Author(s): Thomas E. Osterkamp
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Keywords: No Keywords
Abstract: The ice in the Tanana River near Fairbanks, Alaska, has been observed each winter since 1971. When frazil ice was present in the river the water temperature was usually 1 m in thickness were observed. Snow slush balls were finer-grained and more strongly bonded than frazil ice pans. Anchor ice formations were common and floating anchor ice was observed to transport fine-grained sediments and gravel. The ice discharge of the tributaries was time-dependent with the Delta River being the major contributor. The maximum estimated ice discharge was 33 m3/sec (22% of the flow). There was general agreement between changes in the specific electrical conductance of the water and the ice discharge but the details of this relationship were not clear. Turbidity decreased by more than an order of magnitude during the freeze-up period and was inversely related to ice discharge. Frazil ice jams formed in narrow and/or curved parts of the river by consolidation of frazil ice pans and floes. These jams were the first ice cover to form on the river and were separated by open water areas which froze over by the process of border ice growth. The frazil ice jams produced during freeze-up may become strong points in the river ice cover during break-up and thus initiate ice jams at this time. Internal decay of the river ice results in liquid 3-grain boundaries at temperatures near the melting point of the ice. This liquid 3grain boundaries may provide channels for water flow and may be expected to modify the thermal, mechanical and electrical properties of river ice near its melting point.
Year: 1975