Experimental insights into the effect of event sequencing and sediment input texture on step-pool channel evolution

We conducted flume experiments in a step-pool channel with different sediment supply regimes to explore how the sequencing and the grain-size of sediment pulses affect channel evolution. Our results show that the sequencing of events is not a primary control as the trends in flow characteristics, bedload transport, sediment storage, step evolution, and step frequency were similar in feed phases with different sequencing of sediment pulses. Channel adjustment and step stability in a short timescale (i.e., in a 4-h run) were mostly controlled by the magnitude and frequency of sediment pulses. A coarser sediment feed mixture led to a coarser bed surface which increased both sediment storage in the channel and step stability. Our experiments show that channel evolution in a step-pool channel is primarily controlled by the magnitude and frequency of sediment pulses and the grain size of sediment supply rather than the event sequencing of sediment pulses.