Dear Jennifer,
I have enjoyed reading Mark’s articles at On Line Opinion entitled ‘Fired-Up Forests Have More Impact than Loggers’ and agree with much of what he says. But he must check his facts regarding thinning in Perth water supply catchments.
The Wungong catchment is only 3.8% of the area of Perth catchments. So it is incorrect to say, “Western Australia has been quick to take advantage… ”
This thinning is only a tiny trial, just a PR effort so the West Austraslian government water organisations can trumpet that they are doing something and most of what they say has to have spin “fine tooth combed” out before truth emerges.
The reality of what is happening in Perth water supply catchments can be seen in my graphic at http://au.geocities.com/perth_water/ scroll down to, “Graphic of Catchment Efficiency 1980-2005 showing disastrous falloff 1996-2005 after ceasing catchment management.” Click on thumbnail for a larger graphic.
It is perfectly clear from my graphic that the West Australian government is de facto decommissioning Perth catchments. If catchments had been managed post 1996 as they were before that date so as to keep yields steady, Perth would have enjoyed about 90 GL extra water per year on average. Equal to production from two Kwinana sized seawater desalination plants, which require an investment of about $500 million each now. That puts on scale the cost of catchment neglect.
This colossal bungling extends into other areas of water resources.
North of Perth a pine plantation at Gnangara suppresses the potential of the groundwater there by about 100 GL per year. With incremental water valued by investment required in seawater desalination, Govt claims that the pines are needed to support a proposed plywood industry is simply ludicrous. Timber can easily be sourced on the open market if anyone is of a mind to make plywood and the pines must have a negative net present value now in view of their manifest billion dollar damage to groundwater potential.
The Avon, Murray and Collie Rivers pass about twice Perth’s total water consumption each year but in a weakly saline state. Surely desalination of a small part of these flows would be cheaper and lower impact than seawater desalination and could take place away from the fragile and crowded coast. In fact a private company, Agritech has been valiantly trying to interest the government in a proposal to desalinate water currently wasted to sea each year from the Wellington dam near Collie. This proposal would be at no capital cost to government and would produce water at half government desalination costs and would I am told use gravity in the process thus cutting back greatly on electricity.
Perth is not running out of water, the water is running out of Perth.
The Ancient Romans were vastly better water managers than the West Australian government.
Regards, Warwick Hughes
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.