Sea dikes breaching initiated by breaking wave impacts - Preliminary computational model

Sea dikes are of crucial importance in the defence systems of low-lying coastal areas in Germany as well as in other countries such as The Netherlands and Denmark. Breaches of sea dikes due to storm surges are regarded as the main cause of flood disasters, so that a reliable prediction of both breach initiation, breach formation and breach development is urgently needed. One may distinguish several causes of dike breaching, depending on the structure of the dike as well as on the morphologic, geotechnical and on hydraulic boundary conditions. A breach may be initiated either from the landside by wave overtopping and overflow or from the seaside by repeated breaking wave impacts on a dike slope. For a dike breach initiated by wave overtopping, a PhD research has been completed (D\u92Eliso, 2007). Because the processes associated with the dike breach initiation from the seaside as well as the breach growth itself are completely different, there is an urgent need to investigate the dike breaching initiated from the seaside. The knowledge of the process of breach initiation and development is crucial for the prediction of the initial conditions at the defence line needed to model the flood wave propagation. In order to satisfy those needs, a tiered and modular strategy similar to that adopted by D'Eliso (2007) is applied. Similarly, the complete model consists of a simplified preliminary model and a more process-oriented detailed model. In this report the assumptions of the preliminary model, its implementation, example application and discussion on the limitations and capabilities is presented.Floodsit