A numerical model suitable for tides and tidal currents forecast in Jiangsu offshore areas, China, which includes M2, S2, K1, and O1 tidal constituents, is developed based on the Estuarine and Coastal Ocean Model with semi-implicit scheme (ECOM-si). Comparing the computed values with those of 6 tidal observatories and 12 current stations, the results also show a good agreement.Based on these results, the isoamplitude and the cotidal lines of the main constituents M2 and K1 are given. It is found that semi-diurnal tide constituents M2 has tide-free point and diurnal tide constituents K1 has no tide-free point in this area.
Jiangsu offshore areas are located in the middle of the East China Sea continental shelf. Radial sand ridges on the Yellow Sea seafloor are distributed over the middle part of Jiangsu coast down from the Yangtze River estuary up to the Sheyang estuary, stretching for 200 km latitudinally and 90 km longitudinally (Wang, 2002). There are more than 70 underwater sand ridges radiating from Jianggang, most of which come out of water and become shoals at low water level. These sand ridges are of different heights and in different shapes, and form a peculiar geomorphology, which is unique in the world. The condition of hydrodynamic in this area is very complicated. Many researchers have shown interest in the impact of the distribution of tidal wave and tidal current on the radial sand ridges for a long time (Ren, 1986; Zhang and Zhang, 1996; Zhang et al., 1999; Yan et al., 1999a, b; Tao and Zhang, 2005). Based on the measured data from the integrated survey for coastal zone and tidal plat in Jiangsu Province, combined with some numerical tidal wave results, Ren (1986), Huang and Wang (1987) proposed that there were two different tidal wave systems meeting outside Jianggang, and the strong tidal currents of these tidal wave systems induced the evolution of the sand ridges and were a major factor of the radial plane form.
