Wave‐forced dynamics in the nearshore river mouths, and swash zones. Issue 1 (5th August 2019)

• Record Type: Journal Article
• Authors: Brocchini, Maurizio
• Is Part Of: Earth surface processes and landforms. Volume 45:Issue 1(2020)
• Page Start: 75
• Page End: 95
• Publication Date: 2019-08-05
• Subjects: nearshore hydro‐morphodynamics -- water waves -- nearshore sandbars -- river mouths -- swash zone; Geomorphology -- Periodicals; 551.4
• DOI: 10.1002/esp.4699
• Languages: English
• ISSNs: 0197-9337

Abstract

Abstract: 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 timescale, at most. Local and non‐local mechanisms as well as 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 dynamics are the wave–current interaction and bar generation at river mouths and the sediment presuspension at the swash zone. Fundamental non‐local 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. Major connections across the three subsystems are the upriver propagation of IG waves generated by breaking sea waves and swash–swash interactions, the interplay between the swash zone and along‐river‐flank sediment transport and the evolution of nearshore sandbars. © 2019 John Wiley & Sons, Ltd. Abstract : Local mechanisms, non‐local 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. Fundamental non‐local 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. Major connections across the three subsystems are the upriver propagation of IG waves generated by breaking sea waves and swash–swash interactions, the interplay between the swash zone and along‐river‐flank sediment transport and the evolution of nearshore sand bars. Wave‐forced dynamics in the nearshore and estuaries: a puzzle to be solved. This photograph, taken at the microtidal Misa River estuary (Senigallia, Italy), illustrates through one single view the three subsystems analyzed in the article.