This exploratory project was supported by the National Research Council in 2025-2026. Flows and water levels respectively estimated and measured during the spring breakup period were analyzed from 2011 to 2025 for four very different rivers systems in Canada:
- Klondike River (Tr’ondëk in Hän) near Dawson, Yukon, Home of the Tr’ondëk Hwëtch’in First Nation
- The Hay River (Kátå’odehche in South Slavey) near Hay River, Northwest Territories, Traditional Territory of the Kátł’odeeche First Nation
- Mackenzie River (Dehcho in Slavey) at Fort Simpson, Northwest Territories, Home of the Dehcho Dene people of the Liidlii Kue First Nation
- Chaudière River (Kikonteku in Abénaqui) at Beauceville, Québec, Traditional Territory of the Abénaki people
The project’s objective was to investigate an important question in river ice science and engineering: For a specific river segment, is there a maximum discharge above which all ice jams are mobilized and carried downstream? If this Qmax ice exists, then can we link this parameter to obvious river channel characteristics?
The flow of a river during fast-changing ice conditions (i.e., during dynamic breakup events) is often highly unstable and therefore difficult to estimate at a sub-daily time step. Therefore, part of this project involved reassessing publicly available discharge time series using techniques developed in a former research project.
Then, 15 breakup events were analyzed for all four rivers. Results were generally inconclusive, in part because each selected river segment had been affected by a major/record ice jam flood in recent years. For each hydrometric station (or river segment), an important parameter controlling breakup severity could be identified, generally a downstream resistance to ice movement that varies from winter to winter, and this represents the most important scientific contribution of this project to date.
However, this research is far from over. Current results confirm that Qmax ice can be higher than the average annual maximum (or channel forming) flow (Q2) for some river segments whereas this is obviously not the case in all rivers and streams in Canada. This is an important outcome of this project, and it is not excluded that the discharge at which an ice cover or an ice jam is mobilized may be linked to different types of channel morphologies/gradients/geometries. A subsequent phase to this project will generate important outcomes for flood mapping and ice jam flood forecast projects.