Scientists are designing new compounds to ‘seal’ the surface of large dams and save Australia millions in water being lost annually by evaporation.

An ultra-thin liquid coating called a monolayer limits the escape of water vapour from the effects of wind, heat and sunshine.

The Cooperative Research Centre for Irrigation Futures (CRC IF) is evaluating several types of commercial monolayers in New South Wales and Queensland.

Initial results show monolayer technology is 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.

Evaporation loss from Australia’s two million farm dams is estimated at 1,320,000 megalitres – 2.6 times the capacity of Sydney Harbour – every year. 

The severely depleted water storages across southern Australia 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 what water we have over the coming hot dry summer.

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 CRC IF 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,” says Mr Schmidt.

“Evaporation is a serious problem,” says Ian Aitkinson, CEO of the Irrigation Futures CRC. “For every ten centimetres of water lost by evaporation from a one hectare dam surface, you lose one million litres of water.”

“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 Mr 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 megalitres 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.”

“These figures, based on an estimated eight million megalitres of water stored in Australian farm dams, are conservative.

Some scientists say the potential capacity of farm dams in the Murray Darling Basin alone could be as high as 20 million megalitres, making water savings for farm production and river health even higher,” says Mr Schmidt.

Liquid monolayers can be applied in hot months, or when the cost of water to irrigate crops is high.

Application costs are low, less than 50 cents per square metre, compared to $6-20 for plastic or shade cloths and costs of chemicals are only incurred when the product is applied.

The products are safe to use on all types of water storages.

Factors affecting performance of liquid monolayers are wind speed, water quality and sunshine on product longevity. The research team is developing a better understanding of monolayer performance in different conditions.