Numerical study of the tidal refraction effect on the open coast in southeastern Zhejiang

In this study, the tidal refraction effect on the open coast in southeastern Zhejiang, China, is numerically investigated using an MIKE21-based model. The accuracy of this numerical model was verified by comparing with the measured results. The model was then employed to simulate the tidal propagation and the impacts of intense reclamation planned in the study area. The co-tidal chart and iso-amplitude curves of M2 (principal lunar semi-diurnal), S2 (principal solar semi-diurnal), O1 (lunar diurnal), K1 (lunar diurnal), and the tidal current ellipses of the M2 constituent illustrate the different tidal refraction phenomena from underwater shoals to tidal flats on the open coast. The results showed that the tide spreads along the coast in underwater shoals, while it spreads toward the coast in tidal flats. The spreading direction of the tide was congruent with the main spindle of the M2 constituent tidal current ellipses. Furthermore, the tidal range decreased; tidal refraction effects were weakened after reclamation, and the tidal direction changed.