Reconstruction of an extreme flood hydrograph and morphodynamics of a meander bend in a high?peak discharge variability river (Powder River, USA)

Understanding of morphodynamic processes associated with large-scale floods has recently improved following significant advances modern technologies. Nevertheless, a clear link between flood discharge and in-channel sedimentation remains to be resolved. The hydrological geomorphological data available for the meandering Powder River (Montana, USA) since 1977 makes it perfect laboratory investigate connections point-bar processes. This study focuses on that accreted laterally ca 70 m during 50-year recurrence flood, which lasted about 14 days in May 1978. In September 2018, trench 2 deep long was excavated through axial deposits, 1978 deposits were delineated based georeferenced pre-flood post-flood cross-section surveys. Sedimentological show accumulated at early late stages, when flow confined channel, have similarities classical facies models terms palaeocurrent patterns vertical grain-size trend. However, high-stage conditions, overtopped bar, cross-cutting bar armouring typical Integration sedimentological palaeo-hydrological highlight relation channel cross-sectional area play key role preserving deposits. integrated approach adopted here provides basis advancing palaeoflood hydrology beyond stage estimating peak discharges next hydrographs.