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Improvement of a morphodynamic model applied to tidal inlet environments

Final Activity Report Summary - IMMATIE (Improvement of a Morphodynamic Model Applied to Tidal Inlet Environments)

Tidal inlets are very dynamic coastal environments that are often in delicate equilibrium. Moreover, they play a critical role as they control the exchanges of water, sediments and dissolved substances between estuaries or lagoons and the sea. The latter is particularly relevant in Portugal because of its extensive coastline and the existence of many tidal inlets of social, environmental and economic importance. From the perspective of sustainable development it is essential to understand and be able to predict the long-term evolution of these systems. In order to achieve these goals, one of the most promising avenues is the development of morphodynamic models, which consist of a set of modules to simulate tidal hydrodynamics, wave propagation, sediment transport and morphological evolution.

The IMMATIE project first aim was to advance an existing morphodynamic modelling system (MORSYS2D) that was under development at the ‘National Civil Engineering Laboratory’ (LNEC) of Lisbon, Portugal. The first improvement consisted in implementing a procedure to enhance numerical stability and computational efficiency. The second main improvement was the full coupling of a wave model within the system, in order to have good representation of wave-induced processes which were very relevant at Portuguese tidal inlets.

The improved modelling system was then applied and validated at two contrasting sites:

1. the Óbidos Lagoon, located in the middle of the western coast of Portugal, and
2. the Ria Formosa, located on the southern coast of Portugal.

Once the model was well calibrated using the available field data, yearly morphological predictions were performed and showed that the model was able to reproduce morphological changes reasonably well at both sites. The last step of the project consisted in investigating the physical processes that controlled the dynamic of tidal inlets. The knowledge on tidal inlet dynamics that was gained through the IMMATIE project would be useful in order to improve the management of tidal inlets, both in Portugal and any similar environments elsewhere.