Dispersion in Rough Rectangular Channels

by Eric M. Valentine, Engr.; Ministry of Works and Development, Wellington, New Zealand,
Ian R. Wood, (M.ASCE), Prof. of Civ. Engrg.; Univ. of Canterbury, Christchurch, New Zealand,

Serial Information: Journal of the Hydraulics Division, 1979, Vol. 105, Issue 12, Pg. 1537-1553

Document Type: Journal Paper


A three-dimensional numerical model is developed from a two-dimensional solution reported previously by the writers. A rectangular smooth laboratory flume is used to verify the model without dead zones; two series of field experiments carried out in a water race are then used to test the model for two different roughness conditions. Despite the simplifications involved in the numerical model, it provides a reasonable description of the process in the channel examined. Principally, there is a delay before the Fickian-type dispersion and the dispersion coefficients are comparable with those found in the field. Although the theory has not reached a stage where it can be applied to most rivers, it does lend itself to the possibility of a classification system for dead zones in river channels and it demonstrates the importance of the trapping mechanism to the dispersion process in river channels.

Subject Headings: Numerical models | Three-dimensional models | Two-dimensional models | Hydrologic models | Hydraulic models | Laboratory tests | Flumes | Verification

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