Vertical sediment distribution mechanism in tidal flats -A case study in Zhoushan Archipelago
Vertical sediment distribution mechanism in tidal flats -A case study in Zhoushan Archipelago
复制标题
DOI：
10.1016/j.ecss.2023.108503
复制
发表时间：
2023-10
期刊：
影响因子：
--
通讯作者：
Fangzhou Shen;Yihan Ren;Li Li-Li;Zhiguo He
中科院分区：
文献类型：
--
作者：
Fangzhou Shen;Yihan Ren;Li Li-Li;Zhiguo He
潮滩是连接陆地和海洋环境的纽带，在海岸带生态系统和地貌演化中起着重要作用。以寨罗山岛潮滩为例，研究了潮滩悬浮泥沙浓度、泥沙再悬浮和输移的动力学特征。本文对南岛东部潮滩的波浪、海流和泥沙进行了野外观测。结果表明，流致床面切应力占主导地位。在波浪、潮汐和海流的共同作用下，SSC有两个主周期（12.2 h，6.2 h，60−80%）和三个次周期（23.5 h，8.2 h和5.1 h，20−40%）。平流输运占主导地位，约为沉积物再悬浮的2-3倍，净沉积物通量在岸上。湍流间歇事件在泥沙再悬浮过程中起着重要作用，其发生概率受流速的影响。泥沙的垂向瞬时输移取决于波高。悬浮泥沙垂向剖面表明，在高流速下，考虑絮凝作用的沉降公式更好地拟合了悬浮泥沙的垂向剖面。单颗粒沉降速度在低流速下拟合较好，表明泥沙絮凝作用在低流速下较弱。该研究加深了对淤泥质海岸潮滩近底沉积特征及其控制机制的认识。
Tidal flats connect terrestrial and oceanic environments, and play an important role in the evolution of coastal ecosystems and geomorphology. Taking tidal flat on Zhairuoshan Island (ZRS) as an example, we studied the dynamic characteristics of suspended sediment concentration (SSC), sediment resuspension, and transportation in tidal flats. The field data of the waves, currents, and sediments were obtained from the tidal flat on the east of ZRS Island. The results show that current-induced bed shear stress is dominant. Under the combined action of waves, tides, and currents, SSC has two main periods (12.2 h, 6.2 h, 60−80%) and three minor periods (23.5 h, 8.2 h, and 5.1 h, 20−40%). Advection transport is dominant, at approximately 2–3 times the sediment resuspension, and the net sediment flux is onshore. Turbulent intermittent events play an important role in sediment resuspension, and their probability is affected by velocity. The vertical instantaneous transport of sediment depends on wave height. The vertical profile of SSC shows that, at high current velocity, the sedimentation formula that considers flocculation better fits the vertical profile of suspended sediment using the Rouse formula. The settling velocity of a single particle fits better at low current velocities, indicating that the flocculation of sediment is weak at low velocities. This study improves our understanding on near-bottom sediment characteristics and controlling mechanism in tidal flat in muddy coasts.