The idea was considered in the 19th century, but was found to be infeasible basically due to the elevation and evaporation rate of Lake Eyre.
The (very expensive!) book "Inter-Basin Water Transfer: Case Studies from Australia, United States, Canada, China and India" covers three schemes that were proposed to fill Lake Eyre in the past.
For a natural-flowing canal, it would be 3m deep at the top of Spencer Gulf, have a fall of about 3cm/km and be some 1.8km wide to yield a flow rate of 0.3m/s that would be enough to keep the lake filled. However, salt deposits would quickly build up and reduce the effectiveness of the canal. At some stages the canal would need to go through 60m+ cuttings to traverse a rise that separates Lake Torrens and Lake Eyre South. Concern was that there was no guarantee that the canal would work (sufficient water would flow through it under gravity) nor that evaporation would increase precipitation, as evidenced in other similar areas around the world.
I do think the proposal should be re-investigated today with our increased understanding of engineering and climate. It might even be feasible to construct a pipeline and pump and siphon water to the lake. Or even to just pump water to Lake Torrens (about 30m above sea level) and then let it flow via gravity into Lake Eyre South. Libya's "Great Man-Made River" project is laying thousands of kilometres of 4m diameter pipe to bring bore water from hundreds of metres under their arid interior to their coastal cities and open the interior to agriculture. However there is still the problem of accumulation of salt in the lake bed over time.
Instead, I think a better option is to build the world's biggest desalination plant at Port Augusta and pump fresh water inland to establish forests and agriculture. The brine would be pumped into Lake Torrens or salt pans constructed in the low-lying area between Port Augusta and Lake Torrens and could be harvested for industry like at the salt pans near Adelaide.
- Hey awesome research/feedback there - I knew it had been considered in the 19th (or early 20th) century, but my last search hadn't come up with any further details. That is a hell of a big canal for the natural-flowing water to sustain the lake...
- The "reinvestigation of the idea today" is in part what I hope my page here might accomplish, should it ever get wider exposure. Ideas sometimes need to be re-considered with advances... thank you. (who are you btw? :)
- --Nemo 13:33, 23 October 2008 (EST)