On Tue, Aug 4, 2020 at 2:54 PM Joseph Eisenberg <joseph.eisenb...@gmail.com> wrote:
> 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 > estuary. > > Similarly, should Puget Sound and San Francisco Bay be mapped as > natural=water + water=river? These are also estuaries. > Deferring to local cultural understanding is actually a good start for the other examples. For the Hudson, if you wanted to draw the line from Rockaway Point to Sandy Hook (the two lighthouses commonly understood to mark the entrance of New York Harbor), from the Battery to Liberty Pier (mile 0 of the Hudson as it appears on the nautical charts) or from Spuyten Duyvil to Englewood Cliffs (just upstream from the first distributary, the Harlem River), I'd have no heartburn. The lowest point on the river that would be at all defensible by any argument other than culture (and 'eyeball' geometry - on the map it *looks* like a river) would probably be between Peekskill and Stony Point. That's where you'd start to see mean annual salinity start to fall off sharply. (The seasonal variation is substantial.) That's already getting culturally and "eyeball geometry" start of dodgy. Beyond that, I'd have to consult historical records for the historical maximum retreat of the salt front, but we're already quite some way upriver. Similarly, there's a local understanding of "Fleuve Saint-Laurent" vs "Golfe du Saint-Laurent" - and here I see that the locals have compromised by creating objects for 'Estuaire fluvial', 'Estuaire moyen' and 'Estuaire maritime'. Even there, the 'Estuaire fluvial' does not extend nearly to the tidal limit. The locals certainly make a distinction between the waters of the Sacramento and American rivers and those of San Pablo and San Franscisco Bays, or those of Puget Sound and the many rivers that empty into it. They also make a distinction between the bays, or the sound, and the ocean. -- 73 de ke9tv/2, Kevin
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