A regional ocean circulation model (ROMS) is used to simulate the Chinese land‐derived sediment transport in the Bohai Sea, Yellow Sea, and East China Sea (BYECS). The model includes the effect of currents, tides, and waves on the sediment transport and is used to study the pathway and dynamic mechanisms of the fine‐grain sediment transport from the Huanghe River (Yellow River), the Old Huanghe Delta, and the Changjiang River (Yangtze River) in the BYECS. The seasonal variability of the sediment transport in the BYECS and the sources of the Yellow Sea Trough mud patch, the mud patch southwest of Cheju Island, the mud patch offshore from the Zhejiang and Fujian provinces and the Okinawa Trough mud patch are discussed. The results show that the Huanghe River sediment can be transported to the Yellow Sea Trough, but little makes it to the outer shelf while the Old Huanghe Delta sediment is mainly transported to the Yellow Sea Trough. Most of the sediment from the Changjiang River mouth is carried to the mud patch off the coast of the Zhejiang and Fujian provinces but with part of this sediment also transported to the Yellow Sea Trough. The model shows that it is difficult to transport land‐derived sediment to the Okinawa Trough mud patch under normal conditions. The model also has difficulty accounting for the deposition of sediment in the region to the southwest of Cheju Island and offshore from the Zhejiang and Fujian provinces, an issue requiring further study.

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Wind‐waves, tidal currents, and some other dynamic factors dominate the suspended sediment concentration (SSC) variations in shallow seas and it is difficult to quantitatively evaluate the effects of individual dynamic factors on SSC modulation. This work used the long‐term Moderate Resolution Imaging Spectroradiometer (MODIS) and the high temporal‐resolution Geostationary Ocean Color Imager (GOCI) remote sensing data to quantify the sea surface SSC variations on multiple timescales (intratidal, spring‐neap, seasonal, and long‐term timescales) in the Bohai Sea, and further quantitatively evaluated the effects of corresponding dynamic factors on the SSC modulation. The results indicated that the monsoon associated wind‐waves and stratification played the most important role in modulating SSC, with seasonal SSC variation of 8.1 mg/L in the Bohai Sea. The intratidal current variations played the secondary important role, causing SSC variation of 5.8 mg/L. The spring‐neap tidal current variations led to SSC variation of 3.1 mg/L in the Bohai Sea. In the long run (2003–2014), the SSC of the Bohai Sea decreased slightly with SSC variation of 2.8 mg/L (decline rate: 0.23 mg/L/year), which may be caused by the weakening wind, decreasing sediment load from the Yellow River or the massive reclamation in recent decades. Probably due to the topography, sea bed sediment grain size and river plume, SSC variations in the southern Bohai Sea were more pronounced than those in the northern Bohai Sea.

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