From OpenStreetMap Wiki
Problems of the waterway=brook concept
This tag has a number of serious issues with its definition and its position within the framework of waterway mapping in OSM. These make use of this tag rather counterproductive for the usability of waterway data in OSM. Specifically:
- This tag breaks with the basic convention of waterway tagging that distinction between natural and artificial waterways is a primary criterion. This distinction is of fundamental importance for any more sophisticated analysis and use of the waterway network since artificial waterways do not generally follow the basic rules of natural waterways (like water always taking the steepest path downhill).
- The tags definition is centered on topographical aspects (depression in the ground) and not on water flow as the waterway=* key implies. See also natural=gully and barrier=ditch. Water is only part of the definition insofar that water has to be present at least some part of the year. Water flow OTOH is completely optional.
- The size criteria are vague, especially since it is unclear how depth and width are measured if water is normally absent.
- I agree on your points. This tag should make clear where it fits compared to other waterways. --Jojo4u (talk) 17:32, 4 August 2015 (UTC)
- I also agree, and find it questionable whether there is a need for this tag in the waterway family at all. --Tordanik 19:50, 4 August 2015 (UTC)