Anchor ice effects on river hydraulics

Pan, Jiajia; Shen, Hung Tao; Jasek, Martin

doi:10.1016/j.coldregions.2020.103062

Cited by 9 publications

(2 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Secondly, the estimates of the anchor ice to water heat flux could be used to improve the method used to compute it that uses the same equation used to predict the heat flux between the ice cover and the water. Finally, it is worth noting that recent progress improving and validating river ice process models by comparison to field data has been reported in the literature (Blackburn and She, 2019;Pan et al, 2020;Wazney et al, 2019). https://doi.org/10.5194/tc-2020-161 Preprint.…”

Section: Discussionmentioning

confidence: 99%

Continuous in situ measurements of anchor ice formation, growth and release

Ghobrial¹,

Loewen²

2020

Preprint

View full text Add to dashboard Cite

Abstract. In northern rivers, turbulent water becomes supercooled (i.e. cooled to slightly below 0 °C) when exposed to freezing air temperatures. In supercooled water, frazil (small ice disks) crystals are generated in the water column and anchor ice starts to form on the bed. Two anchor ice formation mechanisms have been reported in the literature: either by the accumulation of suspended frazil particles, which are adhesive (sticky) in nature, on the river bed; or by in situ growth of ice crystals on the bed material. Once anchor ice has formed on the bed, the accumulation typically continues to grow (either due to further frazil accumulation and/or crystal growth) until release occurs due to mechanical (shear force by the flow or buoyancy of the accumulation) or thermal (warming of the water column which weakens the ice-substrate bond) forcing or a combination of the two. Although detailed laboratory experiments have been reported to study anchor ice, but very few field measurements of anchor ice processes have been reported. These measurements have relied on either sampling anchor ice accumulations from the river bed, or qualitatively describing the observed formation and release. In this study, a custom-built imaging system (camera and lighting) was developed to capture high-resolution digital images of anchor ice formation and release on the river bed. A total of six anchor ice events were successfully captured in the time-lapse images and for the first time, the different initiation, growth and release mechanisms were measured in the field. Four stages of the anchor ice cycle were identified, namely: Stage 1: initiation by in situ crystal growth, Stage 2: transitional phase, Stage 3: linear growth, and Stage 4: release phase. Anchor ice initiation due to in situ growth was observed in three events and in the remainder the accumulation appeared to be initiated by frazil deposition. The Stage 1 growth rates ranged from 1.3 to 2.0 cm/hr and the Stage 2 and 3 growth rates varied from 0.3 to 0.9 cm/hr. Anchor ice was observed releasing from the bed in three modes referred to as lifting, shearing and rapid.

show abstract

Section: Discussionmentioning

confidence: 99%

Continuous in situ measurements of anchor ice formation, growth and release

Ghobrial¹,

Loewen²

2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Anchor ice release is thought to occur due to mechanical or thermal forcing or a combination of the two (e.g. Parkinson, 1984;Shen, 2005). The mechanical release of anchor ice occurs when the buoyancy and drag forces are greater than the ice-substrate bond or when these forces are greater than the submerged weight of the anchor ice and the attached bed materials (sands, gravel, or boulders).…”

Section: Introductionmentioning

confidence: 99%

Continuous in situ measurements of anchor ice formation, growth, and release

Ghobrial

Loewen

2021

The Cryosphere

View full text Add to dashboard Cite

Abstract. In northern rivers, turbulent water becomes supercooled (i.e. cooled to slightly below the freezing point) when exposed to freezing air temperatures. In supercooled turbulent water, frazil (small ice disks) crystals are generated in the water column, and anchor ice starts to form on the bed. Two anchor ice formation mechanisms have been reported in the literature: either by the accumulation of suspended frazil particles, which are adhesive (sticky) in nature, on the riverbed or by in situ growth of ice crystals on the bed material. Once anchor ice has formed on the bed, the accumulation typically continues to grow (due to either further frazil accumulation and/or crystal growth) until release occurs due to mechanical (shear force by the flow or buoyancy of the accumulation) or thermal (warming of the water column which weakens the ice-substrate bond) forcing or a combination of the two. There have been a number of detailed laboratory studies of anchor ice reported in the literature, but very few field measurements of anchor ice processes have been reported. These measurements have relied on either sampling anchor ice accumulations from the riverbed or qualitatively describing the observed formation and release. In this study, a custom-built imaging system (camera and lighting) was developed to capture high-resolution digital images of anchor ice formation and release on the riverbed. A total of six anchor ice events were successfully captured in the time-lapse images, and for the first time, the different initiation, growth, and release mechanisms were measured in the field. Four stages of the anchor ice cycle were identified: Stage 1: initiation by in situ crystal growth; Stage 2: transitional phase; Stage 3: linear growth; and Stage 4: release phase. Anchor ice initiation due to in situ growth was observed in three events, and in the remainder, the accumulation appeared to be initiated by frazil deposition. The Stage 1 growth rates ranged from 1.3 to 2.0 cm/h, and the Stage 2 and 3 growth rates varied from 0.3 to 0.9 cm/h. Anchor ice was observed releasing from the bed in three modes: lifting of the entire accumulation, shearing of layers of the accumulation, and rapid release of the entire accumulation.

show abstract

Understanding frazil ice: The contribution of laboratory studies

Barrette

2021

Cold Regions Science and Technology

View full text Add to dashboard Cite

Anchor ice effects on river hydraulics

Cited by 9 publications

References 13 publications

Continuous in situ measurements of anchor ice formation, growth and release

Continuous in situ measurements of anchor ice formation, growth and release

Continuous in situ measurements of anchor ice formation, growth, and release

Understanding frazil ice: The contribution of laboratory studies

Contact Info

Product

Resources

About