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[imperium3]

Okay, so at the moment my new megaproject is looking a little boned. The original plan was to build the Wall from A Game of Thrones, in a map that's half/half neutral and evil biomes. This would be an enormous wall made of ice to separate the biomes, with the fortress being a small cluster of buildings on the neutral side. (and any migrants on the other side can sort their own accommodation out) But we have a small problem.

No major water source.

A project of this scale needs a hell of a lot of water, and there's no river or aquifer. And to my dismay, the caverns are over 100 (!!!) z levels deep and I haven't even found any water in them yet. (Plus I don't fancy building a minecart track so deep to bring the water to the surface, it'd be almost as much work as building the Wall).

The only "water" we have is a couple of small (4-5 tiles) murky pools in the evil biome that are frozen during the winter. I can collect this water easily enough, but I need to find some Dwarf Physics way to multiply the water up to a usably large amount, if that's even possible!

So has anyone tried this before? I'm wondering about how effective repeated freezing/melting might be to automate....

I should further add that one of the biomes is temperate and the other is freezing, so in the summer I have a half/half split of melting and freezing, if that's any help.

[Khanis]

Doesn't need to be completely made of ice. The wall is actually stone it's just so cold and so old that it has permafrost on it.

[imperium3]

Either way, it would take a lot of ice to build. And that's how I want it to be if at all possible

I've been mulling a few ideas...

Will a bridge above stop water from freezing in a cold biome? So by raising/lowering a bridge could I freeze/melt water? (assuming the water is in a pit or something). As I know if you freeze 1/7 water you get 7/7 ice.

[PaleBlueHammer]

Basically there are two ways to get the kind of water you're talking about.

1.  Breach the cavers and find one with water, hopefully up against a map edge.  Presto, infinite water.
2.  DFHack, liquids.  (If you do this be sure to switch from magma first.  Or not.)

[pisskop]

3:  Buckets.  Bucket brigade to get unfrozen water and dump it into a pit where it will not evaporate (more than 1/7 deep).  In winter dump 1/7 water from this liquid source out to freeze.  It thaws and repeat.

[Gigaz]

It is, as far as i know, currently impossible to melt large amounts of water in a reliable way (without creating very much obsidian in the process)
If you want to create water, you must enlarge a murky pool until the water has depth 1-2/7 everywhere. When it freezes, the (now bigger) pool will be full of ice. With a bit of automatization, you can multiply your water reservoir by 3.5 every year. When you start with a pool that covers 20 tiles, you can create 10000 blocks of ice in 5 years.

You can also utilize rain, but you need a biome with very much of it. Empty a murky pool into an underground reservoir and wait for it to refill with rain water, then freeze the whole water. Try not to destroy the murky pool tiles because these are the only ones that spawn water when it rains.

[Person]

Doesn't magma 1 z level below ice cause it to melt? Find a way to move magma underneath water long enough to produce water to fill more tiles to freeze, and then remove it. Done repeatedly, you should be able to make a fairly large reservoir. Sadly I'm not exactly the best dwarf fortress engineer, so I don't have a design for this. You'll probably need a lot of floodgates and mechanisms, but what else are you going to do when it isn't winter.

[Starver]

One method I've used in the past to make a season-synchronised 'tick' (which could be vital aspect to an automated melting/freezing machine, so you aren't sending magma under unfrozen water, or whatever mathoed you were planning) is unfortunately a water-user itself.  (Not necessarily to loss, but needs some 'feed', and there could be evaporation.)  But perhaps you can build it into your water-multiplier anyway in some way, with the following brief description.

Water from an internal location (e.g. from out the side of a hill) is let flow into the outside (or into a specially opened pit, if you don't have any decent hillsides), and flows down, probably in your case to be re-channelled back underground.  When external temperatures plummet to below freezing, this forms a plug, which backs up the outflow and activates a (still inside, but 1Z higher, on the level where the water actually came from, e.g. top of a pump-stack) depth-trigger, indicating freezing conditions.  When the plug unfreezes, the water level drops again, indicating non-freezing conditions.

You can probably work out the specifics of how this would integrate.  I suggest putting the trigger in a normally dry alcove (on the pump-stack level) off to one side of a channel (into Z-1 from the pump-head) that normally takes all the available water.  The plug stops this draining and the pump fills the channel up to the second (pump-height) Z level up, as well as the alcove.

Assuming any evaporation in that cycle isn't depleting more than your ice-works is generating, it should be Ok.  Otherwise a thermocaust below unfrozen water could just as effectively be cycled up and down all the time, only of course without any water-gain at all, for the times the water stays liquid.  So maybe you don't need the thermostatic trigger, anyway.


(Several further replies, while writing, posting anyway, reading these momentarily...)

[Starver]

I've just had a thought that something based upon the "infinite obsidian cave-in" machine[1] might work.  ("Infinite" while the liquid supplies last, this still isn't a solution towards generating that water, only in a way to use it.)  But might not.  Oh look, I've put the details in the (extended) footnote already.




[1] That's two bridges meeting either side of a fully-open tile, with two raised bridges either side of them to make them into 'spouts', one delivering water, one delivering magma.  When done right, the water and magma meet on the open tile and form obsidian, unsupported by anything, which falls (as does any spare water/magma, which adds to the danger of those standing beneath this pretty much intentionally fatal trap).  The raised bridges, either side, were built on top of walls, of which the walls that could have provided support to the formed obsidian have been removed (this worked in 40D, not sure if it does in the latest versions, though), thus providing nothing for the Obsidian to remain supported by.

The water one would be easier, as you only need one 'spout' out into frozen open-air, and no synchronisation would be needed, although I'm not sure if the ice block would survive as 'raw ice' when it hits the bottom, or not.  And this might be a 'raw ice' generator, but still need water-generation to supply.  Needs !!Science!!, I suspect.  Haven't got a current fortress with (at least occasionally) frozen conditions to test any of this, though.  (Though I could try the spout-building aspect, I suppose.)

[imperium3]

Hmmm, well, if I had magma it would be awesome, but given how absurdly deep the caverns are I think it's safe to assume that it would be easier to find and transfer water from there than bring magma up. Unless I'm lucky and have a magma pipe, but I haven't seen one yet...


Gigaz has the best idea so far, though it would be slow given that I really don't have much water to start with. The really difficult part is making a fast way of reversibly freezing/melting water without recourse to magma. And I fear that may not be possible except for the normal pattern of seasons...

As for rain, well, the biome that has the pools only rains elf blood, and while it would be incredibly dwarfy to build a fortress out of frozen elf blood, it's sadly not possible just yet.

fakeedit: Actually, Starver, that's a pretty good idea. Possibly made easier by the biome boundary. The question is whether caved-in ice (which according to the wiki should melt) would just freeze again due to being below freezing air. But maybe if I were just caving-in through a small hole into a wide reservoir, the water may splatter into warm air before it freezes...

This does indeed need !!SCIENCE!! I'll setup a test rig when I get the chance, assuming the ravens [1] are merciful.

[1]Isn't it ironic that when my intention is to build a bloody great wall, the only hostilities i get are from creatures that fly? When I'm large enough to support marksdwarves....

[Gigaz]

Doesn't magma 1 z level below ice cause it to melt?

No, I've tried that. It doesn't work.

[Canadark]

This is an incredible idea. I have a suggestion that I hope somebody could comment on.

If you create an open shaft all the way from the surface down to cavern reservoir, would the exposed water freeze? If so, you could then set up a block factory in the cavern and move them up to the surface with minecarts or wheelbarrows.

The shaft could be hollowed out quickly with this:

Code: [Select]

+xx+
x..x
x..x
+xx++ - wall
x - up/down stairs
. - open space

If my premise is correct, this design would create a 2x2 square that keeps filling with ice. You would need to figure out a way to refill it that doesn't require too much micromanagement. Honestly it would probably be faster just to use a bucket brigade. Devoting 50 or so dwarfs to the movement of water with buckets should give you all the water you need.

I do have one concern though... what will you do when you get to the edge of the map? You can 't build walls there.

[imperium3]

I do have one concern though... what will you do when you get to the edge of the map? You can 't build walls there.

You CAN cast ice though...

[Shades]

edit: I need to read prior posts properly first...

[krenshala]

I'm not sure if it was mentioned already or not, but 1/7 or 2/7 water (can't remember for sure which depth, but I believe only 1/7 is required) turns into 7/7 water after it freezes then melts.

I remember reading that magma only will melt the water above it if the magma is flowing.  Something about the game not doing additional temperature calculations when the magma is "still".  Folks have posted about reliable ways to melt ice on the level above the magma, but they all had flowing, or at least moving, magma in common.