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The long-distance transport of Yellow River sediments has formed an omega-shaped ('Ω') distal muddy deposit in the Yellow Sea. Numerous studies have investigated the sediment dynamics and sedimentary evolution of the deposit, but several key questions remain unanswered due to insufficient observations. To reveal the mechanisms of sediment dynamics and quantify sediment transport and deposition processes, this study collected field datasets in the depocenter of the muddy deposit off the Shandong Peninsula. Bottom mounted tripods were deployed from August 18 to 27, 2017, and from February 23 to March 2, 2018, during which two strong wind events with speeds of over 10.8 m/s occurred. The results showed that near-bed suspended sediment concentration responded directly to varying hydrodynamic conditions, and significant differences in suspended sediment concentration between two wind events could be ascribed to a number of factors (e.g., tidal current, wave periods, wind stress, turbulence). The harmonic analysis demonstrated that suspended sediment variations during the spring tide were directed mainly by resuspension, while resuspension and advection contributed equally at neap tide. The variations in background suspended sediment concentration can be ascribed to the residual current. Furthermore, the sediment transport pattern is similar to the pattern of water circulation. Generally, the along-shore suspended sediment flux is about one order of magnitude higher than the cross-shore flux. In summer, the suspended sediment was transported mainly downcoast. In winter, sediment was transported downcoast during wavy periods and upcoast during calm periods. Advection dominated sediment flux in most cases, except during wavy periods when local resuspension increased significantly, and the contribution of resuspension term to along-shore flux was up to 87%. Meanwhile, cross-shore flux also increased significantly under strong winds, which was simultaneously modulated by downcoast and offshore winds. After statistical analysis, we found that offshore winds controlled the cross-shore sediment transport in winter. Using parameterized calculation and statistical analysis, the average accumulation rate of the study site was estimated to be 0.6 cm/yr. During calm periods, lower background sediment concentration in summer led to lower deposition rates than in winter. In addition, the frequent strong wind events in winter cause extremely high erosion rates. This study provides new perspectives on quantitative variations in suspended sediment transport and regional erosion/deposition from synoptic to seasonal variations in the distal mud deposit. • In-situ observations at the bottom boundary layer were conducted in summer and winter on the muddy deposit off the Shandong Peninsula. • The advection dominates sediment flux in most cases, except for during wind gusts when local resuspension increases significantly. • Combining parameterized method and observational data, the accumulation rate is estimated. [ABSTRACT FROM AUTHOR]

Bottom mounted platforms equipped with current profilers/meters, temperature/salinity and turbidity sensors were deployed for about 10 days in August 2017 over an elongated deposit off the coast of Shandong Peninsula, in order to monitor the hydrodynamics and sediment processes in the bottom boundary layer. In total, semidiurnal barotropic tides dominate the measured currents, accounting for 90% of total variance. However, in the cross-shore direction, greater variance is associated with the semidiurnal internal tidal currents than the semidiurnal barotropic currents. Both the Empirical Orthogonal Functions and normal mode analysis demonstrate that the baroclinic velocity is dominated by the mode-1 internal tides, i.e. the current has a vertical shear with strong opposite flows near the surface and bottom while weak in the middle. Although the bottom slope is subcritical in most area of the deposit, the ratio between the bottom slope and the slope of internal tide characteristics is greater than 0.5, suitable for local internal tide generation. The internal tides generated from the deposit are especially significant considering that the shelf of the Yellow Sea is usually broad and flat. The quantitative estimation of the water column mixing indicate that the bottom dissipation induced by the barotropic tides (6.44ⅹ10−4 m3 s−3) is greater than the internal tides (−0.95ⅹ10−4 m3 s−3), and the total dissipation rate due to bottom drag is 5.49ⅹ10−4 m3 s−3, which is much greater than the interior one due to internal tides (2.69ⅹ10−4 m3 s−3). The internal tidal current alone is not energetic enough to resuspend the local fine-grained sediments. However, in the cross-shore direction, the sediment flux due to internal tides is twice as much as the barotropic component, resulting in a net onshore sediment flux, thus highlighting the advection effect of internal tides in the coastal mass transport. • This investigation is the first to quantify the semidiurnal-band characteristics of baroclinic tidal currents and evaluate the effect of the internal tides to sediment resuspension and transport in the region of a unique elongated mud deposit off the coast of Shandong peninsula. • Mode-1 semidiurnal internal tides, the dominant baroclinic motion, is believed to be related to the steep topography of the deposit and enhanced stratification in summer. • The near-bed stress induced by internal tides is not strong enough to suspend sediments, but its contribution to sediment transport due to advection cannot be ignored. [ABSTRACT FROM AUTHOR]