Design for Hydraulic Geometry of Alluvial Channels

Abstract

A new solution to the stable-channel paradox has been derived based on the contribution of secondary flow to the redistribution of boundary shear stress. This new solution was then combined with the entropy-based bank profile equations, the flow-continuity condition, an appropriate frictional resistance relation, and a sediment transport relation to develop a new geometric model for straight stable alluvial channels. Furthermore, the effect of nonuniform boundary particle sizes was introduced to make the new geometric model applicable to a wide range of both laboratory experiments and natural alluvial rivers. A FORTRAN program was developed to compute the design procedure. The comparisons between the cross-sectional shapes, depths, and widths calculated by the new geometric model and field and laboratory data show that the proposed geometric model is in reasonable agreement with the data both for well-graded and for nonuniform bed materials.