Xiaomiaohong Waterway is a submerged tidal inlet in the southernmost site of radial sand ridges off Jiangsu coasts in China. During its development process, the recognition on the complex current characteristics and evolution trend of channel topography should be solved. With two-dimensional tidal current model, the hydrodynamic characteristics, duration and velocity of the flood and ebb tide, and the residual current are analyzed and calculated in detail. Numerical analysis shows that in the entrance section, the South and South-S channels present the type of ebb tide predomination and ebbing residual current; however, the North, Middle, and South-N channels present the opposite characteristics, which is in concordance with the present dynamic equilibrium morphology with erosion in south and deposition in north in Xiaomiaohong Waterway.
For a submerged tidal inlet system, the time-velocity asymmetry of tides is one of main factors which control coastal material transportation and accumulation. There are two types in general, the flood dominated type and the ebb dominated type (Aubrey and Speer, 1985; Boon and Byrne, 1981; Bruun, 1978). The former refers to Tf < Te (Tf is the flood duration; Te is the ebb duration) and Uf > Ue (Uf is the flood velocity; Ue is the ebb velocity), in which sediments are easily transported and accumulated inner the bay of tidal inlet. On the contrary, the latter refers to Tf > Te and Uf < Ue, and may increase the capacity of net sediment transportation from the entrance to the open sea, which is beneficial to keep relevant stability of a tidal inlet system. The flood or ebb dominance is used with regard to the net sediment transport, in respect of these terms, the flood or ebb asymmetry does not imply the flood or ebb dominance (Brown, 2010).