"river flow" is correct and usable in written English.
You can use it to describe the motion of a river, for example: "The river flow lazily through the meadow."
River flow relates mainly to climate, albeit not in a simple way; for example, in all but Alpine Germany, maximum river flow occurs in winter when evaporation is low, though in the lowlands the peak rainfall is in summer.
"It's best to let the river flow its natural course".
The landward side is quiet watermeadow land with a much-reduced river flow to the turbines.
They built their analyses on historic rainfall and river flow data.
As for the impact on river flow, Marinetek's Räme insists that it's negligible.
Stream and river flow are usually seasonally variable, depending upon precipitation cycles and snowmelt.
Her team carried out five simulations of river flow in the 20th century.
The eastern portions of the falls are mostly dry during times of low river flow.
The target flow levels, based on historical records, are intended to make the river flow far more consistently.
