Distribution, transport and controlling factors of suspended sediment near Rizhao in the west of South Yellow Sea

In this paper, based on the hydrological and sediment observation data collected from the coastal area of Rizhao in October 2020 during the spring tide, the spatial and temporal distribution pattern of ocean current and suspended sediment are studied, and the transport mechanism and controlling factors of the suspended sediment discussed by means of single wide flux mechanism decomposition. The results show that the concentration of suspended sediment in the studied coastal area decreases gradually from shore to sea laterally, and increases gradually from top to bottom vertically. The variation trend of suspended sediment concentration is consistent with the velocity change of tidal cycle, except for the hysteresis effect. The net sediment transport rate per width in the study area varies between 4.72 and 24.68 g/(s·m), and the net sediment transport rate per width near shore is significantly higher than that offshore. The main transport of suspended sediment is advection, followed by tidal pump effect or vertical net circulation. The vertical mixing of water body in the study area is uniform, and its effect on vertical distribution of suspended sediment is rather weak. Tidal current is the major process to cause the tidal cycle change of suspended sediment concentration in the study area. The net transport direction of suspended sediment and tidal residual current are roughly the same in the west coast of the South Yellow Sea, and there is southward net transport trend in general in the far shore area of the open sea. The research results are beneficial to improve the theoretical results of sediment transport pattern in the west of the South Yellow Sea and have certain guiding significance to the engineering construction in the Rizhao coast.