Dear John,
Thanks for the correction. I simply cut and pasted the article without
reading it carefully. I will watch the 'Geelong Advertiser' more
closely in future.
By the way, the few water engineers that I know have developed a
mindset where the unit megalitre is used for capacities and they have
a sense of how big the dams in our system are, see http://www.barwonwater.vic.gov.au/index.cfm?h2o=services.water_levels
, and they don't see a need to convert between megalitres and cubic
measures of any kind; they just develop their megalitre mindset and
then base their reference values using that unit.
Another aspect to the use of megalitres is that there is no fear of
large numbers. Water engineers, like many others, have simply chosen a
unit where almost all, if not all, of the values they use daily are in
whole numbers, which is one of the great strengths of the metric
system. It is possible to choose prefixes for units so that there is
never any need for fractions at all. See http://www.metricationmatters.com/docs/WholeNumberRule.pdf
for some further thoughts on this issue.
Cheers,
Pat Naughtin
Geelong, Australia
On 2009/04/12, at 12:22 AM, John M. Steele wrote:
Indeed, there is a prefix error. This "facts & figures" page
http://www.barwonwater.vic.gov.au/cms/serveDoc.cfm?docId=24911
indicates Barwon water supplies 32000 ML of water annually,
processes 21000 ML of sewage, and serves 270000 customers (that is
apparently population, as household connections is less than half
that, 131000). Thus average household use is therefore around 244
m³ per year.
A thousand-fold error should cause a "whoa, wait a minute"
response. I believe the fact that it didn't is adequate evidence
that megaliters, gigaliters, and teraliters (even with "re"
spelling) are not very intuitive units and throw a great cloud of
confusion over any attempt to visualize or sanity check the amount.
Any form of proper cubic measure, from 32 x 10^6 m³, 32 million
cubic meters, 32000 dam³, 32 hm³, would be a more suitable way to
convey this information, and be less likely to obscure a thousand-
fold error.
Teraliters are frightening.
--- On Sat, 4/11/09, John M. Steele <[email protected]>
wrote:
From: John M. Steele <[email protected]>
Subject: Re: [USMA:44564] Re: FPLA 2010
To: "U.S. Metric Association" <[email protected]>,
[email protected]
Date: Saturday, April 11, 2009, 8:59 AM
You have proven megaliters, gigaliters, and teraliters are used.
That is a staggering amount of water given Geelong's population.
Where does it all go? Irrigation? If I compare with Detroit,
private consumption and industry can't account for much.
A volume of 32 TL/annum meant absolutely nothing to me, a completely
incomprehensible number. Some manipulation led me to it being 32
km³ per year, giving me some sense of what you do to the river. It
also works out to a withdrawal of 1015 m³/s.
It still seemed large, so I compared it to the Detroit River (part
of the connection between Lake Huron and Lake Erie, and the Detroit
Water Dept, which serves a metro region of about 5 million people.
The Detroit River flow varies typically from 4500 m³/s in low lake
level years to 6500 m³/s in high lake level years. The Detroit
Water department handles an average of 673 million gallons per day,
by their figures. Converting, this is 0.93 TL (or km³) per year
(29.5 m³/s) for 5 million people. That figure is reasonably
consistent with my household use of 273 m³/year)
As we use less than 1/32 the water for about 25X the population (is
Geelong under 200,000?), I wonder if there isn't a prefix error in
that news article. (If it isn't an error, you guys need more
conservation effort!)
--- On Sat, 4/11/09, Pat Naughtin
<[email protected]> wrote:
From: Pat Naughtin <[email protected]>
Subject: [USMA:44564] Re: FPLA 2010
To: "U.S. Metric Association" <[email protected]>
Date: Saturday, April 11, 2009, 12:00 AM
On 2009/04/11, at 1:35 PM, Jeremiah MacGregor wrote:
I can see where the terms megalitre, gigalitre and teralitre would
be less cumbersome for the public then their equivalents of cubic
dekametres, cubic hectometres and cubic kilometres.
Dear Jerry and Stan,
Here is an example of the use of gigalitres from our local paper,
The Geelong Advertiser, from October last year. Barwon Water is our
local water supply organisation as we get most of our water from the
Barwon river.
http://www.geelongadvertiser.com.au/article/2008/10/24/26151_news.html
Cheers,
Pat Naughtin
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that
they now save thousands each year when buying, processing, or
selling for their businesses. Pat provides services and resources
for many different trades, crafts, and professions for commercial,
industrial and government metrication leaders in Asia, Europe, and
in the USA. Pat's clients include the Australian Government, Google,
NASA, NIST, and the metric associations of Canada, the UK, and the
USA. See http://www.metricationmatters.com for more metrication
information, contact Pat at [email protected] or
to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter
to subscribe.
Pat Naughtin
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that they
now save thousands each year when buying, processing, or selling for
their businesses. Pat provides services and resources for many
different trades, crafts, and professions for commercial, industrial
and government metrication leaders in Asia, Europe, and in the USA.
Pat's clients include the Australian Government, Google, NASA, NIST,
and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com
for more metrication information, contact Pat at [email protected]
or to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter
to subscribe.
