[Tagging] Rio de la Plata edit war
kevin.b.kenny at gmail.com
Sun Aug 2 14:03:09 UTC 2020
On Sat, Aug 1, 2020 at 6:42 PM Paul Norman via Tagging <
tagging at openstreetmap.org> wrote:
> Starting locally, the Fraser River has a strong tidal influence 25km
> upstream of the coastline/riverbank edge. Fishers report a tidal
> influence 90km upstream. Wikipedia says the Columbia has tidal influence
> up to the first dam, which is 120km upstream of the coastline/riverbank
> edge. There are tidal forecasts published for 75km upstream of the edge.
> Looking in Europe, the Thames is tidal for 80km upstream of the
> coastline/riverbank edge.
Near to me, the Hudson River is an even more extreme example of what you're
talking about. It is tidal for 134 nautical miles (248 km) north of Mile
Zero (which is the tip of the Battery, where it enters New York Harbor).
The salt front ranges from some distance out in New York Harbor during the
spring snowmelt to about Poughkeepsie (124 km upriver) in a dry summer.
Because of resonance effects, the tidal range is actually greatest right at
the Federal Dam in Troy, the northernmost extent of the estuarine region.
If you say that Troy is on the coast, people will look at you as if you
have two heads. If you start to explain that well, the river is tidal, and
dredged to a depth of 9m to accommodate oceangoing vessels, and (yada,
yada, yada), they'll say, 'yeah, I suppose if you want to be THAT way about
it,' and file you mentally under 'insufferable pedant.'
Much farther afield, the Amazon is tidal at least as far as Óbidos,
Brasil, nearly a thousand km from the river's mouth.
As a practical matter, given the woes of coastline maintenance, pushing the
coastline for tens or hundreds of km up most of the world's rivers would be
73 de ke9tv/2, Kevin
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