Many gravel bed rivers in New Zealand's East Cape underwent a phase of notable aggradation following the passage of Cyclone Bola in March, 1988, as massive quantities of sediment were eroded from steep, unstable hillslopes, gullies and large debris flow complexes. The Raparapaririki Stream in the Waiapu River catchment underwent more than 30 m of aggradation - at least 2 m/yr during the peak aggradation phase - burying a bridge in the process. We have used historical cross-section information and aerial photography to reconstruct the sequence of channel building, and have assessed morphologic changes to the channel as aggradation occurred. A digital terrain model of the modern river has been developed using structure-from-motion techniques with high resolution drone photography. The topographic dataset highlights floodplain topography and roughness elements. Using 2D flow simulations to assess the distribution of flows and bed shear stress across the channel, we estimate the transporting capacity of the modern river and the likely distribution of grain sizes transferred under the prevailing flow regime. Based on this analysis, we simulate the transfer of a gravel 'wave' since Cyclone Bola, and the likely trajectory of this highly dynamic system into the future. Results from this work provide insights into the timescale and spatial patterns of catchment response to major sedimentary disturbances in steepland rivers.