[Tagging] Rio de la Plata edit war

Joseph Eisenberg joseph.eisenberg at gmail.com
Tue Aug 4 18:52:44 UTC 2020

It's perfectly possible to make a physical definition of an estuary which
allows the line of the natural=coastline to be placed across the lower
Hudson, rather than at Troy or Albany, if we look at salinity and currents
rather than just tides: and we must, because some parts of the coast in the
tropics have nearly 0 tidal variation (including the region around the Rio
de la Plata).

But the current position of the natural=coastline ways between Argentina
and Uruguay is like if all of Lower New York Bay were outside of the
natural=coastline, and a line was instead drawn from Long Beach NY to Long
Branch NJ.

This is quite serious when it comes to the Saint Lawrence river (Fleuve
Saint-Laurent), which can extend as far west into the Golf of Saint
Lawrence as you want, if we take the current placement of the
natural=coastline along the eastern edge of the Rio de la Plata as a guide.
I would suggest that the natural=coastline should cross no farther
downstream than Quebec City, where the river widens into the huge lower

Similarly, should Puget Sound and San Francisco Bay be mapped as
natural=water + water=river? These are also estuaries.

-- Joseph Eisenberg

On Tue, Aug 4, 2020 at 9:30 AM Kevin Kenny <kevin.b.kenny at gmail.com> wrote:

> On Tue, Aug 4, 2020 at 11:24 AM Joseph Eisenberg <
> joseph.eisenberg at gmail.com> wrote:
>> This means that the line tagged with natural=coastline is on the inland
>> side of all marine water, including mangroves, salt marshes, and tidal
>> channels, as far as possible. It makes sense that in estuaries, the route
>> of the ways tagged natural=coastline should also extend up to the limit of
>> marine influence. In some cases this has been taken to mean the limit of
>> the tides, in others it is the limit of mixing of salt and fresh water.
> I agree that's what the Wiki says. The Wiki says a lot of things.
> In actual practice, in the estuaries of rivers, the 'coastline' is very
> seldom tagged that far upstream.
> I return to the example of the Hudson River. The tidal influence extends
> upstream to Lock and Dam Number One - 248 km from the river mouth. The salt
> front varies strongly with the season. There can be fresh water in New York
> Harbor during the spring snowmelt, or salt water at Poughkeepsie (122 km
> upriver) in a dry summer. (It's also defined somewhat arbitrarily as a
> conductivity of 510 microsiemens/metre at the surface - but surface
> salinity is, in most seasons, higher than the salinity at depth because the
> cold, fresh river water underlies the relatively warm, brackish surface
> water.) Needless to say, the biome is very different between Albany (always
> fresh water) and Yonkers (always salt, except for snowmelt events).
> Oceangoing vessels of up to 9 m draft can ply the river as far as Albany.
> (In less xenophobic times, vessels of friendly nations could clear customs
> at Albany.)
> For pretty much all the rivers in eastern North America, the tidal
> influence extends to the first dam or waterfall. This usually coincides
> with what would be the head of navigation if it were not for modern
> improvements such as locks. Riverports from Augusta, Maine to Macon,
> Georgia would become 'coastal' cities. That's surely no more the local
> understanding on the Kennebec or the Ocmulgee than it is on the Elbe!
> For the Amazon, the situation is even more extreme - the river is tidal
> for a thousand kilometres from what would be conventionally recognized as
> the 'coast'.
> It appears that for most of the world, this rule, if actually implemented
> - and it is important to stress that it is NOT the way things are mapped at
> present - would extend the 'coastline' for tens or hundreds of km upstream
> on most of the first-order rivers of the world.
> Given the fact that even with today's definition, we frequently go for
> months without a consistent coastline to give to the renderer, do we want
> to add tens of thousands more kilometres of 'natural=coastline'? We'd never
> see a coastline update again! (For this reason, I'm inclined to push the
> 'coastline' as far toward the sea as sensibly possible, to have as little
> 'coastline' as possible to get broken, rather than going for months without
> updates or worse, seeing rendering accidents flood whole continents.)
> Moreover, I'm somewhat puzzled at Christoph's insistence that
> 'natural=coastline' have a strict physical definition, and dismiss local
> understanding as merely political and cultural. In almost all other aspects
> of OSM, the understanding of the locals is what governs. That understanding
> is, ipso facto, cultural - but we dismiss it at our peril. Ignoring local
> understanding is a path to irrelevance. (In another OSM domain, I've seen
> this sort of nonsense before; I've actually seen someone seriously suggest
> that a peak should not have its name in OSM unless someone can find a sign
> with the name on it, because asking locals and consulting reference works
> is not 'verifiability in the field.')
> --
> 73 de ke9tv/2, Kevin
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