[Tagging] How to tag small canals?

SelfishSeahorse selfishseahorse at gmail.com
Fri Aug 17 11:16:35 UTC 2018


On Thu, 16 Aug 2018 at 18:20, Christoph Hormann <osm at imagico.de> wrote:
>
> On Thursday 16 August 2018, Martin Koppenhoefer wrote:
> >
> > The canal definition was changed in March 2018, before it said to use
> > canal only for „the largest waterways created for irrigation
> > purposes“
>
> Yes, that was the obvious attempt to expand the narrow scheme to other
> parts of the world in a superficial way oriented at the standard style
> rendering but not at the actual semantics.

Actually, it's only drain that doesn't seem to make sense
semantically, but ditch seems to be fine for smaller canals used for
drainage and irrigation, at least according to the definitions by
Wikipedia[^1] and the Cambridge Dictionary[^2].

[^1]: <https://en.wikipedia.org/wiki/Ditch>
[^2]: <https://dictionary.cambridge.org/dictionary/english/ditch>

I'm not sure if a (smaller) mill race can also be called a ditch, but
i think it makes sense to have at least two tags for man-made channels
of different width.

In my opinion the material of the lining/confine should better be
tagged separately, perhaps confine:material=concrete/wood/....

As for natural waterways, I could imagine the following classification
based on width:

* waterway=stream/brook - possible to jump across (< 1 m wide?)
* waterway=creek - small to medium-sized natural stream (1-3 m wide)
* waterway=river (3-10 m wide)
* waterway=broad_river (> 10 m wide)

Of course we could just use width=*, but it's not always easily
possible to measure the width (e.g. in a forest) and sometimes it
changes often.

However, if new waterway=* values were introduced, it would be
necessary that OSM Carto would render them from the day they were
approved, otherwise people would not use them.

Cheers

Markus



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