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Morphodynamics of wave-dominated beaches
Langue
EN
Article de revue
Ce document a été publié dans
Cambridge Prisms: Coastal Futures. 2022-08-23, vol. 1, p. e1
Résumé en anglais
Abstract Wave-dominated sandy beaches are highly valued by societies and are amongst the world’s most energetic and dynamic environments. On wave-dominated beaches with unlimited sand supply and limited influence of tide ...Lire la suite >
Abstract Wave-dominated sandy beaches are highly valued by societies and are amongst the world’s most energetic and dynamic environments. On wave-dominated beaches with unlimited sand supply and limited influence of tide and geology, beach change has long been conceptualised in the morphodynamic framework of Wright and Short (1984). Such framework describes the occurrence of beach types based on wave conditions and sediment characteristics across the complete reflective–dissipative spectrum. Building on theoretical work, field/laboratory measurements and monitoring programmes, the physical mechanisms underpinning this morphodynamic framework have been progressively unravelled. Cross-shore morphological changes are primarily controlled by equilibrium and beach memory principles with below (above) average wave conditions driving down-state (up-state) transitions associated with onshore (offshore) sediment transport. Such cross-shore behaviour mostly reflects the imbalance between the onshore-directed sediment transport driven by wave nonlinearities and the offshore-directed sediment transport driven by the undertow. Self-organised morphological instabilities resulting from different positive feedback mechanisms are primarily responsible for alongshore morphological variability and the generation of rhythmic morphological features, such as crescentic bars, rip channels and beach cusps. Critically, wave climate and changes in wave regimes are key in driving the coupled cross-shore and longshore behaviour that ultimately explains modal beach state and frequency-response characteristics of beach morphological time series.< Réduire
Mots clés en anglais
sandy beach
morphodynamics
wave-driven current
sediment transport
beach state model
equilibrium response
morphodynamic instabilities
feedback mechanisms
erosion
accretion
Project ANR
Comprendre et prévoir l'évolution contemporaine du traite de côte dans un contexte de changement climatique par assimilation de données satellite dans les modèles hybrides - ANR-21-CE01-0015