Tidal Characteristics of Suspended Sediment Concentrations
Publication: Journal of Hydraulic Engineering
Volume 123, Issue 4
Abstract
Analytical theory is used to describe the tidal constituents generated in suspended sediment concentrations of clay, silt, and sand eroded by M2 and S2 tidal currents. The associated model involves only the fall velocity Ws, the vertical dispersion coefficient E (assumed constant), and water depth D. For Ws> 10 E/D particles remain close to the bed, whereas for Ws< 0.1 E/D particles are well mixed vertically. For Ws>E/D, deposition occurs by advective settling at a rate approximating (1/2)WsCz=0 where Cz=0 is the concentration at the bed. Conversely for E>>DWs settlement is more dependent on the dispersion coefficient E. A deposition rate −α( depth-averaged concentration) is derived by assuming an exponential decay rate e−αt, with typical half-lives of 1 min to 2 h for sand and from 1 to 100 d for clay. In shelf seas, the suspended sediment concentration is likely to be determined by the silt-clay fraction with enhanced mean and MSf constituents compared to the associated diurnal and semidiurnal constituents. Opposition of the M4 and MS4 constituents at neap tide may significantly reduce the anticipated quarter-diurnal component of sediment concentrations.
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Information
Published In
Journal of Hydraulic Engineering
Volume 123 • Issue 4 • April 1997
Pages: 341 - 350
Copyright
Copyright © 1997 American Society of Civil Engineers.
History
Published online: Apr 1, 1997
Published in print: Apr 1997
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