INFLUENCE OF STORM SEQUENCING AND BEACH RECOVERY ON SEDIMENT TRANSPORT AND BEACH RESILIENCE (RESIST)

Large-scale experiments on beach profile evolution and detailed sediment transport processes under varying wave conditions were performed within the HYDRALAB+ transnational access project ‘RESIST’. Five wave conditions were tested, of which two presented high energy wave conditions and three presented low energy wave conditions (including one very low energy condition that was run for a long duration (24 h)). These five wave conditions were combined into three sequences of alternating high-low energy conditions, with similar total power of each sequence. Each sequence departed from an initial 1/15 sloped profile. The experiments resulted in a large data set comprising measurements of high temporal-spatial resolution of the beach profile, water surface elevation, velocity field, sediment concentrations as well as the collection of sediment samples and observations of wave breaking and runup/rundown. The analysis of the beach profiles in the context of storm sequence forcing has highlighted the evolution of the beach towards an equilibrium state for each wave condition. The analysis of sediment transport and bed level changes under high energy, alternating swash events has provided new insights into sand transport processes, including the influence of small differences in waveswash interactions on transport rates, and the mobilisation of sediment in the swash