04 February, 2010

Darling River-Flow Variability and Magnitude

At Christmas time the Darling River at Bourke had ceased to flow and real fears were held for the towns future water supply. Irrigation was out of the question. Then it poured across north/western NSW as the remnants of a cyclone made their way across the continent from the n/w of Western Australia.

The Darling River peaked at Bourke on 23rd January at major flood level height of 10.779 metres with a daily flow level of 47,219 megalitres.

Between the 28th December and the 4th February a total of 1,361,842 megalitres of water (almost three Sydney Harbours) flowed past Bourke. It is estimated that 30,000 megalitres was extracted to fields and off-river storage, by all irrigators from Brewarrina to Louth-2.2% of the total flow.

The water kept in the river as a consequence of the Governments (Federal and State) purchase of Toorale Station and its irrigation licenses was approximately 10,000 megalitres-0.73% of the flow. A pretty poor return on $23.75m!!

The river continues to carry a good flow.

Most of the water flowing past Bourke will be stored in the Menindee Lakes Storage Scheme where approximately 50% will evaporate.

As we Australians seek a better balance between socio-economic and environmental needs these sort of numbers and the fact that such events are not atypical, needs to be more widely understood.

2 comments:

Anonymous said...

One does speculate on the hyperthetical possibility of Minister Wong purchasing the Clyde water entitelements at Bourke and Brewarrina ,combining that volume with the entitlements from three other large licence holders at Bourke and then sending the lot down the Darling ,past Menindee lakes and down to the Murry mouth What joy there would be in S.A.! The recreational activities and small volume farming would be temporarily secure and every one will live happily ever after..Except that is for the residents of Bourke and Bre who will no doubt wonder where their next quid is coming from!!!

David Boyd said...

Anonymous, You may well speculate! But, consider the most recent flow event (which is continuing). It is typical of most Darling flow events. All of the Bourke irrigators combined extracted 2% of the flow. 98% flowed past. Do you really believe that that 2% would make a difference at the mouth of the Murray?? I can tell you that they wouldn't notice the difference!Less than 50% of that 2% would actually get there.
If we are serious about getting a better balance,we need to do something about the inefficiency of using the Lower Lakes as a fresh water storage and the massive evaporative losses from there and Menindee Lakes. That would make a difference.

By the way, you don't need FRESH water for recreation. Sydney has some wonderful water recreational activities on SALT water. The Barrages at the mouth of the Murray should be removed.

The good citizens of Bourke should not be sacrificed FOR NO GOOD REASON.