The Hon Tony Burke MP
Minister for Sustainability, Environment, Water, Population and Communities
Murray-Darling Basin modelling released
9 October 2012
Minister for Water, Tony Burke, today released the Murray-Darling Basin Authority's modelling for 3200GL and 2800GL scenarios after key constraints in the system have been relaxed.
The modelling showed that by relaxing constraints in the system a better environmental outcome could be achieved under both scenarios.
The current version of the Basin Plan does not include the removal of system constraints. With constraints in place that limit the use of environmental water and taking into account social and economic impacts the authority has proposed a 2750GL reduction in diversions.
The model of returning 2800GL to the environment, after relaxing constraints, shows 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.
Mr Burke said the Gillard Government is committed to reform for the Murray-Darling Basin that restores our rivers to health, supports strong regional communities and ensures sustainable food production.
"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,’’ he said.
"I want to work with the Basin States to provide healthy working rivers and this modelling will assist us in this task.
"I'm willing to work cooperatively to find a pathway which delivers the healthy rivers we need in a way which is sensitive to the challenges faced by rural communities."
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 full report on this modelling is available at www.mdba.gov.au/draft-basin-plan/science-draft-basin-plan/hydrologic-modelling-of-relaxed-constraints