Variations in channel morphology reflect the dominant processes acting to incise the channel bed. The most significant incision processes in bedrock rivers are abrasion by bedload impacts and plucking of bedrock fragments. Qualitatively, ripples, flutes, and potholes characterize abrasion-dominated channels in settings that typically have massive rocks with coarse joint spacing. Conversely, channels set into well-jointed rocks are incised by plucking, and are characterized by knickpoints and angular steps. Stream power models fail to capture these variations in erosive process and their associated channel morphology. Interpretations of channel morphology on Earth and other planets are only as good as the understanding of the underlying erosional physics. Hence, the lack of a mechanistic understanding of the interplay of these two dominant processes, and their resultant channel forms, represents an important knowledge gap in the field. I've implemented a model to explore the relative efficacy of abrasion and plucking to variations in flow strength, channel slope, bedload grain size, pluckable block size, and sediment supply.  Results from this model identify quantitatively the transition between abrasion- and plucking-dominated erosion in bedrock channels, providing insight into the most important factors for prediction bedrock erosion rates and associated channel form. The transition in dominant erosive process appears to be most sensitive to changes in slope, and relatively insensitive to variations in grain size.

​

​

​

tl;dr  The transition from abrasion-dominated erosion to plucking-dominated bedrock erosion is highly sensitive to changes in slope, and relatively insensitive to bedload grain size.

​

​

​

Work detailed here is ongoing - email me for more info!

 

​