[Talk-GB] UK coastline data

[Borbus]

On Sat, Jul 13, 2019 at 9:44 PM Colin Smale <colin.smale at xs4all.nl> wrote:
> Coastline would be the high water line, not low water. But your point is
> valid - equating coastline to MHW could better be called a heuristic
> instead of a rule. It works most of the time, but we have to accommodate
> exceptions. All we have to do now, is to define what constitutes an
> exception.

Yes, I agree with this. MHW and MLW are nice because they are
indisputable (assuming accuracy and currency of data). I don't think
anybody would disagree with taking all of the OS MHWS data and tagging
it with "natural=mean_high_water_spring" or something.

The disagreement seems to come over whether those lines coincide with
"natural=coastline" or "natural=water"/"waterway=riverbank". A big
difference with the coastline (and this is especially true for Britain,
of course) is it is actually what defines Britain (the island). I guess
the River Thames is generally considered to be "in Britain".

Could we possibly use administrative boundaries to cut mark the cut off
point between coastline and riverbank then?

That would place the "coastline" at the mouth of the Thames here:
https://www.openstreetmap.org/?mlat=51.5038&mlon=0.6775#map=12/51.4876/0.6736

And the Dart here:
https://www.openstreetmap.org/?mlat=51.5038&mlon=0.6775#map=17/50.38223/-3.59310

-- 
Borbus.
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