The response of sediment transport and morphological evolution to storms with different characteristics

Strong wave-current interaction under the impact of storm events can induce a series of complex sedimentary processes of sediment resuspension and transport and morphology changes, significantly changing the topography of coastal zones. However, coastal sedimentary processes during storm events have not been fully understood. In this study, we developed a wave-current-sediment coupled model to investigate the response of dynamical processes to extreme storm events. The model was first validated against the observed data for both storm conditions during the 2007 Typhoon Wipha and fair-weather conditions in 2016 in the Haizhou Bay (HZB) of the Yellow Sea. The simulated results indicated that the longshore sediment transport was dominated originally by tidal effects which were significantly enhanced by wind-induced waves during the passage of the Typhoon Wipha. Storms with different characteristics correspond to two typical sedimentary dynamic response modes based on a series of numerical experiments. The tidal pumping effect (T3 + T4 + T5) and gravitational circulation term (T6) controlled the total storm-induced sediment flux, and T6 played a crucial and special role, typically in the opposite direction of the dominant wind of the storm. The strong wind could lead to the stratification of the water column, causing the down-slope or up-slope cross-shore sediment transport, resulting in coastal seabed erosion/deposition. In addition, the onshore wind was found to have a stronger impact on the sedimentary process. The methodology and findings of this study provide a scientific basis for understanding the response mechanism of sediment transport during storm events in coastal areas.