Settling Properties of Cohesive Sediments in Lakes and Reservoirs
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 137, Issue 4
Abstract
The fall velocity of fine particles was measured in a column of height 2.50 m and diameter of 0.30 m to model the settling properties of cohesive sediments in lakes and large reservoirs. In contrast to the traditional particle-size-based methods, an approach relying on time and depth variation of sediment concentration was employed to estimate the mean value of fall velocity at any depth and time. Particles at greater depths, particularly for the samples with a higher rate of sediment concentration, accelerated faster and remained at higher velocities for a longer duration owing to a higher rate of flocculation. As a particular property of cohesive sediments, particles for all concentrated samples and in all depths reached their maximum fall velocity at around the same time—15 min after the start of the tests. The low concentration samples reached higher maximum velocities because of the lower rates of hindering, but for a much lower duration in comparison to the higher concentrated samples. An empirical equation is developed to estimate the maximum fall velocity of particles for cohesive sediments where the ratio of flocculation to hindering is highest.
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Acknowledgments
The authors would like to acknowledge Dr. B. Krishnappan at the Canada Centre for Inland Water, Burlington, Canada for his invaluable comments on this research. Acknowledgement is also extended to the Chamran University of Ahwaz, the Centre of Excellence on Operation Management of Irrigation and Drainage Networks, and Khuzistan Water and Power Authority (KWPA) for financial support and facilitation of the experiments.
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© 2011 American Society of Civil Engineers.
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Received: Jan 14, 2010
Accepted: Oct 26, 2010
Published online: Oct 28, 2010
Published in print: Jul 1, 2011
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