Gravel Barrier Beach Morphodynamic Response to Storm Events

Gravel beaches and barriers form a valuable natural protection for many shorelines. Gravel beach response to waves has been studied extensively, for regular and irregular waves, but there is little reported investigation of beach response to bimodal wave conditions, quite commonly experienced at midlatitudes. The paper presents a numerical modelling study of gravel barrier beach response to storm wave conditions. The XBeach non-hydrostatic model was set up in 1D mode to investigate barrier volume change and overwash under a wide range of unimodal and bimodal storm conditions and barrier cross sections. The numerical model was validated against conditions at Hurst Castle Spit, UK. The validated model is used to simulate the response of a range of gravel barrier cross sections under a wide selection of statistically significant storm wave and water level scenarios thus simulating an ensemble of realisations of barrier volume change and overwash. This ensemble of results was used to develop a simple parametric model for estimating barrier volume change during a given storm and water level condition. Attempts were also made to model overwash and crest changes of barriers, however further study Is required. Numerical simulations of barrier response to bimodal storm conditions, which are a common occurrence in many parts of the UK, reveals that barrier volume change and overwash from bimodal storms will be higher than that from unimodal storms if the swell percentage is greater than 40%. The limitations of the modelling approach and the model results are noted. The model is demonstrated as providing a useful tool for estimating barrier volume change, a commonly used measure used in gravel barrier beach management

Gravel Barrier Beach Morphodynamic Response to Extreme Conditions

Gravel beaches and barriers form a valuable natural protection for many shorelines. The paper presents a numerical modelling study of gravel barrier beach response to storm wave condi-tions. The XBeach non-hydrostatic model was set up in 1D mode to investigate barrier volume change and overwash under a wide range of unimodal and bimodal storm conditions and barrier cross sections. The numerical model was validated against conditions at Hurst Castle Spit, UK. The validated model is used to simulate the response of a range of gravel barrier cross sections under a wide selection of statistically significant storm wave and water level scenarios thus simulating an ensemble of barrier volume change and overwash. This ensemble of results was used to develop a simple parametric model for estimating barrier volume change during a given storm and water level condition under unimodal storm conditions. Numerical simulations of barrier response to bimodal storm conditions, which are a common occurrence in many parts of the UK were also investigated. It was found that barrier volume change and overwash from bimodal storms will be higher than that from unimodal storms if the swell percentage in the bimodal spectrum is greater than 40%. The model is demonstrated as providing a useful tool for estimating barrier volume change, a commonly used measure used in gravel barrier beach management

Gaussian process regression approach for predicting wave attenuation through rigid vegetation

Numerical modelling in the coastal environment often requires highly skilled users and can be hindered by high computation costs and time requirements. Machine Learning (ML) techniques have the potential to overcome these limitations and complement existing methods. This is an exploratory investigation utilising a Gaussian Process (GP) data-driven modelling approach that can reproduce, for the given range of conditions in this study, the results of a widely used process-based model, XBeachX, when applied to the challenging problem of wave attenuation through vegetation. This study utilises efficient sampling strategies for data exploration, providing a valuable framework for future studies. The GP model was trained on a synthetic dataset generated using the numerical model XBeachX, which was calibrated using laboratory measurements. Our findings indicate that well-trained ML models can strongly complement traditional modelling approaches, especially in an environment where data sources are increasingly available. We have also explored the underlying interactions of the GP model's input features and their relationship to the model's output through a sensitivity analysis

The morphodynamic response of a gravel barrier to unimodal and bimodal storm wave conditions

Gravel barrier beaches can offer natural protection to coastlines from adversestorm conditions. Understanding the morphodynamics of gravel barrier beachesis vital for the effective and sustainable management of these systems. Here, weuse a synthetic dataset to investigate the morphodynamic response of the gravelbarrier beach at Hurst Castle Spit, located on the Southwest coast of the UnitedKingdom, to both unimodal and bimodal storms. This spit is exposed to wind andswell waves propagating up the English Channel from the Southwest approachesand has suffered repeated storm erosion. The results are analyzed to identify thekey drivers that govern the spatio-temporal gravel barrier morphodynamicresponses to storms and to explore the morphodynamic states of the barrier.We found that the morphodynamic response of the barrier beach is stronglyinfluenced by the combination of storm wave height and still water level. Further,the presence of swell waves can be a controlling factor in the barrier response

Gravel barrier morphodynamic response to unimodal and bimodal storm wave conditions

Gravel barrier beaches can offer natural protection to coastlines from adverse storm conditions. Understanding the morphodynamics of gravel barrier beaches is vital for the effective and sustainable management of these systems. This study utilises an extensive, synthetic dataset simulated using a well-validated XBeach-X coastal hydro-morphodynamic model to investigate the effects of both unimodal and bimodal storm conditions on the morphodynamics of the Hurst Castle Spit gravel barrier beach, located on the Southwest coast of the United Kingdom. The dataset is used to analyse the key drivers that govern the spatio-temporal gravel barrier morphodynamic responses to storms and to quantitatively explore the morphodynamic states of the barrier. Storm wave height combined with water level (with tide and storm surge) primarily determines the morphodynamic response of the barrier beach for a given pre-storm barrier geometry. The study also revealed that swell waves can be a defining factor for morphodynamic change where different swell percentages can lead to very different responses

Gravel Barrier Beach Morphodynamic Response to Extreme Conditions

Gravel beaches and barriers form a valuable natural protection for many shorelines. The paper presents a numerical modelling study of gravel barrier beach response to storm wave conditions. The XBeach non-hydrostatic model was set up in 1D mode to investigate barrier volume change and overwash under a wide range of unimodal and bimodal storm conditions and barrier cross sections. The numerical model was validated against conditions at Hurst Castle Spit, UK. The validated model is used to simulate the response of a range of gravel barrier cross sections under a wide selection of statistically significant storm wave and water level scenarios thus simulating an ensemble of barrier volume change and overwash. This ensemble of results was used to develop a simple parametric model for estimating barrier volume change during a given storm and water level condition under unimodal storm conditions. Numerical simulations of barrier response to bimodal storm conditions, which are a common occurrence in many parts of the UK were also investigated. It was found that barrier volume change and overwash from bimodal storms will be higher than that from unimodal storms if the swell percentage in the bimodal spectrum is greater than 40%. The model is demonstrated as providing a useful tool for estimating barrier volume change, a commonly used measure used in gravel barrier beach management

Gravel Barrier Beach Morphodynamic Response to Extreme Conditions

Gravel beaches and barriers form a valuable natural protection for many shorelines. The paper presents a numerical modelling study of gravel barrier beach response to storm wave conditions. The XBeach non-hydrostatic model was set up in 1D mode to investigate barrier volume change and overwash under a wide range of unimodal and bimodal storm conditions and barrier cross sections. The numerical model was validated against conditions at Hurst Castle Spit, UK. The validated model is used to simulate the response of a range of gravel barrier cross sections under a wide selection of statistically significant storm wave and water level scenarios thus simulating an ensemble of barrier volume change and overwash. This ensemble of results was used to develop a simple parametric model for estimating barrier volume change during a given storm and water level condition under unimodal storm conditions. Numerical simulations of barrier response to bimodal storm conditions, which are a common occurrence in many parts of the UK were also investigated. It was found that barrier volume change and overwash from bimodal storms will be higher than that from unimodal storms if the swell percentage in the bimodal spectrum is greater than 40%. The model is demonstrated as providing a useful tool for estimating barrier volume change, a commonly used measure used in gravel barrier beach management