A Methodology to Predict the Impact of a Marine Structure on Longshore Dynamics and Shoreline Evolution

Abstract

Globally, due to climate change and increased rates of coastal erosion, along with the need to protect sensitive habitats, there is an increasing requirement for a sustainable approach which considers both the effect of the marine environment on critical infrastructure and the impact of that infrastructure on the local environment. This paper presents a methodology for assessing the impact of a marine structure on longshore dynamics and shoreline evolution by using an external coupling of the phase-resolving ARTEMIS wave model and the shoreline evolution model, UNIBEST. The methodology can be applied at any coastal location, but for this study, it was applied to Sizewell Bay on the east coast of England to assess the impact of a shore-normal jetty on a gently curving stretch of shoreline with relatively complex offshore geomorphology. Results from simulating 22 years of shoreline evolution have shown that, at the jetty location, the shoreline at Sizewell will migrate seaward up to 45 m compared with the no-jetty case. Immediately south of the jetty, the shoreline was predicted to retreat landward by about 15 m. This behaviour is similar to observed changes at other locations, and the predicted longshore transport rates are in agreement with findings from previous studies, validating the methodology.