Coastal wave regime influence on Ria de Aveiro inlet dynamics

Abstract

The adjacent coastal zone of Ria de Aveiro lagoon is exposed to a highly energetic wave climate, with a yearly mean significant wave height of 2-2.5 m and wave periods of 9-11 s, corresponding to WNW to NNW swell. Consequently, it should be expected that the lagoon inlet hydrodynamic be dependent on the coupled forcing of tidal wave and wave regime. Thus, the main goal of this study is to assess the influence of the coastal wave regime at the inlet channel dynamics. The modeling system MORSYS2D, comprising the hydrodynamic model ELCIRC coupled with the wave model SWAN, is used to perform this study. The methodology developed consists in forcing the numerical models with local tidal harmonic constituents and with different constant regular wave scenarios typical of the northern Portuguese coast (high and normal wave activity and absence of waves). Under the normal wave activity scenario results show that the inlet channel hydrodynamics is mainly dominated by the tidal forcing. For the highest wave regime are found higher sea levels induced by the wave set-up. Consequently, it was found that the storm events induce important wave's set-up that change the inlet hydrodynamics, requiring that the coupling between waves and tides should required to accurately represent the physical processes of the lagoon. Although the dominant forcing of the Ria de Aveiro inlet hydrodynamics is the tide, it may be concluded that fluctuations at the wave regime influences the sea level and current velocity at the Ria de Aveiro inlet.