The impacts of winter storms on sediment dynamics and shear front variability in the Yellow River Delta

Abstract

Study region Yellow River Delta (YRD), China Study focus Delta evolution exhibits pronounced seasonal variability―seaward progradation in summer due to high sediment supply and weak ocean dynamics, versus winter retreat dominated by storm activity. However, winter storm impacts on sediment dynamics remain insufficiently understood relative to summer processes, limiting systematic assessment of delta evolution. This study combines a well-validated numerical model with in-situ observations to investigate rapid sediment dynamic responses of the YRD to winter storms. New hydrological insights Winter storms trigger substantial sediment resuspension in nearshore areas (bottom SSC peaking at 32.5 kg/m 3 ) and enhance alongshore transport by an order of magnitude. East of the estuary, intensified southward coastal currents replace normal tidal alternation, eliminating inner-ebb-outer-flood shear fronts while prolonging and strengthening inner-flood-outer-ebb ones. Although total shear front duration remains comparable to that under calm conditions, increased intensity restricts offshore dispersal and promotes southward export. Wind direction critically modulates transport: sediment is consistently delivered to southwestern Laizhou Bay under all storm directions, while in the northern delta, transport shifts westward during northeasterly storms and reverses under northerly/northwesterly winds. Storm-driven processes account for ~68% of winter southward sediment flux, a contribution amplified by increasing storm frequency and duration. These findings establish winter storms as a key forcing in the YRD’s “Winter-Transport” phase, shaping its seasonal sediment redistribution, with implications for deltaic management under climate change.