Modelling gravel barrier profile response to combined waves and tides using XBeach: Laboratory and field results

XBeach, a process-based numerical model capable of computing nearshore circulation and morphodynamics, including overwash and breaching, has been used in 1D mode to simulate erosion occurring on a gravel barrier beach (D50 = 11 mm) subjected to wave and tidal forcing during selected tests undertaken during the BARDEX experiments. The model demonstrated good quantitative skill (Brier skill score, BSS, typically 0.65) with respect to beach face erosion, offshore accretion and morphological impacts of washover. XBeach was also used to model storm impacts on a steep (average tanβ = 0.12), 4.5 km-long and 100 m–140 m wide macrotidal gravel barrier (D50 = 2 mm to 10 mm) located in SW England. Although the development of a storm berm was not reproduced well, erosion was predicted with sufficient skill (BSS = 0.60) to meet practical engineering requirements concerned with predicting storm impacts and threshold wave and water level conditions for gravel barrier overwashing.

► XBeach, has been used to simulate gravel barrier erosion.
► Good quantitative skill is demonstrated for laboratory and field cases.
► The model has utility to predict storm impacts and overwashing.