thank you
lovely riffles of thought
while the determination of a thalweg is usually easy
very difficult situations can arise
you can say that again
& especially easy & difficult ones at tripoints
but the depths are much more fluid than the heights
so much less likely to fully mirror their greatest abnormalities
nevertheless i believe there is just such a very rare & very difficult
case as you envisage
involving a recent icj ruling in the quadrifinium neighborhood
& possibly touching on the bwnazmzw quadripoint itself if any
--- In
BoundaryPoint@yahoogroups.com, "Lowell G. McManus"
<mcmanus71496@m...> wrote:
> While the concept of a thalweg is simple enough, its practical
application can
> be as fraught with as many problems as its alter ego, the ridge
line. In fact,
> the ridge line makes a perfect analogy in reverse for the
thalweg.
>
> Early diplomats, with inexact and/or overly simplified notions of
the lay of the
> land, often resorted to ridge lines as convenient landforms on
which to hang a
> paper boundary. These ridge lines, however, were often more
complex than they
> imagined, resulting in conflicting claims and requiring
renegotiation a
> generation or so later. The northern boundary of Maine is a
case in point,
> where the original treaty said "along the highlands..." Reality is
seldom that
> simple. Mountain ranges are not the "woolly worms" that early
cartographers
> used to depict them.
>
> Think of the following problematical ridge lines and invert them
to visualize
> some thalweg problems:
>
> 1. What if a drainage divide follows a relatively low range of
hills in front of
> a higher ridge, the land between them draining around one
end of the higher
> ridge? (If this landscape were inverted to form a waterbottom,
the deepest
> point in a given cross section would not necessarily be the
channel through
> which the current would flow continuously at low water.)
>
> 2. What if the drainage divide splits into two ridges with a
non-draining basin
> between? (In the inverted example of the thalweg, the basin
would be a shoal or
> island, but what if the channels on either side of it both had
their deep and
> shallow sections? This can become very complex in deltas.)
>
> 3. What if the drainage divide flattens out into a plain where
drainage is not
> easily discerned? (The inverse would be the thalweg of a
wide, flat-bottomed
> river.)
>
> I could go on, but I think you can see the point.
>
> While the determination of a thalweg is usually easy, very
difficult situations
> can arise.
>
> Lowell G. McManus
> Leesville, Louisiana, USA
>
>
>
> ----- Original Message -----
> From: "acroorca2002" <orc@o...>
> To: <BoundaryPoint@yahoogroups.com>
> Sent: Friday, August 01, 2003 9:36 AM
> Subject: [BoundaryPoint] Re: eelvru - > thalweg
>
>
> jesper
> a thalweg has nothing to do with the size of a stream
> & is not arbitrary nor any mere matter of opinion
> but is a fact of physics & of natural geography
> exactly in the same way as a watershed or ridge line is a fact
> regardless of the elevation or mass of the heights it divides
>
> or plainer still
> a thalweg is just the absolute bottom line of a valley
> regardless of the dimensions of that valley or of its water flow
>
> so why complicate this utterly simple reality with interpretations
> rationalizations exceptions excuses etc
>
>
> & if you are still with me here
> for purposes of any earnestly punctilious try
> a thalweg junction tripoint is far from an occasion for shrugging
> ones shoulders or throwing up ones hands
> but is actually just as flagrantly obvious & real
> & just as much an occasion for dancing
> as a summit tripoint
>
> indeed
> think of it as a summit tripoint in reverse & you cant miss it
>
> you know
> as in highpointing or lowpointing
> only wetter
>
>
> also a thalweg is definitely not an effect of navigation
>
> on the contrary
> navigation if any seeks & follows the thalweg
>
> there doesnt need to be navigability for there to be a thalweg
>
> there only needs to be running water
>
> in this regard the definition quoted from gideons bible below is
> incomplete & misleading
>
>
> & i am just as sure as you are of the opposite
> that if the treaties specify the thalwegs
> as they usually do in europe & most probably do in these
cases
> then the thalwegs are the boundary lines
> & the thalweg junctions mark the tripoints
>
> so maybe we should look for the treaties before settling this
> but as for how to know where the thalweg is
> if you still cant tell from the above description
> or jans fantastic picture of you pointing straight at a tri thalweg
> please see also my recent answer to jan when he first asked
>
> --- In BoundaryPoint@yahoogroups.com, "Jesper Nielsen"
> <jesniel@i...> wrote:
> > I would think using the thalweg-principle is only for wide
rivers
> where navigation is possible and normal. Probably more often
> outside Europe where small rivers would be used for
navigation
> as well. This makes navigation possible for both countries.
> >
> > For smaller water courses I am sure the middle line is the
> general rule.
> >
> > And how to know where the thalweg is? I guess people
> navigation know. Otherwise onless the countries have
problems
> with one another it's not an issue untill something happens.
Just
> like land borders with poor demarcation: Nobody really cares
> (only freaks) untill it is necessary to find out, with the help of
> surveyors etc.
> >
> > Jesper
> >
> >
> >
> > > THALWEG
> > > 1. «A German term, literally "downstream," with reference to
> > river
> > > navigation. Here referring to the deepest channel in a river,
> > genereally the
> > > most suitable channel for navigation at the normal lowest
> > water level.»
> > > (Biger, p. 522)
> > >
> > > (How to find the deepest channel in a 5 metre broad
river?!?)
> >
> >
> >
> >
> >
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