Wave Set-up and Run-up Variability on a Complex Barred Beach During Highly Dissipative Storm Conditions

International audienceThis study assessed the ability of the SWASH model to reproduce wave set-up and run-up on complex realistic 3D morphology during highly dissipative stormy conditions, based on the most energetic field data set reported in the bibliography (ECORS-Truc Vert’08 beach experiment). Several approaches (1D and 2D) and forcing methods (spectral and parametric) were applied. For the three days of high-energy conditions caused by the Johanna storm, wave set-up was accurately reproduced, with simulation performance in 1D and 2D at R² = 0.66, 0.81 respectively for all data considered; RMSE = 0.13 m, 0.08 m; bias = 0.06, -0.02. Run-up in the 1D configuration is significantly overestimated while in 2D, the reproduction of run-up using spectral forcing was very accurate with R² = 0.73; RMSE = 0.19; bias = 0.04, underlining the role of spectral frequency and directional spread to precisely reproduce the surf zone processes during a storm on a complex barred beach. The maximum estimated values for set-up, run-up and spatial variability of run-up are comparable with results from previous studies, even though significantly higher offshore wave conditions. These results support the hypothesis of a run-up saturation signature in dissipative contexts, mainly influenced by extreme offshore wave conditions