Fluvial channels can experience significant variations to both sediment transport rates and deformations in channel morphology under unsteady flow conditions,especially during flood hydrograph events (Phillips et al., 1990). Within the current study, a series of parametric experiments was conducted to investigate the response of both quasiuniform (sand) and graded (sand-gravel) sediment beds to a range of different unsteady hydrograph flow conditions, defined by three non-dimensional variables: (i) an unsteadiness parameter ΓHG representing hydrograph flashiness; (ii) an asymmetry parameter η defining the ratio of rising and falling limb durations; and (iii) a total flow work parameter W_k.
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