Efficiency of Hanging Silt Curtains in Crossflow
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 142, Issue 1
Abstract
When dredging in sensitive environments, efforts have to be made to limit the free dispersal of suspended fine sediment from the dredging spill. The use of hanging silt curtains as an environmental mitigation measure is especially widespread. Despite frequent application, their ability to reduce turbidity levels through vertical diversion of sediment-laden currents remains the subject of debate. This paper addresses a series of laboratory measurements and numerical model simulations to determine the efficiency of hanging silt curtains, defining a new efficiency parameter. The model was validated against the laboratory experiments. Model simulations focusing on vertical diversion of the sediment-laden current suggest that hanging silt curtains do not have a favorable influence on the settling of suspended sediment when applied in crossflow. The diversion of currents underneath the curtain causes flow separation and intense turbulent mixing, which counteracts settling of suspended sediment particles. The results imply that the widespread application of hanging silt curtains should be reconsidered from a physical point of view.
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Acknowledgments
This research was initiated and partly facilitated by dredging company Boskalis, in particular by Fokko van der Goot, Stefan Aarninkhof, Gerard Hoogewerff, and Karoune Nipius. They are greatly acknowledged for backing up the simulation results with field experience and knowledge on marine ecology. Svasek Hydraulics is acknowledged for its share in the numerical model simulations. Finally, the laboratory staff of the TU Delft Laboratory for Fluid Mechanics is thanked for facilitating the physical model study.
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Information & Authors
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Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 142 • Issue 1 • January 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Sep 22, 2014
Accepted: Apr 13, 2015
Published online: Jun 20, 2015
Discussion open until: Nov 20, 2015
Published in print: Jan 1, 2016
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