HYDRAULIC PERFORMANCE AND STABILITY OF COMBINED RECURVED WALLS

Helgoland is a German offshore island in the North Sea with about 50 km distance to the coast. The main island is protected by dikes and revetments. Due to climate change-induced sea level rise and anticipated increasing wave loads, the existing coastal protection needs to be revised and adapted in the northeastern part of the island. Many requirements besides the hydraulic performance and stability of the coastal protection system needed to be considered: nature conservation, land use, contaminated sites, tourism, visual landscape and existing buildings or infrastructure. Due to the number and complexity of the individual elements, there is no existing data- or process-based design approach, which considers the effects of the combined elements on the wave overtopping rate and wave forces on the seawall. The obvious lack of knowledge is hence addressed in this work, using a combined experimental approach, using medium-scale 2D and 3D experimental tests.