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ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Coastal Ocean Processes
Volume 11 - 2024 | doi: 10.3389/fmars.2024.1459899
This article is part of the Research Topic Climate Change and Human Impact: Assessing Vulnerability and Intensification of Hazards in Estuarine and Coastal Zones View all articles

In-Situ Observations of Wave-and Current-Supported Fluid Mud Dynamics on a Hyperturbid Macrotidal Mudflat

Provisionally accepted
Mingliang Li Mingliang Li 1Dezhi Chen Dezhi Chen 2Hao Wu Hao Wu 1Jieping Tang Jieping Tang 3Yiyi Zhang Yiyi Zhang 4Feng Luo Feng Luo 5Fugang Gou Fugang Gou 6Xulong Gong Xulong Gong 6Ya Ping WANG Ya Ping WANG 1*
  • 1 Nanjing University, Nanjing, Jiangsu Province, China
  • 2 Key Laboratory of Tropical Marine Ecosystem and Bioresource, Fourth Institute of Oceanography, Ministry of Natural Resources, Baihai, China
  • 3 School of Electronic and Information Engineering, Guangdong Ocean University, Zhanjiang, Guangdong Province, China
  • 4 Tidal Flat Research Center of SOA, Nanjing, Liaoning Province, China
  • 5 School of Port, Coastal and Offshore Engineering, Hohai University, Nanjing, Liaoning Province, China
  • 6 Geological Survey of Jiangsu Province, Nanjing, Liaoning Province, China

The final, formatted version of the article will be published soon.

    Wave-and current-supported fluid mud on gently sloped continental shelves represents a type of sediment gravity flow capable of rapidly transporting substantial sediment over short periods, significantly contributing to coastal geomorphic evolution. To investigate the dynamics of intertidal fluid mud events, in-situ observations were conducted from May 9 to May 18, 2017, using a seabed tripod system at the lower intertidal flat of the central Jiangsu coast, China. Fluid mud was observed following a medium wind-wave event, with a maximum significant wave height of 0.42 m. The liquefied seabed, loosened by liquefaction, facilitated bed erosion and sediment resuspension. Fluid mud layers, with mean suspended sediment concentrations (SSCs) exceeding 10 g/L, periodically formed during high slack tide, early flood, and late ebb phases. These layers varied in thickness from 4 cm to 20 cm and exhibited strong stratification caused by suspended sediment. Fluid mud disappeared when the bottom turbulence kinetic energy exceeded a threshold of 0.00045 m²/s² due to an increase in current velocity. The downslope movement of intertidal fluid mud was estimated using a theoretical buoyancy-friction model and validated by observed offshore-directed velocity jets at 0.1 m above the seabed during high slack tide phases. Additionally, onshore winds favored fluid mud formation during early flood phases, while offshore winds favored it during late ebb phases. These observations suggest that fluid mud can form on intertidal flats under conditions where tidal flows and winds align, contributing to a deeper understanding of the formation mechanisms of shallow gravity currents and the improvement of sediment transport models.

    Keywords: Fluid mud, Liquefaction, buoyancy-friction model, Intertidal flat, Jiangsu coast, gravity flows

    Received: 05 Jul 2024; Accepted: 29 Jul 2024.

    Copyright: © 2024 Li, Chen, Wu, Tang, Zhang, Luo, Gou, Gong and WANG. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Ya Ping WANG, Nanjing University, Nanjing, 210093, Jiangsu Province, China

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