Government releases Murray-Darling Basin modelling
The Federal Government has released the Murray-Darling Basin Authority’s modelling for 3200 GL and 2800 GL following the relaxing of key constraints in the system.
Federal Environment Minister, Tony Burke, said the model of returning 2800 GL in environmental flows, after the relaxing of constraints, shows an overall improvement in peak and frequency of high flow events but not enough to reach any more indicator targets.
Returning 3200 GL to the environment and relaxing constraints show an improvement from both 2800GL with constraints removed and previous modelling of 3200 with constraints in place.
"Importantly, this modelling shows that with constraints relaxed, there are improved outcomes for the environment, particularly the Murray River, its main tributaries and the Coorong, Lower Lakes and Murray Mouth,” Mr Burke said.
The improved environmental outcomes from a 3200GL scenario, with constraints relaxed include:
- Meeting five of the previously unmet high flow targets at iconic environmental sites including Australia's largest two river red gum forests - the Barmah Millewa and the Gunbower-Perricoota-Koondrook forests and at the Hattah Lakes system.
- The Murray River floodplain downstream of the Darling River junction could receive flows up to 80,000ML/, benefiting more than 30,000 ha of wetlands and vegetation including the majority of the internationally listed Riverland-Chowilla Ramsar site upstream from Renmark in South Australia.
- The River Murray floodplain inundation will improve from once every eight years to once every five years, resulting in healthier forests and wetlands.
- Improved health of the important Red Gum and Black Box woodland.
- Improved indicators in the Coorong, Lower lakes and Murray Mouth such as salinity levels while maintaining the achievement of flow based indicators.
The key constraints that were relaxed in the model included the amount of water that can be released from Hume dam down the River Murray, from Menindee Lakes down the Darling River and changes to peak flows from the Murray's other main tributaries, the Murrumbidgee and Goulburn Rivers.
The Victorian Government has urged the Federal Government to reaffirm the MDBA’s previous recommendation of 2,750 for environmental outcomes, saying that a 3,200 gigalitre environmental flow would gave a ‘significant socio-economic cost’ for local communities.
The State Government also took the opportunity to slam the South Australian government for being ‘absolutely hypocritical’ in its demand for 3,200 gigalitres while it aims to use the Murray water to bolster its drinking water supplies and mothballing its desalination plant.
The full report on this modelling is available at www.mdba.gov.au/draft-basin-plan/science-draft-basin-plan/hydrologic-modelling-of-relaxed-constraints