EP 1110-2-11
30 Nov 94
Appendix B
Glossary
[Extracted from the U.S. Army Corps of Engineers (1990) and International Association for Hydraulic Research (1986).]
Anchor ice. Frazil ice attached or anchored to the river bottom, irrespective of the nature of its formation.
Beginning of breakup. Date of definite breaking, movement, or melting of ice cover or significant rise of water level.
Beginning of freezeup. Date on which ice forming a stable winter ice cover is first observed on the water surface.
Border ice. An ice sheet in the form of a long border attached to the bank or shore; shore ice.
Breakup date. Date on which a body of water is first observed to be entirely clear of ice and remains clear thereafter.
Breakup jam. Ice jam that occurs as a result of the accumulation of broken ice pieces.
cfs. Cubic feet per second, a measure of flow.
Channelization. Modification of a natural river channel; may include deepening, widening, or straightening.
Conveyance. A measure of the carrying capacity of the river channel.
Floc. A cluster of frazil particles.
Floe. An accumulation of frazil flocs (also known as a "pan") or a single piece of broken ice.
Floodplain. Land area adjoining a water body that is not normally submerged but may be submerged during flood
conditions.
Frazil. Fine spicules, plates, or discoids of ice suspended in water. In rivers and lakes, frazil is formed in supercooled,
turbulent water.
Frazil slush. An agglomerate of loosely packed frazil that floats or accumulates under an ice cover.
Freezeup date. Date on which the water body was first observed to be completely frozen over.
Freezeup jam. Ice jam formed as frazil ice accumulates and thickens.
Gorge. In the past, ice jams were sometimes referred to as "ice gorges."
Grounded ice. Ice that has run aground or is in contact with ground underneath it.
Hanging (ice) dam. A mass of ice composed mainly of frazil or broken ice deposited underneath an ice cover in a region
of low flow velocity.
Hummock. A hillock of broken ice that has been forced up by pressure.
B-1
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