NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
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
welcome"
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
prediction
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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: No virus found in this incoming message.
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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
welcome"
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
prediction
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.
:
:
: :
:
:
:
: --
: No virus found in this incoming message.
: Checked by AVG Free Edition.
: Version: 7.1.405 / Virus Database: 268.11.7/436 - Release Date: 01/09/06
:
:
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
