There were suggestions over a century ago to re-create Lake Tritonis in northern Africa.
There were serious proposals to dig a canal from the Mediterranean to the below-sea-level depression. Various locations were suggested, including Libya and the Qattara depression in Egypt.
Of course, the water would be salt, not fresh, as the original Tritonis was supposed to have been, but it was still claimed that the presence of a large body of water, salt or fresh, would moderate the climate, and water evaporating from the lake and precipitating out as rain would be fresh.
Jules Verne even wrote a novel about such a project, The Invasion of the Sea ( L’Invasion de la mer ) , which had not been translated in English until 20 years ago. The novel climaxes with the destruction of an invading horde by the inrush of the Mediterranean breaking the last barrier between the sea and the newly-built canal.
The OP’s ideas are frankly ridiculous. On the scale of continents, Lake Eyre is tiny. On the scale of human endeavors, digging an artificial lake, artificial canals, and desalinating sea water on those scales is ginourmous.
I’m a decently strong guy for my size & age. I work out. If I really dedicated myself to weightlifting and started shooting steroids I could probably bump up another 50%. But try as I might, I’m not gonna get strong enough to lift a 4 story office building.
That’s the level of scale disconnect the OP is waving away as trivial details.
But he did provide a nice map. The percentage of Australia below 300m elevation is pretty big. Ballpark 2/3rds of the total. The map doesn't show a 150m contour, but some rules of thumb indicate that would be very roughly 2/3rds of the 2/3rds or about 45% of current Australia's land area.
All we need to do is wait for sea level to rise 150m and Australia will have lots more coast, lots less arid interior, and might, just might, be split into 2 halves.
Some of that new coast will have a nice climate. But no beaches. They take a lot longer to form than it’ll take for sea level to jump that much.
Probably the key problem is trying to make an inland sea is the evaporation rate. Sure, dig canal 500 km from the sea. Now if we assume we will just be filling Lake Eyre, which whilst big, is hardly an inland sea, lets think about how much water you will need to keep it filled. Usefully the Oz BOM provide a starting point here. About 3 metres of water per annum. Now Lake Eyre is 9,500 km² in area. So that is about 3 x 10^10 cubic meters a year in evaporation. Or roughly 1000 cubic meters a second. If we had our 4.9m diameter tunnel, the speed of water in the tunnel would be of the order of 50 m/s, or 110 miles an hour in US money. Not doable. Water doesn’t flow like that.
Over a long distance where the only impetus for flow is an almost zero slope, it is mostly like an old river. That means a very large channel and slow. The Mississippi flows at maybe 17000 cubic metres a second. So we need a channel say 1/20th the size of the Mississippi, just to keep pace with evaporation. Australia is very very flat, sure Lake Eyre is below sea level, but the slope is one metre in about 30 km at best. And we want to fill it to sea level. So the flow is going to be very very slow. It is going to be a bigger channel than 1/20 of a Mississippi. And we have hardly made an inland sea. Just a largish lake. As a good approximation we would be looking to build something of the scale of the Mississippi in width and length.
Now the killer. Salt. At 15 meters deep the lake will turnover its contents in less than five years due to evaporation. In reality it isn’t 15 meters deep everywhere and it takes less than this. So the salinity doubles after a few years (ignoring that the lake is already filled with salt, just to jump start the process.) After a decade the lake will be super saline. You can forget it supporting any life. A few more decades and it would be solid.
Desalinated water? Well desalination of seawater can be done as efficiently as 3kWh per cubic metre. So maybe only about 10 gigawatts of power generation needed. 7x24. The Three Gorges power generator in China can manage 18 gigawatts. But Oz is flat, so cheap hydro is out. Solar is the obvious answer. Say we get the price down to 10 cents a kilowatt hour. 30 cents per cubic metre. That is only 10 billion dollars a year in energy costs to stop the lake evaporating. If we could somehow afford to desalinate that much water we would not be leaving it out in the sun. We would be irrigating with it.
I am reminded of Lex Luthor in the first Superman movie making the San Andreas fault open up to create new absolute water-frontages for his worthless desert land.
There have been repeated proposals to do just what PlaceboTarget suggested.
A good place to start reading about these is Michael Cathcart’s The Water Dreamers.
Perhaps the one that strikes me as most similiarly realistic [but not in the book] is the recent ‘Tilt Australia’ scheme - - YouTube, which garnered great support in the early 2000s.
From GuanoLad’s map, a worthwhile inland sea/lake would need to be at least as big as Poland to be worth the outlay. That’s 300,000 sq kilometres of Francis Vaughan evaporation maths, per annum, for ever.
Why not restore the Western Interior Seaway while you’re at it? Much of North America was Mediterranean or Tropical in climate, and its not like you’d be flooding anything important anyways! [/sarcasm, obviously]
Yes, indeed. But with a territory almost the size of Europe, it has a population a little higher than that of Romania.
As I have already said before, Australia could enjoy larger areas of mild weather with the aid of an inland sea (or large lake). I don’t believe it would be a futile effort. Too costly to be worth it? Maybe. But if scientists working on methods of terraforming make any significant progress, I’m sure Australia will be able benefit from their know-how.
I would love to be able to offer a solution. I think that if there is any solution, it must refer to a gradual process where areas of vegetation are created and used as bridge heads to develop permanent green areas along canals and around the lake. Depending on how these new green areas are engineered, the water can be retained successfully and a local water cycle can be put into practice. But I don’t really know how this can be implemented technically speaking.
What makes you think they want a larger population?
And how would your scheme affect all the unique Australian animals, insects, and plants?
Perhaps the people whose traditional tribal areas would be lost might also have an opinion?
It would require decades of study simply to determine the probable effects, and it would be highly controversial to say the least. If you’re going to spend that much money and effort, there are probably many better things to use it for.
I understand that my vision does not correspond with your vision. This is not relevant.
My question refers to the technical possibility of creating an interior large lake in Australia.
If such a plan were to ever become feasible, the Australian people would be the ones to make the final decision through their votes.
Less than an inch. It looks like the Great Australian Basin is less than 1/350th of the area of the oceans. Lake Eyre is only 50 feet below sea level and even if the entirety of the GAB were this low, it would only lower sea levels by a couple of inches if completely full. And I’m assuming that having it above sea level is a non-starter due to the enormous energy costs. Most of the basin is nowhere near that far below sea level and I’m assuming it’s mostly above sea level.
This statement seems to be loaded this with the extremely dubious assumption that it is desirable to increase the size of the human population. If you do think that - why?
If the motivation is not to support a larger population, then presumably it’s about land use. Setting aside national politics for a moment, considering just the common overall interests of humanity, is there some reason why the sparsely populated areas of Australia are a good choice for a massive almost terraforming-scale project to increase land use efficiency?
The southwest corner and southern coast of Australia is Mediterranean forest that gradates into desert. Human intervention could spread the forest. Things like planting seeds and sheltering seedlings. Stabilizing soils. Building catchments to slow the movement of rain to the ocean and raise water tables. Etc.
It would be expensive and need the support of the people who live there, but it would be more sustainable than ditch-digging to the ocean.
Well, there are reasons for this. For one, the water was eventually rerouted the way it was supposed to go, so it wasn’t getting fresh water in…thus it stagnated. As you noted, it wasn’t by design (which if we are looking at the OP it would be). Secondly, it DID bring a lot of benefits initially, but then the area got heavily utilized for agriculture, and a lot of that mean that the only water flowing in was heavily polluted by fertilizer and pesticides. Not good things. I don’t think this is a good counter argument to the OP as it really isn’t similar.
I’d say that what the OP is asking is for an inland sea that would be connected to the ocean (no way could you put fresh water in there and hope it would do much). I could see some benefits to having such an inland sea, though I think the costs would be too high, and there would be a lot more downsides than upside benefits. At a guess it could bring about, eventually, a nice fishing industry, as well as leisure industries. I don’t know enough about climate science to know if it would have a beneficial effect on the local climate there (more rain? maybe cooler? more humidity?).
I’ll reiterate the point above. The cost of engineering and upkeep is larger than any nation could fund. The mooted Nicaraguan canal is 250km long and is hoped to cost 50 billion. We need 500km for the inland sea, 100 billion. But the canal is way way too small. It won’t carry enough water to ever fill the sea. Water will evaporate faster than it could delivered. You need a vastly larger water carrying system. By vastly, I mean hundreds of times larger. So we are in the tens of trillions of dollars. And then the whole project will have a lifetime of a few decades before the sea becomes so salty that it starts to become solid.
Two canals, one feeding, one draining could stop the sea becoming massively salt, but you would need flows of the order of 10000 cubic metres a second to prevent the outflow being so salty that it destroyed the entire ocean ecosystem where it discharged. How you make the water flow is another matter. That would mean energy input. Lots of energy. The capital costs would probably be nearing a hundred trillion dollars. We still are only feeding something the size of Lake Eyre. Still too small to make any climate impact. (We know this, when it fills, it takes some time to drain, it doesn’t appreciably affect climate when it is full.) We need a sea, so maybe ten times the size. That mean ten times the water flows. There isn’t that much money in the world.
The logistics of actually being able to move that much dirt on any human timescale are very likely beyond reach no matter how much money there is.
We are but tiny ants on the scale of geological structures. We think we are pretty clever, but the scale of these things puts our capabilities in perspective. Things like dams and canals take advantage of existing geology. We do a minimum amount of work in just the right place to have an effect. And even then it is on the edge of our capabilities. The inland sea idea is so far off the scale that it becomes incomprehensible.
Politely, your point about Holland is interesting, but a complete tangent from your original point. I think you’d find if they tried that kind of thing now, there’d be a radically different global reaction. Let’s focus on the Australia thing.
So! First, bear in mind that my original cost estimate is for a 4.88m diameter tube. For your terraforming goal, this is basically like trying to fill a swimming pool with an ant’s thimble. That’s ten billion for your figurative straw. You’re really likely looking at tens of trillions of dollars for this work. I don’t think you’d find much political apetite for that big of a spend.
Secondly, consider the cost benefits. You’re not going to be hiring all that many people for the tunnel work. It’ll be a few thousand employed plus support infrastructure. There’s an awful lot of other ways to spend that money to employ people and bolster the economy.
The final reward is the proposed environment change. Frankly, that’s kind of dubious. It may have a cooling effect on the local area, it may also just be desperately humid and as unpleasant as ever. You’re making a big salty sea in the middle of the country, at the cost of untold ecological devastation to what’s already there. Generously, it may be of value for tourism, but salty ocean water isn’t good for agriculture so I think you’re not going to see a return on your investment for at least a century. But feeling generous, I’ll call this point a draw.
The overall assessment suggests it’s primarily a boondoggle. I think you should never be afraid to dream big, because it takes bold thinking to go somewhere great and it makes for a good conversation That said, I think particular bold idea is much too bold to be viable. If your goal is to bolster the economy and employ people, there’s way better ways to spend that money–like basic infrastructure improvements, even if it’s not especially sexy.
I mean, there are multiple communities in Australia that rely on trucked water. I bet there’s a lot of roads that need improving. That trillion dollars could do a lot of water mains and paving.