Wave breaking characteristics and short-term morphodynamic responses under energetic wave conditions in the Yellow River Estuary

This study investigates the relationships between wave-breaking types and short-term nearshore morphodynamic change in the Yellow River Estuary using an integrated numerical framework. The modelling system was validated against buoy observations for wave statistic. Results suggest that depth-induced wave breaking acts as dominant energy sink, forming a stable, shore-parallel high-energy dissipation band at the kilometer scale in the nearshore. The estuary's northern sector features a dual regime dominated by surging breakers accompanied by spilling events, whereas the southern sector is governed predominantly by spilling breakers. This spatial pattern is reflected in differing relationships between extreme wave heights and foam-band morphology. The two breaker regimes drive contrasting near-bed hydrodynamics, with surging breakers generating intense, localized jets and offshore-directed return flows, whereas spilling breakers produce diffused and spatially uniform velocities. Surging-dominated conditions favor the development of bar-swale systems with rhythmic, alongshore variable erosion-dominated patterns, whereas spilling-dominated regimes lead to smoother, deposition-favorable bed evolution. By quantitatively linking breaker-type distributions to near-bed hydrodynamics and the corresponding morphological responses, this study bridges the gap between wave-breaking mechanics and event-scale morphodynamic responses. The proposed process-based framework provides a predictive tool for coastal vulnerability assessment and management in sediment-rich, complex estuarine systems.