Cross-shelf sediment transport and its regulatory mechanisms on the inner shelf of the East China Sea during typhoon events

The cross-shelf sediment transport is important in land-sea interactions and in terrigenous sediment source-to-sink cycle, which is significantly impacted by typhoons. However, despite the scarcity of in-situ observation and satellite data during typhoons, research on cross-shelf sediment transport during these synoptic weather events remains limited. Utilizing a high-resolution FVCOM model, we analyzed the cross-shelf sediment transport and its mechanisms on the inner shelf of the East China Sea (ECS) during Typhoon Chan-hom (2015). Results indicate that typhoons can cause intense responses in marine sediment dynamics and produce significant cross-shelf offshore sediment transport, with suspended sediment flux increase by 2～3 orders of magnitude compared to that under normal weather conditions. The transport is mainly controlled by two mechanisms: (1) the barotropic effect caused by continuous water level accumulation during typhoons, inducing uniform meridional offshore sediment transport, representing an indirect typhoon influence; (2) the "Ratchet Effect" triggered by the rotating wind field, resulting in a downwind sediment transport pattern on both side of the typhoon path, with offshore and onshore transport on the left and right sides, respectively, reflecting a direct typhoon influence. The combined effects of these two mechanisms orchestrate the cross-shelf sediment transport on the inner shelf of the ECS during typhoons.