Dispersion of suspended sediment originated from the Yellow River in the Bohai Sea

Abstract

A suspended sediment transport model was developed to explain the spreading pattern of the suspended sediment originated from the Yellow River in the Bohai Sea. It is a three-dimensional random walk model, which consists of two parts: 1) the movement of the suspended matter in the water body and 2) the deposition and re-suspension processes at the seabed. We conducted two experiments which correspond to spring tide and neap tide. In the case of only considering the tidal current effect, the results showed that most of small and middle sized particles from the Yellow River were transported mainly from Laizhou Bay to Bohai Bay with the coast on the left hand side. In the case of considering the tidal current and density-driven current effects, the results showed that most of small and middle sized particles from the Yellow River were transported mainly from Laizhou Bay to Bohai Bay with the coast on the left hand side, and a part of small and middle sized particles were transported with the coast on the right hand side in Laizhou Bay near the Yellow River mouth. This is due to that the Yellow River fresh water produces a clockwise density-driven current in the surface layer near the Yellow River mouth. However, most of large sized particles were deposited within one day and they did not move again. Furthermore, the spreading area during the spring tide was wider than that during the neap tide due to the re-suspension by the strong tidal current. These results are in agreement with the observed ones from satellite images (Yanagi and Hino, 2005). The results in this study show that the spreading pattern of the suspended sediments from the Yellow River in the Bohai Sea is mainly determined by the Lagrangian tide-induced residual current and the density-driven current.