Ria de Aveiro marginal floodingdependence on oceanic and fluvial drivers and on morphological evolution

Resumo

The assessment of flood drivers magnitude and the flood extension mapping is essential to avoid and reduce the adverse impacts of floods in coastal regions. The main aim of this work is to determine the Ria de Aveiro flood extent area under different oceanic and fluvial drivers as well as under different morphological conditions. This study integrates statistical analysis of the lagoon flooding drivers with hydrodynamic modelling using the unstructured grid model ELCIRC. The results highlight that the lagoon flood extent is highly sensitive to changes on both driving forces and morphological behaviour. In mean tide conditions the lagoon presents an area of 73.4 km2 , which increase when sea level or fluvial discharges rise. The regions more exposed to oceanic inundation are located at the lagoon central area and at the margins of the deepest lagoon channels. Contrarily, the flat areas located at the margins of rivers channels are the regions most exposed to inundation of fluvial origin. Numerical results also highlight the high dependence of the lagoon flooded area on the morphological behaviour. Indeed, the lagoon flooded area increased 16% in spring tide conditions over 1987 and 2012 as consequence of the deepening of lagoon main channels