Laboratory measurements of the fall velocity of fine sediment in an estuarine environment |
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| Authors: | Jiaqi Yang Limo Tang Yuntong She Jiao Sun |
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| Affiliation: | 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China;2. College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China;3. Department of Civil and Environmental Engineering, University of Alberta, 9211 116 St NW, Edmonton, Alberta T6G 1H9, Canada;4. Zhejiang Qianjiang Science and Technology Development Company, Hangzhou 310000, Zhejiang, China;1. Department of Water Engineering, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran;2. Agricultural Engineering Research Institute (AERI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran;3. Department of Water Engineering, College of Agriculture, Isfahan University of Technology, Isfahan, Iran;1. School of Engineering, University of Guelph, Guelph, ON N1G 2W1, Canada;2. School of the Built Environment, Heriot-Watt University, Edinburgh, UK;3. Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, Liverpool, UK;4. Department of Geography, University of Lincoln, Lincoln, UK;1. Department of Civil & Structural Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bandar Baru Bangi, 43600, Malaysia;2. School of Civil and Environmental Engineering, College of Engineering, Nanyang Technical University, 50 Nanyang Avenue, 639798, Singapore;1. Department of Water Resource Engineering, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran;2. Center of Excellence in Hydroinformatics, University of Tabriz, Tabriz, Iran;1. Department of River Engineering and Disaster Management, Faculty of Hydrology and Water Resources, Thuyloi University, 175 Tay Son, Dong Da, Hanoi, Viet Nam;2. Unité de Modélisation Mathématiques et Informatique des Systèmes Complexes (UMMISCO), JEAI WARM, IRD, Sorbonne Université, F-93143 Bondy, France;3. Department of Civil and Environmental Engineering, Faculty of Engineering, National University of Singapore, Singapore |
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| Abstract: | The study of the fall velocity variation of fine sediment in estuarine areas plays an important role in determining how various factors affect the flocculation process. Previous experimental studies have focused solely on the relation between the median fall velocity and influencing factors, while in the current study, the variation of the fall velocity in quiescent water also was examined. The experimental results showed that the vertical distribution of sediment concentration was more uneven, and larger variations occurred earlier during the settling process under higher salinity and/or sediment concentration conditions. The fall velocity initially increased then decreased over time, peaking at ∼20 min after settling began, and stabilizing at a value similar to that in freshwater, regardless of the initial sediment concentration and salinity combinations. Along the water depth, the fall velocity increased monotonically with a gradually decreasing gradient. The median fall velocity increased then decreased with increased salinity. The salinity at which the peak fall velocity occurred depended on the initial sediment concentration. The relation between the median fall velocity and initial sediment concentration displayed an obvious two-stage pattern (i.e., accelerated flocculation and decelerated, hindered settling) at higher salinities; whereas the maximum median fall velocity was observed at two consecutive sediment concentration values under lower salinity conditions. Finally, an empirical equation estimating the median fall velocity of cohesive fine sediment was formulated, incorporating the effects of both salinity and sediment concentration. |
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| Keywords: | Laboratory experiments Fine sediment Estuarine environment Fall velocity Salinity Sediment concentration |
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