Freeze-Up

We will begin with freeze-up processes, to follow the sequence of the winter cycle, which starts with freeze-up, followed by midwinter ice-cover progression and lastly enters the breakup period. In an ice-jam flood forecasting context, it is important to understand the processes of ice-cover formation and the types of ice that form during freeze-up, since different kinds of ice have different characteristics, particularly their strength properties, which can influence the progression of ice jamming during the following spring ice-cover breakup period. In addition, ice jamming and ice-jam flooding can also occur during freeze-up, depending on the hydraulic and meteorological conditions that prevail during freezing. Freeze-up processes are affected by weather conditions, river flow, and channel characteristics such as cross-sectional geometry and slope. Types of ice during freeze-up include skim ice, border ice, frazil, pancake ice, consolidated ice floes and sheet ice.