[Tagging] Waterway river vs stream. Was [Imports] [NUUG kart] kartverket imports to OpenStreetMap
tyrfingosm at gmail.com
Sat Oct 19 12:17:43 UTC 2013
Having a river run into a stream seems strange (unless something (like a
drain or evaporation) reduce the amount of water in the river), or the river
is split into several streams.
I'm repeating some of my arguments from the import list, hopefully to get
some discussion on how to use these tags from the tagging list:
I have considered that the main difference between a waterway=river and a
waterway=stream is the scale/size of the waterway, i.e. a river is more
massive than a stream. A local classification/name may often reflect this
difference. In order to determine the size of a waterway also other aspects
than the width could be considered (like e.g. depth, length, average
discharge (volume rate of water flow), size of the drainage basin, how easy
it is to cross (which would depend on discharge and width) or relative size
compared to other streams in an area (which then of course might depend on
any of the other aspects)).
Currently I am using local classification/name and my best judgement on how
easy it is to cross at foot to distinguish between a river and a stream. How
easy it is to cross is of course subjective (and might differ during the
year), but this information offers a clue to whether a waterway has been
considered as a potential blocking feature or not.
E.g. a short waterway that is 5 m wide, but 5 cm deep and is slow streaming
I probably would tag as a stream (it is easy to cross). However a waterway
that is 2 m wide, but is roaring it's way I probably would tag as a river
(it's difficult/dangerous to cross).
The width of a waterway could be tagged using the width or est_width tags.
Using "if an able person can jump it" as the rule has some issues. How far
does an able person jump? The current WR is 8.95 m. Also this seems a bit
like tagging for the renderer.
And lastly, the width of a natural waterway may not be that easy to verify
because it might change considerably on a very short distance (from 1 to 5 m
width on a 10 m run is without doubt not unusual). So at which point should
it be measured/verified?
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