Diffusion of Sediment in Long Channels

by Gunnar Aronsson, Dr. of Mathematics; Dept. of Mathematics, Univ. of Uppsala, Uppsala, Sweden,

Serial Information: Journal of the Hydraulics Division, 1978, Vol. 104, Issue 6, Pg. 821-837

Document Type: Journal Paper


A model is presented, treating the transport of suspended material in a broad channel under simplifying assumptions. The motion of sediment is treated as a diffusion process and a differential equation is derived. The form of an equilibrium distribution g(y) is derived, corresponding to the classical distribution of Prandtl and Rouse. Mathematically the following two results are proven: (1)If a stationary (time-dependent) state prevails downstream a certain point P, then the distribution downstream P, tends (with increasing distance to P) exponentially to the equilibrium distribution; and (2) if the sediment distribution in the incoming water at a point P is stationary from a certain moment, then the distribution downstream P will tend to the stationary solution exponentially with time. Although these results seem to be physically evident, they have apparently not been proven before.

Subject Headings: Sediment | Diffusion | Moment distribution | Sediment transport | Rivers and streams | Equilibrium | Equations of motion | Mathematical models | Hydraulic models

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