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.
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