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Author Topic: An Artificial Underground River  (Read 2251 times)

Shurikane

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An Artificial Underground River
« on: November 04, 2015, 01:13:43 pm »

I'm baaaaaaaaaaaaack, motherfuckers!   :D

So!  One thing my new fort's going to need will be power.  Lots of power.

According to the Wiki, making a dwarven reactor is feasible, but a big hit on the FPS, so I'm going to reserve that option for last.

Windmills are potentially doable but I don't know if my map has wind yet.  I'll check this out once that stupid goblin siege is over.

I thought of relying on an underground river... only to realize a bit too late that DF2014 does not have this feature anymore.  Whoops.

So, I had a flash.  Underground caverns have lakes that extend beyond the edge of the local area.  I could dig a tunnel that leads from one cavern to the other below, connect two underground lakes together.  If my assumption is right, the upper lake will endlessly drain into my tunnel (as the edge squares supply infinite water) while the lower lake absorbs it all (by the same principle, the lake never floods: the excess water pours off the local area.  Set up some waterwheels in the tunnel, and viola!

...But is my assumption right?  Do underground edge-touching lakes behave like an aquifer or an ocean, or are they considered finite water sources, and my dastardly waterwheel plan is doomed to failure?

Because, if it's not possible, then I'm most likely be going to use the area for the would-be tunnel to other purposes...
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PatrikLundell

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Re: An Artificial Underground River
« Reply #1 on: November 04, 2015, 03:11:18 pm »

Well, your assumptions are basically correct, apart from the complication that I'd guess (without any basis) the resulting water movement probably results in a worse FPS hit than a water reactor (I've never used one). A lake connected to the edge is an infinite source and sink. A better alternative than messing up two lakes is to drain a lake through a fortification by the map edge. A better alternative than that is to drain an aquifer source through an edge fortification.
Finally we have the alternative I use: Induced flow powering water wheels in the aquifer. It probably requires more work than draining off the edge, but should have no FPS impact. I justify the use of this exploit by the fact that I probably use more work to implement it than a drain, and thus that it's really an FPS saving work around.

Wind mills are disappointing because they provide 0/20/40 power depending on embark latitude (so you might get nothing at all) and require a 5 power gear to sit on. In addition to that they're a pain to build in a building destroyer safe manner that also does not provide a flier accessible hole down into your fortress via the power transmission shaft.

Aquifer flow induction: I channel rows of three tile long slits into the aquifer, spaced with two tiles in between. The middle tile in between holds a horizontal axle, while I build two screw pumps on either side, pumping in opposite directions. Get dorfs to pump briefely. Remove the screw pumps. Build one water wheel and verify that it produces power. Build the other and verify. If the first one fails to produce power, rebuild the pumps and redo. If the second one fails, build the pumps between the second and the third slit and pump. Build the second and verify, and the third and verify. Continue. until done.
I don't think you need two pumps strictly, but my highly unscientific superstition/impression is that two pumps give better results than one that's turned around (and I don't even know if you need to turn the pump around). I've found a way that gets me there, so I'm sticking with it until someone else investigates and reports a better way.
« Last Edit: November 05, 2015, 04:50:06 am by PatrikLundell »
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Shurikane

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Re: An Artificial Underground River
« Reply #2 on: November 04, 2015, 03:52:53 pm »

I unfortunately do not have an aquifer, but I'm glad to know underground lakes behave like one.

This means I can put my plan into action:

Dig several artificial rivers to which I will connect an unhealthy amount of water wheels.  They shall be used to power several pump stacks, which shall siphon magma out of the great sea and up towards where I want it to go - that is, the mouth of the volcano I'm sitting on, some odd 80+ Z-layers above.

If I remember correctly, nobody can sneak through fortifications, so if I put these as barriers between my input and output, this should protect my water wheels - and, bonus, allow me to connect a few pumps at the end of the river so I can artificially flood an area to safely grow underground trees.  I suppose I'll need my growing chambers to be 5+ Z-levels high considering the newfangled trees DF has...
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PatrikLundell

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Re: An Artificial Underground River
« Reply #3 on: November 04, 2015, 07:06:10 pm »

- If you've got a volcano, why go down to the sea for magma?
- What's the point with multiple pump stacks (unless they're above each other)? A single stack should be capable of pumping enough magma for any sane purpose (and when I used mine to cauterize an aquifer room the FPS dropped to 0. It recovered afterwards when I'd stopped pumping, though).
- Completely submerged fortifications can be swum through...
- Tree growth requires 2 levels to mature. They can reach higher, but two is enough.
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Flying Dice

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Re: An Artificial Underground River
« Reply #4 on: November 05, 2015, 12:39:13 am »

Yeah, I've done this both by diverting natural rivers and tapping aquifers, and it's a pretty nasty hit to FPS. Of course, that was with ones ~20 tiles wide and 100-200 tiles long, so a smaller scale artificial river probably wouldn't be as bad.

That said, Patrik's essentially correct, you only really need one stack for just about any purpose.

Also note that water lower than 7/7 can still push creatures through fortifications if it's flowing. Grates and bars don't suffer from the same problem, but are vulnerable to building destroyers. Fortifications backed by grates will keep out almost everything, but the only way to be totally certain is to use artifact grates (and good luck getting enough, hah).
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Shurikane

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Re: An Artificial Underground River
« Reply #5 on: November 05, 2015, 06:53:16 am »

- If you've got a volcano, why go down to the sea for magma?
Dwarfier.  :D

Quote
- What's the point with multiple pump stacks (unless they're above each other)? A single stack should be capable of pumping enough magma for any sane purpose (and when I used mine to cauterize an aquifer room the FPS dropped to 0. It recovered afterwards when I'd stopped pumping, though).
I have visions of a design inspired from infernal machines, which always seem to have too many pipes and levers and things than necessary.

Quote
- Tree growth requires 2 levels to mature. They can reach higher, but two is enough.
Perfect.  I'll prepare the setup for that accordingly.  :)

Also note that water lower than 7/7 can still push creatures through fortifications if it's flowing. Grates and bars don't suffer from the same problem, but are vulnerable to building destroyers. Fortifications backed by grates will keep out almost everything, but the only way to be totally certain is to use artifact grates (and good luck getting enough, hah).

I initially wasn't going to bother too much and play it fast and loose - that is, until a forgotten beast crocodile snuck into my fort through a hole I forgot to plug, and proceeded to cause terror in the fort.  Sent my wrestlers after it, took three military casualties and maybe 4-5 civilians, but at least I beat it.  I don't want to repeat this again, however...  One of my dwarves went "missing".  Nobody noticed he fell into the magma sea during the scuffle.

I think fortifications + bars will do enough of a job, mayhaps with lever-activated floodgates along with a bypass so that I can drain the area to rebuild that defense if the need arises (and also to keep the river from flowing until I'm ready to make use of it.)
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Daris

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Re: An Artificial Underground River
« Reply #6 on: November 05, 2015, 07:14:18 am »

In addition to that they're a pain to build in a building destroyer safe manner that also does not provide a flier accessible hole down into your fortress via the power transmission shaft.

Nah, keeping them safe from building destroyers is simple.  Build a wall all the way around.  Floor over the next level up, leaving only the central space open to the sky.  Done.
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Bakaridjan

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Re: An Artificial Underground River
« Reply #7 on: November 05, 2015, 07:17:21 am »

I would use a bridge instead of floodgates since they are impervious to building destroyers and I would put it as the first thing in front of any fortifications or bars. If an FB shows up you can close the whole system off until you deal with it and then turn it back on safely when it's gone. Unless you have a beastly computer, I can't imagine that you're going to want to be running multiple pumpstacks full-time anyways. Because of the FPS issues I generally only turn my pumpstack on to fill an upper reservoir and then I turn it off until I need more red sauce.

Also, if your artificial river is long I would recommend a bridge/floodgate at the exit end as well. You might have trouble filling the river otherwise, because water will keep running off the edge. Let it fill, then open the exit bridge to get the flow moving. It also helps to conserve water and restart it faster if you have to close the input gate.
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Flying Dice

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Re: An Artificial Underground River
« Reply #8 on: November 06, 2015, 07:03:04 pm »

There's actually a more elegant way to deal with things that can get through fortifications+grates. After those, have a long retracting bridge covering a pit that leads into a sub-tunnel which also flows off the map through edge fortifications. Open it long enough to drop whatever the thing is into the pit, then close it again.

Down in the secondary riverway have whatever you please: repeating spikes, fortifications in the walls blocked by long, narrow single-tile bridges you can lower after the water is drained, or even a plain old airlock to let your military inside. Or just leave the thing there to sit and fight whatever else gets dumped down.

Obviously set up a floodgate system so that you can drain the river if you need to make repairs or alterations, that's just common sense.  :P
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Aurora on small monitors:
1. Game Parameters -> Reduced Height Windows.
2. Lock taskbar to the right side of your desktop.
3. Run Resize Enable