Numerical modelling of dissolved-oxygen in a cold- region river

Dissolved oxygen (DO) content is a critical measure of the ability of water bodies to support healthy aquatic ecosystems. To better understand DO behaviour in large cold-region rivers, a onedimensional water quality model is setup for a ~200 km reach of the lower Athabasca River below Fort McMurray, Alberta using the Mike-11 modelling system. A river-ice model is applied to reproduce ice conditions during the cold season so that the effects of ice-cover on the physical/chemical processes in the river system are taken into account. The combined model is used to simulate the transport and transformation of dissolved oxygen (DO) in the river. Modelling results are validated and evaluated using available field measurements. The results of this study gives an insight into the spatial and temporal variation of DO in the lower Athabasca River and provides a better understanding of the important effect of ice cover in the evolution of DO concentration. It can also provide the fundamentals for modelling of different water quality constituent in lower Athabasca River.