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[bela]

Hi everybody,

i have a noob question that has been bugging me: How do you drain caverns (and other things)? I get the general idea with drains, floodgates (or doors) etc., but how do you remove the last tile, the damp one? How do you save the dwarf that digs the last time from drowning?

Thanks, bela

[Meph]

Channel into it from 1 level above.

Also, cavern lakes refill, if a part of them touch the map edge, so not worth the trouble.

[pisskop]

You can just  dig that last tile, and hope that your miner runs away fast enough or isnt pummeled into the wall hard enough to explode.

Channeling from above would work.

Also diagonals will block pressure, giving you more time to flee and more control over the fluid.


Water isnt too bad unless you plan poorly; magma is a different matter.  You might be able to save the miner, but sometimes a sacrifice is required.

[Panando]

It tends to be extremely safe to drain things from below using up/down stairs. Once you've got a drain set up below, just order a down stairs into the bottom of the lake and the dwarf will dig it from below. The dwarf can then escape from the staircase via some level which is not the lowermost level. Obviously, the lowermost level will be extremely flooded.

[Slogo]

You can just  dig that last tile, and hope that your miner runs away fast enough or isnt pummeled into the wall hard enough to explode.

Channeling from above would work.

Also diagonals will block pressure, giving you more time to flee and more control over the fluid.


Water isnt too bad unless you plan poorly; magma is a different matter.  You might be able to save the miner, but sometimes a sacrifice is required.

You can also channel from below with the dwarf over a grate & cistern with an escape door for the level they're on. They'll channel into the water and get wet, but they can move out of the way eventually and just leave by the escape hatch. By the time the cistern fills and the place where the dwarf was is properly underwater they dwarf will be long gone.

[Uggh]

Another way to do it:
dig until only one tile separates you from the water,
build a floodgate on the last open tile,
connect the flood gate to a lever somewhere far away,
build a door on the second to last open tile ,
open the flood gate if not yet open,
dig the last tile-the miner will escape through the door,
close the flood gate,
remove the door.
Don't forget to seal any additional access the miner might have used.

[Panando]

Another way to do it:
dig until only one tile separates you from the water,
build a floodgate on the last open tile,
connect the flood gate to a lever somewhere far away,
build a door on the second to last open tile ,
open the flood gate if not yet open,
dig the last tile-the miner will escape through the door,
close the flood gate,
remove the door.
Don't forget to seal any additional access the miner might have used.

Even easier: Skip the floodgate and just use the door, initially unlinked. After the miner has done the job and escaped through the door, connect a lever to the door. You can do this as connection jobs operate from the tile next to the target, so the door stays closed and holding back the water while being hooked up to the lever.
I normally use doors for fluid control for two reasons:
1) They open/close the instant the lever is pulled.
2) You can set the lever to repeat to make the door open/close extremely rapidly, which atomsmashes liquid out of existence at an extremely rapid rate. This is particularly useful for draining magma and is my useful solution for draining cisterns and stuff (i.e. I build and link the door in advance of filling the cistern).

Maybe toady will one day give a good reason to use floodgates, but for now doors do everything floodgates can and do it better. (the only real reason to use floodgates is they have an identical delay to bridges, allowing you to perfectly synchronize the release of liquid with the cutting off of retreat)

[Bumber]

Would something like this work for draining lakes with tiles at the edge of the map?

Legend:
| Map edge
█ Solid tile
~ Water
X Up-down stair (plus floor grate?)
v Down stair
_ Floor
╬ Fortification (smooth wall then carve fortification)
→ Drawbridge (raise east or west)
O Drawbridge (retracted)

Side View:

Code: [Select]

~~~|
~~~|
█X█|
█_╬|Stage 1

Code: [Select]

~~~|
~v~|
█X█|
█_╬|Stage 2

Code: [Select]

   |
_v_|
█X█|
█_╬|Stage 3

Then you build raising drawbridges over the edge tiles to stop the water from returning:

Code: [Select]

  →|
_v→|
█X█|
█_╬|Stage 4 (Top bridge is supported from side)

Code: [Select]

  O|
_vO|
█X█|
█_╬|Stage 5 (Bridges retracted)

The design extends across for as far as you need, with access to the floor grate and fortification levels. Optionally, you can obsidianize the edges with ‼magma‼ instead of using drawbridges. That would be a pain, though, since I don't think you can build track stops near the edge of the map for the filled minecart method.

[Uggh]

Maybe toady will one day give a good reason to use floodgates, but for now doors do everything floodgates can and do it better. (the only real reason to use floodgates is they have an identical delay to bridges, allowing you to perfectly synchronize the release of liquid with the cutting off of retreat)

That is true, I only use floodgates for style, doors appear out of place in plumbing. Bridges have the added advantage of being hard to destroy.

[0x517A5D]

I've sometimes opened a large drain by caving-in a layer of rock from above.

The key is, when you've dug out the main shape of the drain, dig down stairs in the area where you plan the opening, and up stairs in the layer below.

Then, from directly above the cavern lake, detach a single-layer chunk of rock exactly the size of your planned drain opening.  It will crash through the thin floor between the cavern lake and your drain, and continue crashing through those down stairs, stopping in the second layer where you dug the up stairs.  The drain is now open.

Use a support and lever to trigger the cave-in, or you'll lose miners.  Also make sure there is solid rock on the layer below the up-stairs, or the cave-in will crash through into that space, winding up even further down than you planned.

It takes a lot of preparation, is abusive of game mechanics, and has the potential to be disastrous.  It could only be more dwarfy if it was on ‼fire‼.

[Panando]

It should be noted that the cave-in technique for punching out the floor of a lake is only needed if you are opening a hole in lakes which are 2 or more z-levels deep. As for a single z-level lake it is very safe to just dig the staircase, the reason it is safe is that the moment you open the downstairs in the lake floor, the water starts draining, this means there is less than 7/7 water and the dwarf can breathe and won't drown. The water will drain quickly enough that the water will become low enough that he can dig out the rest of the downstairs in the floor of the lake. Once the digging is done he can either escape from below (any z-level but the lowermost) or you can build a staircase from above down to the lake floor.

For lakes which are more than 1 z-level deep the water flow can be so extreme that it becomes marginally less safe. This is especially true if it's near to the map edge (and if the map edge is 2-z deep) as the water will replenish so quickly that the miner may have great difficulty battling against the water flow to finish digging.

However if your goal is to put a staircase through the lake bed (something I'm oddly obsessed with, as I like perfectly vertical staircases and things like lakes are just engineering challenges to overcome) then draining the lake is not a sensible approach. The sensible thing to do is to drop a plug of rock into the lake then dig the staircase through the rock plug. Exactly like the cave in technique for piercing aquifers, except easier.