Interaction between waves of alluviation and incision in mixed bedrock-alluvial rivers

In the Sklar-Dietrich model of bedrock, incision is caused by wear as alluvial clasts collide with bedrock. The rate of wear is related to a cover factor expressing the areal fraction of the bedrock surface covered by alluvium. This cover factor is related to the ratio of sediment supply to the capacity sediment supply necessary for complete alluviation. This model cannot capture time-varying sediment supply. Here a variant of an earlier model due to Struiksma is used to describe alluvial waves migrating over a bedrock surface. It is shown that even with the same mean sediment supply rate, different patterns of cyclic variation can lead to the evolution of very different equilibrium long profiles in balance with constant base level drop or uplift rate.