Comparison of field data with theories on ice cover progression in large rivers

Abstract

There are many theories pertaining to the progression of ice covers in rivers fed by frazil slush and floes but very few have been examined critically by comparing them with field data. In this paper the existing theories on dynamic ice cover progression are reviewed, an additional one is proposed, and they are classified according to the physical mechanisms that are involved. Finally, they are compared with some existing field data for large rivers. The data are extremely scarce and difficult to obtain because of the costs involved and the dangers in traveling over thin ice when the ice cover is being formed.It is usually easier to get only the critical values of parameters giving the limits of ice cover progression. In this paper, complete data were taken from the St. Lawrence River, the Beauharnois Canal, and the La Grande Rivière where the ice thicknesses along with the flow parameters have been measured.In these cases the existing data are adequate, so they could be grouped to explain the various mechanisms involved and to obtain numerical values for their quantitative determination. Key words: glaciology, river ice, ice dynamics, fluvial processes, ice hydraulics.