Modelling the Erosion in the Scottish Coasts using the Process-Based Approach: Historic Validation and Projection of the Climate Change Scenarios

Twenty percent of the Scottish population live within 1 km from the coast and in the future is expected at a higher risk of erosion and flooding. The Scottish Government have assessed the erosion vulnerability of the Scottish Coasts through the National Coastal Change Assessment project - NCCA. The assessment employed the Coastal Erosion Susceptibility Model (CESM), a parametric-based approach estimating the shoreline changes based on topography, rockhead elevation, proximity, wave exposure, coastal defence, and historic sediment supply. The produced national scale map is showing the historical shoreline evolution at 147 sites, also mentioning the assets in threat. However, the future projections are only locating the sites that can experience erosion, not necessarily indicate that the sites currently undergo or will be eroded.

My doctorate research aims to address this gap, providing a more realistic shoreline change projection using the process-based model. Compare to the CESM, it requires more computational effort but benefiting the decision-maker by visualizing the mechanism of climate changes and human interventions in impacting the coast. The sea states, such as sea-level rise, wave climates, and storms are being altered by climate change. Extreme events are expected to become more frequent in the future and therefore result in a bigger risk of coastal erosion. Moreover, the coastal defence in some cases does not stop the erosion, rather it relocates the threat to other areas. The process-based model will be used to understand this phenomenon.

The Delft3D (open-source), XBeach (open-source), and UNIBEST are the core tools in this research, well-known for coastal modelling develop by Deltares. These suites have been tested in the Netherlands (Sand Engine) and the Korean Coast, performing well in replicating the shoreline change both in long-term and storms condition. In this research, some critical coasts with distinctive characteristics will be taken as a study case. Investigation on these areas not only will elucidate the coastal processes at the specific sites, but also act as a rule of thumb for other sites with a similar environment.

This series of research is designed to be completed in three to four years. The first year is allocated for examining the research question, building a collaboration with the forefront researcher, and collecting the relevant data. The second and third years focus on validating the model and proceeding to project the impact of climate changes and human interventions. The thesis and examination are to be finished in the early of the fourth year.

This research will illustrate how resilient the Scottish Coasts in the changing climate and the more frequent storms. Also, the most effective adaptation measures will be proposed for each area of interest. The advantages and disadvantages of the process and parametric-based approach will be underlined, opening up the possibility of coupling in formulating the strategic shoreline management plans.