The Wind of Changes on the Kapellebank Tidal Flat, The Westerschelde

The existence of tidal flat is beneficial for human beings, but it faces the risk of being vanished by continuous intervention, either by nature or human. Therefore, researches about tidal-flat’s morphodynamics are required for the sake of its preservation. Here, the subject of the research is the Kapellebank tidal flat in the Westerschelde estuary and the field measurement was performed for approximately 1 month. The objective of the study is to understand the hydrodynamics and the resultingmorphodynamics of the tidal flat. The analysis on the measurement data reveals the dominant filling-emptying mechanism at the flanks of the tidal flat. The water from theWesterschelde enters the Kapellebank tidal flat from one flank and it leaves from the other flank. The tidal-flat’s hydrodynamics are also heavily influenced by the spring-neap cycle and the wind speed variation. The spring-neap cycle determines the scale of the flowvelocity as the deeper spring tide propagates faster than the shallower neap tide. Meanwhile, the high wind-speed changes the flood-ebb pattern, creates the local wave, and generates the return current at the tidal flat. The erosion of the tidal flat is mainly caused by the imbalanced sediment flux during the period of the strong wind. As the storm generates the return current, it transports the sediment from the tidal flat toward offshore. Consequently, the bed level of the Kapellebank is eroded as there is more sediment outflux than the sediment influx. The measurement reveals the bottom level of the tidal flat decreased during the stormperiod, but it gradually increased again during the calm wind period. In the end, there was not much change in the bed level hence it can be deduced that the tidal flat is in the dynamic equilibrium. And, as the factors which influence the morphodynamics of the tidal flat are expected to exhibit similar pattern in long term, the Kapellebank tidal flat is expected to remain in the dynamic equilibrium.