[Tagging] Coastal beach definition for mapping.

[Christoph Hormann]

On Wednesday 04 April 2018, Malcolm Herring wrote:
> > It seems some mappers go to the extreme opposite and map the
> > coastline across the mouth of an estuary that is clearly part of
> > the ocean:
> >
> > <https://www.openstreetmap.org/way/186710973>
>
> Many ocean/river boundaries are not arbitrary, but reflect official
> boundaries where a coastal authority's water ends and a river
> authority's water begins.

There is no such thing as an ocean/river boundary - there are political 
boundaries and there are limits of physical geography features.  When 
mappers align geometries of physical geography features (like 
natural=water, waterway=riverbank or natural=coastline) to 
administrative boundaries or baselines that is always wrong and is 
usually done to communicate a certain non-verifiable view of the 
physical reality to underline certain political goals - in case of the 
Rio de la Plata this is the aim to defend the claims Argentina and 
Uruguay make regarding the limits of their territorial waters (which 
are internationally disputed):

http://digitalrepository.unm.edu/cgi/viewcontent.cgi?article=1790&context=nrj
https://www.state.gov/documents/organization/57675.pdf

Independent of that the placement of the coastline at river mouths is 
generally somewhat variable.  I wrote a proposal a few years back aimed 
at defining some verifiable limits for that:

https://wiki.openstreetmap.org/wiki/Proposed_Features/Coastline-River_transit_placement

-- 
Christoph Hormann
http://www.imagico.de/