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Archive for the ‘Evaporation’ Category

New policy-plan: NSW towns to purchase water on the open market in deal to go level 4 to level 3a, others must plan to truck water, open channels banned

Posted by waterweek on 28 September 2007

The NSW Department of Water and Energy, said sufficient water will be provided to all towns to meet demands under Level 4 restrictions. Level 4 restrictions would continue until allocations of at least 20 per cent for high security licences were announced.MBDC flows

New idea: An option was currently being considered that would allow towns to purchase water on the open market if they wish to ease the level of restrictions from level 4 to level 3a. This would be on the basis that towns acquire 20 per cent of the volume to meet level 4 restrictions for that month. Read the rest of this entry »

Posted in agriculture, Allocations, australia, Drought, Emergency, Evaporation, Irrigation, Murray Darling Basin, New ideas, nsw, Policy, Regulation, Town Water, Trade, Water Markets, Water Trade | Leave a Comment »

Armageddon mode: South Australia stops River Murray water flow into Lake Bonney, as moves to disconnect 27 wetlands, to secure downstream flow

Posted by waterweek on 28 September 2007

According to townspeople in Barmera, the State Government’s stoppage of River Murray water flow into Lake Bonney on Tuesday was the “death knell” for Barmera, reported Doug Robertson, in The Advertiser, (27/09/2007, p.18).

Residents contemplate class action: Save Lake Bonney Group organiser Mark Beech, who ran Barmera Backpackers, said business people in the town were considering a class action against the Government for economic loss. He said Lake Bonney would be “dead” if the fresh water supply was cut off for several months.

Supplies cut: Earthmoving equipment moved in on Tuesday, making a 20 metre “temporary” earth barrier across Chambers Creek near Nappers Bridge, about 5 kilometre from the town centre. The Government had cut off River Murray water at 27 sites.

Govt defends action: State Water Security Minister Kaylene Maywald said discontinuing River Murray water from wetlands and lagoons was an emergency response to the drought.

Posted in australia, Drought, Emergency, Environmental Flows, Evaporation, Murray Darling Basin, South Australia, Wetlands | Leave a Comment »

CSIRO cuts evaporation with water basins cover of special semi-permeable shade cloth; evaporation drops 10-fold in Vic test, from 29 megalitres to 2.9 megalitres

Posted by waterweek on 14 September 2007

A project to shade water basins to stop toxic algal blooms from forming has had an unexpected, but welcome, outcome: water loss from evaporation has also dropped dramatically, according to CSIRO publication SOLVE.

No algae: A solution to the problem – exposure to the sunlight that promotes algal blooms – has been to cover water basins with a special semi-permeable shade cloth. In a two-year $1 million trial the covers successfully inhibited the algal blooms, which are costly to clean up, and greatly reduced evaporation. CSIRO’s Dr Niall Finn said that shade cloth, which can be suspended above the water so maintenance work is not hindered, blocks 98 per cent of the light. This prevents the algae from photosynthesising.

And less evaporation: This was the expected outcome, but the bonus has been the effect on water storage. In the Mallacoota basin in Victoria, evaporation loss fell from about 10 megalitres a year to just one megalitre. Across all the covered basins evaporation was cut 10-fold, from 29 megalitres to 2.9 megalitres. “These shade cloths can be used anywhere and would be especially valuable in hotter areas where evaporation is even higher and algal bloom incidences are more prevalent,” Finn said. “They would have a benefit anywhere in Australia, but there may be a limit to the size of storage you can reasonably cover; some larger reservoirs are many hectares in area and even form part of the local ecosystem.”

Experiment to test shade cloths: From 2004, six water basins within East Gippsland Water’s region were monitored for two years. Four of the basins – at Omeo, Swifts Creek, Mallacoota and Cann River – were covered with shade cloths and two were left uncovered as controls. The trial was a collaboration between CSIRO, which conductetd the research, Gale Pacific, which made the shade cloths, Superspan, which made the cover structures that held the cloths in place, and East Gippsland Water. The shade cloths had to be strong, durable, UV-stable, resistant to abrasion, flexing and heat, and be able to sustain tension for long periods in extremes of heat and cold and in windy conditions. They are knitted from high-density polythylene monofilament yarns and tapes and supported externally by steel cables and poles from the basin banks.

Ready for use everywhere: Gale Pacific’s chief executive Peter McDonald says he is confident the cloths will be used by water boards around Australia, and possibly abroad.

Reference: SOLVE August 2007. Telephone enquiries: 1300 363 400; email: solve@csiro.au; website: http://www.csiro.au

Erisk Net, 13/8/2007

Posted in algae, australia, Drought, Evaporation, Victoria, Water Week Vol 0411 | Leave a Comment »