Hydrodynamics of Knik Arm: Modeling Study
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 139, Issue 3
Abstract
An adaptive hydraulics (AdH) model was applied to lower Knik Arm near the Port of Anchorage, Alaska, to assess its ability to model a macrotidal system with complex hydrodynamics, including the formation and evolution of numerous gyres that are prominent at this site. Lower Knik Arm is an ideal system for this model evaluation because of the large tide range (approximately 10 m at Anchorage) and complex geometry of the system, which results in high velocities and the formation of numerous eddies throughout the study area. One eddy of primary importance is the one generated by Cairn Point, which occurs near the Port of Anchorage. Limitations of previous modeling studies and the availability of recent field data enabled this evaluation. The AdH results were compared with field data (water surface elevations, fluxes, and velocities) collected in August of 2002 and 2006, and favorable comparisons obtained for tidal amplification and eddy generation indicate that AdH reasonably reproduces the complex hydrodynamic conditions in lower Knik Arm. Simulations were also performed to investigate the importance of eddy viscosity specification, frictional specification, and bathymetry on the generation/evolution of eddies present in the system. Upon completion of the model validation, simulations were performed with modified Cairn Point configurations to investigate the impact to the eddy generated at the port. These results illustrate the variation in eddy generation through lengthening, lowering/reducing, or raising Cairn Point.
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Acknowledgments
The work described and results presented in this paper were obtained through research sponsored by the U.S. Army Corp of Engineers Alaska District and the U.S. Army Corp of Engineers System Wide Water Resources Program (SWWRP). Permission to publish this paper was granted by the Chief of Engineers, U.S. Army Corp of Engineers.
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Information
Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 139 • Issue 3 • May 2013
Pages: 232 - 246
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Aug 12, 2011
Accepted: May 30, 2012
Published online: Jul 28, 2012
Published in print: May 1, 2013
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