Past river classifications use incommensurate typologies at each spatial scale and do not capture the pivotal role of topographic variability at each scale in driving the morphodynamics responsible for evolving hierarchically nested fluvial landforms. This study developed a new way to create geomorphic classifications using metrics diagnostic of individual processes the same way at every spatial scale and spanning a wide range of scales. We tested the approach on flow convergence routing, a geomorphically and ecologically important process with different morphodynamic states of erosion, routing, and deposition depending on the structure of nondimensional topographic variability. Five nondimensional landform types with unique functionality represent this process at any flow; they are nozzle, wide bar, normal channel, constricted pool, and oversized. These landforms are then nested within themselves by considering their longitudinal sequencing at key flows representing geomorphically important stages. A data analysis framework was developed to answer questions about the stage‐dependent spatial structure of topographic variability. Nesting permutations constrain and reveal how flow convergence routing morphodynamics functions in any river the framework is applied to. The methodology may also be used with other physical and biological datasets to evaluate the extent to which the patterning in that data is influenced by flow convergence routing. Copyright © 2018 John Wiley & Sons, Ltd.

River corridors exhibit landforms nested within landforms repeatedly down spatial scales. In Pasternack et al. (), a new, scale‐independent, hierarchical river classification was developed that uses five landform types to map the domains of a single fluvial process – flow convergence routing – at each of three–five spatial scales. Given those methods, this study investigated the details of how flow convergence routing organizes nested landform sequences. The method involved analyzing landform abundance, sequencing, and hierarchical nesting along the 35 km gravel/cobble lower Yuba River in California. Independent testing of flow convergence routing found that hydraulic patterns at every flow matched the essential predictions from classification, substantiating the process–morphology link. River width and bed elevation sequences exhibit large, nonrandom, and linked oscillations structured to preferentially yield wide bars and constricted pools at base flow and bankfull flow. At a flow of 8.44 times bankfull, there is still an abundance of wide bar and constricted pool landforms, but larger topographic drivers also yield an abundance of nozzle and oversized landforms. The nested structure of flow convergence routing landforms reveals that base flow and bankfull landforms are nested together within specific floodprone valley landform types, and these landform types control channel morphodynamics during moderate to large floods. As a result, this study calls into question the prevailing theory that the bankfull channel of a gravel/cobble river is controlled by in‐channel, bankfull, and/or small flood flows. Such flows may initiate sediment transport, but they are too small to control landform organization in a gravel/cobble river with topographic complexity. Copyright © 2018 John Wiley & Sons, Ltd.