dv said:

sibeen said:

mollwollfumble said:

> Are you hinting that if the oceans rise by a metre, we should desalinate and pump inland for crops etc? Seems unlikely because of the sheer volume of one metre of ocean is and the amount of energy that would be needed.

> 361,132,000 km^2 is the size of the oceans. One metre thick, the volume is 361,132,000,000,000 cubic metres, or 361,132 cubic kilometres. That’s a large volume to treat and pump.
Sure, 361,132,000,000,000 cubic metres sounds like a lot but when you work it out it’s only a cube with sides of about 71 kms.

> If we made a reservoir 71 km deep, the water at the bottom would have a pressure of 710 MPa (ignoring increase in density due to compression). Designing for that would be an interesting problem.

It’s only a few metres over the Earth’s land surface. Oh wait, that was the original problem wasn’t it. LOL.

Desalination and pumping inland isn’t much use for lowering sea level, but it’s extremely useful for decentralising population.

I’m happy to pump water inland in Australia without desalinating it first, as it flows back to the coast it desalinates our salt lakes on the way.

I wonder what volume Make Eyre could store when it’s feeding a river to the coast? Then multiply that by other countries around the world.

Let’s see what Lake Eyre could hold. Maximum depth 70 metres plus extra because of the slope on the river leading to the coast. Say a really mild slope of 0.3 metres per km (from river slopes in Gulf country). Distance 400 km so add 120 metres to the depth = 190 metres. Surface area roughly 1,200,000 square kilometres. Take average depth to be between a third and a half of maximum depth. That’s 100,000 cubic kilometers, nearly a third of the 361,000 cubic kilometres mentioned above.

That’s larger than the Caspian sea. That makes it rather large. The Caspian has a volume of around 78,000 km^3. Lake Superior only has a measly 12,000 km^3.

I suspect you’d be pumping water for a while.

Worth a thread

I agree that pumping would take a while. New Orleans had a drainage system that can pump 1,300 cubic metres per second. That’s one km^3 in 9 days. So at that rate it would take quite a few years.

mollwollfumble said:

dv said:

sibeen said:

That’s larger than the Caspian sea. That makes it rather large. The Caspian has a volume of around 78,000 km^3. Lake Superior only has a measly 12,000 km^3.

I suspect you’d be pumping water for a while.

Worth a thread

I agree that pumping would take a while. New Orleans had a drainage system that can pump 1,300 cubic metres per second. That’s one km^3 in 9 days. So at that rate it would take quite a few years.

To do say 1 km^3 per week from the sea to the L Eyre basin, how big would the pipe have to be?

mollwollfumble said:

dv said:

sibeen said:

That’s larger than the Caspian sea. That makes it rather large. The Caspian has a volume of around 78,000 km^3. Lake Superior only has a measly 12,000 km^3.

I suspect you’d be pumping water for a while.

Worth a thread

I agree that pumping would take a while. New Orleans had a drainage system that can pump 1,300 cubic metres per second. That’s one km^3 in 9 days. So at that rate it would take quite a few years.

Does that include the flowing out, needed to desalinate.

party_pants said:

mollwollfumble said:

dv said:

Worth a thread

I agree that pumping would take a while. New Orleans had a drainage system that can pump 1,300 cubic metres per second. That’s one km^3 in 9 days. So at that rate it would take quite a few years.

To do say 1 km^3 per week from the sea to the L Eyre basin, how big would the pipe have to be?

At 10 m/s (which is bloody fast), you’d need 165 m2. Say 15 m diameter.

I’m not understanding how pumping sea water inland results in desalination.

I assume you are talking about delivering water to a high point so it flows back out to sea. In that case would an aqueduct and a seaside Archimedes screw or series of be more efficient.

And the other thing, for such an expensive operation to remove salt, how long would it take to remove the salt, if it is only a few years do the maths still stand up.

party_pants said:

Lake Eyre when “full” is about 9500 km^2 surface area.

Yes. But when full it is nowhere near high enough to flow through Lake Torrens to Spencer’s Gulf, it’s only a couple of metres deep.

The figure of 1,200,000 square kilometres is for Lake Eyre Basin. In this case the total area would be less than Lake Eyre Basin because that contains some high country to the East, but on the other hand I would have to add Lake Torrens and its basin to that because it’s not normally considered part of the Lake Eyre Basin. A height of 190 metres minus 15 metres (because the bottom is below sea level) is 175 metres above Sea Level, which includes almost all of the Diamantina and many other rivers. The Diamantina is only 35 metres above sea level when it crosses from Qld into SA.

175 metres above sea level takes it up to Latitude 23 degrees south, 50 km north of the Tropic of Capricorn.

The Rev Dodgson said:

I’m not understanding how pumping sea water inland results in desalination.

I think you would be pumping it out:

Lake Eyre, officially known as Kati Thanda–Lake Eyre, contains the lowest natural point in Australia, at approximately 15 m below sea level, and, on the rare occasions that it fills, is the largest lake in Australia covering 9,500 km². Wikipedia

The Rev Dodgson said:

I’m not understanding how pumping sea water inland results in desalination.

sea water is less saline than lake eyre, so it would wash salt out.

AwesomeO said:

I assume you are talking about delivering water to a high point so it flows back out to sea. In that case would an aqueduct and a seaside Archimedes screw or series of be more efficient.

And the other thing, for such an expensive operation to remove salt, how long would it take to remove the salt, if it is only a few years do the maths still stand up.

Lake Eyre was once part of an Inland sea. The salt is not just restricted to the lake and is probably topped up as rainwater drains into it. To get a better idea about salt and farming, there are a number of studies detailing the problems of rising salt.

> I assume you are talking about delivering water to a high point so it flows back out to sea. In that case would an aqueduct and a seaside Archimedes screw or series of be more efficient.

Yes. It’s the flow back to the sea that takes the salt away from the existing salt lakes and future lake.

> And the other thing, for such an expensive operation to remove salt, how long would it take to remove the salt, if it is only a few years do the maths still stand up.

The main aim would not be to remove salt, but add coastline. The pumping operation would be slow.

Can we get an OP? What is the background of this discussion and what is the actual question?

dv said:

Can we get an OP? What is the background of this discussion and what is the actual question?

I think it was this:

monkey skipper said:

hey … do you think desalination and pumping water inland will become part of the world future when sea levels rise? They wouldn’t pump sea water inland but after topping up coastal freshwater supplies would inland pumping be part f a management strategy?

It seems drastic but once sea level rise is obvious to all I imagine that is when innovations occurs.

Bogsnorkler said:

The Rev Dodgson said:

I’m not understanding how pumping sea water inland results in desalination.

sea water is less saline than lake eyre, so it would wash salt out.

OK, but after you have reduced the salinity to ocean water levels, surely that’s still way too salty to be any use for agriculture?

The Rev Dodgson said:

Bogsnorkler said:

The Rev Dodgson said:

I’m not understanding how pumping sea water inland results in desalination.

sea water is less saline than lake eyre, so it would wash salt out.

OK, but after you have reduced the salinity to ocean water levels, surely that’s still way too salty to be any use for agriculture?

>>When the lake is full, it has the same salinity level as the sea, but as the lake dries up and the water evaporates, salinity increases.<<

Wiki

I’d be looking at what salt is attracted to,

or what attracts salt, then scale that up.

maybe build more of those roman concrete walls that attracts salt

The Rev Dodgson said:

Bogsnorkler said:

The Rev Dodgson said:

I’m not understanding how pumping sea water inland results in desalination.

sea water is less saline than lake eyre, so it would wash salt out.

OK, but after you have reduced the salinity to ocean water levels, surely that’s still way too salty to be any use for agriculture?

Sure, but it’s nearby. Agriculture could use rainwater, or desalinated lake water, or recycled water from sewage. Plenty of options. Or even the salt tolerant franken-plants that we were discussing earlier.

PS, although the Lake Eyre Basin extends almost to Alice Springs, Mount Isa and Broken Hill, the expanded lake wouldn’t. Alice Springs is 545 m above sea level, Mt Isa is 356 m above sea level, Broken Hill is 315 metres above sea level, all way above the 175 metre lake surface.

I’m more in favour of a smaller lake than this one, where the desalination comes from pumping the hypersaline water from a smaller lake back to the sea.

Tau.Neutrino said:

I’d be looking at what salt is attracted to,

or what attracts salt, then scale that up.

maybe build more of those roman concrete walls that attracts salt

That might help the growing sea water problem

its a lot of roman concrete though.

How long does it take salt to settle? I am thinking a large v shaped trench, as the water slows and becomes still, at that point, water from the bottom is desalinated and pumped out, the fresh or water less salty would be recycled back to the head to carry out another load of salt.

Check out the 168 metre level. It would have to be kept lower than that to avoid flooding into the Darling River.

AwesomeO said:

How long does it take salt to settle? I am thinking a large v shaped trench, as the water slows and becomes still, at that point, water from the bottom is desalinated and pumped out, the fresh or water less salty would be recycled back to the head to carry out another load of salt.

I think convection would keep the water mixed.

Or as an alternative to expensive desalination pumped to evaporating ponds.

AwesomeO said:

Or as an alternative to expensive desalination pumped to evaporating ponds.

Do we really want megatons of salt in the interior?

AwesomeO said:

How long does it take salt to settle? I am thinking a large v shaped trench, as the water slows and becomes still, at that point, water from the bottom is desalinated and pumped out, the fresh or water less salty would be recycled back to the head to carry out another load of salt.

You have nearly 4 metre annual evaporation rate at Lake Eyre, so if you are pumping saltwater into it, you would most likely be increasing the salt level.

http://www.bom.gov.au/watl/evaporation/

AwesomeO said:

How long does it take salt to settle? I am thinking a large v shaped trench, as the water slows and becomes still, at that point, water from the bottom is desalinated and pumped out, the fresh or water less salty would be recycled back to the head to carry out another load of salt.

Forever. It doesn’t settle. Eventually it floats but the water has to get hypersaline for that to happen, which could be done with water collected using a solar still. We get salt for the table and for chemical industries (eg. Orica) by skimming it off the surface of ponds.

Tamb said:

AwesomeO said:

Or as an alternative to expensive desalination pumped to evaporating ponds.

Do we really want megatons of salt in the interior?

I guess it depends on what the objectives of this are, that might be desirable if the objective is to desalinate and it is a cheaper option. Salt has a price but not sure where Australia is or if it can compete against the tyranny of distance in exporting salt.

A few things come to mind. Maximally filling the Eyre Basin (ie filling it to the point that it begins to spill to the south) will destroy ecosystems and townships. Do the same to other basins (Caspian etc) and basically you’ve got an unprecedented ecological and humanitarian disaster.
Also, we are expecting a 1 m or so sea level rise by the end of the century. Desalinating 360000000000000000 litres of sea water (360 quadrillion litres) might well be more expensive and complicated than just switching to a carbon-neutral economy to prevent climate change…

mollwollfumble said:

AwesomeO said:

How long does it take salt to settle? I am thinking a large v shaped trench, as the water slows and becomes still, at that point, water from the bottom is desalinated and pumped out, the fresh or water less salty would be recycled back to the head to carry out another load of salt.

Forever. It doesn’t settle. Eventually it floats but the water has to get hypersaline for that to happen, which could be done with water collected using a solar still. We get salt for the table and for chemical industries (eg. Orica) by skimming it off the surface of ponds.

Don’t look back moll, or you will turn into a pillar of salt

AwesomeO said:

Tamb said:

AwesomeO said:

Or as an alternative to expensive desalination pumped to evaporating ponds.

Do we really want megatons of salt in the interior?

I guess it depends on what the objectives of this are, that might be desirable if the objective is to desalinate and it is a cheaper option. Salt has a price but not sure where Australia is or if it can compete against the tyranny of distance in exporting salt.

I was thinking of the destruction of the environment when the inevitable flood occurs.

PermeateFree said:

mollwollfumble said:

AwesomeO said:

How long does it take salt to settle? I am thinking a large v shaped trench, as the water slows and becomes still, at that point, water from the bottom is desalinated and pumped out, the fresh or water less salty would be recycled back to the head to carry out another load of salt.

Forever. It doesn’t settle. Eventually it floats but the water has to get hypersaline for that to happen, which could be done with water collected using a solar still. We get salt for the table and for chemical industries (eg. Orica) by skimming it off the surface of ponds.

Don’t look back moll, or you will turn into a pillar of salt

That’s a Lot to think about.

> You have nearly 4 metre annual evaporation rate at Lake Eyre, so if you are pumping saltwater into it, you would most likely be increasing the salt level.

Some subtlety would be needed. And a rather huge set of pumps.

mollwollfumble said:

> You have nearly 4 metre annual evaporation rate at Lake Eyre, so if you are pumping saltwater into it, you would most likely be increasing the salt level.

Some subtlety would be needed. And a rather huge set of pumps.

You sure would.

:)

mollwollfumble said:

> You have nearly 4 metre annual evaporation rate at Lake Eyre, so if you are pumping saltwater into it, you would most likely be increasing the salt level.

Some subtlety would be needed. And a rather huge set of pumps.

Solar pumps of course, otherwise you’d be adding to the problem.

Tamb said:

AwesomeO said:

Tamb said:

Do we really want megatons of salt in the interior?

I guess it depends on what the objectives of this are, that might be desirable if the objective is to desalinate and it is a cheaper option. Salt has a price but not sure where Australia is or if it can compete against the tyranny of distance in exporting salt.

I was thinking of the destruction of the environment when the inevitable flood occurs.

We’d have to dam the tributaries, so avoid natural floodwaters filling the lake :)

Tamb said:

mollwollfumble said:

> You have nearly 4 metre annual evaporation rate at Lake Eyre, so if you are pumping saltwater into it, you would most likely be increasing the salt level.

Some subtlety would be needed. And a rather huge set of pumps.

Solar pumps of course, otherwise you’d be adding to the problem.

You would need to pump water in and pump the water out under extreme conditions. Don’t think any development money will be found.

Perhaps we should try a smaller salt lake and basin as an experiment first. There’s a few in WA and NT that are so remote it won’t really matter if we fuck it up.

party_pants said:

Perhaps we should try a smaller salt lake and basin as an experiment first. There’s a few in WA and NT that are so remote it won’t really matter if we fuck it up.

It will to the flora and fauna living there, plus be on Aboriginal land, but why worry, we are far more important and have the right to attempt even the most ludicrous idea.

party_pants said:

Perhaps we should try a smaller salt lake and basin as an experiment first. There’s a few in WA and NT that are so remote it won’t really matter if we fuck it up.

Years ago there was a scheme mooted to cut a channel from Spenser’s Gulf to Lake Eyre in order to make a inland sea. Natural evaporation was then supposed to make rain in the interior.

Tamb said:

party_pants said:

Perhaps we should try a smaller salt lake and basin as an experiment first. There’s a few in WA and NT that are so remote it won’t really matter if we fuck it up.

Years ago there was a scheme mooted to cut a channel from Spenser’s Gulf to Lake Eyre in order to make a inland sea. Natural evaporation was then supposed to make rain in the interior.

Oh, I think we can forget the natural evaporation and increased rainfall idea.

We know that is not going to happen unless we build an artificial mountain range a kilometre high and several dozen long.

party_pants said:

Tamb said:

party_pants said:

Perhaps we should try a smaller salt lake and basin as an experiment first. There’s a few in WA and NT that are so remote it won’t really matter if we fuck it up.

Years ago there was a scheme mooted to cut a channel from Spenser’s Gulf to Lake Eyre in order to make a inland sea. Natural evaporation was then supposed to make rain in the interior.

Oh, I think we can forget the natural evaporation and increased rainfall idea.

We know that is not going to happen unless we build an artificial mountain range a kilometre high and several dozen long.

Where would the 4 metre annual evaporation over a vast area end up?

PermeateFree said:

party_pants said:

Perhaps we should try a smaller salt lake and basin as an experiment first. There’s a few in WA and NT that are so remote it won’t really matter if we fuck it up.

It will to the flora and fauna living there, plus be on Aboriginal land, but why worry, we are far more important and have the right to attempt even the most ludicrous idea.

Inundating the land to fill the whole basin probably would, yes.

On the other hand just filling a lake with desalinated water and keeping it topped up might be a huge boost to the area.

AwesomeO said:

party_pants said:

Tamb said:

Years ago there was a scheme mooted to cut a channel from Spenser’s Gulf to Lake Eyre in order to make a inland sea. Natural evaporation was then supposed to make rain in the interior.

Oh, I think we can forget the natural evaporation and increased rainfall idea.

We know that is not going to happen unless we build an artificial mountain range a kilometre high and several dozen long.

Where would the 4 metre annual evaporation over a vast area end up?

The great dividing range.

AwesomeO said:

party_pants said:

Tamb said:

Years ago there was a scheme mooted to cut a channel from Spenser’s Gulf to Lake Eyre in order to make a inland sea. Natural evaporation was then supposed to make rain in the interior.

Oh, I think we can forget the natural evaporation and increased rainfall idea.

We know that is not going to happen unless we build an artificial mountain range a kilometre high and several dozen long.

Where would the 4 metre annual evaporation over a vast area end up?

Dunno. Wherever the wind takes it. The Andes in South America perhaps??

mollwollfumble said:

AwesomeO said:

party_pants said:

Oh, I think we can forget the natural evaporation and increased rainfall idea.

We know that is not going to happen unless we build an artificial mountain range a kilometre high and several dozen long.

Where would the 4 metre annual evaporation over a vast area end up?

The great dividing range.

And then fall on the Western side.

dv said:

A few things come to mind. Maximally filling the Eyre Basin (ie filling it to the point that it begins to spill to the south) will destroy ecosystems and townships. Do the same to other basins (Caspian etc) and basically you’ve got an unprecedented ecological and humanitarian disaster.
Also, we are expecting a 1 m or so sea level rise by the end of the century. Desalinating 360000000000000000 litres of sea water (360 quadrillion litres) might well be more expensive and complicated than just switching to a carbon-neutral economy to prevent climate change…

Also there is nothing magical about the year 2100. Ice will continue to melt after that date.

It seems very unlikely to me that sea level rise will be limited to 1 m, even if GHG emissions fall much faster than they have been.

Maybe we could make the scheme pay for itself by introducing Nile Perch to the basin and creating a fishing industry.

party_pants said:

Maybe we could make the scheme pay for itself by introducing Nile Perch to the basin and creating a fishing industry.

Or Tilapia.

Tamb said:

party_pants said:

Maybe we could make the scheme pay for itself by introducing Nile Perch to the basin and creating a fishing industry.

Or Tilapia.

Oh please… No.

roughbarked said:

Tamb said:

party_pants said:

Maybe we could make the scheme pay for itself by introducing Nile Perch to the basin and creating a fishing industry.

Or Tilapia.

Oh please… No.

Don’t worry, in 500,000 years or so they will have evolved into a new species. Oops.

Fishing is a vital part of any such scheme.

mollwollfumble said:

roughbarked said:

Tamb said:

Or Tilapia.

Oh please… No.

Don’t worry, in 500,000 years or so they will have evolved into a new species. Oops.

Fishing is a vital part of any such scheme.

We will have pissed off to Mars by then.

The idea of filling the area you are describing will likely only ruin the land as we know it and we will have to grow plankton to eat.

mollwollfumble said:

roughbarked said:

Tamb said:

Or Tilapia.

Oh please… No.

Don’t worry, in 500,000 years or so they will have evolved into a new species. Oops.

Fishing is a vital part of any such scheme.

I have a much better idea, why don’t we build a giant rocket ship and put it into orbit around the sun. We could prepare pizzas then put them outside to cook. We could then teleport them back to earth to waiting customers. It would save a fortune on cooking costs and provide a super-fast delivery service.

PermeateFree said:

mollwollfumble said:

roughbarked said:

Oh please… No.

Don’t worry, in 500,000 years or so they will have evolved into a new species. Oops.

Fishing is a vital part of any such scheme.

I have a much better idea, why don’t we build a giant rocket ship and put it into orbit around the sun. We could prepare pizzas then put them outside to cook. We could then teleport them back to earth to waiting customers. It would save a fortune on cooking costs and provide a super-fast delivery service.

Mmmm. Pizza. Please implement this service ASAP.

:)

PermeateFree said:

mollwollfumble said:

roughbarked said:

Oh please… No.

Don’t worry, in 500,000 years or so they will have evolved into a new species. Oops.

Fishing is a vital part of any such scheme.

I have a much better idea, why don’t we build a giant rocket ship and put it into orbit around the sun. We could prepare pizzas then put them outside to cook. We could then teleport them back to earth to waiting customers. It would save a fortune on cooking costs and provide a super-fast delivery service.

You know what teleporting is, don’t you? It’s sending a list of ingredients and cooking instructions to the far end of the beam for them to cook the pizza there, and destroying the original. We already have that, it’s called the internet.

Lake Torrens has only filled twice since European settlement. To a depth of 1m. It would not be very useful as part of a waterway connecting to the sea.

The Rev Dodgson said:

party_pants said:

mollwollfumble said:

I agree that pumping would take a while. New Orleans had a drainage system that can pump 1,300 cubic metres per second. That’s one km^3 in 9 days. So at that rate it would take quite a few years.

To do say 1 km^3 per week from the sea to the L Eyre basin, how big would the pipe have to be?

At 10 m/s (which is bloody fast), you’d need 165 m2. Say 15 m diameter.

Or a canal 33 m across and 5 m deep. Flowing at 36 km/h.

party_pants said:

The Rev Dodgson said:

party_pants said:

To do say 1 km^3 per week from the sea to the L Eyre basin, how big would the pipe have to be?

At 10 m/s (which is bloody fast), you’d need 165 m2. Say 15 m diameter.

Or a canal 33 m across and 5 m deep. Flowing at 36 km/h.

1 km^3 per week is easy.
We put a Macquarie 800 in the tas irrigation scheme that put out 2000L/sec @ about 20m head

bote 500km 2000lps, 3m ID steel pipe, 12m head loss

Stumpy_seahorse said:

party_pants said:

The Rev Dodgson said:

At 10 m/s (which is bloody fast), you’d need 165 m2. Say 15 m diameter.

Or a canal 33 m across and 5 m deep. Flowing at 36 km/h.

1 km^3 per week is easy.
We put a Macquarie 800 in the tas irrigation scheme that put out 2000L/sec @ about 20m head

bote 500km 2000lps, 3m ID steel pipe, 12m head loss

Oh good. Easy-peasy then.

Now I just need an unlimited supply of cheap energy to run the pumps and desalinate the sea water at the coast.

party_pants said:

Stumpy_seahorse said:

party_pants said:

Or a canal 33 m across and 5 m deep. Flowing at 36 km/h.

1 km^3 per week is easy.
We put a Macquarie 800 in the tas irrigation scheme that put out 2000L/sec @ about 20m head

bote 500km 2000lps, 3m ID steel pipe, 12m head loss

Oh good. Easy-peasy then.

Now I just need an unlimited supply of cheap energy to run the pumps and desalinate the sea water at the coast.

there’s a desal plant at Whyalla not being used and the world’s biggest solar power farms going into Port Augusta… will that do?

Stumpy_seahorse said:

party_pants said:

Stumpy_seahorse said:

1 km^3 per week is easy.
We put a Macquarie 800 in the tas irrigation scheme that put out 2000L/sec @ about 20m head

bote 500km 2000lps, 3m ID steel pipe, 12m head loss

Oh good. Easy-peasy then.

Now I just need an unlimited supply of cheap energy to run the pumps and desalinate the sea water at the coast.

there’s a desal plant at Whyalla not being used and the world’s biggest solar power farms going into Port Augusta… will that do?

Would SA let me borrow them?

party_pants said:

Stumpy_seahorse said:

party_pants said:

Oh good. Easy-peasy then.

Now I just need an unlimited supply of cheap energy to run the pumps and desalinate the sea water at the coast.

there’s a desal plant at Whyalla not being used and the world’s biggest solar power farms going into Port Augusta… will that do?

Would SA let me borrow them?

with the government we have at the moment, sure… go for it.
Do it while the opposition is no better…

party_pants said:

The Rev Dodgson said:

party_pants said:

To do say 1 km^3 per week from the sea to the L Eyre basin, how big would the pipe have to be?

At 10 m/s (which is bloody fast), you’d need 165 m2. Say 15 m diameter.

Or a canal 33 m across and 5 m deep. Flowing at 36 km/h.

In China they have the south-north water transfer project, which is a pair of long canals and some shorter ones. They’re aiming for 44.8 km^3 per year. That’s getting close to 1 km^3 per week.

I did see specs for the canal fall rate and cross section once. But I don’t see it on the web.