It would certainly need to be above Haverstraw - the current there http://tbone.biol.sc.edu/tide/tideshow.cgi?site=Haverstraw+%28Hudson+River%29%2C+New+York+Current shows significant tidal reversal. I haven't found a gaging station farther upriver that reports tidal currents. Croton Point, where the river broadens to form the Tappan Zee, would probably be the lower limit. Even that seems unreasonably far upriver.
The tidal range increases as you move upstream from there. The greatest tidal range in the entire river is at Troy. One Native American name for the river was "Mahicantuck" which means, more or less, "the river flows both ways." The estuarine situation will always be hard to deal with, and I think we'll simply need to have rough guidelines and then trust the judgment of the locals. On Mon, Sep 3, 2018 at 2:51 PM Christoph Hormann <o...@imagico.de> wrote: > > On Monday 03 September 2018, Kevin Kenny wrote: > > Imagico's proposal is perhaps objective, but surely doesn't match > > perception in my part of the world. It seems odd that the 'coastline' > > must extend upward to https://www.openstreetmap.org/way/90929525 - > > but that is, according to Imagico's definitions, simultaneously the > > lowest and highest permissible limit. [...] > > Then you have misunderstood the proposal. > > With the Hudson river obviously the tidal case applies so you have the > lower limit as: > > With significant tides the coastline should go upstream at least to a > point where on waterflow is going downstream for a significantly longer > part of the tidal cycle than it goes upstream due to raising tide. > > This is evidently always below the upper limit (range of tidal > influence). > > I can't say for sure where i would place the lower limit in case of the > Hudson - The Narrows is quite definitely too low - but the current > closure seems fine. > > For low volume tidal rivers (i.e. without a salt wedge and no > significant influence of the water volume on the ocean salinity) it > would also be possible to define the lower limit through salinity (not > in absolute terms but as a fraction of the open ocean salinity in the > area). > > -- > Christoph Hormann > http://www.imagico.de/ > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
