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Re: dam-l Fw: Running on entropy (fwd)

Sounds like a fascinating paper.  Is there an electronic copy available?

Phil Raphals
Helios Centre

At 01:53 00-03-07 -0500, Dianne Murray wrote:
Date: Mon, 28 Feb 2000 20:26:01 -0800
Subject: Fw: Running on entropy
From: Michael A Rozengurt <mrozengurt@juno.com>

Dear Collegues,

Welcome for DISCUSSIOM! Thanks. Misha Rozengurt

--------- Forwarded message ----------
From: Don McAllister <mcall@superaje.com>
To: Michael Rozengurt <mrozengurt@juno.com>
Date: Mon, 28 Feb 2000 08:48:21 -0500
Subject: Running on entropy
Message-ID: <38BA7CA5.3DF6BA82@superaje.com>
Some preliminary thoughts inspired by Rozengurt's 1999 Running on
entropy.

Dear Michael,
Thank you for sending your stimulating paper.

I have read your paper with deep interest.  It raises, as your earlier
papers have, profound questions about the impacts of impoundment of
rivers.  Especially valuable is the calculation of truncation levels
beyond which ecosystems will be severely impaired.

If I understand it correctly the stochastic calculations involve mainly
subtraction of impaired from unimpaired runoffs.  But there is another
stochastic component which could be measured.  That is simply the
day-to-day or week-by-week variability of existing flow (whether
impaired or not).  One would measure that variability by calculating the
standard deviation or standard error of the flow volume values.  With
measurements for the unimpaired and impaired flow variation, one could
compare the degree in reduction of variation (that I would assume would
occur) and its statistical significance.  Perhaps you have done that
here or in another paper and I have not understood it.

The talk of energy and river plumes inspires me to ask whether there has
been an attempt to measure changes in length of river plumes in
unimpaired and impaired river outflows.  Presumably this would be tricky
to measure because of stochastic variation and because the angle of the
plume might change due to wind and other currents.  But if high
resolution satellite photos or aerial photos were available at say
weekly intervals, one could conduct measurements on plume length.  Plume
length would have implications about the area affected by entrainment
and river-water-mixing processes.

I have read somewhere that silicon is a limiting factor for diatom
growth, perhaps it was in one of your papers, perhaps not - memory is
getting old and impaired!  But apparently rivers are one of the sources
of silicon.  It would be nice to be able to work that factor into
impacts of reduced outflow.  Would it also be reduced because of
particulate capture behind dams, as well as by reduced flow?

One of my particular interests in the effects of dams on coastal-marine
ecosystems is the extent of the impact.  How large a marine area is
affected by the impounding and regulated flows?  That is how many
hundred square kilometres have reduced fish catches, changes in
biodiversity, etc.?  Again, I appreciate that this is a tricky
calculation; one would have to have some cut-off level to demarcate
"impact."

How does the velocity of water in the lower part of rivers change before
and after dams are constructed?  Is there some available data which
could be analyzed?

A point I have tried to draw into the discussion is the reduction in
LOD, large organic debris, or simply small to large fragments of would.
Logs and branches tend to get captured behind dams.  Yet in unimpaired
rivers such LOD formed an important river and marine habitat and food
source.  There is a good book on this topic and I believe in a couple of
months, a conference will be held in western US.

Another issue I tried, unsuccessfully, to draw public attention to in my
little article on Hudson Bay, was the effect of changed flow regimes on
freeze-up and break-up times for sea ice.  I did not have data, but
freshwater freezes more quickly than salt, and the changed coastal flows
would change the degree of open water adjacent to estuaries.  That would
change the amount of sunlight penetrating the water (snow-covered ice
reflects sunlight) and hence phytoplankton production, the amount of
open water available for migrating birds and marine mammals, and gaps in
ice would could initiate more general breakup of sea ice in spring.  But
all that is surmise, but surmise that could be answered by examination
of aerial or satellite photos.

It would be interesting to measure the progressive changes in the St.
Lawrence River estuary and the Gulf of St. Lawrence as dams were built
through the Great Lakes basin.  Here is a river that does not have a
delta, and so differs from some of those that you have studied.

Thanks for writing such as stimulating paper. It is a major
contribution. I do hope that you continue in this line of research.

Cordially,

don
Don McAllister

Philip Raphals
Directeur adjoint
Le Centre Hélios
326, boul. St-Joseph, suite 100 
Montréal (Quebec)
Canada
H2T 1J2

(514) 849-7091 (téléphone)
(514) 849-6357 (fax)

raphals@centrehelios.org
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