Who doesn’t love to go to the beach to enjoy the surf and sand and watch the waves crash against the shore? But beaches are vulnerable to coastal storms, with storm surge and waves that cause erosion and shoreline retreat. Also, such erosion could be exacerbated by rising sea levels. More accurate erosion forecasts would enable better coastal management. The morphodynamic numerical model XBeach effectively predicts erosion on beaches with a mild slope. However, there have been few studies of steep sandy reflective beaches. Because the wave energy and oscillations on these beaches affect swash zones differently, improved model parameters would help.
Researchers sought a model that would work on steep beaches without requiring constant calibration and validation. In their study in the Journal of Waterway, Port, Coastal, and Ocean Engineering, authors Juan L. Garzon, Óscar Ferreira, and Theocharis A. Plomaritis performed a sensitivity analysis of the main morphological parameters used for XBeach calibration and used the results to calibrate and validate XBeach for two storm events with different severity at two steep beaches. Learn how this work will contribute to obtaining better model performances in such environments in the paper “Modeling of Coastal Erosion in Exposed and Groin-Protected Steep Beaches” at https://doi.org/10.1061/(ASCE)WW.1943-5460.0000719. The abstract is below.
Process-based models are suitable tools for reproducing storm-driven erosion. However, their performance has been mainly examined on mild-slope sandy beaches and their use on steep beaches still represents a challenge. Here, open-source process-based model XBeach experiments were combined with topographical measurements collected for two storms (16- and 5-year return period) to obtain a reliable model. The model parameters “facua” (parameterized wave asymmetry and skewness sediment transport component), “bermslope” (upslope transport term for semireflective beaches), and “wetslope” (critical avalanching submerged slope) were utilized for calibration and validation. The 16-year storm simulations on an exposed beach revealed that whether bermslope increased and “facua” must be reduced, and vice versa, to properly simulate erosion. Adding bermslope provided excellent results for these storms when using facua and wetslope values close to the recommended values. In a groin-protected site, XBeach was successfully calibrated and validated for the tested storms using these parameters, although with different values. These experiments demonstrated that the appropriate use of these parameters can satisfactorily simulate morphological changes on steep beaches for different hydrodynamic conditions and coastal settings (exposed and groin protected).
Read the paper in full in the ASCE Library: https://doi.org/10.1061/(ASCE)WW.1943-5460.0000719.