Morphodynamics of wave-dominated beaches

Abstract

Sandy beach morphology exhibits a large variability in space and time. Closely associated with such morphological variability are changes in the surf zone processes, such as type of wave breaking, wave energy gradients, strength and character of nearshore currents, and modes of sediment transport. The beach model morphodynamic framework of [1] captures this mutual feedback between morphological and hydrodynamic variability, and describes the occurrence of beach types across the complete reflective-dissipative spectrum. In this review, we provide this framework with a stronger physical underpinning by drawing on the results of several decades of coastal research, whilst also highlighting existing gaps in our knowledge and providing future perspectives. This review will provide physical coastal researchers with an enhanced morphodynamic framework within which to place their beach research and interpret their results, as well as providing them with suggestions for future research.

Morpho-dynamic Induced Rip Currents in Klayar Beach, Pacitan, East Java, Indonesia

“…Figure 5. Tectonic setting of the Indonesian archipelago [24] As a system, beach morpho-dynamic consists of elements of morphology, waves and flow, sediment transport and bed change, and as a process refers to interactions between morphology and hydrodynamic including wave, tide, and wave-driven currents involving sediment movement [25,26,27]). Interactions between beach morphology and hydrodynamic processes take place when waves reach the surf zone.…”

Shoreline modelling on timescales of days to decades

“…Extending reduced-complexity models to the long-term presents new challenges which are beyond the scope of detailed discussion here, but will likely include the use of rules-based modelling approaches (Castelle and Masselink, 2023) and models with highly flexible grids and dynamic boundary conditions to cope with the high levels of coastal distortion (Roelvink et al, 2020), as well as a comprehensive consideration of eustatic and isostatic sea level variations.…”

A Large Sediment Accretion Wave Along a Northern California Littoral Cell

“…The morphodynamic state of the sandy beach areas (Gold Bluffs and regions south; Figure 1) as interpreted from aerial and satellite imagery includes reflective to intermediate morphology (transverse‐bar‐and‐rip to rhythmic‐bar‐and‐beach) (cf. Castelle & Masselink, 2023). The linear, reflective shoreline generally occurs in the summer to early fall, with more complex beach states in the winter to spring, the latter of which often includes megacusps with approximately 300–500 m wavelengths and cross‐shore amplitudes of 10–50 m. Thus, the study area exhibits seasonality in both the offshore wave forcing and the shoreline morphology.…”

“…Beaches are dynamic landforms owing to the near persistent movement of sediment by oscillatory ocean waves and time‐varying supplies of sediment to littoral cells from sources such as dunes, bluffs, and rivers (Anthony et al., 2014; Castelle & Masselink, 2023; Inman & Brush, 1973; Komar, 1998; Masselink & Russell, 2006; Nienhuis et al., 2020; Yates et al., 2009). The morphodynamics of a beach a important, in turn, because they influence shoreline position, nearshore hydrodynamics and flooding, coastal habitats, and the ability for humans to use and inhabit these coastal landscapes.…”

“…The volume and grain sizes of sediment within a littoral cell will have direct effects on shoreline positions and coastal morphodynamics (Castelle & Masselink, 2023). The sediment mass balance of a littoral cell includes sediment inputs from processes such as river discharge and bluff failure, sediment storage within landforms such as offshore bars, beaches and dunes, and sediment losses from offshore transport to the continental shelf or deep sea (Bray et al., 1995; Inman, 2005; Patsch & Griggs, 2008; Rosati, 2005).…”