Projects - MOWADI - 3D MOrphodynamic modelling of WAve Dominated Inlets

MOWADI aims at: 1) developing a 3D morphodynamic modelling system, incorporating recent developments on wave-current interactions; 2) determining the strengths and weaknesses of these systems compared to their 2D counterparts; 3) improving our understanding on the behaviour of wave-dominated tidal inlets at various time scales, combining model applications with field and remote sensing data; 4) contribute to support management decisions on two specific Portuguese inlets.

To reach these goals, we will first integrate the latest theoretical developments on wave-current interaction in 3D on a hydrodynamic community model (SELFE). Then, based on the existing modelling systems available at LNEC, a state of the art 3D and parallelized morphodynamic modelling systems will be built, with the objective of improving morphological predictions and the understanding of the dynamics at wave-dominated inlets. The modelling system will be applied at two highly dynamic wave-dominated inlets, which combine strong socio-economical and environmental issues. Although these two systems show some morphological similarities, they display distinct morphological behaviours. The Albufeira Inlet closes naturally every winter, while the Óbidos Inlet only closes exceptionally. These contrasting behaviours are probably due to differences in the ratios between wave energy and tidal prisms at the two inlets, but this hypothesis has to be verified with the modelling system.

For the two sites, field measurement of waves for different positions within a cross-shore profile will be carried out, in order to investigate the characteristics of wave breaking. Wave-induced and tidal currents will be sampled in several positions of the water column, using an ADCP placed on the ebb-deltas. Synchronously, a bathymetric/topographic survey and a characterization of sediment grain-size repartition will be carried out. Morphological changes after the field experiments will be remotely and qualitatively investigated using monthly satellite images.

In addition to providing a first level of understanding of the dynamics of the two inlets, these field measurements will allow for a fine calibration and validation of the modelling system. Six months morphodynamic simulations will then be performed, starting from the baseline bathymetry sampled during the field campaigns and forcing the modelling systems with results from tidal and wave regional models routinely used at LNEC. Morphological predictions will be compared to the morphological changes deduced from aerial photographs and satellite images. Once morphological predictions are judged satisfying, the modelling system will be used to perform synthetic tests (e.g. tuning the wave conditions or the tidal range) in order to investigate the physical processes responsible for the morphological changes observed.

Finally, a synthesis will be made on the knowledge gained throughout the project and recommendation will be proposed to improve the management of the two selected systems. More generic conclusions, applicable to other tidal inlets, will also be proposed.

Objectives

Develop a 3D morphodynamic modelling system, incorporating recent developments on wave-current interactions
Determine the strengths and weaknesses of these systems compared to their 2D counterparts
Improve our understanding on the behaviour of wave-dominated tidal inlets at various time scales, combining model applications with field and remote sensing data

Impacts

Contribute to support sustainable management of tidal inlets on the Portuguese coast

Team
NEC: André Fortunato (Investigador Responsável), Paula Freire, Francisco Sancho, Alberto Azevedo, Nicolas Bruneau , Guillaume Dodet, Aphonse Nahon
NRE: Lígia Pinto
Université de La Rochelle: Xavier Bertin
FCUL: Rui Taborda, Ana Silva
FCUP: José da Silva

Publications

Fortunato, André B; Nahon, Alphonse; Dodet, Guillaume; Rita Pires, A; Conceição Freitas, M; Bruneau, Nicolas; Azevedo, Alberto; Bertin, Xavier; Benevides, Pedro; Andrade, César; Oliveira, Anabela. 2014. "Morphological evolution of an ephemeral tidal inlet from opening to closure: The Albufeira inlet, Portugal", Continental Shelf Research 73, -: 49 - 63.
Dodet, Guillaume; Bertin, Xavier; Bruneau, Nicolas; Fortunato, André B; Nahon, Alphonse; Roland, Aron. 2013. "Wave-current interactions in a wave-dominated tidal inlet", Journal of Geophysical Research: Oceans 118, 3: 1587 - 1605.
Pinto, L.L.M.A. (2010). Modelação da morfodinâmica de estuários, Tese de doutoramento, Universidade de Coimbra, 188 pp.
N. Bruneau, G. Dodet, X. Bertin and A. B. Fortunato, 2011. Development of a three-dimensional coupled wave-current model for coastal environments, /J. Coastal Res/., SI64, 986-990.
Nahon, A., Azevedo, A., Fortunato, A., Sancho, F., Dodet, G., Bruneau, N., Freire, P., Simões Pedro, L., Bertin, X., Breilh, J.-F., Proença, B., Lira, C., Sousa, H., Bosnic, I., Cascalho, J., Carapuço, M., Alves, M., Ribeiro, M., Taborda, R., Silva, J., 2011 - Relatório LO01 – Relatório Técnico da Campanha MOWADI LO01 – Lagoa de Óbidos: 26/09/2011 a 29/09/2011. LNEC, 20 p.
Nahon, A., Fortunato, A., Sancho, F., Dodet, G., Bruneau, N., Freire, P., Bertin, X., Proença, B., Andrade, C., Freitas, C., Ribeiro, F., Bosnic, I., Cascalho, J., Alves, M., Pires, R., Taborda, R., Silva, T., Ribeiro, M., 2010 - Relatório LA01 – Relatório Técnico da Campanha MOWADI LA01 – Lagoa de Albufeira: 21/09/2010 a 04/10/2010. LNEC, 18 p.
Bruneau, N., A.B. Fortunato, G. Dodet, P. Freire, A. Oliveira e X. Bertin (2011). Future evolution of a tidal inlet due to changes in wave climate, sea level and lagoon morphology (Óbidos Lagoon, Portugal), Continental Shelf Research, 31: 1915-1930.
Bertin, X., N. Bruneau, J.-F. Breilh, A.B. Fortunato e M. Karpytchev (2012). Importance of wave age and resonance in storm surges: the case Xynthia, Bay of Biscay, Ocean Modelling, 42: 16-30.

Year: 2010-2013

Coordinator(s): LNEC - Laboratório Nacional de Engenharia Civil (National Laboratory for Civil Engineering)

Funding: Fundação para a Ciência e a Tecnologia (FCT)

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