Evaporation solution

Australian researchers are designing and testing new compounds to reduce evaporation from large dams.

Covering large surface areas of water with thin liquid coatings called monolayers can limit the escape of water vapour, leading to big water savings, according to Australian researchers.

The Australian Cooperative Research Centre for Irrigation Futures (CRC IF) is evaluating several types of commercial monolayers in New South Wales and Queensland. Initial results show that the monolayer technology is cost-effective compared to other evaporation control methods.

The spray-on mixture spreads quickly over water surfaces, forms an environmentally-friendly protective layer, and can reduce evaporation loss by up to 40 per cent.

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 Erik Schmidt of the University of Southern Queensland.

‘While plastic covers are suitable for small dams up to five hectares in size, really large dams need another solution, such as monolayers,’ said Schmidt.

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. With dams and large metropolitan water storages losing such vast amounts, the technology could be a godsend to farmers, irrigators and water supply managers across Australia.

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

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