Portuguese title: Estudo da Morfodinâmica da Embocadura da Ria de Aveiro
Acronym: EMERA
Period: September 2005 till June 2009
Status: Completed
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| Institute |
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- National Laboratory of Civil Engineering; Estuaries and Coastal Zones Division (LNEC-DHA-NEC), more, partner
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| Abstract |
Process-based modelling is believed to give a detailed insight on the long-term morphological changes of inlets and the respective roles of tides and waves in driving these changes. The use of these tools is a valuable resource to support adequate management decisions at systems undergoing pronounced morphological changes such as the Ria de Aveiro tidal inlet and entrance channel. The main goal of this project is thus to study the morphodynamics of this area, using two distinct but interconnected methodologies: field work and several numerical modelling approaches.
The sedimentological characterization of the study area will be performed through detailed sampling of bottom and suspended sediments under different conditions. Simultaneous measurements of velocity vertical profiles will allow the estimation of sediment fluxes. Foraminifera analysis of sediment samples will be used to identify the main source of sediments to this area. These results will be used to extend the characterization of the study area, as inputs to the morphodynamic models and to strengthen the validation of the several models.
A two-dimensional horizontal morphodynamic modelling system (MORSYS2D), combining modules for hydrodynamics, waves, sediment transport and bathymetry updates, will be improved and explored. Specific changes in each of the modules and in the controlling script code will be performed, to obtain a more robust and flexible modelling system.
A new morphodynamic equilibrium response model (‘box model’) will also be developed and applied in this project. These models, which are based on simple concepts, have proved to be efficient to study the large-scale morphological evolution of tidal inlets.
The use of process-based models requires a schematization of the input conditions, through field data (to be collected in the frame of the project or historical data) and numerical models. An unstructured grid hydrodynamic model of the Ria de Aveiro and adjacent coast will be applied using one of models currently available in MORSYS2D, providing the elevation and velocity fields for the morphodynamic analysis, as well as additional insight into th circulation in the system. A new methodology will be developed to simplify a given offshore wave regime into a subset with fewer representative waves, that cause the same morphological evolution as the complete set of measured waves. The simplified wave regime will be used for forcing in the morphodynamic system.
The above tools will be used to analyse specific items such as the sediment budget and trends of erosion/deposition in this area, relative importance of waves and currents importance on the long-term evolution of the inlet and its seasonal evolution, and the transposition of sediment across the inlet.
This proposal outlines a project that will provide valuable (and presently inexistent) knowledge of the morphodynamics of Ria de Aveiro inlet that can be relevant for adequate management of this area. |
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