Modelling the morphodynamics of sandy coastal systems under a changing climate

Morris, Chloe Sarah

Abstract

Coasts are vulnerable to changing environmental conditions and are likely to be affected by predicted sea level rise and wave climate variations over the next century. Predicting the likely response of coastal systems to these changes, including altering erosional patterns and flood potentials, is complex and involves understanding their morphodynamics and key sensitivities. Whilst numerical models can be powerful tools for the exploration and prediction of environmental behaviours, mesoscale coastal models tend towards one-line approaches that are unable to simulate the combined effects of wave action and sea level rise (e.g. COVE and CEM).

In this thesis the development and application of a new two-dimensional numerical model is presented, designed to simulate coastal morphodynamics at the mesoscale to a higher resolution than afforded by existing models of its kind. The Coastline Evolution Model 2D (CEM2D) has been built upon the core principles of the one-line Coastline Evolution Model but with increased complexity in the domain structure and representation of sediment transport processes. CEM2D has shown to simulate fundamental cause-effect relationships in coastal environments and demonstrated its ability to evolve key shoreline shapes according wave-driven sediment transport processes (including cuspate headlands, sand waves and spits). The results of the modelling exercises reinforce the theory of high angle wave instability and compare well to the planform morphology of natural coastal environments worldwide, including the Carolina Capes (USA) and Spurn Point Spit (UK).

Insightful dynamics are observed in the evolution of the simulated coastal environments when subject to sea level rise. Coastal landforms show a varying ability to keep pace with rates of rise at 1 m and 2 m per 100 years, representative of relatively extreme values of change over the coming century. The results suggest that there is a sensitive balance between the wave energy delivered to the shoreline, the balance of cross- and longshore sediment transport, the sediment budget and the level of geomorphic activity that occurs in the systems. These factors determine whether the shoreline erodes, landforms are submerged or progradation occurs and whether remnant morphologies can be preserved in the bathymetric profile. Whilst it is observed that sea level rise plays a significant role in coastal evolution, the wave climate conditions remain the principal agent in defining their planform morphology.

Citation

Morris, C. S. (2019). Modelling the morphodynamics of sandy coastal systems under a changing climate. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4222460

• Thesis Type: Thesis
• Deposit Date: Jun 25, 2020
• Publicly Available Date: Feb 23, 2023
• Keywords: Geography
• Public URL: https://hull-repository.worktribe.com/output/4222460
• Additional Information: Department of Geography, The University of Hull
• Award Date: Mar 1, 2019