[Tagging] Waterway river vs stream

Philip Barnes phil at trigpoint.me.uk
Sat Oct 19 20:37:45 UTC 2013

On Sat, 2013-10-19 at 22:13 +0200, Christoph Hormann wrote:
> On Saturday 19 October 2013, Jonathan wrote:
> >
> > It seems a river is something that has a source and a mouth (either
> > where it joins the sea, lake or a larger river).  So I would say that
> > only streams that have been named "River ...." or "The River ..."
> > should ever be tagged as a river, everything else is a stream.
> Be careful here - different languages use different distinctions and 
> even in English use of the terms might differ by country or region.  
> And of course duplicating information that is already in the name tag 
> is not necessary.

Just in the UK I can think of Brook, Clough and Beck. And thats just the
Midlands and some of the North of England.

> > One option might be to tag every natural watercourse water=stream and
> > strahler=[1...12] and then let the renderer choose how to display it
> > based on the strahler order?
> No, first of all this kind of topological measure is not possible to 
> determine locally by the mapper since it depends on the whole river 
> system upstream from the point in question (and even more: it requires 
> complete data of it).  Second it is not suited for use in map rendering 
> from a cartographic viewpoint.
> I explained the requirements for an importance rating for rendering of 
> rivers in:
> http://www.imagico.de/map/water_generalize_en.php
> The only really important thing for allowing good rendering of the 
> waterways is to have correct orientation and connectivity of all ways - 
> which is a huge problem in the OSM data, in my opinion one of the most 
> severe we have (together with the notoriously broken boundary relations 
> maybe).
Phil (trigpoint)

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