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    Re: Tidal constants
    From: Geoffrey Butt
    Date: 2006 Sep 2, 20:59 -0500

    George wrote:

    "If Geoff has any information to offer, perhaps off-list, it would be

    Yes.  Although grounded in grounded in astronomical data the issues raised
    have strayed a bit from the NavList purpose.  A few points to sign off with:

    George also wrote:
    " . . .  for the waters around the English Channel and the Atlantic coast of
    France. In general, those areas are not much affected by silting and
    dredging, so presumably the harmonic constants given in part 3 of my 1995
    tables should still work reasonably well."

    I intend to compare changes to tidal constants over the years with the broad
    nature of the ports.  Liverpool, for example, maintains a major dredging
    programme which has altered over the years in response to changes in traffic
    type and the development of new terminals.  On the other hand Milford Haven
    has such a broad and deep entry that I would expect there to be little
    change in tidal constants.

    The other side of the coin is that resources to gather more refined tidal
    information will be focused on ports of commercial and military
    consequence.  So even locations with unchanging topography may acquire
    changes in published data through more complete analysis of more and better
    observational data.  Silting ports like Preston, with a major decline in
    commercial traffic, will I suspect experience real tidal changes - but there
    is little incentive to monitor these.

    When I was last in the Elbe estuary I noted the large number of tidal
    measurement buoys:  it will be interesting to look at data for Hamburg

    Geoff Butt

    : contact George Huxtable at george@huxtable.u-net.com
    : or at +44 1865 820222 (from UK, 01865 820222)
    : or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
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