Bedrock channel morphology

Abstract

Analyses of 41 bedrock channel reaches indicate quantifiable relationships between bedrock channel morphology and reach- scale hydraulic and substrate variables. Discriminant analysis was used to develop a discriminant criterion based on reach-averaged channel gradient, substrate heterogeneity, and Selby rock-mass strength. This criterion correctly classified 70% of the observations into one of five channel morphologic types. Channels formed at higher gradients have a morphology that effectively maximizes the erosional force, whereas a morphology that evenly distributes flow energy or dissipates flow energy internally is associated with lower gradients. These results suggest that bedrock channel morphology, like alluvial channel morphology, reflects a quantifiable balance between hydraulic driving and substrate resisting forces.