37TH QUEENSLAND GARDEN EXPO

In 2003, Golden Valley Orchards were offered the opportunity to work with the NCEA (National Centre for Engineering in Agriculture) and NetPro Pty Ltd on a research project evaluating the effectiveness of (among others) NetPro’s dam-covers.

Renato says of his first impressions of the idea: “Evaporation is a pretty big problem – I thought it was definitely a good idea. The only problem was the expense: the cover cost two hundred thousand but we received a subsidy of eighty thousand.”

The dam in question is the main dam for Golden Valley Orchards, holding some twenty-five million gallons (133ML), has a surface area of eight acres (3.3ha). The Golden Valley Orchards extend over 200 acres (83ha), irrigated from this dam and a couple of other smaller dams.

The dam cover was completed by November 2003. Five years down the track, Renato says “We are very happy with it (the cover). It reduces evaporation losses by over 90%, so you could say there was hardly any evaporation.” This is tribute indeed, for according to the Bureau of Meteorology maps, the Stanthorpe region’s average annual evaporation is higher than its average annual rainfall (evaporation 1600mm/year; rainfall 1000mm/year).

The net outcome for Golden Valley Orchards is “we have saved so much water that it’s made a difference between having enough water and not”, says Renato. He continues: “What do we lose here? Over meter a year? Look at that over four years: four meters over the surface area of the dam … that’s a lot of water!”

The original trial results have been reported by NCEA in 2005. An abridged copy of the report is available in our Support section.