The patches of land that I’m interested in slope at 45 deg down to the water, are covered in land-based vegetation, and must flood once every 5 years if that. I call them riverbanks!
What I particularly don’t want is to have the area landuse=meadow join what is rendered as water, because these in-between areas aren’t usable at all.
Next time I’m down there I’ll take a photo and pick this up again - on the wiki discussion page if that’s the better place.
In the meantime, any reason not to mark up a picture of a physical river with the tagging in the appropriate places, and put that in the wiki? Sometimes the same word is used for the tagging and for referring to the physical feature, but it’s not obvious which is which.