553 / 2024-09-18 12:09:47

Cross-shore sediment transport on an open tidal flat: Wind-driven flow reversal and fluid mud

Wind-driven flow reversal,Fluid mud,Gravity flow,Sediment transport,Tidal flat,Jiangsu coast

Session 17 - Advances in Coastal Hydrodynamics and Sediment Dynamics for a Sustainable Ocean

Understanding sediment transport processes within tidal flats is crucial for developing effective land-ocean interaction management strategies. However, the cross-shore sediment transport on tidal flats induced by episodic events, such as wind-driven flow reversal (WDFR) and fluid mud (FM), remains insufficiently understood. This study focuses on the central Jiangsu tidal flat, where two field campaigns were conducted during winter and summer, respectively. During the winter campaign, WDFR events were identified. During WDFR, the wind reversed the tide-only flow direction, resulting in significant cross-shore sediment fluxes. Interestingly, the near-bottom suspended sediment concentration during WDFR was lower than that during calm conditions, indicating enhanced upward sediment transport due to turbulent mixing caused by strong waves during WDFR. During the summer campaign, FM occurred frequently during tidal slack periods when current-induced bottom stress was low. The settling from the overlying fluid into the bottom layer plays a pivotal role in initiating FM events. These FM events resulted in substantial cross-shore sediment fluxes, exceeding the long-shore components. This study highlights the need to appropriately address the contributions of WDFR and FM to cross-shore sediment transport in similar coastal environments.