Key:waterway/Narrow variants

There was some discussion that waterway=ditch does not differentiate a waterway from a waterway=stream by size, but only by having been excavated by human intervention. Comparing the first and the last picture in the table below I propose that waterway=stream isn't suitable for the full range of differents streams. Some of these might well be man made, but the problem stays the same.

I have tagged some of the first examples as waterway=brook for now, until there's some sort of a guideline.

Image	Approximate width	Description	Tags?
	20 cm	An intermittent brook, just a narrow depression most of the time.
	40 cm	An intermittent brook, just a narrow and possibly moist depression most of the time.
	60 cm	An intermittent waterway, possibly just a moist depression part of the year. Ditch, brook or stream?
	80 cm	A waterway filled with water most of the year, but could run dry in the summer. Ditch, brook or stream?
	1 m	A stream filled with water year round. All but the elderly could just jump over it.
	1.5 m	A stream filled with water year round. Not all would, but most people could still jump over it.
	1.7 m	A stream filled with water year round. Most people wouldn't try to jump over it, even if many could with a running start.
	2.0 m	A stream filled with water year round. Only few could jump over it.