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[Bumber]

Started a fort in 0.47.05 and I'm having issues getting my well filled. The water won't flow through my inverted U-bend:


There should be plenty pressure to get it up to Z+1, but it just sits there. Both grates are on downward slopes. The water comes directly down from the middle of a river. Is it something to do with the drawbridge (shown as ≈≈) being closed while the tunnel filled?

[A_Curious_Cat]

It might.  What level is the water source on.  In order for the inverted U-bend to work, the water source needs to be on z+1 or higher.  Also, what’s the water level over the bridge?  Use ‘k’ to find out.

Actually, come to think of it, could you answer a couple of questions?

1.  Did you unpause the game?

2.  Could you follow the aqueduct “upstream” to make sure it has enough water in it?  There is water in the tile above the stairs in the left hand image, isn’t there?

3.  Is there another bridge somewhere that you’ve forgotten to open?

[Bumber]

Water source is about 8 levels above. Water level over the bridge is 7/7.

1. Yes.
2. It's all 7/7 in the river except the downstream map edge.
3. Nope. The only other bridge is a retracting one that empties the well into a map edge drain, which is currently dry.

I switched the fluid display, and the tile north of the bridge is switching between ≈ and ~. The tile south of the bridge cycles between ≈, ~, and ▲, occasionally turning white. When the bridge is shut, the tile the bridge expands into, as well as the tile to the north, both behave like south one (minus the ▲.)

[A_Curious_Cat]

Water source is about 8 levels above. Water level over the bridge is 7/7.

1. Yes.
2. It's all 7/7 in the river except the downstream map edge.
3. Nope. The only other bridge is a retracting one that empties the well into a map edge drain, which is currently dry.

I switched the fluid display, and the tile north of the bridge is switching between ≈ and ~. The tile south of the bridge cycles between ≈, ~, and ▲, with one of those being white (~ I think.) All others in the tunnel are constant blue ≈.

What’s your FPS?  You might just need to wait.  Are you sure you don’t have a leak somewhere?  What’s on z-1?

[Bumber]

What’s your FPS?  You might just need to wait.  Are you sure you don’t have a leak somewhere?  What’s on z-1?

100 (30). Undiscovered tiles; dug through them real quick and it's all solid diorite. The floors of the aqueduct are all constructed diorite blocks, including the ramps as well as the up stair at the very north of the tunnel.

The vertical shaft passes through an aquifer, but that's still ~5 z-levels above the U-bend.

[PatrikLundell]

Water moves only if something triggers movement, so when it's static you can have walls of water that just sit there (removing cavern trees from within cavern lakes with ballista bolts leave holes in the water, for instance, and reclaims of ocean fortresses have reported walls of water on the border between the ocean and land).

I've had issues with water not starting to flow when opening drawbridges on tunnels that has upwards going components, but only drain the lower part. In those cases atom smashing some water with a drawbridge (that happens to be present upstream) triggers ripples that get water flowing again. I suspect it might be possible to use DFHackery to reduce the amount of water on a tile to 6/7 to trigger a ripple (I don't know if "liquids" can remove water).

(I also see that you're afflicted by click-baitish as well. Yuck!)

[Bumber]

Ready for something weird?

Exposing any new tile in the 16x16 block z-column that contains the vertical shaft causes the water to flow up into the inverted U-bend and start filling the well.

Edit: It's limited to tiles at or above the level I labeled Z+0

This works only until the bridge is closed. It has to be done again when the bridge is re-opened.

Edit 2: Further testing indicates it's actually digging any tile, from Z+0 to the river's z-level, within the shaft's 16x16 block z-column or any tile horizontally adjacent (including diagonals) to those. Digging a down stair to reveal a tile at the river's z-level isn't sufficient, but digging an up stair into the revealed tile is.

[A_Curious_Cat]

Bug?

[Bumber]

Bug?

Probably. I'll upload a report soon.

http://www.bay12games.com/dwarves/mantisbt/view.php?id=11688

[feelotraveller]

Noticed on the difficulties mentioned in the bug report about reproducing.  Strikes me that

The vertical shaft passes through an aquifer, but that's still ~5 z-levels above the U-bend.

may well be relevant.  Something along the lines of the aquifer containing the 16x16(x16?) block setting the flow (bit? flag?) of all non-moving water within it.  Altering any tile in the immediate area would get it moving by triggering a re-evaluation of flow status.  Anyways something to look at.

[A_Curious_Cat]

Noticed on the difficulties mentioned in the bug report about reproducing.  Strikes me that

The vertical shaft passes through an aquifer, but that's still ~5 z-levels above the U-bend.

may well be relevant.  Something along the lines of the aquifer containing the 16x16(x16?) block setting the flow (bit? flag?) of all non-moving water within it.  Altering any tile in the immediate area would get it moving by triggering a re-evaluation of flow status.  Anyways something to look at.

You might want to bring that up in the comments section of the bug report.

[Bumber]

@feelotraveller
I tried the attempt to reproduce on the same map, though.

[Urist Lovestone]

Is your bridge on the Same Z level as the water flow and not 1 above? It should function like a wall while it's down and block it. A fort or two ago I tried construction an artificial underground river, once entire sections flooded to 7/7 I didn't have any flow but if there was any tile less than 7/7 it seemed to work.

Not to high jack your thread but I also have a water pressure question. I made a U bend and somehow I got lucky enough to hit an aquifer for the actual intake at the bottom of the U where it needs to come up 1 more Z level, I remember reading on the wiki it would pressurize it but I wasn't 100% sure then sort of forgot that was an aquifer level and cracked the brook source to empty into it a bit later when I finished more construction on the well it was going to feed. Some hijinks ensued when the brook unexpectedly froze.

If I can figure out how to drain the section, then dig out the aquifer tiles and replace it with constructed walls floors will it restore the water pressure? Or did that just permanently lower the intake a Z level like a diagonal tile break does?

I already have a work around in place but I think someone like our countess might of mismanaged some aspects of the fort like planting seeds for alcohol in favor of making mail shirts, and the dwarfs are getting kind of close to having a tantrum about drinking brook water through the ground. I'm a bit amused this happened because I'm trying to picture a dwarf just shoving his head into the dirt to suck up the underground river water under there I had no idea dwarfs could drink brooks with the ground cover over it. They're overall seem really not happy with the situation. It made me think of how to power the machines though and a mega project for that.

[Bumber]

Is your bridge on the Same Z level as the water flow and not 1 above? It should function like a wall while it's down and block it. A fort or two ago I tried construction an artificial underground river, once entire sections flooded to 7/7 I didn't have any flow but if there was any tile less than 7/7 it seemed to work.

The bridge is on the same level as the flow and functions like a wall when raised. As the bug report shows, there's nothing wrong with the design in theory. The water will spontaneously pressurize and fill the well if something triggers a recalculation.

[Urist Lovestone]

When you close the bridge, it's all cut off from everything right? Just a full 7/7 with no upper or lower Z levels to go to closed off? You might need a drain tile, like I accidentally dug into with a current fort. When I tried doing an artificial underground River on lets say last fort, I left a tile to drain off to but I had to construct it in segments, and had to fill and drain it in sections. It behaves a lot differently on if it has tiles to fill or drain from, I haven't worked out drains correctly yet. I lost that fort in a siege. Current fort, I had a weird pressure spike when the brook froze on this one and it ignored the pressure level and flooded that Z level but was blocked off more than where the water could go and a ton of tiles were stagnant 2/2 depth. If the water can pack in there and has no where to go I don't think it'll have any flow. You might need a drainage tile.