Response of tidal dynamics to the construction of Yangshan Deepwater Harbor, Shanghai, China

Coastal constructions can strongly modify local hydro- and sediment dynamics. The Yangshan Deepwater Harbor (YDH) is constructed on a tidal-dominated archipelago in the Changjiang Estuary. Three key passages are closed by the harbor's construction. Responses of tidal dynamics, including tidal range, tidal constants, and tidal asymmetries, are thoroughly investigated in this study. The observed hourly tidal data at Xiaoyangshan station shows that the tidal range, tidal amplitudes, and flood-dominant tidal asymmetry increased during the constructions from 2001 to 2005. Tidal levels at other stations indicate that the tidal dynamics in the YDH is quite different spatially. A high-resolution Finite-Volume Coastal Ocean model (FVCOM) model study confirms that the response of tidal dynamics is very different in space. Closure of passages decreases tidal amplitudes in the lee but increases tidal amplitudes in the stoss. Shallow-water tides dominate the tidal asymmetries in the sea area. Thus, the increase of tidal asymmetry around the Yangshanshan station is mainly resulted by the siltation relating to the constructions, and the decrease of tidal asymmetry in the East Entrance is mainly due to the stronger attenuation in high-frequency tides by tidal choking.