Author(s): Haitham Ghamry, Shazy Shabayek, Christos Katopodis

Linked Author(s): Haitham Ghamry, Christos Katopodis

Keywords: Ice hydrodynamics; Habitat; Finite element; Numerical modeling;

Abstract:

Flow management in the Athabasca River in northern Alberta, Canada, particularly in winter, is a key issue for oilsands developments and ecosystem integrity. The River2D model was used to examine the effect of ice cover on the physical habitat conditions for two reaches of the Athabasca River. Comparisons for ice-free and ice-covered conditions were made using bed elevations, water depths, velocities, and Froude numbers. Grain roughness size and distribution for the channel bed was assumed the same for both conditions. These comparisons indicate significant bed changes and larger water depths in winter compared to summer, probably during ice-formation and from ice cover roughness. Bed Changes were more pronounced along the river banks than the thalweg. Ice-covered conditions produced lower water surface elevations, counteracting increased water depths and increased roughness from the ice-cover. Ice-covered conditions produced lower velocities and lower Froude numbers over most of each of the three reach areas. The presence of the ice cover increases the flow resistance which in turn reduces the average flow velocity. To accommodate the discharge, the flow area increases, resulting in larger flow depths. The trends for velocities and Froude numbers for ice-covered and ice-free conditions were comparable. An examination of simulated velocities showed that matching measured water velocities was less accurate for parts of some cross-sections than others. Although the level of accuracy may be adequate for several purposes, further work on velocity simulation is warranted as velocities are a key component in estimating ecological utility and fish habitat use as a function of river discharge.

DOI: https://doi.org/10.3850/38WC092019-1171X

Year: 2019