Effects of Tide and Wave on the Transport of Water and Sediments off the
Yellow River Mouth in Winter
Abstract
The fresh water and sediments transport from the Yellow River mouth
downstream along the coast into the Laizhou Bay under the northeasterly
wind in winter. The sediment transport is convergence in the river
mouth, divergence in the downstream area, and convergence in the north
of Laizhou Bay. Tide and wave are the two main forcings affecting the
transport of water and sediments off river mouths. For the
high-turbidity Yellow River mouth and the adjacent sea, tidal forcing
enhances the subtidal downstream transport of water and sediments off
the river mouth into the Laizhou Bay, whereas wave forcing has little
effect on the advection of water and sediments. The sediment
resuspension is controlled by the bottom shear stress induced by tide
and wave. The tide-induced bottom shear stress is higher in the north of
Laizhou Bay and south of Bohai Bay due to the stronger bottom tidal
current. The wave-induced bottom shear stress plays a more important
role in sediment resuspension, which is higher in the nearshore region
along the Yellow River Delta away from the coast to some extent on
account of the maximum near-bottom wave orbital velocity. Tidal mixing
strengthens the upward diffusion of bottom suspended sediments. Without
tidal forcing, the decreased bottom shear stress suspends less sediment
above bed. On the other hand, the enhanced stratification hinders the
upward diffusion of the bottom sediment due to the lack of tidal mixing,
resulting in higher suspended sediment concentration (SSC) in the bottom
layer in the offshore region.