[Tagging] Waterway river vs stream

Jonathan bigfatfrog67 at gmail.com
Sat Oct 19 18:00:49 UTC 2013


As ever this is an interesting question, when is a river not a river, 
when it's a stream?  Or when is a stream not a stream, when it's a river?

Reading some articles: http://water.usgs.gov/wsc/glossary.html#Stream 
and http://en.wikipedia.org/wiki/Stream and 
http://en.wikipedia.org/wiki/River I get the feeling that all 
watercourses are streams however some become large enough to be called 
rivers, but they are still streams.

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.

The are 1st order streams and 12 order streams, as per 
http://en.wikipedia.org/wiki/Strahler_Stream_Order.

Also, bear in mind, a watercourse can be named "The River ..." and yet 
be tagged as a stream at its lower orders!

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?  Any watercourse that is already "named" as 
a river should be so named?

Yet again, I feel that as mappers we spend too much time trying to 
define the world around us when we should just be describing it, let the 
renderer and the user define based on their viewpoint. I don't think it 
is for us to decide when a river is a river and not a stream?

Jonathan

http://bigfatfrog67.me

On 19/10/2013 17:03, Christoph Hormann wrote:
> I think the whole issue should be split into two separate questions: The
> verifiability of the rule and the rule itself.
>
> As far as verifiability is concerned - it seems the question how far an
> able person can jump is not an issue here.  As i said before i would
> interpret the rule from a practical standpoint, i.e. tag as stream if i
> generally would assume crossing this waterway with dry feet would be
> considered feasible on a hike by most people without disabilities.  Of
> course there will be borderline cases but there always are, even if a
> quantative rule exists.
>
> The question of changing width of a waterway can also be answered from a
> practical perspective - it is sufficient for the waterway to have
> occasional points where it can be crossed to qualify.
>
> This interpretation of course also means that the tagging of a waterway
> does not only depend on the properties of the waterway itself - a 1
> meter wide 'stream' running in a steep walled gorge 10 meter wide on
> top cannot practically be jumped across.
>
> Which leads me to the rule itself which - as noted previously - does not
> make much sense as a mandatory top level distinction for waterways.
> But it has been around for a long time and a lot of data has been
> tagged based on it.  This in my opinion means changing the meaning of
> the existing river/stream distinction - even if there was a practically
> verifiable alternative rule - would serve no purpose except devaluing
> existing data as well as newly entered information.  The only sensible
> way to change things would be to move the distinction into a secondary
> tag (something like crossable=* for example, that would also allow
> tagging the possibility to wade through) and to re-tag all waterways
> with a uniform primary tag (natural=waterway would be an obvious choice
> although it could be useful to make the distinction natural/artificial
> waterway indeed mandatory).
>
> Greetings,
>




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