Author(s): Einar Tesaker

Linked Author(s): Einar Tesaker

Keywords: No Keywords

Abstract: The thermal expansion is of particular importance along certain lakes where the soil contains coarse enough rocks for protection of the shoreline against wave action. Under such conditions, waves may wash away the finer particles leaving the larger rocks free to be pushed onshore by the ice, finally forming a natural revetment. This feature may be observed along many lakes with rather constant winter surface levels. It is typical for lakes of moderate size where ice pile-up caused by wind is of minor importance. The lower ice surface has almost stable (0C) temperature, while temperatures within the ice vary with meteorological conditions. The variation is small in snow covered ice. Significant expansion may there­fore mainly occur for ice without snow cover under one of the following situations, both most likely to happen soon after the ice cover formation: i) Rising air temperature. ii) Snowfall during freezing temperatures. (The snow will insulate against heat loss, and the ice will approach water temperature). Cracks in the ice will usually reduce intermediate contraction to a fraction of the expansion. During few decades all available coarse material within the zone of ice covered level variations may in this manner be carried onshore. Juridical complications occur where a regulated lake never becomes ice covered before draw down. In this case the natural revetment will be formed below high water level, and the new shoreline will be left open to wave erosion. The paper refers examples from up to 50 year old cases of regulated lakes.

DOI:

Year: 1990