抄録
In rivers in mountain areas, a series of steps are often observed on bedrock. They are thought to be cyclic steps formed due to erosion of bedrock, which should be driven by abrasion due to bedload sediment transport. We demonstrated a series of flume experiments of the formation of cyclic steps on bedrock by abrasion due to bedload transportation using weak mortar as the model bedrock. The shapes of cyclic steps are dependent on the sand feed rate under the water discharge of this experiment, i.e., a short upstream-facing slope and a long downstream facing slope for the lower sand feed rates, whereas long upstream-facing slope and a short and steep downstream facing slope for the higher sand feed rates. This result differ from our previous study, whose water discharge was lower and the shape of the steps was independent from the sand feed rate. In the case of higher discharge, sediment cover affects the location of vortices caused by the hydraulic jumps to make the short and steeper downstream facing slope.
