The old Navy rule of thumb was to ensure that shipboard desalination
plants could provide 50 gal of water per day per man in addition to what
was needed for propulsion plant needs. That 50 gal figure works out to
just about 192 L daily for each man or about 70 m3 per man per year.
Those human needs include drinking water (the rule was prevalent in days
of non-air-conditioned ships!), showers, laundry, and cooking.
Once we get our new house built (soon, I hope!) we will look at the
expense of installing tanks and gutters to capture the rainfall from its
roof and that of our tractor shed. Recently we had a moderately heavy
rainfall of nearly 50 mm. That house runoff would have amounted to about
6 m3 and the tractor shed's runoff would have amounted to about 4 m3. I
won't say that such runoff is wasted, since we are sitting on a 100 ha
farm and that water supplies some of the needs of the pasture land and
forest around us. But it might be nice to redirect the runoff to the
gardens and livestock.
Jim
Michael Payne wrote:
Interesting that most of this water requirement is for agriculture. I
looked at my water usage at home and it varies each year depending on
how much I water my lawn in summer. Last year we used about 6,3 cubic
meters for two, the previous year we used 11 cubic meters. This is
showers, laundry and watering the garden when required, normally July
August. Bear in mind I'm gone a lot and use hotel water. Still it does
not seem like a lot of water when I compare it to the 1000 cubic meters
needed per person in the article below.
On another note, I read recently that it's illegal in a couple of
western states to collect rainwater off your roof. In Colorado they are
trying to change the law.
Mike Payne
----- Original Message ----- From: "James R. Frysinger"
<[email protected]>
To: "U.S. Metric Association" <[email protected]>
Cc: <[email protected]>
Sent: Saturday, 13 June 2009 13:36
Subject: [USMA:45230] Precipitation and water needs
I participate in CoCoRaHS (http://www.cocorahs.org/), an organization
that collects daily precipitation observations from a rapidly growing
network of nearly 10 000 volunteers in the U.S. (Please consider
joining!) After the daily report has been submitted the acknowledgment
page appears and it contains some sort of anecdote, which changes
periodically. Below my signature is the one that appeared today.
It's nice to see that this anecdote is entirely metric (with but one
exception), as is our National Weather Service. Ironically, CoCoRaHS
requires non-metric values from its volunteers; everything is measured
in inches on their reports.
I have my Davis Vantage PRO 2 weather station set up to read out in
metric units and must then do a conversion to submit my precipitation
reports. Since NWS keeps its records in metric units, it would be nice
if CoCoRaHS migrated in that direction. They could start by allowing
metric data submission as a option and then migrating their volunteers
toward using metric rain gauges, etc.
The anecdote reproduced here then would be immediately relevant to the
volunteers, since one liter is the same as a millimeter of rain
falling on one square meter of surface. And of course one cubic meter
is the same as 1000 liters.
My records show that my 100 hectare farm received 1208.3 mm of rain
last year, a droughty year since the normal for this area is closer to
1500 mm. Still, that means that 1.2 million cubic meters of rain fell
on my farm in 2008, enough to "support" 1200 people. That's the beauty
of the metric system -- ease of calculation. So one can calculate the
area of some location in square kilometers and then look at the annual
rainfall there. Every millimeter of rain that fells on each square
kilometer of that location is the amount needed by one person -- one
to one!
My mode of getting that water to them was provision of timber, eggs,
and cattle as well as potable runoff (downstream and via aquifers).
Jim
Water Footprint
The minimum water that each person requires, on average, for drinking,
hygiene and growing food is about 1,000 cubic meters per year. That's
about 2/5 of an olympic size swimming pool. Because the distribution
of global water resources varies widely, some people get much more
than this and some people get less.
Researchers have recently developed the concept of a "water
footprint". As indicated on the water footprint web page
(http://www.waterfootprint.org), “The water footprint of an
individual, business or nation is defined as the total volume of
freshwater that is used to produce the goods and services consumed by
the individual, business or nation.”
You can figure out your own water footprint using the calculator
(quick and more extensive versions) on this site as well learn the
total water required to produce various products. Some interesting
facts about our water use from the water footprint web site:
* *The production of one kilogram of beef requires 16 thousand
litres of water.
* *To produce one cup of coffee we need 140 litres of water.
* *The water footprint of China is about 700 cubic meter per year
per capita. Only about 7% of the Chinese water footprint falls outside
China.
* *Japan with a footprint of 1150 cubic meter per year per capita,
has about 65% of its total water footprint outside the borders of the
country.
* *The USA water footprint is 2500 cubic meter per year per capita.
In addition to the water footprint web site, check out the
August 2008 issue of Scientific American to learn more about the
global variability of fresh water.
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
