Abstract
Barred macrotidal beaches are affected by continuous horizontal displacements of different hydrodynamic zones associated with wave transformation (shoaling, breaker and surf zones) due to significant tide-induced water level changes. A series of wave and current meters, complemented by a video imagery system, were deployed on a barred beach of northern France during a 6-day experiment in order to characterize the spatial and temporal variability of wave-induced processes across the beach. Wave and current spectral analyses and analyses of cross-shore current direction and asymmetry resulted in the identification of distinct hydrodynamic processes, including the development of infragravity waves and offshore-directed flows in the breaker and surf zones. Our results revealed a high spatial variability in the hydrodynamic processes across the beach, related to the bar-trough topography, as well as significant variations in the directions and intensity of cross-shore currents at fixed locations due to the horizontal translation of the different hydrodynamic zones resulting from continuous changes in water level due to tides.
Highlights
An increasing number of papers were published on the morphodynamics of barred macrotidal beaches, which gave some insight into the morphological behavior of intertidal bar-trough systems (e.g., [1,2,3,4,5,6])
Continuous records of waves showed that wave heights were strongly modulated by changes in water level due to tides, this being especially obvious in the shallow nearshore and intertidal zones (Figure 3C)
Our measurements of wave and current parameters across the surveyed beach showed distinct hydrodynamic signatures characterizing each zone dominated by either shoaling, breaking and surf processes, the limits of which having been determined visually by the position of breaking waves during discrete time periods
Summary
An increasing number of papers were published on the morphodynamics of barred macrotidal beaches, which gave some insight into the morphological behavior of intertidal bar-trough systems (e.g., [1,2,3,4,5,6]). The hydrodynamics of barred macrotidal beaches are complex and highly variable both spatially and temporarily due to cross-shore morphological variations (bar-trough topography) and to large vertical tidal fluctuations that induce significant horizontal translations of the different hydrodynamic zones associated with wave transformations (shoaling, breaker and surf zones). The changes in wave height and in current velocities and directions that take place over macrotidal beaches during a single tidal cycle have major impacts on the dynamics of intertidal bars that almost continuously experience changes in on-offshore shear stress at the bed which strongly control net sediment transport and, bar evolution [4,8,9,17]. Due to the complex interrelations between water level, wave heights and wave- and current-induced bed stress, which considerably vary over time at any given location, and from place to place across the beach, the modeling of intertidal bar formation and evolution is still a challenging issue [26]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
