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Characterization of Suspended Frazil and Surface Ice in Rivers Using Sonars Open Access


Other title
frazil ice
surface river ice
underwater sonars
Type of item
Degree grantor
University of Alberta
Author or creator
Ghobrial, Tadros I.R.
Supervisor and department
Hicks, Faye (Civil and Environmental Engineering)
Loewen, Mark (Civil and Environmental Engineering)
Examining committee member and department
Loewen, Mark (Civil and Environmental Engineering)
Sigurdson, Lorenz (Mechanical Engineering)
Hicks, Faye (Civil and Environmental Engineering)
Liu, Yang (Civil and Environmental Engineering)
Daly, Steven (US Army Cold Regions Research and Engineering Laboratory)
Steffler, Peter (Civil and Environmental Engineering)
Department of Civil and Environmental Engineering
Water Resources Engineering
Date accepted
Graduation date
Doctor of Philosophy
Degree level
This research describes laboratory and field experiments aiming at developing techniques for obtaining quantitative measurements of suspended frazil ice and surface ice characteristics in rivers using sonars. A series of laboratory experiments were conducted to correlate the sonar backscatter signal from a high (546 kHz) and low (235 kHz) frequency units with direct measurements of frazil concentration. The sonar measurements showed that the high frequency unit is more sensitive to the presence of suspended frazil particles than the low frequency unit, especially at lower concentrations. A strong correlation was found between the acoustic relative backscatter from both sonar units and the measured concentrations. This calibration was conducted over a range of frazil mass concentrations between 0.012 and 0.135 % and the majority of observed frazil particles were disk shaped, varying in diameter from 0.25 to 4.25 mm. An algorithm has been developed to measure surface ice characteristics using field data from the high and low frequency sonars, a 2 MHz current profiler, and a monitoring station, deployed on the North Saskatchewan River in the north east of Edmonton, AB, Canada, during the 2009/2010 freeze-up season. The validity and the accuracy of these measurements were tested and results are presented. Over the entire season, pans/rafts drafts ranging from 0.1 to 1.0 m and pan/raft lengths ranging from 0.6 to 8.0 m were measured. The sonar proved to be very accurate in detecting the exact surface ice conditions locally above the sonar beam. Acoustic field data gathered during suspended frazil events have been processed and analyzed to provide estimates of frazil concentration and particle sizes using laboratory regression equations and fluid disk scattering model. In total, eight frazil events were detected with the sonars during the field deployment. Preliminary linkages between the meteorological (air and water temperatures) and surface ice conditions measured at the site, and the duration and magnitude of the detected frazil events are presented. Concentrations ranging between 0.01 and 0.05% and disk radii between 0.13 and 0.21 mm have been estimated from the field data.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Ghobrial, T.R., Loewen, M.R., Hicks, F., 2009. Frazil Ice Measurements Using the Shallow Water Ice Profiling Sonar. Proceedings of 15th Workshop on River Ice, St. John’s, Newfoundland and Labrador, June 15 - 17, 2009, pp. 14-26.Ghobrial, T.R., Loewen, M.R., Hicks, F.E., and Maxwell, J., 2010. Monitoring Frazil Ice Evolution during Freeze-up using the Shallow Water Ice Profiling Sonar. Proceedings of the 20th IAHR International Symposium on Ice, Lahti, Finland, June 14 to 18. 12p.Ghobrial, T.R., Loewen, M.R., and Hicks, F.E., 2012. Laboratory calibration of upward looking sonars for measuring suspended frazil ice concentration. Cold Reg. Sci. Technol. (70): 19-31.

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