Numerical Study On Impact Of Bohai Sea Topography Changes On The Tidal Wave System

Topography in Bohai sea evolved a lot in the past30years, having a significantimpact on the tidal wave system.In this paper, I set up a numerical experimentbased on FVCOM, using coastline and depth data of2002, in the region of Bohai Seato study the traits of M2, S2, K1, O1tides. And I collected data from19stations alongBohai coastline to validate the model results. Then I set up another numericalexperiment based on data of the year of1972to to study the impact of Bohaitopography changes on tides system. Then found out that the evolution of topographycause the location of non-tide points move northeastward and amplitude intensity ofrelated tides change. In addition, tide type and maximum possible tidal range in Bohaisea also change. For M2、S2tides, the location of non-tide point near Yellow Riverestuary move about20km northeastward and amplitude intensities decreased inBohai Bay, however, increased in Laizhou Bay. For K1、O1tides, the location ofnon-tide point move10km or so northeastward and amplitude intensities decreased innorth part of the Bohai Bay, obviously. Region of diurnal and irregular diurnal tidaltype, adjacent to Yellow River estuary and Qinhuangdao Sea,has expanded. Inaddition the maximum possible tidal range near the Yellow River estuary also hasincreased. And impact on tidal flow include: The evolution of topography cause thechanges of maximum velocity and rotation characteristics of the tidal flow.Maximum possible speed range of tidal flow and tidal flow type in Bohai also vary.For the semidiurnal tide: The maximum tidal flow velocity decreased in thesouthern part of Bohai Bay, while increased in Laizhou Bay and the region nearYellow River estuary. And the intensity of rotating flow enhanced in central of Bohai; For the diurnal tide: The maximum tidal flow velocity increased in westernpart of Laizhou Bay and area near Yellow River estuary where the intensity ofrotating flow also enhanced. In the eastern side of Laizhou Bay, the irregular half-dayzone of tidal flow disappeared, Maximum possible speed range of tidal flowincreased in Laizhou Bay and region near Yellow River estuary. Evolution of Bohaiterrain makes tidal energy flux distribution also slightly changed near the YellowRiver mouth. Tidal energy in Bohai is also sensitive to topography changes. Finally, Idesigned another two numerical experiments to investigate the factors which causethe movement of M2non-tide point located near Yellow River estuary. And it turnedout that the variation of water depth made non-tide point move northeastward,whereas the other factor made the non-tide point to move southeastward.