If you were to float a paper boat in flood-stricken Tamworth, in theory it would drift 1000 kilometres into Menindee Lakes six weeks from today. But there its journey would end.
The flood dumped on the New England region by 160 millimetres of rain in 24 hours this week will take weeks to creep through the meandering network of river systems across north-west NSW and do little to ease drought conditions for any distance downstream, according to a Newcastle University environmental engineer, Professor Gary Willgoose.
The flood is a bonanza for local irrigators along the banks of the Namoi River, where cotton is the main summer cash crop and about 50 extra-allocation water licences have been granted this week, but barely a trickle will get beyond that to the Darling.
About 135,000 megalitres of extra water will flow out of Tamworth's swollen Peel River and into the Namoi as a result of the flood, said State Water's northern manager, Craig Cahill.
"I think we'll see about 45,000 of these pumped out by the irrigators, which is not as much as they could take, because the water is moving a bit too fast for the pumps," Mr Cahill said.
"We are looking at 50 to 60 pump sites that have expressed an interest in accessing those flows."
Professor Willgoose estimated that if everyone holding a valid water licence in northern NSW was able to access the amount they are entitled to on paper, the rivers would be pumped completely dry.
"This has been a big problem for the national water inventory," Willgoose said.
"Even more worrying, you have farmers who have taken out bank loans on the basis that they can grow crops using the entitlements, so you have numbers of them who are technically bankrupt at the moment.
"That is before you start looking at the issue of environmental flows and recharging the wetlands."
Despite the grumbles of downstream graziers, the real reason why the flood will not ease the drought much beyond its own neighbourhood is 13 million years old.
A chain of huge volcanoes erupted across New England in prehistoric times, sending lava out across the landscape and laying the basalt foundation for the richest farming soil in the state.
The black soil of the Liverpool Plains also absorbs water like a sponge and the flood will replenish local aquifers that have been undernourished for at least five years.
"Most of it would certainly be percolated into the ground water," said Dr Glenn Wilson of the University of New England's School of Environmental and Rural Science.
"I'd also expect a fair bit of it to get absorbed by the banks, which are spongy. Most of it will simply soak away."
Professor Willgoose gave the mythical paper boat borne on the Tamworth flood "fifty-fifty" odds of reaching the Darling River but said its chances of sailing on to the Murray were "hundreds to one - or nil".
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