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Re: orion-list Dr Falk's 10 hours

Hi, David West,

Happy to hear that you researched water needs before backpacking around the
Grand Canyon... the resemblance to Qumran, however, is indeed modest. The
Colorado River runs through there, the pine forests run nearly up to the
Park, and the North Rim is closed in winter due to heavy snow. A better
comparison would be the desert near Yuma, or The Saguaro National Forest
south of Ajo.

>Hard science on the water consumption of hardworking, sensible
>people who adopt intelligent strategies to avoid the heat of the
>day may not exist.

Oh, they exist all right; a great deal of research has been done on the
subject. I gave two already. (Adolph's was BG -- before the creation of
Gatorade ca. 1970's.) The internet is a great resource for Mac-Information,
but when it comes to serious research, the library beats it all hollow.

Of the several hundred items that turned up on a quick search of LOC, I
pulled out 47 refs directly relevant to this discussion -- all with bibs,
in just 25 minutes.* These range from studies concerning: Libya to Bursina
Faso, from India to Australia, from Israel to Japan, from the USA to the
Sudan. Works appear written in, for example, English, Japanese, Polish,
German, French, Turkish, and Hebrew. There are studies for design engineers
and studies on Israel's climate problems; one performed at the request of
the Mandate officials. None of these studies has anything to do with athletes
and everything to do with living and working under high heat conditions.

>The largest consumption number that I have seen is "4 to 8 oz. every 15
>to 20 minutes during heavy exercise". Strangely, that range stretches from
>.75 liters per hour (your experience, Dr Falk) to 2 liters per hour (Dr
>Altman's conservative number.) The citation for that figure is a bit tricky.

Not too surprising <G> as both figures are correct. Consumption is directly
proportional to loss which depends upon many factors of which the most
important are: ambient temperature, nature of the physical labor, advective
loss (i.e increased evaporation due to wind), and solar radiation (ambient
temperature only measures the temperature in the shade). Note that the
radiation figure is strongly affected by clothing; even one extra layer of
loose cloth can reduce its effect substantially.

Cheerfully yours,


* If anybody would like the bibs, please contact me privately.
Dr. Rochelle I. Altman, co-coordinator IOUDAIOS-L  risa@hol.gr

For private reply, e-mail to "Rochelle I. Altman" <risa@isis.hol.gr>
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