New model for improved water forecasting

A new method for forecasting seasonal water allocations could be the “single most important” development to help reduce the impact of the next drought on Mallee irrigators.

The method has already been trialled on the Goulburn River system and was found to be much more accurate than the current method in predicting what water allocations will look like during the course of a season.

Now, University of Melbourne researchers are working with Goulburn–Murray Water, Murray–Darling Basin Authority, the Bureau of Meteorology and the Mallee Regional Innovation Centre (MRIC) to update the model for the Murray River system.

University of Melbourne research fellow and project team member Tristan Graham.

The project was identified as a priority for the Mallee region as part of MRIC’s drought consultations and has been funded by the Australian Government’s Future Drought Fund.

MRIC consultant Tim Cummins said the new method was able to reduce the uncertainty of water allocation outlooks by up to 50 per cent.

“Increasingly we are seeing horticultural enterprises developed in the Mallee with people more prepared to rely on the water market to meet their water requirements each year, and they are going to be the major beneficiaries of this project,” Tim said.

“What it means is people would have more certain information about the water allocations they may get, so they can make better, more definite decisions about what to do with the water – whether to sell, buy or hold – and what crops to plant.

“It should also make the market more efficient because there is more information and more certainty, so people can make decisions with less risk for them.

In times of drought, having more certainty about where allocation levels are going to end up will help minimise the need for irrigators to dry off high-value orchards and vineyards. Drying off crops would result in a significant economic loss in that year. But because we’re dealing with perennial horticulture crops, it would take another four or five years to get those irrigated lands back to full development.

The new method produces water allocation outlooks based on the Bureau of Meteorology’s seasonal streamflow forecasts, which are grounded in the weather and catchment condition of the current year.

In contrast, the old method provides estimates based on scenarios from historical climatic records (e.g., wet, average, dry and extreme dry), and the likelihood of each of those scenarios playing out in the current year is not communicated to irrigators.

Three-month streamflow forecast sourced from the Bureau of Meteorology.

The University of Melbourne’s Professor QJ Wang said while no decisions had been made, Northern Victoria Resource Manager Dr Mark Bailey was keen to implement the new method. This would involve running both methods in parallel to give stakeholders time to get used to the new system.

“With the support of the Mallee Regional Innovation Centre and the Victoria Drought Hub, we are now working to evaluate the technology on the Murray system, which is much more complex,” QJ said.

“This project really needed the help of Goulburn–Murray Water, the Murray–Darling Basin Authority and the Bureau of Meteorology. All the organisations have been enthusiastic and supportive, and what it probably comes down to is that they all see the practical value of the project and the difference it could make to water users and the market.”