31/05/2018 - Maurizio Brocchini
DICEA, Università Politecnica delle Marche, Ancona, Italy
The role of wave forcing on the main hydro-morphological dynamics evolving in the shallow waters of the nearshore and at river mouths is analyzed. Focus is mainly on the cross-shore dynamics that evolve over mildly sloping barred, dissipative sandy beaches from the storm up to the yearly time scale, at most. Local mechanisms, nonlocal mechanisms and connections across three main inter-related subsystems of the nearshore - the region of generation and evolution of nearshore bars, river mouths and the swash zone - are analyzed. The beach slope is a major controlling parameter for all nearshore dynamics. A local mechanism that must be properly described for a suitable representation of wave-forced dynamics of all such three subsystems is the proper correlation between orbital velocity and sediment concentration in the bottom boundary layer ; while specific are the wave-current interaction and bar generation at river mouths and the sediment presuspension at the swash zone. Fundamental nonlocal mechanisms are both Infragravity (IG) waves and large-scale horizontal vortices (i.e. with vertical axes), both influencing the hydrodynamics, the sediment transport and the seabed morphology across the whole nearshore.