We designed a set of flume experiments with a simple, well-defined bed configuration to test our modified sediment transport equation. The experiments were conducted in a small (15 cm wide, 4.5 m long) flume set at a gradient of ten percent. This is the steepest gradient at which fluvial processes have been hypothesized to dominate over debris flow scour and deposition. At this gradient, the influence of the immobile grains on the flow and sediment transport will be relatively large. Thus our experiments should provide a test of sediment transport equations at the limit of their applicability. We maintained a constant slope in our experiments to enable comparisons between all experimental runs. The flume bed consisted of two layers of 30 mm immobile spheres: a closely packed bottom layer (λ/D of 1) and a top layer in which λ/D varied from 1 to 5 in the different runs. (Yager et al., 2007)
