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Flow Velocity Distributions in Ice-Covered Rivers

Author(s): S. Samuel Li

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Abstract: In northern countries, rivers are commonly covered with ice during the winter season. River ice often creates harsh conditions in terms of aquatic ecology, water resources development and operation, and flooding hazards. This paper focuses on velocity distributions at ice-covered river sections. The presence of an ice cover on the river surface causes changes to the distribution of flow velocities underneath from that under open-water conditions. Understanding the changes is critical to a wide range of applications. We present an analysis of velocity distributions on the basis of winter measurements of water velocity made from ice-covered rivers in Canada. The analysis produces results of the cross-sectionally averaged velocity, the maximum velocity and its location, and more importantly the non-uniformity of velocity. Temporal changes in velocity distributions are also discussed. We further determine the momentum and energy coefficients from empirical expressions in terms of the cross-sectionally averaged velocity and the maximum velocity. The values of the coefficients cannot be taken as unity because of the highly nonuniform velocity distributions. Discussions of turbulence shear stresses and length scale in the riverbed boundary layer are given.


Year: 2012

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