RESUSPENSION OF SEDIMENTS ALONG THE BOTTOM BOUNDARY LAYER:A REVIEW

The bottom boundary layer (BBLs) is a complex interaction layer between seawater and bottom sediment, which affects the erosion, re-suspension and deposition of sediments. Some pollutants carried by sediment particles may be released into the water during the processes. Therefore, studying the BBLs has become increasingly important in both scientific significance and the practical application. The scope of the bottom boundary layers, in our concern, is far beyond the range of the boundary layer in traditional fluid mechanics, it is defined hereby as the part of seabed interface where the currents and seabed sediment interact. The sediment suffers from erosion and re-suspension under the action of the waves through the following three failure modes:seabed shear failure, seabed liquefaction and shock destruction. In addition, ocean currents, storm surge, human activities and the disturbance of sea creatures play certain roles which should not be ignored for sediment re-suspension. The in-situ observation of sediment re-suspension is one of the most basic and important methods for research of sediment re-suspension, which include water sampling, OBS, LISST-100, ADCP/ADV and the electrical measurement. The exchange between the suspended sediment and the bottom sediment directly affect the changes in suspended sediment concentration. Quantitative analysis of sediment re-suspension has become one of the main research topics of marine sedimentation. The paper systematically analyzed and summarized the achievements of previous researchers. On the basis of the comprehensive review focusing on the bottom boundary layer theory, the influence factors of seabed sediment re-suspension, the in-situ observation of sediment re-suspension and the quantitative analysis of seabed sediment re-suspension are also discussed. The work will provide references for further researches.