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
