[Tagging] coastline v. water

Brian M. Sperlongano zelonewolf at gmail.com
Thu Nov 19 04:34:51 UTC 2020

This was fascinating reading.  I do agree that we ought to have a
definition for what gets tagged natural=coastline, and I think it's fine if
that definition has some subjectivity.

I would offer something as simple as:

"The coastline should follow the mean high tide line.  In some cases this
rule would result in the coastline extending an unreasonable distance along
the banks of tidal rivers.  In those cases, mappers should identify a
reasonable choke point at which to terminate the inland extent of coastline

This would clearly include bays and coves on the marine side of the coast.
For rivers, local mappers could decide on where the coastline stops by
consensus, and the decision space is limited to a discrete set of
chokepoints in the river geography (or when the river stops being tidal if
the tidal portion is reasonably short).

An objective definition that we can all live with is probably not
achievable, but a partially-subjective one would at least minimize the
arbitrary decision-making while still allowing flexibility for edge cases.

On Wed, Nov 18, 2020 at 5:07 PM Christoph Hormann <osm at imagico.de> wrote:

> > Eric H. Christensen via Tagging <tagging at openstreetmap.org> hat am
> 18.11.2020 21:19 geschrieben:
> >
> > [...]
> First: the matter has been discussed at length previously so i would
> advise anyone who wants to form an opinion on the matter to read up on past
> discussion where essentially everything relevant has been said already.
> Most relevant links:
> https://lists.openstreetmap.org/pipermail/tagging/2020-July/054405.html
> and resulting discussion:
> https://lists.openstreetmap.org/pipermail/tagging/2020-August/thread.html#54434
> https://wiki.openstreetmap.org/wiki/Proposed_Features/Coastline-River_transit_placement
> Second:
> >
> > Now, some of the feedback that has been presented[2] is that because it
> is tidal it is part of the sea.  [...]
> As you can read in the proposal linked above the range of tidal influence
> forms the upper limit of the range practical coastline mapping in areas
> with significant tidal range but as it is in practical mapping not the
> universally used limit.
> Third:
> While this is ultimately not relevant because the delineation of tags in
> OSM should be based on verifiable criteria obviously i have never seen any
> map that displays ocean water and inland waterbodies in differentiated form
> that shows the Chesapeake Bay as inland water.
> Classical examples with differentiated rendering are TPC/ONC (caution:
> links go to large images):
> http://legacy.lib.utexas.edu/maps/tpc/americas-pacific-index.html
> http://legacy.lib.utexas.edu/maps/onc/txu-pclmaps-oclc-8322829_g_21.jpg
> --
> Christoph Hormann
> http://www.imagico.de/
> _______________________________________________
> Tagging mailing list
> Tagging at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/tagging
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