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[denito]

Edit:  I changed the title to reflect the fact that the water wasn't actually going past the floodgates; my real problem was that I wasn't draining the ocean right period.

I'm on a map with a nice 4z level deep ocean an aquifer inland that's 1z level below the ocean.  So I dug a 3-tile wide tunnel under the ocean floor to connect it with the aquifer.  I figured, why bother draining the ocean 1 level at a time?  I'm going to dig a hole at the bottom like a giant tub drain and do it all at once!

I built a double-floodgate system:  at one end of the tunnel, floodgates seal the chamber where I breached the aquifer.  At the other end of the tunnel, other floodgates seal the chamber where I breached the ocean.  I figured that way I'd be *sure* to be able to shut it off if needed.

Everything went great up until I tried to breach the ocean.  Even breaching the aquifer wasn't a problem; I did that first.  I channeled out a large chamber under the aquifer and had my miners standing on floor grates, so that when my miners dug out from the aquifer the water fell through the grates, leaving the miners time to dig a dozen of the aquifer tiles out.

Then I tried to breach the ocean and that is when everything went to hell in a hurry.  I designated a large number of upward ramps, but as soon as 1 was dug the whole chamber filled instantly.  I lost 3 legendary miners instantly.  (I should have switched to peasants when breaching the ocean; I just thought that, you know being legendary, they'd be fast enough to dig more than one tile and maybe even get out.  I underestimated the speed at which the ocean flows!)

Now here's the funny thing:  the ocean immediately started draining and met up with the aquifer water and filled the aquifer chamber instantly.  It did this THROUGH A SET OF CLOSED FLOODGATES.  The floodgates on the aquifer chamber were closed.

Now here's the part that sucks:  the miners only managed to open one ramp up to the ocean floor, and this they did only across a diagonal and it' underneath an existing upward ramp on the ocean floor.  It's only one tile and not even the full flow at that.  So although the ocean is getting a lot of level "6" water tiles, it's not draining fast enough to keep up with the refilling.  I think the diagonal and/or the upward ramp thing is resetting the pressure.

So I closed the floodgates to seal off the ocean side of the tunnel and it's STILL draining through both sets of floodgates.  I'd like to drain the tunnel and branch off it to breach the ocean again, but with the ocean ignoring my floodgates that's not working well.  It also makes me wonder how I will "put the ocean back" afterwards if I succeed in draining it.  Oh well - I have magma so I could always drop some cast obsidian on it and plug the hole.  Still, I didn't think the ocean was supposed to ignore your floodgates.  I don't have any other ways for the water to go around the gates, although there are stairs to the surface in both chambers.  Could it be "pathing" over the surface?

[kefkakrazy]

Pretty sure that diagonals cancel pressure, for starters.

As for anything else? Maybe there's a gap someplace. I dunno.

[denito]

OK I'm going to say that draining the ocean into an aquifer does NOT work.  (Maybe it used to work in an old version and doesn't now?)  I just dug two more tunnels into the ocean, one at the top Z level of ocean and one at the bottom, without any mistakes this time.  Neither channeling the coast into a tunnel that drains into an aquifer nor putting a "tub drain" tunnel in the floor of the bottom level of the ocean leading to an aquifer are fast enough to drain it.  You get a flurry of "6-7-6-7" depth while it fills the initial void, but after that, the ocean water level returns to 7 all around.

[Time Kitten]

alright, besides the diagonals, do you have at least two spaces over the aquifeer?  As water can still rest attop it in some occasions.

[Jude]

I thought the ocean was an infinite water supply and couldn't be drained. it would make sense...

[MrFake]

Then I tried to breach the ocean and that is when everything went to hell in a hurry.  I designated a large number of upward ramps, but as soon as 1 was dug the whole chamber filled instantly.  I lost 3 legendary miners instantly.  (I should have switched to peasants when breaching the ocean; I just thought that, you know being legendary, they'd be fast enough to dig more than one tile and maybe even get out.  I underestimated the speed at which the ocean flows!)

Water teleports.  What may have happened was every water tile on the surface of the ocean was looking for a place to teleport to, and they all found it simultaneously when the miners opened that hole.  That instant influx of water was really all those tiles teleporting in.

It may be possible that when that much water tries to teleport, it ignores floodgates, but that sounds sketchy.  Are the tunnels filling with water to any depth higher than where you breached the ocean, or higher than the aquifer?  If not, then I'd say the ocean is draining into the aquifer, as that seems to be what happens in that case.  However, you'd probably see a very quick drop in the ocean level, and maybe other oddities.

Diagonals may eliminate 'pressure,' in the sense that they have different teleportation rules.  Is it possible to make a diagram of how you initially breached the ocean?  What about a diagram of the tunnel between the ocean and aquifer, as well as one or two z-levels above and below?

Also,

Even breaching the aquifer wasn't a problem; I did that first.  I channeled out a large chamber under the aquifer and had my miners standing on floor grates, so that when my miners dug out from the aquifer the water fell through the grates, leaving the miners time to dig a dozen of the aquifer tiles out.

So you 'd'ug those tiles below, then c'h'anneled the tiles above, right?  Then built the floor grates as you channeled each tile?  Where did the water go when it was falling through the grates?  A large basin?  I'm just curious, as I have a large aquifer project and this sounds useful.

[Quietust]

It is absolutely possible to "mostly" drain the ocean into an aquifer, though it's generally a really really bad idea - done properly, it will cause the game to drop to about 1 frame per minute while the entire ocean instantaneously drains away (such that all water located above "empty space" will be gone), and even after it's done it'll still lag horribly as the map edges desperately try to refill it.

[denito]

It may be possible that when that much water tries to teleport, it ignores floodgates, but that sounds sketchy.

I think what happened was that it appeared the ocean was draining past the floodgates, but what really happened was 2 unrelated things simultaneously:  the aquifer finished filling the chamber on one side of the floodgate, and the ocean water teleported into the empty tunnel instantly.  So it looked like it was going past the floodgate, but actually it was just the aquifer filling the void on one side and the ocean filling the void on the other.  Once both voids were filled, it took a while but the ocean eventually settled down.  It wasn't really going through the floodgate.  Perhaps I should change the title of this thread.  Unfortunately it doesn't drain (much) with the floodgates open either.

Even breaching the aquifer wasn't a problem; I did that first.  I channeled out a large chamber under the aquifer and had my miners standing on floor grates, so that when my miners dug out from the aquifer the water fell through the grates, leaving the miners time to dig a dozen of the aquifer tiles out.

So you 'd'ug those tiles below, then c'h'anneled the tiles above, right?  Then built the floor grates as you channeled each tile?  Where did the water go when it was falling through the grates?  A large basin?  I'm just curious, as I have a large aquifer project and this sounds useful.

Well that is one good thing that came out of this - it turned out it's a GREAT way to safely open an aquifer.  Note that it won't help you get past an aquifer that you're trying to dig down through; this is for when you are digging at the edge of an aquifer and you for some reason actually want the water to come out and fill the mine.  You have to already have a way to get to the Z level below the aquifer to do this anyway.

As for the method in detail, I'm not sure you're misunderstanding my explanation, or I'm misunderstanding your summary, so I'll just explain it from scratch:

Let's call the Z level below ground -1, the one below that -2, etc.  On about Z level -4 I found the outer boundary of my aquifer.  I dug out the dry stone around it until I'd exposed a whole wall of damp stone.  Then I dug a large chamber underneath that wall of damp stone on Z level -5.  I dug a 1 tile wide channel right by the wall on Z level -4, and covered the channel with grates, on Z level -4.  That way my dwarves could still get to the exposed aquifer wall across the channel.  Then I dug out the wall of damp stone all at once.  The water that came out ran down through the grates into the chamber on Z level -5, so Z level -4 didn't get too much water until the dwarves had time to get out.

You couldn't really use this as a technique to get below an aquifer because if you could find a dry place on Z level -4 to dig down to Z level -5, then you wouldn't need to breach the aquifer anyway.

Maybe if you used pumps you could pump UP to a chamber on Z level -3, but then the wiki already says you could use pumps to breach an aquifer so that's not really news to anyone.

[denito]

It is absolutely possible to "mostly" drain the ocean into an aquifer, though it's generally a really really bad idea - done properly, it will cause the game to drop to about 1 frame per minute while the entire ocean instantaneously drains away (such that all water located above "empty space" will be gone), and even after it's done it'll still lag horribly as the map edges desperately try to refill it.

Clearly I'm not doing it properly then.  But I wonder what part I have wrong?  Did I not expose enough aquifer tiles as sinks?  Do I need a wider tunnel to the aquifer?  Is it not working because I have a U-dip in my tunnel?  (In order to avoid "cancels dig: wet stone" spam, I sunk the tunnel 2 Z levels below the ocean and then pop back up at the end.

I'm not scared of the frame rate drop.  I have a really fast desktop machine.

[UristMcGunsmith]

I'm not scared of the frame rate drop.  I have a really fast desktop machine.

You're new, aren't you?

Edit: to give you an example, my friend has a quad core 2.66 ghz, 5 GB Ram, Nvidea Gforce 9800 DDR3, a liquid coolant system, and several other goodies, and he cannot do what you are attempting without the game nearly locking up.

You know not the dark foe that appears before the glow of your moniter, the dark foe of the DF FPS machine.

[Grendus]

That 1 FPM is with with DF assigned to it's own core in a dual core, "very powerful" desktop PC. If I tried to do it on my 3 year old laptop, we're talking .1 FPM if you're lucky. Water is painfully inefficient right now, a leaky waterfall consumed 30 FPS on one map.

To paraphrase Martin, simulating that much fluid motion is like your computer trying to calculate all the forces acting on a B12 bomber in a hurricane.

[Quietust]

A straight path is sufficient to drain an ocean - any diagonals will prevent pressure from moving the water through at the maximum rate.

Code: [Select]

Good:
##~##
##~##
##~~~
#####
#####

Bad:
##~##
##~##
###~~
#####
#####

As has been suggested, if you do manage to drain the ocean into an aquifer, you'll know immediately, since the game will appear to completely lock up, only redrawing the screen once a minute or so as it moves all of the water down the hole and into the aquifer (since aquifer tiles can suck up pressurized water, unlike the map edge which requires the water to flow off naturally).

[Magua]

Unless I'm reading wrong, it sounds like you're approaching the aquifer from the side/bottom, yes?  Something like this?

Code: [Select]


XXXXXXXXXXXXXXXocean
XXXXXXXXXXXXXXXocean
XXaquifer XXXXXocean
XXXXXXXXX       XXXX
XXXXXXXXXXXXXXXXXXXX

I highly doubt that would work, as aquifers are also an infinite *supply* of water.  Whenever I've dumped water into an aquifer, I've had to do it from above, something like this:

Code: [Select]


[code]

XXXXXXXXXXXXXXXocean
XXXXXXXX  _Pp Xocean
XXaquiferX pP_Xocean
XXXXXXXXXX Pp   XXXX
XXXXXXXXXXXXX___XXXX


[denito]

Unless I'm reading wrong, it sounds like you're approaching the aquifer from the side/bottom, yes?  Something like this?

Code: [Select]


XXXXXXXXXXXXXXXocean
XXXXXXXXXXXXXXXocean
XXaquifer XXXXXocean
XXXXXXXXX       XXXX
XXXXXXXXXXXXXXXXXXXX

I highly doubt that would work, as aquifers are also an infinite *supply* of water.  Whenever I've dumped water into an aquifer, I've had to do it from above, something like this:

Code: [Select]


[code]

XXXXXXXXXXXXXXXocean
XXXXXXXX  _Pp Xocean
XXaquiferX pP_Xocean
XXXXXXXXXX Pp   XXXX
XXXXXXXXXXXXX___XXXX


Your first diagram is EXACTLY what I did.  Sh*t.  I'll have to try doing it like your second diagram.  Does it still work if there's a staircase to the surface at the top of the "hump" in your second diagram, or do I have to do it all sealed?

Edit:  And is there a way to arrange it with gravity feed instead of pumps?  Or, if I do use pumps, I wonder if with enough pumps running full steam before I open it, if they can keep the water low enough to allow a miner to survive breaching the ocean floor?

[numerobis]

a miner to survive breaching the ocean floor?

This is not usually a concern.  There are three solutions: embark with an extra pick; have the miner walk back the way he came; breach the ocean floor with a ramp.  Then as the entire ocean rushes in, the miner will calmly walk up the ramp, and up the now merely damp seafloor and on home.

It will take minutes for the first frame, and it will be very slow as the seafloor drains.  After a few thousand frames, it will have sped up to being extremely slow.