Abstract
Aggregates of cohesive suspended particles in estuarial waters are formed by Brownian motion, differential settling, and velocity gradients. Aggregates formed by Brownian motion and differential settling are weak and have low densities, compared to those formed in moderate velocity gradients. The densities and shear strengths of aggregates formed in a range of velocity gradients were measured using a capillary viscometer and a concentric cylinder viscometer. It was found that different aggregate structures could exist over short ranges of velocity gradients, and that the structures stable at lower ranges of velocity gradients had lower shear strengths and lower densities. The structures can be described as aggregates of aggregates, with successively higher orders at successively lower ranges of velocity gradients.
Sediment beds formed from such aggregates have a structure that is one order higher than that of the depositing aggregates. The rate of deposition of suspended aggregates under a given bed shear stress depends on the strength of the bond between the depositing aggregate and the bed. Further, as material accumulates on the bed, the mounting overburden crushes the lower aggregates, depending on their strength, causing increasing bed density and shear strength below its surface. The properties of the depositing aggregates determine the rate of sediment deposition and the rate of increase of resistance to erosion for a short distance below the bed surface.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
Similar content being viewed by others
References
Alishahi, M. R., and Krone, R. B., “Suspension of Cohesive Sediment by Wind-Generated Waves,” Hydr. Engr. Lab., U. of Calif., Berkeley, 1964, pp 24.
Bradley, R. A., and Krone, R. B., “Shearing Effects on the Settling of Activated Sludge,” J. Sanitary Engr. Div., ASCE, 1971, pp 59–79.
Edzwald, J. K., Upchurch, J. B., and O’Melia, C. R., “Coagulation in Estuaries,” Env. Sci. and Techn. 8 1974, pp 58–63.
Einstein, A., “A New Determination of Molecular Dimensions,” Annals of Physics 191911, pp 289-306, 34, 1911, pp 591-592.
Gust, G., “Observation of Turbulent Drag-Reduction in a Diluted Suspension of Clay in Sea Water,” J. Fluid Mech., 75, 1976, pp 29–47.
Hawley, N., “Settling Velocity Distribution of Natural Aggregates,” J. Geoph. Res. 87, No. C12, 1982, pp 9489–9498.
Hunt, J., “Self-Similar Particle Size Distributions during Coagulation: Theory and Experimental Verification,” J. Fluid Mech. 122, 1982, pp 169–185.
Kandiah, A., “Fundamental Aspects of Surface Erosion of Cohesive Soils,” Ph.D. Thesis, U. of California, Davis, 1974, pp 236.
Kirby, R., and Parker, W. R., “The Distribution and Behavior of Fine Sediment in the Severn Estuary and Inner Bristol Channel, U.K.,” Canadian J. Fish and Aquatic Sci., 40, Suppl. No. 1, 1983, pp 83–95.
Kranck, K., “Dynamics and Distribution of Suspended Particulate Matter in the St. Lawrence Estuary,” Naturaliste can 106, 1979, pp 163–173.
Krone, R. B., “Flume Studies of the Transport of Sediment in Estuarial Shoaling Processes,” Hydr. Engr. Lab. and Sanitary Engr. Lab., U. of Calif., Berkeley, 1962, pp 110.
Krone, R. B., “A Study of Rheologic Properties of Estuarial Sediments,” Hydr. Engr. Lab. and Sanitary Engr. Res. Lab., U. of Calif., Berkeley, 1963, pp 91.
Krone, R. B., “A Field Study of Flocculation as a Factor in Estuarial Shoaling Processes,” Tech. Bull 19, Committee on Tidal Hydraulics, Corps of Engineers, U. S. Army, 1972, pp 62 plus App.
Krone, R. B., “Aggregation of Suspended Particles in Estuaries,” Estuarine Transport Processes, The Belle Baruch Library in Marine Science No. 7, U. South Carolina Press, 1978, pp 177–190.
McCave, I. N., “Size Spectra and Aggregation of Suspended Particles in the Deep Ocean,” Deep Sea Res. 1984, pp 329–352.
Mehta, A. J., Parchure, T. M., Dixit, J. G., and Ariathurai, R., “Resuspension Potential of Deposited Cohesive Sediment Beds,” in Estuaring Comparisons, V. S. Kennedy, Ed., Academic Press, New York, NY, 1982, pp 591–609.
Owen, M. W., “The Effect of Turbulence on the Settling Velocity of Silt Floes,” Proceedings of the Fourteenth Congress of the Int. Ass, for Hydr. Res., Sept., 1971, D4-1 to D4-6.
Parchure, T. M., “Erosional Behavior of Deposited Cohesive Sediments,” Ph.D. Dissertation, Coastal and Oceanographic Engr. Dept., U. of Florida, 1984.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1986 Springer-Verlag New York, Inc.
About this paper
Cite this paper
Krone, R.B. (1986). The Significance of Aggregate Properties to Transport Processes. In: Mehta, A.J. (eds) Estuarine Cohesive Sediment Dynamics. Lecture Notes on Coastal and Estuarine Studies, vol 14. Springer, New York, NY. https://doi.org/10.1007/978-1-4612-4936-8_4
Download citation
DOI: https://doi.org/10.1007/978-1-4612-4936-8_4
Publisher Name: Springer, New York, NY
Print ISBN: 978-0-387-96296-2
Online ISBN: 978-1-4612-4936-8
eBook Packages: Springer Book Archive