The dominant channel forming discharge is often assumed to be
the bankfull flow.
For example Knighton (1998) argued that "since it seems
reasonable to suppose that river channels are adjusted on average
to a flow which just fills the available cross-section, dominant
discharge has been equated with bankfull flow, thereby giving it
additional
morphogenetic significance."
The dominant discharge is supposed to give the same effects as
the whole range of
discharges occurring (Brandt, 2000).
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Brandt, S.A., 2000: Classification of geomorphological effects
downstream of dams. Catena, vol. 40(4), pp. 375-401.
doi:10.1016/S0341-8162(00)00093-X Knighton, D., 1998. Fluvial Forms
and Processes: A New Perspective. Arnold, London, xv+383 pp.