The Coalition proposal to dam rivers in northern Australia to create a massive food bowl has been floated before, as have various schemes for harvesting water from what is perceived to be the over-watered and under-populated north and redirecting it to the under-watered and populated southern regions of the country.

Both of these ideas are superficially attractive, especially when you sit in an office in water-restricted Canberra, Sydney, Melbourne, Adelaide or Perth, look at a map of Australia and see that 60% of the continent’s runoff is in the north.