A Full-Size Hybrid Dune Field Experiment: Design and First Results
摘要
Coastal defense strategies increasingly include hybrid dunes, which combine sandy dunes with hard structures. In the case of hybrid dunes, the sandy system and hard elements interact. Wave impact, reflection runup as well as dune erosion and scour are all being affected by both the hard elements and sandy parts. To better understand these interactions, we conducted a field experiment, with a hybrid dune setup to measure hydrodynamics and dune erosion during storms. The experiment setup contains four cross sections to compare the morphological development at a sandy dune (1), dike-in-dune (2), vertical wall-in-dune (3) and dike (4). The works took place in the winter of 2024/2025. The various storms that occurred caused strong erosion to the test setup. Preliminary results show that while the hard elements slowed down dune retreat behind them, the beach morphology in front remained remarkably similar. Erosion may have been governed by large-scale sediment availability in the system, beach elevation and hydrodynamics rather than by hard-soft interactions at the hybrid dune.