Initiation of river ice breakup

Abstract

The time and severity of ice breakup in northern rivers are two major concerns in forecasting spring flooding potential. Breakup initiation is studied herein using historical data obtained from hydrometric gauge records. The water stage at the time of breakup initiation is adopted as a pertinent index, in accordance with earlier work by others which suggests that this stage is related to a characteristic stage during freeze up; thickness and competence of the ice cover; and channel characteristics. A conceptual model of the breakup process is developed and shown to explain the relevance of some of these factors. Implications of the model regarding the severity of breakup are outlined. Weaknesses of the model are identified and possible means of improvement are discussed.