The effects of flood history on sediment transport in gravel-bed rivers

摘要: The transport of coarse sediment during floods often exhibits hysteresis patterns from changes in flow fields, channel geometry, bedforms, or supply conditions. Flume experiments that simulate hydrographs tend to confirm is a consequence the progressive organization surface sediments terms grain protrusion, imbrication, orientation, and roughness. Hysteretic are also highly dependent on kind conditions, type simulated hydrograph. A factor has not been investigated extensively effect timing sequencing bedload transport. Depending its magnitude duration, each flood leaves bed different condition, which influences next event, representing river bed’s memory past floods, can determine future responses natural disturbances. In this study, I effects sequences events, i.e., history, through series flume three types stepped symmetrical (ranging short-duration/high-magnitude long-duration/low-magnitude events) under recirculation Hydrographs were as sequence same with events sequences, order explore antecedent conditions results show previous event decreases rates transported by certain hydrograph around 40% if high-magnitude precedes another one 70% low-magnitude similar magnitude. does affect rate subsequent flood, but reduces event.