Abstract: An alluvial river is subjected to bed resistance against its water flow and tends to reach a relative equilibrium state in different river patterns since the parameters of its channel cross-section morphology and plane form are changing as a result of adapting to the varied flow and sediment conditions. Two main factors determine the channel pattern of a river: the flow’s driving force and the river’s activity, and the thrust and resistance of river flow represent the forces of action and reaction respectively. This paper adopts a riverbed activity indicator and a bank activity indicator for channel patterns and considers the flow resistance law to construct river patterns discriminating curves. Also, the effect of riparian vegetation on riverbank strength is taken into account in the construction of the curves. These indicators are proved effective in deciding different river patterns by using selected datasets from laboratory tests and natural rivers.