W.A. Govt propaganda takes water supply “post rain”

In full page newspaper advertisements in Perth on the 7th and 8th of July the Western Australian government controlled water Authority, Water Corporation, published this graphic with a blue trendline (Govt. statistical experts say 1960-2006 average ??) showing water supply from rain ending in about a decade from now.
WA Govt Perth dam inflow and 1960-2006  trend

The graphic is headlined, “Why we can no longer rely on the rain”.
The graphic above is dodgy in its construction because the stream flow data is certainly not homogenous over its timespan 1911-2006. There is a range of flow data post the 1970′s whereas pre-1970′s the data is ONLY from one tiny catchment, Wungong which is only 3.8% of the area of Perth catchments. Note also this huge change in the data available is exactly at the period of this mid-1970′s fall off in rain and inflows. I have asked WaterCorp for the historic flow data and they refuse to give it to me on grounds I might use it on the internet.

The Govt. Dam inflows graphic conveys more serious mis-information, spin, propaganda, one could say lies, in that the fall off in flows in the last ten years is not due to declining rainfall, to the extent they claim.
Inflows are falling off because catchment vegetation understorey and regrowth is NOT being managed (thinned) as it was pre 1995. My graphic below (added May 2008) demonstrates how catchment rainfall continues in an average band (~900 mm per year each May to October), yet inflows continued to decline.
Post mid 1990's fall of in catchment efficiency
The graphic below from a WaterCorp publication shows clearly the huge benefits of catchment thinning, we could easily aim for inflow yields of 6% instead of the current near 3%. Incremental water production is now priced at an investment of a $Billion per 45 GL of water per year, from the estimated cost of the proposed Binningup seawater desalination plant. That means that just in the four years 2002-2005, by refusing to manage catchments to an average yield of 6%, the Government has wasted inflows of circa 100 GL per year, that would cost an extra $2Billion investment in seawater desalination to produce each year. To put this inflow on scale I have inserted a small 2 on the Govt inflow graph, above the red bar for 1982, when inflows were 98.3 GL. To get that water each year by seawater desalination, which is the direction the Govt. is heading, we need to invest more than $2Billion, then there are running costs and other impacts the Govt. tries to minimise.
It is perfectly clear that if catchments had been sensibly managed post 2001 we would have had an extra ~100 GL per year in our dams over that period and would not have needed to waste precious taxpayer money on high impact seawater desalination.
Huge gains in water yields from catchment thinning
There is an impression out in the media, carefully fostered by Govt., that catchments are being managed. This is just more Govt. spin, in fact Water Corporation are engaged on a 12 year TRIAL, and only in the tiny Wungong catchments, only 3.8% of total catchment area.
For background and possible reasons why the WA Govt acts as strange as it does re water.

Who would have thought we could be so cursed with a profligate multi-$Billion dollar money wasting Government who will not go and sensibly harvest available rainwater.

5 comments to W.A. Govt propaganda takes water supply “post rain”

  • Beachgirl

    I thought you were being tough on the Govt Warwick but then I dug their advert out of the weekend paper and sure enough, a few minutes with a ruler and scale shows that the thick blue line does hit zero flows about 10 years from now.
    Has a drop in rainfall like that ever happened anywhere ?
    It sure is a brave prediction by the Govt.
    Also my daughter who knows more maths than me says the blue line is a TREND not an average.
    Reading your other pages too I am impressed that your Govt assumes the high rainfall years pre 1970′s were “normal”. How can they know that ? Why not view the post mid 70′s years as normal, maybe the earlier years were abnormally wet.

  • Steve Sadlov

    2007 figure must have been taken in the midst of the annual dry – something like Jan 15 – LOL!

  • Brent

    The blue line is more of a line of best fit. You theory on the idea that catchment vegetation in the understory is being destroyed is a possible explanation. I have the idea it is more on the climate change. Areas aren’t getting hotter there just hotter for longer and evaporation rate is now faster than precipitation rate. Because of this it doesn’t rain for weeks anymore as it used to but rains for a day or two and it’s a hot sunny day for another three days and the cycle repeats. Because of this soil that absorbs water is unable to become moist and thick with water making an impermeable layer stopping water from entering the soil and creating runoff. This runoff is the problem because our dams are made so runoff is the main supplier. And as runoff is slowly becoming unavailable the water crisis is created were water is being used up by our growing population and water hungry gardens and appliances. This is what the government should be focusing on and Industry is the main water guzzling culprit using two thirds of the water.

  • WSH

    Brent – The blue line is a ridiculous and laughable prediction unworthy of a modern Govt. Dept. which most people would expect to run on scientific principles.
    You have my point about catchment mangagement wrong.
    The point is that for decades WaterCorp have allowed the catchment bush to grow unchecked, thus constantly driving down the water yield to the dams. The rainfall data clearly shows there has been no trend downward in rain over 34 years. May to October catchment rain averages a very ample 920 mm per year.
    The slogan, “our drying climate” is quite simply a pack of lies. Any minor drying took place in the mid-1970′s.
    I hope you have seen my, “There never was a rain shortage to justify seawater desalination for Perth’s water supply” – note the downloadable word doc.
    Then for Perth hills rainfall updated 1975-2008.

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