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Examines in Marine Biology & Oceanography

Experimental Study on the Settling Velocity of Coastal Mud in Quiescent Water: The Case of Huangmaohai Estuary, South China Sea

Submission: November 14, 2017; Published: February 21, 2018

DOI: 10.31031/EIMBO.2018.01.000511

ISSN: 2578-031X
Volume1 Issue3


A series of laboratory experiments were carried out to investigate the settling behavior of cohesive sediment/mud from Huangmaohai Estuary of the South China Sea. Based on the experimental observations and measurements, the influence of the flocculation phenomenon, tube geometries, initial mud concentration and salinities on the sediment settling velocities were investigated systematically. Experiments showed complex time-varying settling processes of the cohesive sediment in quiescent water, which were divided into two successive stages:

i) The stage of the flocculated sediment settling.

ii) The stage of sediment packing and consolidation.

During the transition between these two stages, there was an abrupt change of the settling velocity. Time-dependent settling velocity was then described with functions obtained from regression analysis, which showed a linearly decreasing settling velocity during the first stage and an exponential decreasing trend during the second stage. The influence of tube diameter variation was negligible on the mud settling process, while the tube length had significant influence on the transition pattern between two stages. Mud concentration played an important role in the flocculation formulation, and finally dominated the settling velocity of the cohesive sediment. It led to a distinguished peak value of the settling velocity corresponding to an initial sediment concentration of 20kg/m3. Salinity also exhibited obvious impact at the beginning stage of the settling, which presented a lowest settling velocity corresponding to a salinity of 15% for 50kg/m3 mud samples.

Keywords: Coastal mud; Settling velocity; Flocculation

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