In a bid to discover ingenious ways to save water, Australian scientists have designed a group of compounds that help 'seal' the surface of large dams. These products can save Australia millions of dollars, in water being lost annually by evaporation.
It works this way. An ultra-thin liquid coating called a monolayer will help limit the escape of water vapor, brought about by wind, heat and sunshine.
Currently, the Cooperative Research Center for Irrigation Futures (CRC IF) is evaluating several types of commercial monolayers in New South Wales and Queensland. Meanwhile, initial results have shown monolayer technology to be cost-effective compared to other evaporation control methods.
The spray-on mixture spreads quickly over large water surfaces, forms an environmentally friendly protective layer, and can reduce evaporation loss by up to 40 per cent, say scientists.
Evaporation loss from Australia's two million farm dams is pinned down at 1,320,000 megalitres, which is 2.6 times the capacity of Sydney Harbour, every year.
Across southern Australia, the severely depleted water storages are even more vulnerable to evaporation loss due to their shallow water levels and large surface areas.
Monolayer technology, if widely adopted, could help save available water over the coming hot dry summer, emphasize the scientists.
Fast-spreading monolayers are easy to apply and more affordable than other types of evaporation controls, such as floating covers or shade cloth, according to CRCIF researcher Mr. Erik Schmidt of the University of Southern Queensland.
"While plastic covers are suitable for dams up to five hectares in size, really large dams need another solution, such as monolayers," Schmidt opines.
"Evaporation is a serious problem," warns Ian Aitkinson, CEO of the Irrigation Futures CRC. "For every ten centimeters of water lost by evaporation from a one hectare dam surface, you lose one million liters of water."
He adds:" We need better storage systems. Good dam design and well-positioned windbreaks help, but ultimately we need a durable, affordable and environmentally friendly product that protects water storages from the ravages of our harsh sun and dry climate."
According to Schmidt, even a 30 per cent reduction in evaporation afforded by monolayers will result in significant savings for Australian farmers.
"We could save 260,000 mealtimes of water a year from being lost through evaporation. There would be a dual benefit: it would lead to additional crop production of $130 million and increased environmental flows in our rivers", he adds.
Liquid monolayers can be applied in hot months, or when the cost of water to irrigate crops is high, say researchers.
The costs of application costs are low, less than 50 cents per square meter, as against $6-20 for plastic or shade cloths. Besides, the costs of chemicals are only incurred when the product is applied. The products are safe to use on all types of water storages, stress the scientists.
The factors that affect performance of liquid monolayers are wind speed, water quality and sunshine on product longevity. Meanwhile, the research team from the CRCIF is developing a better understanding of monolayer performance in different conditions.