Modelling of the Beach Evolution at Norfolk Coast of the UK Under Storm-conditions

Due to global climate change effects, extreme events are expected to become more frequent in the near future. In recent decades, beach nourishments have been increasingly used in the UK and worldwide, successfully protecting coastal populations and infrastructures against severe storm surges. Inspired by the “Zand-motor” in the Netherlands, the sand-scaping project at the Bacton gas terminal along the east coast of the UK is the biggest nourishment ever implemented in the country with more than 1.5 million m³ of sand. Accurately predicting the impact of nourished material on beach morphology is key for successful projects. However, the mixed sediment transport dynamics involved in the nourishment projects is yet to be fully understood and accurately modelled at the scheme scale. This paper describes a novel algorithm implemented in the process-based model COAST2D (Pan, 2011) to deal with mixed sediment. The model is applied to a proposed sand-scaping site at Bacton on the east coast of the UK with a computational domain of 6 km by 2 km domain and selected storm conditions. Native and coarser nourished sediments with a median grain size of respectively 350 μm and 450 μm are considered in the model. The results show that the proposed algorithm for the mixed sediment transport is capable of predicting morphological changes at the site with an acceptable accuracy.

Keywords: Coastal morphodynamics, Process-based modelling, Beach nourishment, Mixed sediment transport, Coast2D