Numerical Simulation of the Interaction Between Abrasion and Freeze–Thaw Weathering in a Bedrock Channel

Bedrock channel evolution is shaped by the combined effects of mechanical incision and weathering processes that operate under seasonal variability. This study employs numerical simulations to examine how bedload-impact abrasion and freeze–thaw weathering interact to drive bedrock channel cross-sectional adjustment under seasonal forcing of discharge and temperature. A set of numerical experiments systematically varies initial alluvial thickness, bedrock tensile strength, high-flow discharge, and freeze–thaw erosion depth. The results indicate sediment cover exerts strong control on abrasion efficiency. Thin alluvial cover enhances the tool effect and promotes center-focused incision, whereas thicker cover increasingly suppresses abrasion across the channel bed and stabilizes cross-sectional geometry. Higher bedrock tensile strength weakens only abrasion-driven incision, resulting in a reduced abrasion-to-weathering removal area ratio in more resistant substrates. Discharge shows a threshold-like influence on incision, with abrasion intensifying sharply once discharge exceeds the threshold and producing a deeper incision near the channel center. Freeze–thaw weathering removal is concentrated along channel banks and margins, promoting lateral modification at moderate prescribed erosion depths but becoming strongly suppressed at the largest depth due to enhanced debris production. Together, these responses define three characteristic regimes: abrasion-dominated, interaction-dominated, and freeze–thaw-dominated. These regimes offer a framework for interpreting coupled seasonal processes in bedrock channel evolution.