A new morphodynamic instability associated with cross-shore transport in the nearshore
The existing theory for shore-transverse rhythmic sand bars relies on morphodynamic instabilities involving the wave-driven longshore current and rip currents. Intriguingly, transverse finger bars are common on coasts with sediment excess, something not related to those currents. Here we show that,...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/349991 |
| Acceso en línea: | https://hdl.handle.net/2117/349991 https://dx.doi.org/10.1029/2020GL091722 |
| Access Level: | acceso abierto |
| Palabra clave: | Ebro River Delta (Spain) Self-organizing systems Sediment transport Ebro delta Coastal processes Cross-shore sediment transport Morphodynamic instability Self-organization Shore-transverse sand bars Ebre, Delta de l' (Catalunya) Sistemes autoorganitzatius Sediments (Geologia) -- Transport Àrees temàtiques de la UPC::Física |
| Sumario: | The existing theory for shore-transverse rhythmic sand bars relies on morphodynamic instabilities involving the wave-driven longshore current and rip currents. Intriguingly, transverse finger bars are common on coasts with sediment excess, something not related to those currents. Here we show that, if the actual beach profile is above the equilibrium profile, cross-shore transport can induce an instability triggered by onshore transport together with wave refraction by the emerging bars. We use a numerical model that filters out the dynamics associated to longshore and rip currents but includes a simplified version of cross-shore transport and is able to reproduce the formation of shore-transverse bars. The alongshore spacing scales with the wavelength of the incident waves and the cross-shore extent is approximately equal to the distance from shore to the depth of closure. The modeled bars compare qualitatively well with observations at El Trabucador back-barrier beach (Ebro delta, Western Mediterranean Sea). |
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