Reclaiming the Sahara: Terraform the Desert

[Cikomyr]

How possible is it?

I have heard of the multitrillion dollar project that would basically retransform the whole of the Sahara into a forest/arable land, but i find it too ambitious (and frankly, unrealistic funding wise). I got thinking about a more progressive process.

Would it be possible, with irrigation and strategic tree planting, to retransform the Sahara, region by region, into a fertile land? I know from my experience in Dubai that sufficient number of plants in an area would create microclimate able to change wind patterns and humidity. Could it work on a somewhat large scale over a few thousand acres?

[J-H]

You need to import lots of organic matter to build soil fertility, and irrigate it over a long period of time so that the everything has time to put down roots and start drawing up nutrients from far down in the soil/sand. It requires importing a lot to get it started, and I don't think there are any local sources (unlike what was done in Greening the Desert, or unlike that guy in Kenya? who was using Zai pits to plant trees and stop desertification).

I don't know the Sahara that well, but areas that don't get any rain at all probably won't be able to be re-greened...

[Cikomyr]

You need to import lots of organic matter to build soil fertility, and irrigate it over a long period of time so that the everything has time to put down roots and start drawing up nutrients from far down in the soil/sand. It requires importing a lot to get it started, and I don't think there are any local sources (unlike what was done in Greening the Desert, or unlike that guy in Kenya? who was using Zai pits to plant trees and stop desertification).

I don't know the Sahara that well, but areas that don't get any rain at all probably won't be able to be re-greened...

They dont get rain now. But its amazing thr changes in climate greens bring to a region.

[LibraryOgre]

I'm reminded of the old theory "Rain follows the plow (https://en.wikipedia.org/wiki/Rain_follows_the_plow)." Basically, "Look at the places people farm. They have lots of rain. Therefore, rain goes where people farm."

[Cikomyr]

I'm reminded of the old theory "Rain follows the plow (https://en.wikipedia.org/wiki/Rain_follows_the_plow)." Basically, "Look at the places people farm. They have lots of rain. Therefore, rain goes where people farm."

You are making fun of me.

I do not appreciate it.

There used to be vegetation in these locations before. Therefore, there used to be rain. Man activity changed the climate patterns.

[snowblizz]

There used to be vegetation in these locations before. Therefore, there used to be rain. Man activity changed the climate patterns.

Yes and no...

There's the massive "problem" with the prevailing aircurrents which are all tied in together. Also the Atlas mountains creates some rain shadow. Humans or no, there'd be deserts in these regions (the ones along the capricorn and cancer tropics) anyway. You could certainly reclaim some of the land, but unlikely all of it in feasible way. Essentially you'd constantly be working against prevailing climate and geographical patterns. You say "before" before when... Scandinavia used to be in the tropics millions of years ago, but that doesn't mean it is feasible to go back.

[LibraryOgre]

I am not making fun of you. Regreening the Sahara would be a massive undertaking, far beyond simply reintroducing plant life, because the Sahara was formed due to massive climate change... the melting of glaciers and subsequent aridification of the land. Simply bringing in more plants wouldn't do it; you have to create the ecological condition that lets those plants thrive.

EDIT: In fact, I'll go so far as to say that it is far easier to cause desertification by removal of plants than it is to reverse it by their reintroduction.

[-Sentinel-]

This past couple of days, out of curiosity, I made some Internet research about crops that can thrive on seawater: a lot of places in the world, such as the Middle East and Southern California, have plenty of seawater close at hand but a shortage of fresh water. Such crops could, at the very least, ensure food security in dry areas and perhaps create a "critical mass" of vegetation to make the place slightly less arid.


Here's (http://www.theguardian.com/science/2014/oct/18/humble-potato-poised-to-launch-food-revolution) an interesting Guardian article on salt-tolerant potatoes.

And here's (http://www.wired.co.uk/news/archive/2009-05/01/irrigation-system-can-grow-crops-with-salt-water) a Wired article on an irrigation system that desalinates seawater cheaply.

Lastly, here's (www.miracosta.edu/home/kmeldahl/articles/crops.pdf) a Scientific American article on adding halophytes (salt-tolerant plants) to our diet, as opposed to breeding or genetically modifying the plants we already eat to make them more salt-tolerant.

[J-H]

EDIT: In fact, I'll go so far as to say that it is far easier to cause desertification by removal of plants than it is to reverse it by their reintroduction.

Definitely. Adding plants does not rebuild the soil instantly; taking them away and leaving bare soil (to be eroded, to crust over, etc.) destroys it quickly. What most people don't realize is that plants do not grow and thrive in a sterile medium - they require the soil food web (bacteria, fungus, nematodes, etc.) to properly access nutrients. It's a topic that has only started getting a lot of attention in the last couple of decades. Elaine Ingham is pretty much the global expert on the topic.... her book is on my to-buy list, and I unfortunately missed a chance to hear her speak when she was in town early this summer.

I took a class on soil health put on by HMI a couple of weeks ago, and I have a batch of (hopefully fungal, but I'm not buying a microscope yet) compost tea brewing right now.

The alternative is just dumping petroleum-based fertilizer on your crops every year, which further messes up the soil life balance and creates a cycle of dependence...plus nasty runoff for anyone downstream.

When you look at the amount of topsoil that is left uncovered and vulnerable to erosion and the wind by modern agriculture, it's pretty insane. The number will vary based on your source and the estimating method, but in America alone it's somewhere between a few hundred billion and maybe a trillion tons per year.
(here's a recent article: http://www.seattlepi.com/national/article/The-lowdown-on-topsoil-It-s-disappearing-1262214.php)

Maybe someone should coin the term "Peak agriculture"? I'm not a Malthusian, but I do think that our grandchildren will have some serious problems if we don't switch to more sustainable practices.


Anyway, back to the original topic

1) Eliminating herbivores (and their predators) from a system can also contribute to desertification - see the work of Allan Savory (he's got a TED talk) on the topic.

2) Reclaiming the desert requires importing organic matter (to rebuild soil), importing water, importing plants, and eventually the introduction of herbivores, managed to prevent over/under-grazing... all while keeping the local government(s) and populations happy, keeping them from destroying the project by overgrazing it, etc. Even the man who stopped the desert (http://www.odditycentral.com/news/meet-yacouba-sawadogo-the-man-who-stopped-the-desert.html) couldn't stop his own government. The human element is actually the one that's most likely to cause any project to fail.

[cobaltstarfire]

I don't know about the Sahara, but I think some deserts or arid places probably could be.

There's somewhere, that has a problem with an invasive tree slowly changing an arid environment into a greener place, it's largely facilitated by the wild [donkeys] really loving to eat the tree/seeds and then pooping them out all over. I dunno if the trees are changing the environment enough to make it farmable, but they're apparently causing trouble for native species as they spread.

I wish I could remember where I had read about that...I can't even remember if it was a credible source or not though.

[Dodom]

While it'd be nice to be able to reclaim some land, lets not forget that even deserts have a role in the global ecological balance:

http://www.scientificamerican.com/gallery/saharan-dust-feeds-atlantic-ocean-plankton/

Sand acts as a plankton fertiliser. It takes some for the oceans' food chain to get going.

[Eldan]

Regarding there being vegetation there, I'm wondering. If that is true, was that vegetation there before the continents moved more or less into the modern positions?

Because macroclimate, i.e. the large wind systems that move worldwide, create bands of wet and dry climate that more or less stretch around the world. The Sahara is on a dry latitude and I don't think much could be done to make it rain there.

[Rockphed]

Regarding there being vegetation there, I'm wondering. If that is true, was that vegetation there before the continents moved more or less into the modern positions?

Because macroclimate, i.e. the large wind systems that move worldwide, create bands of wet and dry climate that more or less stretch around the world. The Sahara is on a dry latitude and I don't think much could be done to make it rain there.

As I understand it, the Sahara was much greener at the end of the last ice age. So was the Arabian Peninsula. It has something to do with glaciers melting, I think.

[BannedInSchool]

You don't have to go back that far for a wet Sahara: https://en.wikipedia.org/wiki/Neolithic_Subpluvial (from about 7500–7000 BCE to about 3500–3000 BCE). We just have to change the Earth's orbit and viola!

[Cikomyr]

You don't have to go back that far for a wet Sahara: https://en.wikipedia.org/wiki/Neolithic_Subpluvial (from about 7500–7000 BCE to about 3500–3000 BCE). We just have to change the Earth's orbit and viola!

Youd just shift misery around the place. I want to increase arable land :(

[-Sentinel-]

I think the places we need to worry about are not the deserts that already exist, since very few people actually live there. We need to worry about the inhabited places where desert is encroaching, like the southern fringe of the Sahara, and where a semi-arid climate is turning into an arid one, like Southern California and many Mediterranean areas. We should keep desert from spreading before we even think about pushing it back.

Southern California is tricky, because it is home to more people than its environment can support. As the population grew, we adapted the landscape to human needs, for example by building the Hoover Dam, and people kept moving in and living like they did in greener states. However, as we've seen these past few summers, we're now reaching the limit of what engineering can do: even by controlling the flow of water, there just isn't enough to meet the demand. It's getting harder to grow crops. Southern Californians won't die of thirst, but they need to get used to the idea that maybe they don't need their greener-than-green lawns and golf courses.

In Africa, I think the main problems are overgrazing and a general lack of effective land management.

As for Haiti, it's a disaster. The Duvalier dictatorship completely wrecked the environment. Seriously, look at this satellite pic of the Haiti/Dominican border (https://wattsupwiththat.files.wordpress.com/2013/06/haiti_domrepub_deforestation.jpg).

[factotum]

I agree with -Sentinel-. We need to stabilise places that are already being desertified--in addition to his example, what about the Aral Sea? That used to cover 68,000 square kilometres, it's now down to a few thousand at most due to its feedwaters being diverted for agriculture. The damage to the ecology in the region is massive.

For the same reason, even if we *could* somehow convert a desert into arable land, would it be a good idea to do so? What sort of knock-on effects would that have, and what sort of ecosystems might we be wiping out?

[Yora]

If no Sahara sand is blown across the Atlantic, it certainly would have an impact on the Amazon jungles. Not sure how, but it would change things.
Since the Sahara in its current form is geologically extremely young, it's the result of a significant climate change. To turn it back to how it was 10,000 years ago would mean to change the whole global climate and that generally messes up any established agriculture.

I think the problem with California is that it was settled during a time of unusually high rain, creating the false impression that the region could support a lot more people than it really does most of the time. But now all the people are already there and it's close to impossible to get them back out. I believe the only practical solution is probably to severely cut down on water consumption. Which would mean moving much of the water intensive agriculture to other regions. Which still can get pretty disruptive to the regional economy, even in a post industrial country like the US.

[J-H]

To paraphrase Shakespeare: "The first thing we do, let's kill all the lawns." An acre of lawn takes more water per year (on average) than an acre of grain.

[thorgrim29]

Depends where you live, if you have rainy summers there's no reason to force everyone to kill their lawns.

[Yora]

In Germany, not watering your lawn during an average summer might leave it a bit patchy by late august and the green look a bit dull, but that's all. Britain would most likely be even wetter.
Though I think usually we don't water crops either. Greens maybe, but not grain.

Having a nice brilliant green English lawn in Arizona is pretty insane, though.

[LibraryOgre]

Houston, lawns grow whether you want them to or not. The only way to keep them not-lawns is to plant something that kills grass.

[Cikomyr]

Lawn is native to Britain. Part of the reason my SO and I arent really trying to have that specie. We try insteas a lawn of clovers.

[Kalmageddon]

If I'm not mistaken, there was some kind of idea where with relatively simple structures it was possibile to harness the heat of the desert and use it for what amounted to climatization, lowering the temperature and condesing humidity.

[J-H]

Lawn is native to Britain. Part of the reason my SO and I arent really trying to have that specie. We try insteas a lawn of clovers.

Around here, all the clover species grow over 6" tall... anything over 6"H in your front lawn gets a door-hanger from Code Enforcement unless it's a tree, shrub, landscaping, etc.

I'm in North Texas. Instead of letting our lawns go brown and dormant in summertime, we run sprinklers several times per week so that they can stay green and growing so that we have to mow them more often.

[Cikomyr]

Around here, all the clover species grow over 6" tall... anything over 6"H in your front lawn gets a door-hanger from Code Enforcement unless it's a tree, shrub, landscaping, etc.

I'm in North Texas. Instead of letting our lawns go brown and dormant in summertime, we run sprinklers several times per week so that they can stay green and growing so that we have to mow them more often.

Yhea.. Kind of normal when you have a plant specie displaced from its environment.

Lawn presence is artificial, and requires absurd amount of wasted water to be preserved.

[NichG]

Around here, all the clover species grow over 6" tall... anything over 6"H in your front lawn gets a door-hanger from Code Enforcement unless it's a tree, shrub, landscaping, etc.

I'm in North Texas. Instead of letting our lawns go brown and dormant in summertime, we run sprinklers several times per week so that they can stay green and growing so that we have to mow them more often.

This kind of thing would convince me to burn, salt, and pave over my front lawn.

[cobaltstarfire]

I don't think Arizona folks have yards, not with grass anyway, all the times I've had layovers there the yards have all been rocks/gravel, possibly decorated with succulents, but I can't tell from in an airplane.


Around here, all the clover species grow over 6" tall... anything over 6"H in your front lawn gets a door-hanger from Code Enforcement unless it's a tree, shrub, landscaping, etc.

I'm in North Texas. Instead of letting our lawns go brown and dormant in summertime, we run sprinklers several times per week so that they can stay green and growing so that we have to mow them more often.

Man you must live in a nice part of North Texas...in my experience all the grass is a nice drab brown/straw color...Sometimes in spite of an irrigation system. Though there's lots of yards and businesses who use native plants around here, so I suppose things are still a little greener looking than they would be if it was just grass.

Even this year in spite of all that crazy rain we got earlier in the summer, most of the grass is dying, quite a few trees and bushes have been dying off, or developing bald patches.

[Tyndmyr]

Youd just shift misery around the place. I want to increase arable land :(

That's quite doable. See also, the Netherlands.

This has the advantage of being far more convenient than traveling to a desert.

[J-H]

Even this year in spite of all that crazy rain we got earlier in the summer, most of the grass is dying, quite a few trees and bushes have been dying off, or developing bald patches.

Insufficient organic matter in the soil, combined with unhealthy soil biology. A lot of the soil life got drowned in the deluge. Many of them need oxygen as well as water., which is one of the reasons why soil needs to be un-compacted to be healthy.

[weaseldust]

In the past, I've daydreamed about redirecting the Congo up through the CAR into Lake Chad, and wondered what the effects would be. It would take a lot of digging, but not trillions of dollars.

[cobaltstarfire]

Insufficient organic matter in the soil, combined with unhealthy soil biology. A lot of the soil life got drowned in the deluge. Many of them need oxygen as well as water., which is one of the reasons why soil needs to be un-compacted to be healthy.

Ahhh, it never occurred to me that dirt outside of a pot could get noticeably compacted, but that makes a lot of sense now that you have me thinking about it. (I keep a ton of potted plants, so I understand that compacted soil and inadequate drainage can be pretty bad for plant life)

I guess all the trees around the edges of the lakes are probably going to slowly die off too since most of them were under water for months...

During that time, thinking about California's terrible drought I got to wondering how feasible it'd be to pipe water from places getting too much to places in need. Mainly thinking about how we pipe oil all over the place, but I'm not sure we have any lines that go through the Rockies so i have no idea how easy that would be to do with water pipes...

[Rockphed]

Ahhh, it never occurred to me that dirt outside of a pot could get noticeably compacted, but that makes a lot of sense now that you have me thinking about it. (I keep a ton of potted plants, so I understand that compacted soil and inadequate drainage can be pretty bad for plant life)

I guess all the trees around the edges of the lakes are probably going to slowly die off too since most of them were under water for months...

During that time, thinking about California's terrible drought I got to wondering how feasible it'd be to pipe water from places getting too much to places in need. Mainly thinking about how we pipe oil all over the place, but I'm not sure we have any lines that go through the Rockies so i have no idea how easy that would be to do with water pipes...

California already pipes water from lots of places, some of them inside California, but also Wyoming, Utah, Nevada, and Oregon. The thing is that it is expensive to build said aquaducts and it can be expensive to run them. California is about at the point where the options are serious water rationing or desalination. Desalination requires quite a bit of energy to get the salt out of the water, and then a bunch of energy to get the water uphill to where people want to use it (unless you are desalinating water to irrigate farms that are below sea-level, then you can let the water run down-hill to the fields). Also, desalination plants take time to build. Finally, they draw sea-water in to them, creating problems for life that lives near their intakes.

[Lord Torath]

I don't think California gets any water from Utah except via the Colorado River (which flows through both states). Las Vegas has been trying to get water from the Snake Valley aquifer for years now, but the native tribes on the Utah half of the valley have been arguing that taking water from the Nevada side would drain the Utah side as well. Utah is also contemplating a pipeline from Lake Powell (on the Colorado River) to the St George area (south-western Utah), but that keeps getting held up as well, and considering that Lake Powell is already getting lower every year, I don't think it's that good an idea.

Moving water around is hard, because generally the areas that have too much don't regularly have too much. Most of the time they want what they have, and only occasionally deal with flooding.

[cobaltstarfire]

California already pipes water from lots of places, some of them inside California, but also Wyoming, Utah, Nevada, and Oregon. The thing is that it is expensive to build said aquaducts and it can be expensive to run them. California is about at the point where the options are serious water rationing or desalination. Desalination requires quite a bit of energy to get the salt out of the water, and then a bunch of energy to get the water uphill to where people want to use it (unless you are desalinating water to irrigate farms that are below sea-level, then you can let the water run down-hill to the fields). Also, desalination plants take time to build. Finally, they draw sea-water in to them, creating problems for life that lives near their intakes.


I suspect desalination won't be very viable either in the long run even beyond the problems you've mentioned, I've heard they tried desalinization in Australia and it ended up being a black hole for money, and didn't help very much with their drought situation.

I didn't know that California already piped water in though, that's interesting, California and how it handles its water is really weird from my understanding, but piping it in must make it even more convoluted. My mom's moving to Florida from Cali...though Florida isn't much better for its water situation since salt water is starting to infiltrate Florida's water table in many places.

[J-H]

Water rights are a touchy issue... the states that are giving water to CA have grown enough that they need it for themselves. There's a whole web of legal agreements going back over the last 5-8 decades. It's a big mess.



I guess all the trees around the edges of the lakes are probably going to slowly die off too since most of them were under water for months...

Young trees? Maybe. One of my apple trees lost the top 3' out of 6, and regrew branches lower down on the trunk. Established trees will probably be fine. They have enough stored energy in their roots and trunk to survive and put on new growth... just as they store energy to survive winter. If they put on their new growth and then get it completely knocked out a couple of times in a row, they'll be in trouble.
Being underwater may have even gotten some extra organic matter and nutrients deposited around them, although I'm not sure how fast everything will go back to normal as far as the soil life goes.

[Rockphed]

I suspect desalination won't be very viable either in the long run even beyond the problems you've mentioned, I've heard they tried desalinization in Australia and it ended up being a black hole for money, and didn't help very much with their drought situation.

I didn't know that California already piped water in though, that's interesting, California and how it handles its water is really weird from my understanding, but piping it in must make it even more convoluted. My mom's moving to Florida from Cali...though Florida isn't much better for its water situation since salt water is starting to infiltrate Florida's water table in many places.

Looking at the wikipedia page for one Australia Desalination plant, (which I should report for being not very neutral in tone) it looks like desalination is about 5 times as energy intensive as normal methods of getting fresh water. However, there is a hard limit on how much fresh water you can get by natural means.

[cobaltstarfire]

I know very little about it other than it wasn't as great as people expected (done no research into it just what I've heard from folks living down there).

I haven't lived in California in a long time(20+years), but when I did it was pretty notorious for black outs and brown outs. It leave me wondering if California can easily meet the energy needs to run enough desalinization plants, if one of the main issues is power consumption.

Seems like either way, any place that is facing desertification is only going to have a harder and harder time dealing with it.

[factotum]

During that time, thinking about California's terrible drought I got to wondering how feasible it'd be to pipe water from places getting too much to places in need. Mainly thinking about how we pipe oil all over the place, but I'm not sure we have any lines that go through the Rockies so i have no idea how easy that would be to do with water pipes...

The longest water supply tunnel in the world is the Delaware Aqueduct in New York State, which is 85 miles long. Would 85 miles be sufficient to carry water from a watered area of California to the part that needs it? I suspect not, so you'd need to build one even longer--lord only knows what that would cost.

[cobaltstarfire]

The longest water supply tunnel in the world is the Delaware Aqueduct in New York State, which is 85 miles long. Would 85 miles be sufficient to carry water from a watered area of California to the part that needs it? I suspect not, so you'd need to build one even longer--lord only knows what that would cost.

Well apparently California does pipe water (see further up thread)

The original thought came from thinking about the long oil pipelines we have/want to build, and while I'm at it, no I don't know how long any of the oil lines are, nor how long it'd take to build them, cost, or how it would compare to a similar amount of water pipes.

Which is why I asked a question about it in the first place.

[snowblizz]

Well apparently California does pipe water (see further up thread)

The original thought came from thinking about the long oil pipelines we have/want to build, and while I'm at it, no I don't know how long any of the oil lines are, nor how long it'd take to build them, cost, or how it would compare to a similar amount of water pipes.

Which is why I asked a question about it in the first place.

When water costs enough to make it worth it, I bet they could run water through the Alaskan oil pipe. (No not really, it probably needs to be specifically designed for it). The easiest and cheapest methods would still be to conserve water and not try to live like the UK in a climate that is almost desert. IIRC there was something about farmers eg not paying for water so the incentive to not waste it when irrigating was nil. There was this plastic bucket thing someone pitched on Sharktank, but the problem was that changing the way you have always done it for even a tiny extra costs has never been popular. The problem isn't only the supply, but very much on the demand side.

The Trans Alaska Pipeline is 800 miles, took about 3 years to build and cost more than 8 billions dollars.

[Tyndmyr]

When water costs enough to make it worth it, I bet they could run water through the Alaskan oil pipe. (No not really, it probably needs to be specifically designed for it). The easiest and cheapest methods would still be to conserve water and not try to live like the UK in a climate that is almost desert. IIRC there was something about farmers eg not paying for water so the incentive to not waste it when irrigating was nil. There was this plastic bucket thing someone pitched on Sharktank, but the problem was that changing the way you have always done it for even a tiny extra costs has never been popular. The problem isn't only the supply, but very much on the demand side.

The Trans Alaska Pipeline is 800 miles, took about 3 years to build and cost more than 8 billions dollars.


I'm not familiar with the specific bucket referenced, but farming does not happen on the bucket level. Hundreds of acres of land automatically irrigated through pipes is more normal. It isn't merely a tiny extra cost, it would require utterly restructuring society and going back to farming by hand, instead of primarily via automated systems.

[snowblizz]

I'm not familiar with the specific bucket referenced, but farming does not happen on the bucket level. Hundreds of acres of land automatically irrigated through pipes is more normal. It isn't merely a tiny extra cost, it would require utterly restructuring society and going back to farming by hand, instead of primarily via automated systems.

It was meant for growing trees, orchards and so on placed on planting I think, essentially provided shade for the area around the root/stem drastically reducing the evaporation, or some such. I think it was like 2 bucks but could in the long run save you thousands on water. (I think it was also meant to be combined with drip irrigation and would increase yields)

Stuff like drip irrigation instead of having it spray around the field it would drastically reduce water usage.

[Tyndmyr]

It was meant for growing trees, orchards and so on placed on planting I think, essentially provided shade for the area around the root/stem drastically reducing the evaporation, or some such. I think it was like 2 bucks but could in the long run save you thousands on water. (I think it was also meant to be combined with drip irrigation and would increase yields)

Stuff like drip irrigation instead of having it spray around the field it would drastically reduce water usage.

Ah. Those exist. They're usually called "plastic ground cover", and are usually done via sheets, where it is practical to use them, rather than fiddling around with individual bits for each tree.

Stuff like this and drip irrigation are already in widespread use where it makes sense to do so. People who farm for a living tend to know a bit about it compared to folks on reality television.

[J-H]

The plastic isn't that great for the soil, has to be replaced, breaks down over time, etc., and represents a recurring expense. I think the Shark Tank box was something similar to a Groasis box (link (http://www.groasis.com/en/summary/information-about-the-groasis-growboxx-plantcocoon-groasis-waterboxx-plantcocoon-and-the-groasis-technology-to-combat-desertification-through-reforestation)), which has developed a much more reasonable price point since I last looked at it. The point is to reduce the work resources required for each tree to get to the point where it's healthy and well-established.

It's intended for trees, while most industrial agriculture is based on annual crops (wheat, corn, soy, etc). Some work is being done to breed perennial grain plants, but the yields aren't there yet. Tree crops are great, but don't have widespread acceptance yet, and are usually at a premium price point. If we didn't have such a strange and artificial system (unhealthy monocropped soils growing GM crops sprayed with chemicals and nourished by petroleum products, some of which people are paid to turn into gas, next to fields where farmers are paid not to grow crops, etc.) it might be different.

Mark Shepard's book Restoration Agriculture gives a good overview of the topic; his property is 105 acres, which is large enough that we're talking about mass production instead of small-scale homesteads.

I'm shooting for the 10-to-25 acre homestead within the next 2 years; trees, canes, chickens, ducks, goats, bees, and a few thousand square feet of sweet potatoes.

[cobaltstarfire]

methods would still be to conserve water and not try to live like the UK in a climate that is almost desert. IIRC there was something about farmers eg not paying for water so the incentive to not waste it when irrigating was nil.


My understanding with California is that while farming is a pretty big water sink, another problem is that certain communities can just ignore the rationing because they can foot the bill, and those particular communities are using a disproportionate amount of water, and feel they are entitled to it, regardless of how it effects other communities or agriculture. There are areas in California where water consumption apparently went up when the state started rationing. It'd probably help a little bit if California could enforce its water restrictions more seriously.

[halfeye]

The surface of the Earth is 70% water. There shouldn't be shortages.

I don't understand how California is so dry, they are next to the ocean and the winds should blow toward them.

[Emperordaniel]

The surface of the Earth is 70% water. There shouldn't be shortages.

Pretty much all of that is saltwater, though - 96.5% of Earth's water comes from the oceans and is too salty to drink, 69% of the freshwater that's left (less than 3% of the water on Earth is fresh) is locked up in the glaciers and icecaps and is too solid and/or inaccessible to drink, while 30% of Earth's freshwater is located in underground aquifers, which have varying levels of difficulty to reach; only about one-quarter of one percent of Earth's freshwater (itself a minuscule percentage of the total water on Earth) is easily accessible in the form of lakes and rivers. (http://water.usgs.gov/edu/earthhowmuch.html)

Drinkable water just isn't that easy to come by.

[halfeye]

Pretty much all of that is saltwater, though -

Drinkable water just isn't that easy to come by.
I love that image:

http://water.usgs.gov/edu/pictures/full-size/global-water-volume-fresh-large.jpg

It just shows the situation.

Desalination is a problem, but the answer ought to be to build huge canals connecting to the sea and let evaporation desalinate the water and bring in new seawater.

[BannedInSchool]

Desalination is a problem, but the answer ought to be to build huge canals connecting to the sea and let evaporation desalinate the water and bring in new seawater.
Like a gigantic solar still? You'd still need to remove the salt and other things from your canal, and building a moat parallelling the coast (because it's uphill inland) presents multiple problems, IMO. Heh, also a little funny in a thread started about fertilizing the Sahara you're basically proposing replacing land with salt ponds.

[halfeye]

Like a gigantic solar still? You'd still need to remove the salt and other things from your canal, and building a moat parallelling the coast (because it's uphill inland) presents multiple problems, IMO. Heh, also a little funny in a thread started about fertilizing the Sahara you're basically proposing replacing land with salt ponds.
I don't think you're understanding it. The water would get to the land as rain. The canals would be huge. you might want to store the the salt, yes, but you really only need to keep it thin enough that the water can flow in to replace evaporation.

I see on the globe that the Sahara goes all the way to the Atlantic. That is strange, I'd expect there to be mountains between the coast and the desert that would be green on the seaward side. It's also odd that the Amazon basin east of the Andes is humid.

[Alent]

The surface of the Earth is 70% water. There shouldn't be shortages.

I don't understand how California is so dry, they are next to the ocean and the winds should blow toward them.

It makes more sense when you stop and look at the big picture. California produces something like 95% of America's fruits and veggies, which themselves are something like 80~99% water. Around 80% of California's water is used in farming every year. I can't find an actual numeric quantity for this on google in a short amount of time, so I'm going to build a case for "why?" out of what I did find:

Take the weight of all the fruit and vegetables that California ships and multiply it by 0.95 and you have reasonable guess as to the amount of water that has to be replaced every year to maintain water levels. I can't find numbers on that at a short glance, but one article I found mentions a single carrot company from California harvests twice the weight of the empire state building in carrots per year. Carrots are 87% water, and one source says the building weighs 365,000 tons, so that's 635,100 tons of water per year (calculator is saying that's 190,035,116.883 gallons, but I'm not sure I used the right ton.) being removed from the ground and most/all of it shipped out of state (some of it out of country) by one company. Now realize that's one company and there are many others growing many other crops.

California is exporting 70~80% a Non-trivial amount of it's water every year in tiny edible containers.

(Note that I have omitted Evaporation as a consequence of not being able to find concrete numbers. It varies too much by crop and irrigation method.)

[cobaltstarfire]

I poked around a little bit (Norrens post reminded me of some articles I read earlier this year that constantly talked about how much water you need to grow a single almond, beats me why almonds are the bad guy though).

And I found a nice graphical chart (http://www.businessinsider.com/amount-of-water-needed-to-grow-one-almond-orange-tomato-2015-4) that shows how much water you need for a couple of common fruits/veggis/nuts

The paper the graph is derived from talks about the blue/green/grey/combined water footprints for various food, oil, and textile crops. And has a big long list of them.

The paper uses a creative commons license, so it's freely available, and may prove useful to the discussion in some way I guess, at least for folks who can make sense of it. It's a rather beyond me so I can't say how good the methodology and such are.

[Bavarian itP]

I love that image:

http://water.usgs.gov/edu/pictures/full-size/global-water-volume-fresh-large.jpg

It just shows the situation.



Except that you can't really recognize the volume of the water bubbles on the 2D representation, so it's more like it skews the situation.

[Alent]

I poked around a little bit (Norrens post reminded me of some articles I read earlier this year that constantly talked about how much water you need to grow a single almond, beats me why almonds are the bad guy though).

Almonds have a peculiar status in California. They amount to something like 10% of the state's water usage by itself according to some sources, and as I understand it are also one of the more lucrative exports (also one of the crops they export internationally). Most crops grow in a season and letting them go fallow doesn't mean 1~4 years of non-production. If Almond trees could be replanted and regrown in a single year or otherwise stop nut production on a dime, they wouldn't be the designated antagonist of the water shortage. The profit margin is also causing issues because it's seeing an expansion of Almond Farming, meaning a larger amount of water will be semi-permanently tied up in almond farming.

To give you an idea of how lucrative, the first chart I found says we shipped 236.2 million pounds of Almonds to China alone from 2011~2012. That's a lot of nuts, and the growth chart on almond production I saw from that same source looked fairly close to an exponential growth rate, production somewhere around 2 billion pounds of almonds a year. Fortunately, the edible parts of Almonds are dried fairly well, being less than 5% water, so the water used to grow them mostly stays in the local ecosystem rather than getting shipped out like with my earlier example with carrots, so... yeah, not as bad as other crops like Alfalfa and such, but the inflexibility means they have to be worked around.

[Emperordaniel]

I don't think you're understanding it. The water would get to the land as rain. The canals would be huge. you might want to store the the salt, yes, but you really only need to keep it thin enough that the water can flow in to replace evaporation.

I see on the globe that the Sahara goes all the way to the Atlantic. That is strange, I'd expect there to be mountains between the coast and the desert that would be green on the seaward side. It's also odd that the Amazon basin east of the Andes is humid.

Not so strange, seeing as the prevailing air currents in those regions of the world blow from east to west (https://en.wikipedia.org/wiki/File:Map_prevailing_winds_on_earth.png) - the Amazon gets its precipitation from the Atlantic, while water evaporating over the Sahara tends to get blown back out over the Atlantic.

[Closet_Skeleton]

You could probably genetically engineer a strain of Super Kudzu that will grow in the Sahara without much water and turn the sand into soil over a few decades.

But OMG super KUDZU what have you done you fools WE'RE ALL DOOMED!!!



There used to be vegetation in these locations before. Therefore, there used to be rain. Man activity changed the climate patterns.

Not all climate change is man made.

Most habitat change is, but that's got little to do with climate and a lot of that is just due to diseases we spread around.


I agree with -Sentinel-. We need to stabilise places that are already being desertified--in addition to his example, what about the Aral Sea? That used to cover 68,000 square kilometres, it's now down to a few thousand at most due to its feedwaters being diverted for agriculture. The damage to the ecology in the region is massive.

For the same reason, even if we *could* somehow convert a desert into arable land, would it be a good idea to do so? What sort of knock-on effects would that have, and what sort of ecosystems might we be wiping out?

The Aral Sea was destroyed to turn steppe grassland into farmland. The same thing done to the Great Plains earlier, but they used Aquifers rather than rivers.

There should be a optimum arrangement of earth's resources for the nicest climate zones, but our science is probably not yet in the right place to calculate it and our diverse nations would never agree to it. The Aral Sea went because Russia was more powerful than Uzbekistan so the later couldn't complain about having its agriculture weakened so Russia could have more farmland. What's probably going to continue to happen is that strong countries aren't going to be willing to suffer a 10% reduction in farmland so the planet can have 40% more.


I see on the globe that the Sahara goes all the way to the Atlantic. That is strange, I'd expect there to be mountains between the coast and the desert that would be green on the seaward side. It's also odd that the Amazon basin east of the Andes is humid.

The Atlas mountains are between the Sahara and the Mediteranian. 2000 years of intensive agriculture have used up most of the Aquifers and destroyed what used to the most fertile region in the Mediterranean after the Nile valley.

Most of Spain and the Levant's current dry climate are due to deforestation in the bronze age and early iron age (Pheonicians needed wood for their ships).

[BannedInSchool]

Not so strange, seeing as the prevailing air currents in those regions of the world blow from east to west (https://en.wikipedia.org/wiki/File:Map_prevailing_winds_on_earth.png) - the Amazon gets its precipitation from the Atlantic, while water evaporating over the Sahara tends to get blown back out over the Atlantic.
Here's a nice diagram from the 'Pedia Hadley Cell (https://en.wikipedia.org/wiki/Hadley_cell) page:
https://upload.wikimedia.org/wikipedia/commons/thumb/9/9c/Earth_Global_Circulation_-_en.svg/400px-Earth_Global_Circulation_-_en.svg.png
The Sahara has the dry descending air that dumped its water ascending at the equator before travelling back north at high altitude where it's not going to gain any more water vapor from travelling over the ocean surface. Boiling the coastal oceans won't help that much because that air isn't headed to the interior of the Sahara on average.

[Cikomyr]

Hmm.. Where can you get soil in large quantity? The sea bed, maybe?

Scrape the bottom of the ocean?

[halfeye]

Hmm.. Where can you get soil in large quantity? The sea bed, maybe?

Scrape the bottom of the ocean?
Too salty.

Desalinate it and yes, but that's more or less no IRL.

I do like that Hadley cell stuff thanks BannedInSchool for that.

[factotum]

Hmm.. Where can you get soil in large quantity? The sea bed, maybe?

Scrape the bottom of the ocean?

Probably not, for the reason halfeye pointed out--too salty. Not to mention the difficulty of getting it up to the surface in the first place. If you genuinely wanted to reclaim the Sahara you'd need to plant stuff there that can grow on sand and hold it together with its roots (e.g. the sort of stuff you'd find on a beach)--eventually, once enough generations of that have grown and died, you'll start getting a natural organic soil forming from the remnants. Not a quick process by any means!

[Cikomyr]

Probably not, for the reason halfeye pointed out--too salty. Not to mention the difficulty of getting it up to the surface in the first place. If you genuinely wanted to reclaim the Sahara you'd need to plant stuff there that can grow on sand and hold it together with its roots (e.g. the sort of stuff you'd find on a beach)--eventually, once enough generations of that have grown and died, you'll start getting a natural organic soil forming from the remnants. Not a quick process by any means!

Tsokay. I dont expect it to be anything fast. The point is to let smarts and understanding of the world to change it for the better.

So... Desert plants. Or beach plants. Gotcha.

[Tyndmyr]

It makes more sense when you stop and look at the big picture. California produces something like 95% of America's fruits and veggies, which themselves are something like 80~99% water. Around 80% of California's water is used in farming every year. I can't find an actual numeric quantity for this on google in a short amount of time, so I'm going to build a case for "why?" out of what I did find:

Take the weight of all the fruit and vegetables that California ships and multiply it by 0.95 and you have reasonable guess as to the amount of water that has to be replaced every year to maintain water levels. I can't find numbers on that at a short glance, but one article I found mentions a single carrot company from California harvests twice the weight of the empire state building in carrots per year. Carrots are 87% water, and one source says the building weighs 365,000 tons, so that's 635,100 tons of water per year (calculator is saying that's 190,035,116.883 gallons, but I'm not sure I used the right ton.) being removed from the ground and most/all of it shipped out of state (some of it out of country) by one company. Now realize that's one company and there are many others growing many other crops.

California is exporting 70~80% of it's water every year in tiny edible containers.

(Note that I have omitted Evaporation as a consequence of not being able to find concrete numbers. It varies too much by crop and irrigation method.)

This is ludicrously off base. The vast majority of water used to grow a crop is not actually part of the edible crop.

It's a little like people. Yes. A good chunk of you is water. But that quantity of water is trivial compared to the quantity of water you consume over your lifetime.

[Alent]

This is ludicrously off base. The vast majority of water used to grow a crop is not actually part of the edible crop.

It's a little like people. Yes. A good chunk of you is water. But that quantity of water is trivial compared to the quantity of water you consume over your lifetime.

If you can give me the amount of division between crop and plant, I will be happy to adjust the math and update the post to reflect it. (I looked, but got mixed data and it was biased towards hating on Almonds and Alfalfa. Google sucks as a source sometimes.)

I still believe even hammering that out with more data that the amount exported will be non-trivial.

[Rockphed]

If you can give me the amount of division between crop and plant, I will be happy to adjust the math and update the post to reflect it. (I looked, but got mixed data and it was biased towards hating on Almonds and Alfalfa. Google sucks as a source sometimes.)

I still believe even hammering that out with more data that the amount exported will be non-trivial.

Then you are going about it wrong. Look up how much of each food stuff California exports, then look up the water content per ton of that food stuff. I found something on the first page of google that is a government looking site. It doesn't seem to have exports, per ce, but it is a start. For instance, California produced 47,200 tons of artichokes in 2013. A 128g serving of artichoke contains 109g of water, or 85%. So, assuming that all artichokes were sold outside California, 40,193 tons of water left the state because of artichokes. Okay, probably a bit more because water is used in photosynthesis to make sugars. A gallon of water weighs 8.34 pounds, so about 10,000 gallons of water left California as artichokes that year. How much total water did artichoke farming consume in 2013?

[Knaight]

Looking at the wikipedia page for one Australia Desalination plant, (which I should report for being not very neutral in tone) it looks like desalination is about 5 times as energy intensive as normal methods of getting fresh water. However, there is a hard limit on how much fresh water you can get by natural means.
It still makes desalination not particularly practical right now. A break through in energy production or a tightening of freshwater supplies (e.g. actually getting nuclear fusion up and running with a decent energy output:input ratio) would make it more practical in the future.


If you can give me the amount of division between crop and plant, I will be happy to adjust the math and update the post to reflect it. (I looked, but got mixed data and it was biased towards hating on Almonds and Alfalfa. Google sucks as a source sometimes.)

I still believe even hammering that out with more data that the amount exported will be non-trivial.

It's not just "the division between crop and plant". You're assuming that the water that goes into plants generally stays as part of the plant mass, and that the water sprayed on plants goes into them at high efficiency. Neither of those are good assumptions. More accurately, a bunch of water is sprayed on the plants, much of which is lost to evaporation. Some is sucked into the plants, but even after the plants have it they still lose some to the air gradually (which would be drying out, if they didn't get more to replenish it). That dramatically underestimates water use.

A better approach would be trying to find numbers on the amount of water used in total, the percentage that goes to agriculture, and the amount of crops grown.

[Dire Moose]

I'm a little unclear on how cost-effective desalination really is.

In general, most of the literature I have read on desalination portrays it as very energy-intensive, impractical, and expensive.

Yet this contrasts with most of what my dad told me about his time in the navy, where all the ships he served on had "evaporators" that were used as the main method of providing drinking water for the crew.

If devices like that can easily be manufactured on a large enough scale for shipboard operation, why is it so difficult to do something similar for other purposes?

[halfeye]

I'm a little unclear on how cost-effective desalination really is.

In general, most of the literature I have read on desalination portrays it as very energy-intensive, impractical, and expensive.

Yet this contrasts with most of what my dad told me about his time in the navy, where all the ships he served on had "evaporators" that were used as the main method of providing drinking water for the crew.

If devices like that can easily be manufactured on a large enough scale for shipboard operation, why is it so difficult to do something similar for other purposes?
The crew of a warship only need drinking water ands ideally washing water. Agriculture needs a lot more than that.

[Traab]

This kind of thing would convince me to burn, salt, and pave over my front lawn.

I want to do that so badly. My back yard too. I hate mowing. Mainly because my lawnmower is a piece of junk. It lasted one summer and has been "repaired" a dozen times since then only for it to instantly break down again.

[Cikomyr]

The crew of a warship only need drinking water ands ideally washing water. Agriculture needs a lot more than that.

Plus, lets be honest, most of the time a warship will have spare power in drove.

[BannedInSchool]

Plus, lets be honest, most of the time a warship will have spare power in drove.

You mean navy warships aren't the smart cars of the sea? :smallwink:

[Cikomyr]

You mean navy warships aren't the smart cars of the sea? :smallwink:

I know you are jocular.. but my point is that a Navy warship requires lots of power to be at full combat readiness. But during downtime (which is, like, 99.5% of its operation time) that generator is just sitting there not being really used at full capacity. Hence why they can afford to desalinize lots of water for the crew, which is still ludicrously small compared to the agricultural needs.

[Alent]

On the naval warship stuff, I somehow expect the evaporators that produce drinking water to be run almost exclusively off waste heat from the ship powerplant.


Then you are going about it wrong. Look up how much of each food stuff California exports, then look up the water content per ton of that food stuff. I found something on the first page of google that is a government looking site. It doesn't seem to have exports, per ce, but it is a start. For instance, California produced 47,200 tons of artichokes in 2013. A 128g serving of artichoke contains 109g of water, or 85%. So, assuming that all artichokes were sold outside California, 40,193 tons of water left the state because of artichokes. Okay, probably a bit more because water is used in photosynthesis to make sugars. A gallon of water weighs 8.34 pounds, so about 10,000 gallons of water left California as artichokes that year. How much total water did artichoke farming consume in 2013?

Part of the reason for going about it wrong came from starting with dead ends and not starting over once I'd hit enough of them to confuse me. I expected more of the big picture metrics to be centrally available and when they weren't I got impatient and sloppy trying to kludge together metrics and hypothesis.

I think I found the chart you pulled the artichokes produced stats from. I don't remember seeing this the other day, so either I overlooked it or had the wrong search terms. Either way, I can't find the total water consumption of artichoke farming. Looking for the other metric, the amount of water required to produce an artichoke plant, the best I'm finding is stats for "amount of water required to produce an artichoke leaf". (and the number of leaves on an artichoke seem variable.)

On the upside, using a site I found looking for the water required for an artichoke I can find the stats for how much water it takes to produce a carrot, and that government looking page (Was on page 2 for me?) has the pounds of carrots produced in California. So, revisiting Carrots using the following statistics and the "100% export" assumption: (probably bad due to population density in California)


1,927 million pounds of carrots harvested in California in 2013.
A carrot is 87% Water, resulting in 1,676 (and change) million pounds of water (201 million gallons)
It takes 14.88 gallons of water to grow a pound of carrots, resulting in 28.6 billion gallons of water.
California uses 34 million acre feet of water for agricultural use, or 1.1080613 gallons.

This is looking way more reasonable, tho'. (Unless I pooched the math again.) Excluding things like sugar synthesis, since I don't know how to calculate the water captured by that, it looks like 201 million gallons of water shipped out in carrots, for 0.7% of the water used to grow it. That 201 million converts to 616 acre feet of water, or 0.0018% of agricultural water. Now I just need to start adding up the rest of everything and see how far north or south of 1% it lands. (I'm expecting between 2 to 5% total water loss per year once everything is added up. See below.)

According to a BBC article I'm seeing which I need to fact check to make sure it's not misrepresenting gross domestic and international as international or total growing water with trapped water, apparently Alfalfa Hay international exports account for 306,842 acre feet of water, almost a percent of total California agricultural water by itself. (which is almost exactly 100 times as much as Nestle bottled water uses in total, at 3068 acre feet.)

I'll see tomorrow if I can rearrange this excel sheet and start adding in other crops from that site to see how much acre feet goes out. I hadn't expected Alfalfa to crush Nestle. Determining if the resultant percentage is non-trivial... that could be hard given the data available. Oh well. On the upside, one source says while California is using 80% of it's water for agriculture right now, the agricultural water use is only 29% during a good "wet year", which should make it trivial provided the water seeps back into the aquifer, but until the drought actually ends...

Anyway, I'm done smashing my head against math for the night, and turning my dyscalculic brain back to things without numbers for me to transpose.

[Tvtyrant]

California doesn't need to desalinize anything. It has plenty of water for people to live on, what it doesn't have is the water for cash crops. If all high water crops and most cash crops were banned then the state would have plenty to account for food and its population.

[factotum]

So, assuming that all artichokes were sold outside California, 40,193 tons of water left the state because of artichokes. Okay, probably a bit more because water is used in photosynthesis to make sugars. A gallon of water weighs 8.34 pounds, so about 10,000 gallons of water left California as artichokes that year.

Something doesn't add up there? 40,000 and change short tons would work out as 80 million pounds, or about 10 million gallons of water if your estimate of ~8lb per gallon is correct.

[halfeye]

Which Artichokes?

Jerusalem artichokes are sort of like potatoes, Globe artichokes are giant thistles, totally different sorts of plants.

https://en.wikipedia.org/wiki/Jerusalem_artichoke

https://en.wikipedia.org/wiki/Artichoke

[Tyndmyr]

If you can give me the amount of division between crop and plant, I will be happy to adjust the math and update the post to reflect it. (I looked, but got mixed data and it was biased towards hating on Almonds and Alfalfa. Google sucks as a source sometimes.)

I still believe even hammering that out with more data that the amount exported will be non-trivial.

Doing it that way, yes. You're ignoring that water goes into and out of an organism throughout it's lifecycle. Total water used is not directly related to how much water is exported in the fruiting part of it. Water used, and then re-entering the local water cycle is not exported.

So, water exports are not a significant component of water use. If we look at almonds, you've got about 3.4b cubic meters of water used for the crop, or 2.3b cubic meters used for exported almonds. If you look at actual amount of almonds produced, it's about 1.85b pounds.

It should be fairly obvious that a pound of almonds does not contain 2 cubic meters of water. Total usage is MUCH higher than export volume.


I'm a little unclear on how cost-effective desalination really is.

In general, most of the literature I have read on desalination portrays it as very energy-intensive, impractical, and expensive.

Yet this contrasts with most of what my dad told me about his time in the navy, where all the ships he served on had "evaporators" that were used as the main method of providing drinking water for the crew.

If devices like that can easily be manufactured on a large enough scale for shipboard operation, why is it so difficult to do something similar for other purposes?

The military does not operate at a profit. That isn't it's purpose. It operates at a huge loss.

Note that you've got nuclear reactors on a lotta ships, too, so you've got a given level of power available. Any not used is wasted. This is a different scenario from on land.

So, basically, these situations are wholly unlike each other, and there is no conflict between those sources of information.


California doesn't need to desalinize anything. It has plenty of water for people to live on, what it doesn't have is the water for cash crops. If all high water crops and most cash crops were banned then the state would have plenty to account for food and its population.

And if they banned the people, they'd have plenty of water for the crops.

Thus, the disagreement.

Long story short, you've got a crapton of people and industry in an arid region, and nobody wants to move or use less. Of course, everyone is eager to volunteer that the OTHER guy sacrifice greatly.

[cobaltstarfire]

A better approach would be trying to find numbers on the amount of water used in total, the percentage that goes to agriculture, and the amount of crops grown.

I would recommend finding the paper I mentioned earlier, which does exactly that.

[Knaight]

The crew of a warship only need drinking water ands ideally washing water. Agriculture needs a lot more than that.

Plus, as Tyndmyr mentioned a lot of these ships have nuclear reactors on board. Things being somewhat power intensive isn't exactly a huge limitation.

[factotum]

Plus, as Tyndmyr mentioned a lot of these ships have nuclear reactors on board. Things being somewhat power intensive isn't exactly a huge limitation.

That's true in the States, but not so much outside it. Apart from submarines the UK has no nuclear-powered vessels and none are planned to be built, for instance. Even in the US navy I think the majority of the ships in terms of numbers (if not in tonnage) would be conventionally powered. However, the other point made earlier--namely, that the military don't particularly care if something's expensive so long as it meets an operational requirement--is probably more the reason they'll desalinate seawater for their ships rather than carry huge amounts of water tankage on-board; space taken up by water tanks is space you can't use for stuff that the ship needs to fight.

[Knaight]

That's true in the States, but not so much outside it. Apart from submarines the UK has no nuclear-powered vessels and none are planned to be built, for instance. Even in the US navy I think the majority of the ships in terms of numbers (if not in tonnage) would be conventionally powered. However, the other point made earlier--namely, that the military don't particularly care if something's expensive so long as it meets an operational requirement--is probably more the reason they'll desalinate seawater for their ships rather than carry huge amounts of water tankage on-board; space taken up by water tanks is space you can't use for stuff that the ship needs to fight.

Plus, it's a bunch of mass you need to move around, so just having large water reserves is extremely energy intensive shipboard.

[Rockphed]

Part of the reason for going about it wrong came from starting with dead ends and not starting over once I'd hit enough of them to confuse me. I expected more of the big picture metrics to be centrally available and when they weren't I got impatient and sloppy trying to kludge together metrics and hypothesis.

I'm glad you took my interjection in a positive way. Looking at it, it could easily have been interpreted as "You should feel bad because you are doing it WRONG!" Such was not my intent.


Something doesn't add up there? 40,000 and change short tons would work out as 80 million pounds, or about 10 million gallons of water if your estimate of ~8lb per gallon is correct.

Erm, my defense is that I was, and am, very tired. I probably misplaced a decimal (or 3 as the case may be). :smallredface:

[Alent]

I'm glad you took my interjection in a positive way. Looking at it, it could easily have been interpreted as "You should feel bad because you are doing it WRONG!" Such was not my intent.

I feel bad enough for doing everything wrong as it is. (If there's a way to have a first instinct that starts with "Wrong" every time, I am proof it exists.) So if I got angry every time someone told me such, I'd never get anything done. :smallamused:

I haven't made much progress on account of how much is going on for me right now, but at least I have what seems a solid methodology. Even if I don't find the result I'm expecting, I may end up just making this into a really neat infographic.