Alluvial Channel Resistance Related to Bed Form

Existing data from flume tests over ripple or dune beds are used to investigate the variation of resistance to flow with shear velocity. Lines plotted to represent points at constant depth suggest that there are certain conditions of flow at which ripples reach a maximum stage of development, offering maximum resistance to flow. A similar conclusion is made for the dune bed form. Comparing flows over the same bed material, it is suggested that the maximum stage of ripple development occurs at the same value of v_*, irrespective of depth; and the maximum stage of dune development occurs at the same value of V/v_*, irrespective of depth to a close approximation. Canal data show similar characteristics to flume data, only over a limited range.