Ice processes in a steep river basin

This paper describes ice processes that take place in steep (1% and 7%) streams of the cool temperate humid continental climate. The formation, thickening, sculpting, and melting of a suspended ice cover over step-pool sequences and plane-bed channels is presented and explained. The initial formation of anchor ice accumulations, their distribution in the channel, and the chronology of environmental conditions driving the ice dynamics are described. These ice processes can generate significant variations in discharge under cold conditions and create transient morphological patterns. The suspended ice cover dynamics is driven by the development and thickening of anchor ice weirs and dams. The reported ice processes are significantly different from those associated with a floating ice cover in low-gradient stream channels. Heat balance considerations suggest that a complete suspended ice cover cannot be sustained throughout winter in all but the coldest climates.

Research Highlights
► Ice processes in steep channels are driven by anchor ice production and melting.
► Icing contributes to anchor ice accumulations and surface ice thickening.
► The freezeup period often leads to the formation of a partial, suspended ice cover.
► Heat transfer considerations suggest that a suspended ice cover is rarely complete.
► Spray ice plays a dominant role in the development of ice over fast flowing water.