MODELLING RAPID COASTAL CATCH-UP AFTER DEFENCE REMOVAL ALONG THE SOFT CLIFF COAST OF HAPPISBURGH, UK

Abstract

There are currently no well-established methods of predicting coastal catch-up, i.e. the response of shores to the removal of existing coast protection. Such estimates are vital to inform decisions around the renewal of such structures. At a deeper level, the lack of predictive methods undermines progress towards more sustainable approaches to coastal management, and the implementation of policies of managed realignment. Some progress has been made in recent years using the SCAPE numerical modelling tool (e.g. Walkden et al, 2015). That study demonstrated coastal response that included retreat beyond the position the shore would have been expected to reach in the absence of coast protection (i.e. coast protection apparently causing a net loss of land). That study raised important questions, but was limited in the respect that it represented the coast in two-dimensions (i.e. without alongshore interactions). In this work we illustrate how the novel Coastal Modelling Environment (CoastalME, Payo et al. 2017) is able to reproduce coastal catch-up at Happisburgh at the East coast of UK, and to do so with more physical realism than was possible with the SCAPE model, including accounting for alongshore variations).