Morphodynamic modelling of a nourished beach

Beylard, Benjamin ORCID: https://orcid.org/0000-0003-4612-1839 2023. Morphodynamic modelling of a nourished beach. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The focus of this study is to introduce and evaluate the performance of the 2DH coastal process-based model COAST2D that incorporates a novel engineering approach to multi-fractional sediment dynamics. This new method assumes that sediments of similar size adopt similar behaviours (mixing) when exposed to given hydrodynamic forcing. It is expected to improve computational efficiency while accurately predicting beach nourishment evolution. To assess the performance of the mixed sediment algorithm, the mor-phodynamic evolution of the Sandscaping Bacton gas terminal (UK), is computed under different hydrodynamic conditions. A series of tests are conducted under both calm and storm conditions of different in-tensities between the 20th of September 2019 and the 05th of February 2020. The model results are then compared with field data to determine the magnitude of model error. Additional tests are also performed to identify the origin of these errors and evaluate the model’s sensitivity. Overall, COAST2D model captures properly the early-life evolution of the Bacton nourished beach (6 months). the steep artificial beach slope transitions towards a more dissipative state and shore-parallel sand bars appear in the surf zone. Comparisons with field data reveal that the model predicts accurately the trend of erosion along the Sand-scaping’s wider area as well as the redistribution of the eroded sand downstream although globally underestimating the erosion/accretion volumes. Assumptions made or potential errors in model set-up or data manipulations contribute to these differences. Nevertheless, the results of the study at hand remain encouraging regarding the capa-bilities of the mixed sediment approach to accurately represent the evolution of a nourished beach.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	1). Coastal hydrodynamics and morphodynamics 2). Mixed sediment transport 3). Soft coastal engineering 4). Beach nourishment 5). Process-based modelling 6). COAST2D
Date of First Compliant Deposit:	28 June 2023
Last Modified:	28 Jun 2023 12:58
URI:	https://orca.cardiff.ac.uk/id/eprint/160656

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