AbstractRegression equations with the form y =f(q), whereyis a channel characteristic andqis a discharge of a particular frequency are widely used in fluvial geomorphology. They imply that channel geometry is related to a dominant discharge. For this to be so, the river must be ‘in regime’ i.e. its characteristics must fluctuate about a mean condition which is effectively stationary at the time scale considered. The static regression‐dominant discharge approach does not fully describe the relationship between channel characteristics and discharge and an alternative model is proposed with the formy(t)= ∞ 00h(u)‐q(t‐u)du. This model states that channel form is a product of the whole series of discharges experienced by the channel. The dominant discharge‐static regression approach provides a working approximation of the relationship between channel characteristics and discharge only when temporal variations inqare small or whenyis insensitive to