Numerical Study of the Interaction Between Wet‐Dry Weathering and Bedload Induced Abrasion

Erosion and weathering have always been considered as key factors regulating landscape morphodynamics. In this study, we implemented a numerical model that incorporates the effect of abrasion by saltation as well as the effect of slaking by wet‐dry weathering. Our numerical results indicate abrasion and weathering acting together on bedrock beds, that is, abrasion leads to a deep inner channel, and weathering leads to flat benches on the channel margins. We also inquired how changes in the water discharge, alluvial cover, bedrock strength and weathering depth define the abrasion and weathering rates. We found that changes in water discharge can control the weathering rate and depth and thereby the channel shape. Alluvial cover acts as tools or cover to determine the abrasion rates. Our results show that bedrock strength minimally changes the channel cross‐section while weathering depth controls the valley depth. Since weathering and abrasion occur at different heights in the channel cross‐section, there is little opportunity for weathered bedrock to be abraded. However, weathering and abrasion interact indirectly through changes in channel morphology. The internal channel incision lowers the elevation of wet‐dry weathering zone, and the formation of the bedrock bench reduces the bedload transport rate, which drives saltation‐abrasion. Key Points New model for the morphodynamics of a bedrock channel due to saltation‐abrasion and wet‐dry weathering The model is able to replicate the formation of a deep inner channel at channel center and flat bedrock bench on the channel margins Weathering and abrasion indirectly interact with each other through changes in channel morphology