Observations of waves' impact on currents in a mixed-energy tidal inlet: Arcachon on the southern French Atlantic coast

Sénéchal, Nadia; Sottolichio, Aldo; Bertrand, Frédèric; Goeldner‐Gianella, Lydie; Garlan, Thierry

doi:10.2112/si65-347.1

Cited by 13 publications

(7 citation statements)

References 14 publications

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“…Nonetheless, northwesterly dominant waves have deviated the estuary mouth some 30 km downdrift in the past 3 ka (Féniès et al ., ). The annual mean significant wave height is 1.77 m (in 50 m water depth, according to Charles et al ., ) and the mean tidal range is 2.7 m (twice the semi‐diurnal tidal component amplitude, measured on the ebb delta shield by Senechal et al ., ). This mixed‐energy environment, as defined by Hayes (), has moulded an inlet with a transitional morphology (Hubbard et al ., ).…”

Section: Methodsmentioning

confidence: 97%

Imprints of wave climate and mean sea level variations in the dynamics of a coastal spit over the last 250 years: Cap Ferret, SW France

Nahon

Idier

Sénéchal

et al. 2019

Earth Surf Processes Landf

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In coastal areas, sea level rise (SLR) and changing wave climates are expected to be the main oceanic drivers of shoreline adjustments. These drivers have been shown to vary on a wide spectrum of spatial and temporal scales. Nonetheless, a general rule about how this variability impacts global shorelines remains to be articulated. Here, we discuss the impacts of wave climate changes and SLR on the evolution of a barrier spit-inlet system over the last 250 years. The distal end of the Cap Ferret barrier spit, SW France, has undergone large-scale oscillations that were well correlated with variations of the decadal average of the winter North Atlantic Oscillation (NAO) index. The local wave climate hindcast supports that increased alongshore wave energy fluxes associated with the positive phase of the NAO were responsible for the updrift retreat of the spit. By opposition, the spit has elongated downdrift when waves were less energetic and more shore normal, as during the negative phase of the NAO. In addition, lower rates of SLR appeared to be necessary for the spit to develop, as higher rates of SLR very likely forced the adjacent inlet to enlarge, at the expense of the spit. These results should help to predict and detect coastal adjustments driven by climate change and by climate variability.

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Section: Methodsmentioning

confidence: 97%

Imprints of wave climate and mean sea level variations in the dynamics of a coastal spit over the last 250 years: Cap Ferret, SW France

Nahon

Idier

Sénéchal

et al. 2019

Earth Surf Processes Landf

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“…Because of the well developed ebb delta and the sandbar (continuation of Cap-Ferret), the swells do not propagate inside the Arcachon Lagoon (Nahon, 2018) and the outer inlet can be often saturated with wave breaking (Senechal et al, 2013). According to the hydrodynamic classification proposed by Hayes (1980), the Arcachon Lagoon corresponds to a "transitional inlet" under a "mixed-energy regime".…”

Section: Study Areamentioning

confidence: 99%

The contribution of short-wave breaking to storm surges: The case Klaus in the Southern Bay of Biscay

et al. 2020

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This study investigates the contribution of shortwave breaking to storm surges through a high-resolution hindcast of the sea state and storm surge associated with the extra-tropical storm Klaus. This storm made landfall in January 2009 in the Southern Bay of Biscay and produced the largest storm surges observed in this region over the last 20 years, with 1.70 m in the Arcachon Lagoon and 1.10 m in the Adour Estuary. A fully-coupled 3D modelling system, which uses a vortex force formalism to represent wavecurrent interactions, is applied with a spatial resolution down to 35 m in the surf zones in order to properly compute the wave-induced setup. Modelling results reveal that the wave setup contributes by up to 40 % and 23 % to the storm surge peak in the Adour Estuary and the Arcachon Lagoon respectively. Accounting for wave forces in the circulation model improves storm surge predictions by 50 to 60 %. This is explained by the dominant role played by wave forces in the momentum balance at the inlets under storm waves. Numerical experiments further reveal that the wave-induced setup can be tidally-modulated, although this phenomenon seems to be sitespecific. Finally, a sensitivity analysis highlights the importance of the model grid resolution in the surf zones to correctly resolve the wave setup along open-ocean coasts. Inside the lagoon, the storm surge and wave setup are

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“…Flow velocities can reach 2 m/s southward the Cap Ferret sand spit (Cayocca 2001 ), whereas high energy North Atlantic of swells traveling mainly from the W-NW sector generate a strong southerly longshore drift of approximately 700,000 m 3 of sediment per year (Michel and Howa 1997 ). Nevertheless, current profi les and waterlevel measurements recorded during the severe Joachim storm in December 2011 show that under severe wave conditions (Hs > 6.0 m) and despite high incidence of waves from the NW (nearly 10°), the longshore drift is weaker (l < 1 m/s) than under "usual" storm conditions associated to Hs = 4-5 m (Sénéchal et al 2013 ).…”

Section: Hydrological and Hydrodynamic Characteristicsmentioning

confidence: 99%

The Arcachon Bay Estuary: A “Collage” of Landscapes

Bertrand¹

2013

World Geomorphological Landscapes

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Observations of waves' impact on currents in a mixed-energy tidal inlet: Arcachon on the southern French Atlantic coast

Cited by 13 publications

References 14 publications

Imprints of wave climate and mean sea level variations in the dynamics of a coastal spit over the last 250 years: Cap Ferret, SW France

Imprints of wave climate and mean sea level variations in the dynamics of a coastal spit over the last 250 years: Cap Ferret, SW France

The contribution of short-wave breaking to storm surges: The case Klaus in the Southern Bay of Biscay

The Arcachon Bay Estuary: A “Collage” of Landscapes

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