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The Forum > Article Comments > Drip-fed figures > Comments

Drip-fed figures : Comments

By Jennifer Marohasy, published 31/5/2005

Jennifer Marohasy argues Australia has many options when it comes to providing adequate water supplies.

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A recent report has highlighted another major water source that has been ignored as a result of second rate analysis. An Iceberg had broken away from the Ross Shelf in Antarctica and drifted 1000km to the Casey Station. It held 220 cubic km of water or nine times the total annual runoff of the murray darling basin.

The cost of towing such icebergs to Australia has been assessed in the past but this analysis was based on the cost of fuel and to the comparatively low value of the end product. I have not examined this work closely but it appears that a number of favourable considerations may have been ignored.

The main omission being the extraordinary motive energy available from the winds known as the roaring forties. These winds were vital to the viability of Australian agricultural exports in the 19th century and a detailed costing of wind powered iceberg transport is long overdue for re-appraisal.

Ice is also easily drilled and shaped so there appear to be few technical hurdles to the cutting off and shaping of ice into more streamlined "ship-shapes" that could be augmented by "strap-on" keels, rudders and masts. The size of shaped ice required would rule any spectacular tacking feats but a low cost water delivery system may well be under our very noses.
Posted by Perseus, Tuesday, 31 May 2005 12:19:15 PM
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I don't yet know much about this issue but I must say your email is fascinating and I definitely am going to start finding out more. Wow, what a feat if it were able to be achieved.
Posted by greenman, Tuesday, 31 May 2005 1:31:02 PM
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One option Beattie ought to consider is allowing a reduction of tree cover in the catchment areas of the urban reservoirs. This can be achieved at very little cost and would have added spin-off effects to other land users. In some parts of the world ie Texas USA, landholders are now being paid to clear trees off their land to enhance that city's water supplies. Similarly in South Africa there has been dramatic increases to stream flows from clearing tall woody vegetation from the riparian zone(from 9-44% per 10% of catchment cleared). Unaddressed tree thickening in the catchment areas of SE Queensland's urban reservoirs will result in dire consequences forurban water users. Surely this problem requires a balanced approach, utilising all measures that are available to us to some degree.
Posted by Charlie, Tuesday, 31 May 2005 6:44:51 PM
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The impact of thinning on catchment water yield was made known to the cradle/navel of the green movement, Byron Shire Council, in 2003.
Mullumbimby is facing a serious water shortage from it's dam on the Wilson's Creek and the council was presented with the 1953 aerial photographs which prove that the shires catchments had undergone a three fold expansion in forested area over the past half century, especially since the demise of the Hillcountry Dairies and Banana Growing.

Despite the evidence that overstocking of trees posed a serious threat to biodiversity from wildfire the council has continued with a mix of expensive alternatives and tighter water use restrictions. The species involved in any regrowth thinning would have yielded a profit for the landowners concerned, restored dry season flows to a creek that was once permanent, restored soil moisture profiles to match the original forest profiles, delivered an extra 5000 ml/pa of water to the dam which would then be sold to customers for $5 million. But still, the horse refuses to drink.
Posted by Perseus, Wednesday, 1 June 2005 10:24:53 AM
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It seems to me this is simply a problem of numbers. We only seem to worry about water when our dams get below 50% capacity. Currently, in Sydney they are about 40% capacity.

But if we halved the size of our dams then they would be at 80% capacity and we wouldn't have to worry any more.
Posted by mhaze, Tuesday, 7 June 2005 11:31:08 PM
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