Influence of Velocity Moments on Sand Bar Movement During CROSSTEX

During the 2005 CROSSTEX laboratory experiments, a series of bar generation and degeneration events and repeated cycles of offshore and onshore transport were documented. These changes were driven by regular modifications to the specified incident wave field. Based on collected bathymetric data we first assessed the spatial and temporal movement of two sand bars. We used hydrodynamic and video data to relate the movement of these bars to the occurrence of wave breaking and the magnitudes of undertow, velocity skewness and acceleration skewness. This analysis indicates that undertow currents generated the first sand bar through offshore-directed transport. The second bar was formed by onshore transport, with the first bar serving as the likely sediment source. On the other hand, onshore migration and degeneration of both sand bars correlated well with acceleration skewness.