Abstract: Tidal current asymmetry exerts evident impact on offshore sediment transport and topographical evolution in the estuary. However, due to the lack of long-term and high-frequency tidal velocity records, studies in this regard are insufficient. In this research, a two-dimensional numerical model is applied to simulate the tidal current in the Yangtze River Estuary. Non-stationary harmonic analysis together with the skewness method is applied to study the flow velocity asymmetry (FVA) and flow duration asymmetry (FDA), and further to reveal the transportation of suspended coarse and fine sediments. Results show that shorter duration of ebb current is favorable to the landward transport of fine sediments. Meanwhile, enhancement of the residual flow leads to larger ebb velocities, resulting in the seaward delivery of coarse sediments.

Key words: tidal current asymmetry, non-stationary harmonic analysis, tidal skewness, sediment transport, Yangtze River Estuary, spatial-temporal distribution