The Impact of Winter Storms on Sediment Transport Through a Narrow Strait, Bohai, China

The Yellow River is one of the most significant sources of terrestrial sediment to the global seas, and the Bohai Strait is the only pathway that delivers Yellow River‐derived sediments from the shallow Bohai Sea to the Yellow Sea. To investigate sediment transport processes through the strait under the influence of storms (strong northerly winds) that frequently occur in winter, we deployed two sets of observing platforms equipped with Acoustic Doppler Current Profilers (ADCP) and a suite of other sensors in the strait in January 2018. Aided by a system of high‐resolution models, we reconstructed sediment dynamics in response to the strong northerly wind of a winter storm. Model results show that the instantaneous suspended sediment flux (SSF) is highly aligned with tidal currents, while the net sediment flux has a clear dependence on variations in exchange flow and sediment resuspension. Enhanced coastal currents, intensified wave motions, and higher suspended sediment concentrations indicate that the through‐strait sediment flux during outflows is greater than during inflow conditions. Such SSF asymmetries are believed responsible for the net sediment export through the Bohai Strait in wintertime. Diagnostic analyses provided insights into the dynamic mechanisms of exchange flow variations influenced by both the strong northerly winds and the wind‐triggered coastal trapped waves in the shallow, narrow strait via geostrophic effects. This study highlights the importance of storm‐induced horizontal exchange processes in a coupled bay‐shelf system. The aim of this study is to characterize the dominant processes that control net wintertime sediment fluxes through a narrow strait. Flows, waves, and sediment concentration were measured in the strait during a winter storm. A well‐validated model showed that wintertime flows in the strait are dominated by alternating, strait‐wide inflow and outflow. Occasionally, however, inflows and outflows are concurrent over different sections of the strait. Based on a numerical model, our calculations of sediment flux for the entire winter revealed that large net sediment flux occurred when both winds and waves were strong. These results provide a better understanding of how sediment transport in a bay‐shelf system has driven by both local and remote forcing mechanisms. Winter storms can generate low‐frequency oscillations of barotropic flows accompanied by sea surface height fluctuations in Bohai StraitBoth local wind and wind‐triggered coastal trapped waves are responsible for exchange flow variations at synoptic time scalesThe combination of intensified wave motion and exchange flows strongly alters the pattern and quantity of the sediment flux in Bohai Strait