40d Talk:Water pressure

Verification of U-bend bug. [1] VengefulDonut 12:37, 7 January 2008 (EST)

Do you happen to have a save file so I can poke it a bit? --SL 11:06, 15 January 2008 (EST)

I don't, but it has been reliably reproducible. VengefulDonut 23:37, 15 January 2008 (EST)

Deep water pressure bug?

I just had an odd experience. I lucked into a map with a brook high up on a mountain slope, a deep ravine next to it with an extremely narrow mouth I could easily wall off, and goblin buildings down at the bottom of the slope. So I made a huge five-level-deep reservoir and dug a floodgate-controlled tunnel from the lowest level right into the basement of one of the goblin forts. The reservoir was filling slowly so I had the opportunity to test-fire the flood in some disposable save games while the reservoir was still only partly full; it gave the wonderful drowned-goblin corpse-fountain effect I was hoping for. But once the reservoir had finished filling up to 7 on the highest level, even with the brook that was feeding it, opening the floodgate produced only a disappointing unpressurized trickle. It wasn't until I dug a single channel square at the edge of the reservoir, introducing a single non-7 square to the uppermost water layer, that the torrent instantly let loose with all its pressurized might. A known issue? Some of this page is a bit too arcane for me to follow right now so I'm not sure if it's mentioned. Bryan Derksen 01:59, 28 June 2008 (EDT)

That's almost certainly because it's being treated as part of the brook, since brooks and rivers don't produce (and even neutralize) water pressure. --Edward 14:49, 28 June 2008 (EDT)

Ah, so if I closed the floodgates feeding the reservoir to sever the connection with the brook it'd pressurize? Interesting physics in DF world. :) Bryan Derksen 03:09, 30 June 2008 (EDT)

Are aquifers treated the same way? I have a pond fed by digging stairs up into an aquifer, and dug out the wrong tiles around my pump. My entire fort should be submerged, but all I got was a pond at permanent 7/7.

Aquifers don't generate water pressure, and don't fill z-levels higher than the one on which they were originally found. Aosher 18:29, 12 March 2009 (UTC)

To clear out

Water sources attempt to generate water in tiles adjacent to pressurized tiles. They will not generate water in tiles above
pressurized tiles unless the water source has nowhere else to generate any water, and they will never generate water above 
the water source's z-level. 

What exactly does this mean? If I understand right, then it's a lie--Dorten

What do you think conflicts with the model? VengefulDonut 02:43, 9 February 2009 (EST)

Things like this (side view)

≈≈≈≈≈≈≈# ≈≈≈
≈≈≈≈≈≈≈#≈≈≈≈≈≈++
≈≈≈≈≈≈≈###≈#####
≈≈≈≈≈≈≈≈≈≈≈#
############

The blue water tiles should not be filled before the plus marked ones (empty). But this situation can easily be made ingame--Dorten 07:07, 18 March 2009 (UTC)

Water U - BUG

http://mkv25.net/dfma/movie-1407-pressurebugwithfortification

W≈≈≈###  ## z  0
###≈###≈### z -1
###≈###≈### z -2
###≈≈≈≈≈### z -3

W - Water from a water source
# - Solid wall
≈ - Water

The water does not go up to the z-level it came from.

Note that this will only happen if the water is able to drain on its source level (e.g. you tapped the side of a river) - if the water on the left side is unable to escape in any other direction (e.g. if you dam the river), the right side of the U-bend will fill up. --Quietust 15:34, 9 September 2009 (UTC)

U Bend Bug

I found a quirky Pressure bug using a U-bend into my main reservoir. I have it tapped directly into the river with a floodgate(1) right at the river to control things. The surprise was when I went to irrigate my fields, I was pulling water out through floodgate(2) to fill a vault to irrigate my fields with since the main reservoir was way too large for this purpose. So I had left floodgate(1) open expecting it to naturally refill as quickly as I drained it. It did not. It instead pulled the water out filling my vault, emptied the main reservoir and sat there doing nothing. Floodgate(1) is wide open still, so it SHOULD be refilling, but isn't. Toggling (1) closed and reopened seems to reset the pressure and allow the main reservoir to fill.

    ≈≈River≈≈1≈▒▒▒▒▒▒
    ▒▒▒▒▒▒▒▒▒▒≈▒...▒▒
          ▒▒▒▒≈▒...▒▒
          ▒▒▒▒≈≈≈≈≈2≈≈≈
          ▒▒▒▒▒▒≈≈≈▒▒▒▒
          ▒▒▒▒▒▒▒▒▒▒▒

It's a little unclear on why it behaves this way. It has something to do with multiple floodgates, when one opens, it doesn't seem to bother to check the state of other floodgates that might also affect pressure on this waterway. It may also be important that the top of my reservoir is lower than the river itself, so once it's done filling it may be shutting off the water flow logic since it's full now and doesn't need to waste CPU cycles, and then forgetting to check it again when I pull water away from that.Doctorzuber 09:12, 12 July 2009 (UTC)

overflow behaviour

"to a z-level one level lower than the source."

That is just plain contradicting the next sentence. Also, I have read the article at http://www.gamasutra.com/view/feature/3549/interview_the_making_of_dwarf_.php?page=10 , but, please, explain then:

On level '1' I have a tunnel filled with water, steadily being refilled by a pump. It drops its content one level down ('0') through a channel tile, into a room that is open to level '1' via a stairway. The room fills with water and when all tiles are at 7/7 water starts pouring out back to level '1' - lots of water. Of course this makes perfect sense. If there is another mechanism at work that has nothing to do with the pressure model ("Pumps do not create pressure"), then there should still be a warning, or a rewording because, seriously, how is that not "water pressure" --Birthright 16:50, 12 July 2009 (UTC)

By not creating it, it means that the water coming out is at zero pressure. By dropping the water, it can now gain pressure if any of the tiles above it are at 7/7. -Edward 19:25, 23 July 2009 (UTC)

Oceans

I'm torn on whether to add something specifically about oceans on here. I tunneld into an ocean three z-levels below the ocean's surface with a door which I figured would allow my miner to escape with minor flood beeing the only damage. When I breached the ocean, the room immediatly filled with water. I thought that was odd but I let my miner do his this, and as soon as he opened the door the game went to 0 FPS for about 2 minutes and suddenly my whole fortress below that points (a good 6 z-levels with some sizable rooms) was 7/7. instantly in game time. You can see why I'm tempted to add a warning. Planetofthedwarves 18:40, 23 July 2009 (UTC)

Damn, you got romped. Definetly add that warning!--CrazyMcfobo 18:56, 23 July 2009 (UTC)

That's no different than would happen with any other large body of water with several Z-levels above where you breached. Fill a giant (x&y, not Z) tower that reaches into the ground with water, and then breach it.. You'll get the same instant fill to a certain level. -Edward 19:24, 23 July 2009 (UTC)

Fast aqueducts

I'm hoping to transport water a long distance quickly. Side view of initial layout:

▒ target ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒≈≈river≈≈▒
▒▒ area ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

The obvious naive approach is to dig a tunnel leading to the river:

         _____________________
▒ target                       ≈≈river≈≈▒
▒▒ area ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

My overall impression from this page is that the water might move faster if a pump on a higher Z-level is involved:

         __________________▒ %%
▒ target                     ▒▒≈≈river≈≈▒
▒▒ area ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

Is that right? Does it help to add more pumps further down the tunnel to re-pressurize? And is there additional risk of flooding? --HebaruSan 04:30, 27 November 2009 (UTC)

With high certainty: (a) In the second solution, water will seek to rise back up to the level of the pump, so yes there is the risk of flooding vs. the naive approach. (2) Multiple pumps (in sequence) will not help, water does not lose its pressure over distance. With less certainty.. what will be faster? I suspect that digging some space under the river to feed a pump on the same z-level as the river will be faster than either way, because the pump intake will be kept more full by pressure of the river trying to fall down into the pump intake. Cheepicus 07:22, 27 November 2009 (UTC)

         _____________________
▒ target%% %% %% %% %% %% %%   ≈≈river≈≈▒
▒▒ area ▒▒ ▒▒ ▒▒ ▒▒ ▒▒ ▒▒ ▒▒  ▒▒▒▒▒▒▒▒▒▒▒
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

--Kami 08:25, 27 November 2009 (UTC)

The setup time for that is high, and a single pump pumping into a hallway filled with 7/7 tiles will put the water at the end instantly anyway, so it's not really faster, either, right? Cheepicus 11:15, 27 November 2009 (UTC)