Numerical Analysis of Monsoon Impact on Sediment Transport in the Eastern Qiongzhou Strait

This study employs a coupled SCHISM-WWM model to investigate monsoon controls on sediment dynamics in the eastern Qiongzhou Strait, a vital marine sand reservoir. Modeling results demonstrate distinct sediment transport by monsoons. Winter northeast monsoons drive westward currents with northern sector velocities averaging 17.83 cm/s (peak 44.86 cm/s), sustaining high-energy flow conditions that optimize sediment mobility in central-eastern areas and enable efficient offshore-directed sediment transfer. Conversely, summer southwest monsoons establish eastward circulation marked by velocity heterogeneity (maximum 41.49 cm/s), where flow deceleration and directional variability in sheltered zones promote preferential sediment accumulation. Winter's northeast monsoon generates westward bedload fluxes (0–15,000 kg/m) driven by currents exceeding 20 cm/s, whereas summer southwest monsoons induce eastward transport (up to 25,000 kg/m) through localized vortex deposition. Spatial analysis indicates tidal dominance over western sediment flux (80% contribution), contrasting with monsoonal current control in eastern regions (65% flux contribution). These insights contribute to a deeper understanding of the mechanisms governing monsoon-influenced sediment transport.