Short term morphodynamics of an intertidal bar on megatidal ebb delta

Robin, Nicolas; Levoy, Franck; Monfort, Olivier

doi:10.1016/j.margeo.2009.02.006

Cited by 25 publications

(30 citation statements)

References 41 publications

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“…The behavior of swash bars, features with typical scales larger than 100 m, has been well documented (Oertel, 1972(Oertel, , 1975Hine, 1975;Hubbard et al, 1979;FitzGerald, 1984;Smith and FitzGerald, 1994;Kana et al, 1999;Balouin et al, 2001Balouin et al, , 2004Robin et al, 2007Robin et al, , 2009Son et al, 2010). However, our findings differ from prior publications in several ways.…”

Section: Discussioncontrasting

confidence: 46%

Mobility of meso-scale morphology on a microtidal ebb delta measured using remote sensing

2014

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Section: Discussioncontrasting

confidence: 46%

Mobility of meso-scale morphology on a microtidal ebb delta measured using remote sensing

2014

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“…The essentially mesoscale to macroscale approach adopted here reposes on the use of vertical aerial photographs, but is supported by short-to medium-term monitoring of beach and bar topography and bar-shoreline morphodynamics. The paper complements recent work on the surf and swash processes involved in megatidal bar mobility [Robin et al, 2009]. The discussion of the results is followed by the proposal of a conceptual model of swash bar development and interactivity with the shoreline for a megatidal environment.…”

Section: Introductionmentioning

confidence: 65%

Short‐term to decadal‐scale onshore bar migration and shoreline changes in the vicinity of a megatidal ebb delta

Robin¹,

Levoy²,

Monfort³

et al. 2009

J. Geophys. Res.

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[1] Swash bar development has been well documented from coasts with low to moderate tidal ranges, while studies of the effects of these forms on the morphology and dynamics of the adjacent shore in large tide range environments are rare. The analysis of sequential vertical aerial photographs was combined with field work in order to highlight the effects of swash bar development on the adjacent shoreline in the vicinity of a megatidal inlet (mean spring tidal range of 11 m). Swash bars are observed to form on the ebb tidal delta and to migrate landward before welding onto the coast. A close relationship was noticed between the position of the swash bar and shoreline dynamics. The bar protects the shore against wave attack in a sedimentary system controlled by longshore transport. This protective role is, however, modulated by the large tidal range. As the bar migrates upward toward the high-tide level and the subaerial beach, it develops morphologically into a transverse form that acts as a cross-shore obstacle to longshore sediment transport, thus resulting in shoreline accretion updrift and in strong erosion downdrift. This disturbance may persist for years because of the relatively slow speed of movement of the bar at this stage, an aspect characteristic of large tide range environments. This pattern of behavior differs fundamentally from that documented in the literature where the perturbation of the longshore sediment transport occurs over shorter periods. An original conceptual model of swash bar morphodynamics and repercussions on the adjacent shoreline for this megatidal environment is proposed.Citation: Robin, N., F. Levoy, O. Monfort, and E. Anthony (2009), Short-term to decadal-scale onshore bar migration and shoreline changes in the vicinity of a megatidal ebb delta,

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“…These flows occur due to an imbalance between the offshore‐directed wave setup‐induced barotropic pressure gradient and onshore‐directed wave breaking‐induced acceleration, and could be related with the onshore swash bar migration measured by Robin et al . [] in a macrotidal inlet located in Normandy (France). Ranasinghe et al .…”

Section: Discussionmentioning

confidence: 99%

“…Robin et al . [] analyzed the relative importance of different hydrodynamic processes on ebb delta bar migration in a macrotidal environment using detailed morphological and hydrodynamic measurements. Their study suggested that at this site, sediment transport and the modification in bar morphology were induced mainly by surf zone processes and associated littoral currents.…”

Section: Introductionmentioning

confidence: 99%

The role of morphology and wave‐current interaction at tidal inlets: An idealized modeling analysis

2014

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The outflowing currents from tidal inlets are influenced both by the morphology of the ebbtide shoal and interaction with incident surface gravity waves. Likewise, the propagation and breaking of incident waves are affected by the morphology and the strength and structure of the outflowing current. The 3-D Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system is applied to numerically analyze the interaction between currents, waves, and bathymetry in idealized inlet configurations. The bathymetry is found to be a dominant controlling variable. In the absence of an ebb shoal and with weak wave forcing, a narrow outflow jet extends seaward with little lateral spreading. The presence of an ebb-tide shoal produces significant pressure gradients in the region of the outflow, resulting in enhanced lateral spreading of the jet. Incident waves cause lateral spreading and limit the seaward extent of the jet, due both to conversion of wave momentum flux and enhanced bottom friction. The interaction between the vorticity of the outflow jet and the wave stokes drift is also an important driving force for the lateral spreading of the plume. For weak outflows, the outflow jet is actually enhanced by strong waves when there is a channel across the bar, due to the ''return current'' effect. For both strong and weak outflows, waves increase the alongshore transport in both directions from the inlet due to the wave-induced setup over the ebb shoal. Wave breaking is more influenced by the topography of the ebb shoal than by wave-current interaction, although strong outflows show intensified breaking at the head of the main channel.

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Short term morphodynamics of an intertidal bar on megatidal ebb delta

Cited by 25 publications

References 41 publications

Mobility of meso-scale morphology on a microtidal ebb delta measured using remote sensing

Mobility of meso-scale morphology on a microtidal ebb delta measured using remote sensing

Short‐term to decadal‐scale onshore bar migration and shoreline changes in the vicinity of a megatidal ebb delta

The role of morphology and wave‐current interaction at tidal inlets: An idealized modeling analysis

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