Below is a link to an article on the Flinders/Liechardt rivers water.
www.clw.csiro.au/publications/waterforahealthycountry/nasy/documents/GulfOfCarpentaria/NASY-Flinders-Leichardt-Region-factsheet.pdf
Your link while interesting is rather optimistic on greening Australia and the amount of water available from Northern coastal streams. Do some maths on how much water you need to water 1 square km - 1 GL will give you the equivalent of 1mm of rain over 1 sq km. That wouldn't lay the dust out west let along grow anything significant. Perhaps - given time, reforestation would increase natural transpiration & rainfall over the area but Australia is a dry land. Also diverting too much water from coastal streams will affect coastal ecology and industry - prawns would be affected by lack of flows in gulf rivers for instance.
It is very difficult to understand all the impacts of such large projects. We may be better off investing in more closed ecology/hydrophonic type systems that minimise water loss though it may mean dietary adaptions.
