Equilibrium shoreline modelling of a high-energy meso-macrotidal multiple-barred beach

Castelle, Bruno; Marieu, Vincent; Bujan, Stéphane; Ferreira, Sophie; Parisot, J. P.; Capo, Sylvain; Sénéchal, Nadia; Chouzenoux, Thomas

doi:10.1016/j.margeo.2013.11.003

Cited by 88 publications

(76 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The model has considerable potential as a predictive tool, but a longer and higher resolution observational time series (at least monthly observations over a period > 5 years) is required to further develop and validate the model (cf. Castelle et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

“…It may be suggested that the change in wave conditions is more relevant in driving bar morphological change than the absolute values of the wave parameters: e.g., all offshore migration events occurred following an increase in H/L, whereas all onshore migration events coincided with falling H/L values. If changes in the wave conditions are more relevant in driving bar behaviour than actual wave parameters, an equilibrium type of response model, involving deviations from antecedent wave conditions is worth pursuing (e.g., Yates et al, 2009;Davidson et al, 2013;Castelle et al, 2014). Following Davidson et al (2013), bar dynamics are related to the product of the wave energy flux P and a disequilibrium term (Ω m -Ω), where Ω m is the background antecedent value for Ω, and Ω represents the instantaneous value.…”

Section: Beach and Nearshore Morphologymentioning

confidence: 99%

See 1 more Smart Citation

Role of wave forcing, storms and NAO in outer bar dynamics on a high-energy, macro-tidal beach

et al. 2014

View full text Add to dashboard Cite

Outer sand bar dynamics on a high-energy macro-tidal beach were investigated using long-term (multi-year) field datasets of intertidal morphology and offshore bathymetry. Utilising a 15-year time-series of Argus video images, five distinct outer bar types were identified: Mega Rip, Longshore, Crescentic, Crescentic Attached and Welded. The most common classification was Crescentic Attached, with the outer bar oscillations being out of phase with the inner bar oscillations, as would be expected for the shore-normal wave approach at this site. The outer bar had a typical amplitude of 0.5-1 m and a longshore wavelength of 600 m. Changes in outer bar morphology were related to measured and modelled nearshore wave data. However, the outer bar morphology changed over a much longer time scale (monthly-to-annual) than the daily-to-weekly variations in wave height and period. An extended duration of energetic wave action was required to bring about an upstate bar transition to the Longshore or Mega Rip state, where the bar then remained arrested for a significant amount of time, requiring several months of low wave conditions to induce a down state transition through Crescentic to Welded. This slow morphological response is explained by extended relaxation times attributed to the large tidal range at the study site where the outer bar morphology is only active for part of the tidal cycle (several hours around low tide). The configuration and position of the outer bar were related: the more upstate (downstate) bar types being associated with a more offshore (onshore) bar position. The detrended outer bar position was significantly related to a forcing term based on wave power and disequilibrium of the dimensionless fall velocity with offshore (onshore) bar migration occurring when wave conditions were more (less) energetic that the antecedent conditions. The upstate end member (Longshore or Mega Rip) was attained sometime during the winter months for 14 out of the 16 years of monitoring; the outer bar remained attached to the low tide shoreline over the winter 2005/2006 and 2010/2011. These two winters with incomplete upstate cycles were characterised by the lowest winter wave conditions and negative winter North Atlantic Oscillation (NAO) indices, suggesting that the winter NAO is correlated with both beach state and nearshore bar configuration. KEYWORDS

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Beach and Nearshore Morphologymentioning

confidence: 99%

Role of wave forcing, storms and NAO in outer bar dynamics on a high-energy, macro-tidal beach

et al. 2014

View full text Add to dashboard Cite

show abstract

“…This is illustrated in Fig. 2e based on a time series of 3-hourly H s offshore of Truc Vert beach with the superimposed 90-day moving average over the period 2000-2014 using the wave data described in Castelle et al (2014).…”

Section: Physical Settingmentioning

confidence: 99%

“…This is addressed in this study. The topographic surveys were averaged alongshore to derive a mean beach profile (for more details, see Castelle et al 2014and Splinter et al 2014a. Figure 1c shows the superimposed mean profiles surveyed from 2005 to 2013 where the elevation is given with respect to the local mean sea level, highlighting the large vertical and cross-shore variability.…”

Section: Physical Settingmentioning

confidence: 99%

“…storms) to years has recently been simulated with fair skill using wave-driven empirical equilibrium-based models (e.g., Davidson and Turner 2009;Yates et al 2009;Davidson et al 2013;Castelle et al 2014;Splinter et al 2014a). These models can also reproduce the interannual shoreline variability that sometimes exceeds the seasonal variability (e.g., Castelle et al 2014). However, model skills strongly depend on the availability and quality of wave data.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Statistical modeling of interannual shoreline change driven by North Atlantic climate variability spanning 2000–2014 in the Bay of Biscay

et al. 2016

View full text Add to dashboard Cite

Modeling studies addressing daily to interannual coastal evolution typically relate shoreline change with waves, currents and sediment transport through complex processes and feedbacks. For wave-dominated environments, the main driver (waves) is controlled by the regional atmospheric circulation. Here a simple weather regime-driven shoreline model is developed for a 15-year shoreline dataset (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014) collected at Truc Vert beach, Bay of Biscay, SW France. In all, 16 weather regimes (four per season) are considered. The centroids and occurrences are computed using the ERA-40 and ERA-Interim reanalyses, applying k-means and EOF methods to the anomalies of the 500-hPa geopotential height over the North Atlantic Basin. The weather regime-driven shoreline model explains 70% of the observed interannual shoreline variability. The application of a proven wavedriven equilibrium shoreline model to the same period shows that both models have similar skills at the interannual scale. Relation between the weather regimes and the wave climate in the Bay of Biscay is investigated and the primary weather regimes impacting shoreline change are identified. For instance, the winter zonal regime characterized by a strengthening of the pressure gradient between the Iceland low and the Azores high is associated with high-energy wave conditions and is found to drive an increase in the shoreline erosion rate. The study demonstrates the predictability of interannual shoreline change from a limited number of weather regimes, which opens new perspectives for shoreline change modeling and encourages long-term shoreline monitoring programs.

show abstract

Sediment supply to beaches: Cross‐shore sand transport on the lower shoreface

Aagaard

2014

JGR Earth Surface

View full text Add to dashboard Cite

Many beaches have been built by an onshore supply of sand from the shoreface, and future long-term coastal evolution critically depends on cross-shore sediment exchange between the upper and the lower shorefaces. Even so, cross-shore sediment supply remains poorly known in quantitative terms and this reduces confidence in predictions of long-term shoreline change. In this paper, field measurements of suspended sediment load and cross-shore transport on the lower shoreface are used to derive a model for sediment supply from the lower to the upper shoreface at large spatial and temporal scales. Data collection took place at five different field sites that exhibit a wide range of wave conditions and sediment characteristics. Data analysis shows that both suspended sediment load and cross-shore sediment transport scale with the grain-related mobility number which ranged up to ψ ≈ 1000 in the measurements while the effect of orbital velocity skewness is more limited. A 1 year long simulation of sediment transfers between the lower and the upper shorefaces on a natural beach compares well with transport rates estimated from long-term bar migration patterns and aeolian accretion on the same beach.

show abstract

Equilibrium shoreline modelling of a high-energy meso-macrotidal multiple-barred beach

Cited by 88 publications

References 32 publications

Role of wave forcing, storms and NAO in outer bar dynamics on a high-energy, macro-tidal beach

Role of wave forcing, storms and NAO in outer bar dynamics on a high-energy, macro-tidal beach

Statistical modeling of interannual shoreline change driven by North Atlantic climate variability spanning 2000–2014 in the Bay of Biscay

Sediment supply to beaches: Cross‐shore sand transport on the lower shoreface

Contact Info

Product

Resources

About