Any river can have two varying regimes at different points in its course. For example, the River Rhone has different regimes both when it meets the River Saone near Lyon, and then later on near Beauclaire.
The average annual variations of hydrological variables. Beckinsale (1969) states "seasonal fluctuations of river discharge, represented by the mean monthly flows are river regimes which vary regionally in relation to precipitation, temperature, evapotranspiration and drainage basin characteristics."
The term is applied to flow regimes which are explained by the flow regimes, which are defined by the Froude and Renolds numbers and associated bed-form types.