Sediment Resuspension in the Yellow River Subaqueous Delta During Gale Events

During winter, strong winds and waves significantly enhance sediment resuspension in the Yellow River Delta. Based on the continuous and high-resolution data on water levels, wave heights, current velocities, and echo intensities collected by the Acoustic Doppler Current Profiler at different depths (5 m and 12 m) in the northern Yellow River Delta simultaneously, this study investigated the sediment resuspension during gale events and tranquil conditions. In deeper waters (12 m), the suspended sediment volume concentration (SSVC) showed a strong correlation with current speed (r = 0.74), while in shallower waters (5 m), the SSVC correlated more closely with wave height (r = 0.72). The thorough analysis of gale events revealed that the maximum wave heights during northwest gales were 23.80% and 34.59% lower than that during northeast gales at deep and shallow stations, respectively, primarily due to the longer wind fetch associated with northeast gales. Conversely, the maximum current velocities during northwest gales were 10.34% and 37.31% higher than that during northeast gales at deep and shallow stations. In deeper waters, the maximum wave–current induced shear stress (τcw) and SSVC during northwest gales were 30.38% and 3.70% higher than those during northeast gales, highlighting current-driven resuspension. In contrast, in shallower waters, the maximum τcw and SSVC during northeast gales were 47.35% and 4.94% higher than those during northwest gales, underscoring the dominance of wave-induced resuspension.