Different effects between cold front and tropical cyclone on short-term morphodynamics in the Changjiang Delta

Wu, Xuefeng; He, Qing; Shen, Jian; Peng, Zhong; Guo, Leicheng; Xie, Weiming; Lin, Jianliang

doi:10.1016/j.jmarsys.2023.103961

Cited by 2 publications

(1 citation statement)

References 88 publications

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“…Despite the general dominance of winter storms over typhoons in annual or long-term longshore sediment transport from the Yangtze Delta, individual typhoons may lead to greater sediment redistribution than individual winter storm, because the maximum wind speeds of typhoons tend to be higher than the maximum wind speeds of winter storms (e.g., Figure 4A), and the increased wave height and sediment resuspension during individual typhoons are usually greater than those during individual winter storms (Yang et al, 2023;Wu et al, 2024). Larger increased waves during typhoon events also mean greater area of sediment resuspension, because larger waves can disturb deeper seabed (Yang et al, 2023).…”

Section: Discussionmentioning

confidence: 99%

Sediment resuspension and transport in the offshore subaqueous Yangtze Delta during winter storms

Tian,

Yang,

Zhang

et al. 2024

Front. Mar. Sci.

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Storm-induced episodic sediment redistribution in coastal systems can reshape geomorphic bodies, disrupt ecosystems, and cause economic damage. However, cold-wave-storm-induced hydrodynamic changes and residual sediment transport in large, exposed subaqueous deltas, such as the Yangtze Delta, are poorly understood because it is typically expensive and difficult to obtain systematic field data in open coast settings during storm events. We conducted a successful field survey of waves, currents, changes in water depth, and turbidity at a station (time-averaged water depth of 20 m) in the offshore subaqueous Yangtze Delta over 10 days during winter, covering two storms and two fair-weather periods. During the storm events, strong northerly winds drove southward longshore currents (~0.2 m/s) and resulted in increased wave height and sediment resuspension, thereby leading to massive southward sediment transport. In contrast, both southward and northward transports were limited during the fair-weather periods. A better understanding of the storm-induced sediment transport can be obtained by using an approximately half-day lag in sediment transport behind wind force, given the time needed to form waves and longshore drift, the inertia of water motion, and the slow settling velocity of fine-grained sediment. Our results directly support previous findings of southward sediment transport from the Yangtze Delta during winter, which is deposited in the Zhejiang–Fujian mud belt in the inner shelf of the East China Sea. In addition, the southward sediment transport from the Yangtze Delta occurs mainly during episodic storm events, rather than during the winter monsoon, and winter storms dominate over typhoons in driving southward sediment transport from the delta. This study highlights the importance of storms, especially during winter storms, in coastal sediment redistribution, which is of particular significance when considering the projected increase in storm intensity with global warming.

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Section: Discussionmentioning

confidence: 99%

Sediment resuspension and transport in the offshore subaqueous Yangtze Delta during winter storms

Tian,

Yang,

Zhang

et al. 2024

Front. Mar. Sci.

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Mechanism of rapid accretion-erosion transition in a complex hydrodynamic environment based on refined in-situ data

Jiang,

Xie,

Zhang

et al. 2024

Front. Mar. Sci.

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Morphological changes in estuaries are typically discussed on decadal time scales, with reported changes often exceed several decimeters. In our study, we utilized refined in-situ data to investigate bed-level changes and rapid accretion-erosion transitions during tidal cycles off the Changjiang Estuary. A field study employing a high-resolution bottom tripod system was conducted, measuring various parameters such as water level, waves, velocity profiles, near-bottom suspended sediment concentration (SSC), and bed level changes over ten tidal cycles. Our findings reveal significant and intense bed level changes occurring at the scale of tidal cycles. The data suggests that downward sediment transport plays a dominant role in the overall accretion tendency throughout the study period. Additionally, our research introduces a dynamic critical bed shear stress that increases during tidal cycles, deviating from fixed values. We also present a new quadrant analysis method to elucidate the primary processes controlling near-bed sediment transport. The results highlight the importance of horizontal advective sediment transport in frequent accretion-erosion transitions at tidal-cycle timescales. This implies a frequent exchange of sediment between adjacent shoals and channels in the seaward region of the North Channel in the Changjiang Estuary, which holds significance for future navigation and construction management.

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Different effects between cold front and tropical cyclone on short-term morphodynamics in the Changjiang Delta

Cited by 2 publications

References 88 publications

Sediment resuspension and transport in the offshore subaqueous Yangtze Delta during winter storms

Sediment resuspension and transport in the offshore subaqueous Yangtze Delta during winter storms

Mechanism of rapid accretion-erosion transition in a complex hydrodynamic environment based on refined in-situ data

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