Modelling coastal erosion and sediment transport on the Dungeness Foreland, UK

Ageing coastal defence across the UK is challenging managers to redesign schemes to be resilient, cost-effective and have minimal or beneficial environmental impact. We take Dungeness and Romney Marsh, a region of high value in terms of habitat and energy infrastructure, as a case study that could potentially be a site for a ‘sandscaping’ project, i.e. an innovative, large-scale beach recharge scheme. At present, this location has both modified gravel barrier defences and engineered structures. We present results for a feasibility study to improve understanding of how ‘working with natural processes’ to manage coastal flood and erosion risk could provide and support defences protecting this site, ensuring an energy supply that is resilient to climate change. This modelling study investigates the impact of re-engineering the coastline with a series of sandscaping options that mimic the natural shape and former evolution of the Dungeness coastline. Particle tracking is used to show the potential pathways of recharged sediment (fine and medium sand) movement along the coastline in both calm and stormy conditions. A coastal evolution model is also applied to assess the alongshore impact of different intervention designs. It is found that the main sediment drift is likely to be towards the north along the coast and that considering larger interventions could possibly provide increased protection for up to 100 years. Further, a series of three smaller sandscaping interventions offers the greatest immediate reduction in erosion rate. The natural drift within the system causes the initial peninsula-shaped intervention to form a recurve that could potentially create additional areas supporting essential natural habitat within the area