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 (1,531KB)
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6,011,000 Yen (FY1998; 2,003,000 Yen)
Based on a three-dimensional primitive-equation dynamic numerical model, the general circulation of the East China Sea and the Yellow Sea is studied with a 0.25 x 0.25 horizontal grid and a realistic bottom topography. We consider the tide current and Kuroshio simultaneously. The model tide harmonic constants agree very well with the 81 coastline stations' observations in this area. The path of the Kuroshio agrees with longterm observations; a branch of the Kuroshio enters the East China Sea and reaches nearly 29N, and thus controls a large part of the East China Sea. A branch of the Kuroshio goes northward and forms the Tsushima warn current.
In order to know the silt quantity of the navigation channel in Changjiang estuary, a horizontal 2-D numerical model of both suspended and bed load transport in the area is established. The suspended and bed load transport equations and sediment transport capacity formulas under the action of tidal currents and wind waves have been used. It applies an automatically generated boundary-fitted grid with orthogonal curvilinear coordinates. The verification of calculation shows the sediment concentration and the deformation of sea bed can be successfully simulated.
The usage of organochlorine pesticides during early 1950s to early 1980s had polluted the marine environment of the Changjiang Estuary. But after banned using, DDT and BHC content in newest sediments decreased rapidly to 0.25¡Á0.3lng/g and 0.35¡Á0.47ng/g respectively. Compared with data before 1980, DDT and BHC content in sediments of the Changjiang Estuary reached relative lower level. due to dilution of a large amount bedload from upper Changjiang River and high sedimentary rate in the Changjiang Estuary.
East China Sea, Changjiang Estuary, Numerical Model, Tidal Current, Silt, Sediment