs 2.15 m, Dir 299.5ºN e Tp 11.6 s, e Hs mais frequente de 1.00 1.50 m associada a Dir 300 310ºN e Tp 8-10 s, o regime geral regista eventos máximos com Hs de 13.13 m. Eventos de Hs>5.00 m representaram 3.69% das ocorrências, sendo que Hs>9.50 m ocorreram exclusivamente para Dir 270 290ºN e Tp 16-22 s, e os valores médio e máximo de Hs no inverno/verão marítimo foram 2.66/1.63 m e 13.13/8.32 m, respetivamente. Da análise mensal verificou-se que as médias de Hs e Tp são máximas em janeiro, 3.02 m e 14 s, respetivamente, e mínimas em julho, 1.39 m e 9 s, restringindo se as médias mensais de Dir a 289 311ºN, com as obliquidades extremas, oeste/noroeste (289/311ºN), em janeiro/agosto. Da comparação com outros estudos concluiu-se que a sazonalidade e anos atípicos influenciam as análises baseadas em períodos restritos e que uma análise baseada numa série temporal de dados de agitação marítima muito longa robustece a representatividade dos parâmetros expostos neste estudo.
Year: 2016
Author(s): Oliveira, J. N.; Oliveira, F. S. B. F.
Keywords: Figueira da Foz; Agitação marítima; Coasta oeste portuguesa
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Characterization of the hydro-agricultural development of the Lezíria Grande de Vila Franca de Xira and of the Mouchão de Alhandra
The agricultural area of the Lezíria Grande de Vila Franca de Xira is part of one of the case studies at the Tagus Research Site, in the scope of the BINGO project (Horizon 2020). Thus, as a support for the characterization of this area, three exploratory visits were performed to the agricultural area of the upper Tagus estuary, and in particular to the irrigation area of the Lezíria Grande de Vila Franca de Xira (Aproveitamento Hidroagrícola da Lezíria Grande de Vila Franca de Xira) and to one of the adjacent
Year: 2016
Author(s): Rodrigues, M.; Freire, P.; Fortunato, A. B.; Alves, E.
Keywords: Droughts; Floods; Mouchão de Alhandra; Lezíria Grande de Vila Franca de Xira; Exploratory visits
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E7
We present herein the implementation, test and performance comparison of GPUs inphysical and cloud/virtual environment of: i) an image processing algorithm for coastalapplications using Synthetic Aperture Radar (SAR) imagery; ii) a hybrid programmingalgorithm (CPU/GPU) to automatically compute the correspondences between similarimages. The first test is based on an algorithm developed by LNEC in OpenCL and therespective Python wrapper. The second test uses the photogrammetry software
Year: 2016
Author(s): Azevedo, A.; Rogeiro, J.; Oliveira, A.; Rico, J.; Inês, A.; Barateiro, J.
Keywords: Cloud computing; GPU; Hybrid GPU/CPU; Image processing
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Impacte do prolongamento do molhe norte da embocadura do rio Mondego nas praias adjacentes a sul
A necessidade de proteger as povoações costeiras e mitigar o efeito erosivo observado na costa oeste portuguesa, resultante da carência sedimentar, levou a que a extensão de 30 km de linha de costa (LC) a sul da Figueira da Foz tenha sido fortemente intervencionada através da construção de esporões e defesas longitudinais aderentes. Este estudo caracteriza o transporte sedimentar potencial induzido pela agitação marítima combinada com a variação do nível do mar devida às marés astronómica e meteorológica a sul da embocadura do rio Mondego, no período de 1952 a 2010. Com base na análise estatística da série temporal de parâmetros de onda (hindcast) relativos ao referido período, identificou-se um regime com grande variabilidade interanual e sazonal e bastante energético, com 40% de ocorrência de Hs superior a 2 m e direção média 299.5ºN. Do cálculo do transporte longitudinal potencial (LITDRIFT) destacam-se valores anuais bastante variáveis, entre 580 1500 x103 m3.ano-1, com deriva para sul de média 385 x103 m3.ano-1 em 78% dos anos, identificando-se também a distribuição transversal do transporte longitudinal na zona ativa, com extensão variável (~2000 m). Entre 2008 e 2010 foi prolongado o molhe norte da embocadura do rio Mondego em cerca de 400 m, motivando o principal objetivo do presente estudo: avaliar o impacte desse prolongamento nas praias a sul, recorrendo a modelação numérica (LITLINE). O modelo de evolução de LC foi calibrado (1996-2001) e verificado (2001-2008) com base em LC observadas e dados de agitação marítima sinóticos. A previsão da evolução nos 12 anos subsequentes ao prolongamento evidencia um recuo generalizado da LC, acentuado a sotamar dos esporões existentes.
Year: 2016
Author(s): Oliveira, J. N.; Oliveira, F. S. B. F.
Keywords: Processos costeiros; Modelação numérica; Figueira da Foz; Evolução da linha de costa; Transporte sedimentar longitudinal
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Outro
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Estuarine and coastal morphodynamics
N/A
Year: 2015
Author(s): Fortunato, A. B.; Bertin, X.; Coco , G.; Concejo, A.; Dias, J. M.; Fernandes, E.; Larson, M.; Matias, A.; Oliveira, A.; Silva, P. A.; Dias, J. A.; Azeiteiro, U.; Costa , M.; Boski, T.
Keywords: coastal; Estuarine
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