What is "riffles"

Usage examples of "riffles".

For a time the contest was in doubt, and then Kathy was struggling upright in the shallows, just above where the riffles started.

Just an interesting chip bobbing in the riffles, or a drifting piece of wood such as a log with a viable knot.

In twenty-four hours he would be in a farmhouse which smelt of paraffin and beeswax and good cooking, looking out on a green valley with a shallow brown stream tumbling in riffles and drowsing in pools under banks of yellow bent.