Bed shear stress over subaqueous dunes, and the transition to upper-stage plane beds



Plane beds that replace small bedforms (e.g. ripples) on the backs of subaqueous dunes are dynamically similar to upper-stage plane beds. Local bed shear stresses at the position on dunes where plane beds develop may be two to three times larger than on a completely plane bed under the same general hydraulic conditions. These observations help explain the transition from dunes to a wholly upper-stage plane bed.