Abstract
In bedrock channels, the areal fraction of alluvial cover is generally modeled as a simple function of sediment supply relative to the transport capacity. Other factors are likely to be important, especially the roughness of the underlying bedrock surface. In this study, we report the results of experiments on the interaction between bed roughness and alluvial cover fraction.
Our results show that: 1) the areal fraction of alluvial cover is larger when the surface roughness is larger; 2) when bedrock roughness is rough, the cover fraction gradually increases with sediment supply; 3) low-roughness bedrock requires a relatively large sediment supply before any alluvial patch is formed, and as supply increases, rapidly transitions to a fully alluvial channel.
