[Tagging] Deprecate water=pond?

Joseph Eisenberg joseph.eisenberg at gmail.com
Thu Nov 12 19:27:14 UTC 2020


Re: is water=* tag needed?

On Thu, Nov 12, 2020 at 9:36 AM Brian M. Sperlongano <zelonewolf at gmail.com>
wrote:
> "Is a water= tag even needed at all in these cases then? natural=water +
name="Foobar Pond" seems to cover it.  I'm not sure what specific added
information is conveyed by "lake", "pond", or even "lake_pond".  It's a
natural body of water with a name.  If we need tagging to indicate
freshwater vs brackish vs saltwater, or depth, or murkiness, those seem
like separate tags.

>
> > "I think the question here isn't if pond makes sense for data consumers.
Mappers are what matters in this case. If there is a little 4 meter pond,
mappers will not tag it as a lake because it sounds wrong. So they will
probably tag it just natural=water. But then we lose information about if
it is a little lake, a reservoir, a fountain or a wastewater dump. That's
why we need the pond."

So originally all lakes and semi-natural ponds were tagged just
natural=water, while reservoirs were landuse=reservoir,
retention/detention/infiltration basins were landuse=basin, the area of
 rivers was mapped with waterway=riverbank. And then, as now
leisure=swimming_pool was used for swimming pools, while seas and coastal
waters were delimited with natural=coastline ways (as they still are). Salt
ponds could be mapped with landuse=salt_pond.

This meant that there were separate tags for seas and marine water (all
areas outside of the coastline), for natural inland still water
(natural=water), man-made still water features (landuse=reservoir / =basin
/ =salt_pond), and for rivers (waterway=riverbank) - which are natural
flowing watercourses.

But there wasn't a clear way to map the area of a canal or ditch: an
artificial area of flowing water, so the tagging system was missing one
ingredient.

Some mappers used waterway=riverbank since canals are similar to rivers,
while others used natural=water even though this was for lakes.

Instead of making a new tag for canals or ditches or drains, its was
proposed to just use natural=water for all inland water areas, including
rivers, canals, reservoirs, and basins, with the addition of the tag
water=* to describe the type of water area. This was somewhat
controversial, since it meant mapping man-made watercourses and waterbodies
under natural=* but it was approved:
https://wiki.openstreetmap.org/wiki/Proposed_features/Water_details (Apparently
this was already in use in Russia before it was adopted by the global
community?)

Now the proposal had a couple problems: it suggested water=cove and
water=lagoon for areas which are clearly outside of the coastline and part
of the marine water system, but in practice this has not happened,
natural=bay has been used for these areas instead of natural=water, so the
distinction between marine and inland water has remained mostly clear
(except in the difficult situation of estuaries).

But since water=pond is not clearly defined as natura/semi-natural vs
man-made, we have a large number of features where the water=* tag is not
providing this information. Since the previous tagging system clearly
distinguished natural from man-made water bodies, this would be a loss for
database quality.

I wish it was possible to just redefine water=pond as "a man-made pond",
but since this is not likely to succeed, we should provide clear
alternatives.

Of course it will remain possible to just use natural=water with no
additional tag, if it's not known whether an inland body of still water is
man-made or natural.

-- Joseph Eisenberg
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