The Blog

A Note on Murray River Salinity

Posted on: September 13th, 2011, By: admin, 1 Comment

Rising river salinity levels were an issue in the Murray Darling until the construction of salt interception schemes and the implementation of the Salinity and Drainage Strategy in the 1980s.     When the comprehensive strategy to reduce salinity was put in place Morgan, a town just upstream of Lock 1, was chosen as the key indicator locality for the entire Basin [1].

Daily salinity readings are available for Morgan from January 1938 to the present [2].   Low flow conditions associated with drought are normally associated with higher river salinity levels [3].  During the drought of 1975 and 1982 levels were relatively high at 1,560 and 1,425 EC, Figure 1.     However, during the recent drought river salinity levels continued to fall consistent with the trend of falling salinity since implementation of the comprehensive salinity strategy [4].

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The Disputed Natural History of the Lower Murray

Posted on: July 24th, 2011, By: Jennifer Marohasy, No Comments

MOST of the water the Murray Darling Basin Authority plans to take from irrigators under its new plan will be sent to the Lower Lakes in South Australia ostensibly to keep the River Murray’s mouth open and the Lower Lakes full of fresh water. An alternative would be to let the Southern Ocean flood through the River’s mouth and fill Lakes Albert and Alexandrina with sea water. This salt water solution is being resisted on the basis the lakes were naturally fresh but that is not what the microfossils in the sediment of the lakes indicate.

It is not contested that the lakes formed approximately six thousand years ago when the Southern Ocean broke through the modern coastal sand barriers of Sir Richard Peninsula and Younghusband Peninsula filling the interdunal areas. That point of entry, now known as the Murray River’s mouth, remains dynamic and has moved 6 kilometres over the past 3000 years.

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Award for Yarra, Makes Mockery of Murray Darling ‘Crisis’: Danny O’Brien

Posted on: June 29th, 2011, By: admin, 1 Comment

The short-listing of Melbourne’s Yarra River for the International Riverprize, billed as the “world’s most prestigious environmental prize”, just goes to highlight how farcical the debate over river health has become.

The National Irrigators’ Council said while the Yarra is being lauded as among the world’s best, the Murray-Darling Basin – which has more water available for environmental flows – is said to be in “crisis” and need of “saving”.

“For all the hand-wringing over the health of the Murray-Darling, it’s salient to remember that it has 58 per cent of flows available to the environment[1], while the Yarra has only 57 per cent,[2]” said NIC CEO Danny O’Brien.

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End the Barrage of SA Spin

Posted on: June 26th, 2011, By: Jennifer Marohasy, 1 Comment

IT is time to get angry about all the misinformation spun by South Australian politicians over so many years about the Murray River.

The latest piece of nonsense is from Dean Brown, South Australian Liberal Premier from 1993 to 1996, claiming in last week’s The Land newspaper that without the barrages there wouldn’t be enough sea water coming in through the Murray mouth, or fresh water down the river, and so the lakes would become hypersaline (The big barrage question, June 16, page 12).

It may be the case that during drought there is not enough water coming down the river, but as long as the barrages are open the Southern Ocean will push in. This has been the case at least since European settlement and it is the same situation with the large east-coast Rivers including the Fitzroy in Central Queensland and the Clarence in northern NSW.

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Calculating Evaporation from the Lower Lakes

Posted on: June 15th, 2011, By: Jennifer Marohasy, 1 Comment

Water reform in the Murray Darling is focused on restoring end-of-system flows which means in large part taking water from upstream environments and communities and sending it to the Lower Lakes.

This terminal coastal lakes sytem was once tidal, but since construction of a series of barrages has been managed as an artificial freshwater oasis. In an article in The Australian newspaper in July 2008, Tim Flannery is quoted suggesting that opening the barrages and letting the area flood with seawater would save 1,300 gigalitre of freshwater that would otherwise be lost to evaporation.[1]

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