The frictional force of a river bed (also called channel roughness). A rough bed of boulders, pebbles, and potholes exerts more friction than a smooth, silky channel. Lamarre and Roy (2005) Geomorph. 68, 1–2 examine the effects of roughness on mean flow velocity. See manning's roughness coefficient. The term is also applied to a glacier bed; see Rippin et al. (2004) Ann. Glaciol. 39.
Subjects: Earth Sciences and Geography — Ecology and Conservation.