Williams, J.J., Esteves, L.S., Conduche, T., Barber, P., Tindle, A., 2014. Using Combined Modelling Approaches to Improve Coastal Defence Design: a case study at Hopton, UK. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 018–022, ISSN 0749-0208.
A storm that occurred close to the spring tidal maxima in March 2013 resulted in beach lowering and cliff recession of c. 5 m along a 110 m frontage at Hopton-on-Sea, UK and threatened the static caravan park of Bourne Leisure Ltd. This paper reports a study using XBeach and MIKE21 models to assist with the design of new coastal defences to reduce cliff and beach erosion. Two schemes are examined here: three fishtail rock groynes (Scheme 1); and ten ‘double-head’ curved rock groynes (Scheme 2). The selected design must provide acceptable level of protection and, to be granted consent, no adverse environmental impact must be demonstrated. Current practice using a single numerical model can provide a cost-effective tool for coastal defence assessments. However, the work presented here show that when good agreement between complementary models can be demonstrated, greater confidence can be given to model results. Specifically, refinements to the present scheme design were made possible by the use of the XBeach model, which allowed identification of the cross-shore limits of sediment transport in storm conditions, and by the MIKE21 model which allowed quantification of alongshore scheme impacts. Together, the model results have assisted the development of an improved final scheme design which minimizes potential environmental impacts.