Hydraulic and Hydrological Regime of Ice-Affected Channels at Freezeup

Measuring the channel discharge of an ice-affected channel is imperative for socio-economic and ecological reasons. Under open water conditions, the channel discharge can be easily obtained using a rating curve. The production of ice and the development of ice features such as a floating ice cover and anchor ice accumulations significantly affect the stage-discharge relationship. In addition, they significantly impact the actual channel discharge. While in-situ discharge measurements cannot always be performed in mid-winter and even less so during freezeup, it is nonetheless possible to evaluate the channel discharge by understanding the watershed dynamics and ice processes that take place along the channel and its tributaries. This paper reports water stage and discharge trends of the freezeup period along channels of distinct sizes and morphologies. These trends are associated with characteristic ice processes at the local and watershed scales, and are related to other parameters such as the air temperatures and precipitation. Identifying typical ice processes signatures can help engineers and hydrologists to distinguish between ice-induced water stage variations and actual discharge variations. Despite the complexity of freezeup processes taking place along cold and temperate regions channels, evaluating the discharge of any channel can be facilitated by understanding the type and timing of ice processes and by monitoring some key parameters that could complement water stage records.