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Difference between revisions of "v0.31:Aquifer"
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Revision as of 20:38, 15 October 2010
| This article is about an older version of DF. |
An aquifer is a subterranean layer of Template:L-bearing rock or Template:L. Attempts to mine through the layer will result in the mined-out squares immediately filling with Template:L, effectively halting excavation at or below their level. This, in conjunction with the fact that they are often located in areas rich in Template:L, and Template:L, makes it difficult to find great quantities of Template:L in areas with aquifers, making for more challenging gameplay.
Aquifers can't be drained - the groundwater is limitless. Template:L aquifer stone stops producing water. Aquifers located in Template:L areas will produce salty water. Aquifers do not only produce water - if the incoming water is pressurized, an aquifer tile may instead absorb it. Just like with water production, this ability will not be disabled no matter how much water it absorbs.
Where they are found
Aquifers are found in most Template:L layers and some porous rock layers. They often span several rock layers. They are recognizable at the embark screen by the ≈≈≈≈≈ to the right of that layer.
Layers which CAN contain aquifers:
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
- Template:L
Layers which CAN'T contain aquifers, despite their names suggesting otherwise:
Dealing with aquifers
Digging at a change in level
Though an aquifer seems a daunting obstacle, it is possible to dig through it, given a ample supply of building material (rock or wood) and any unevenness in the depth of the aquifer. The basic facts:
- An aquifer layer will absorb an unlimited amount of water draining in from above.
- With an up/down stairway or channel designation, a dwarf can break through the floor of the cell beneath him. That means a dwarf can stand on top of an aquifer layer, dig an up/down stairway, and make it drain into the layer beneath it, if that layer is also an aquifer or has an open path to an aquifer layer nearby.
- A stairway may be swamped to dangerous levels with water draining in from the squares around it, but many stairways in a clump mean that the drainage to the next layer wins out.
- Constructing a wall, up/down stairway, or channel in an aquifer layer prevents any water from originating in that square. A wall prevents water from draining down into the next layer from any source, while the stairway or channel lets it come in from other squares and drain.
These points support the following method:
- Dig around at the level just above where you encountered the aquifer, placing up/down or down stairways according to your preferred city grid plan. Training up a few miners in this way will help later. Spot some points where the next level (as seen from down stairways) varies in wetness from one spot to another.
- For the following, pause the game after every square dug out and make sure the miners dig both layers at the same rate and redesignate when they cancel your plans automatically. Dig a 5x5 hollow square of up/down stairways at the change in level, going down as far as you can. The lower aquifer should accept water from the upper aquifer, allowing you to drain the upper aquifer (at least partway). Then gradually take on the area in the middle, building walls and/or staircases to fill in and stop the flow as you expand. Eventually you should get command over the source of flow, and can dig a hole in the center of the bottom-most layer surrounded by a 3x3 ring of impermeable rock.
- Caveat: sometimes only the top of the aquifer changes depth, but the bottom stays at the same level. In this case you will get nowhere. Sometimes the aquifer is two or more layers thick and it doesn't offset enough to let you all the way through - in this case, sometimes you can use the cave-in method to get through one layer, then use this method to get through the next. And sometimes you'll just find a hole right through when you investigate the change in level, because you're at a biome boundary and it's not aligned perfectly.
The ore method
On maps where the aquifer is not held in a layer of soil, but instead is held in a Template:L such as sandstone, it may be possible to tunnel down through deposits of ore such as magnetite. For this to work you have to find a spot where there is coincidentally an ore deposit on each Z-level you need to dig through. This is only possible through tiresome trial and error, or through the use of a utility like reveal.exe. The trial and error method can be accomplished somewhat more easily by digging up/down stairs to reveal the layer underneath them without actually digging into the underlying layer. This method is more complicated with aquifers located in layers of Template:L, as large clusters of Template:L will support the aquifer and thus cannot be used to provide a path through it.
The magma/obsidian method
If you have access to a supply of magma, you can create your own obsidian caissons. By channeling into the aquifer layer and then filling these channels with magma, it is possible to create a wall of obsidian between your working area and the Template:L-bearing rock or Template:L. However, changes to world generation with the last version have made this method more difficult than it once was, as it is now harder to find magma vents that extend above the aquifer level.
The cave-in method
If there are enough layers above the aquifer, then letting non aquifer rock fall into the aquifer layer gives an area of diggable rock. This requires at least 2 natural dry layers. If multiple aquifer layers are to be breached, things get more complicated. First Template:L out the area of aquifer that will be replaced. Then dig out all connecting floors and walls to the block that will fall (build a support to hold it until you are ready for collision). A Template:L may be useful to assign unnecessary dwarves to a safe area. When everyone is clear, de-construct the support with a lever. (If you forgot to bring stone, then you may instead build a constructed floor to support it, designate it to be destroyed, and have a Template:L standing ready in case the unlucky one survives.)
After the collapse, do not dig out the outer edge of the fallen rock.
This does not work with Template:L walls since they deconstruct on cave-in.
If you build many rings inside one another in your top drop layer, you can breach multi-level aquifers with as little as 2 natural layers of dry soil above it. Drop the rings from the outside to the inside using constructed arms to hold the center rings in place. Once a ring drops into the water below it, pump out the water in the center and dig down another layer. When that is complete, drop the next ring and continue the process until you are through. Since you start dropping rings from the outside it is necessary to know how many levels deep the aquifer is before you begin.
Some might regard this method as cheating, so use it at your own risk.
Note: There is a bug that may prevent this method from working, collapsed layers may turn into the aquifer layer type that was dug out at that level. So, for example: We have three layers, layer 1 has the caving in section, and is not an aquifer. Layer 2 is a dug out layer that is also not a aquifer. And Layer 3 which is dug out and is an aquifer. Now, the bug, say layer 1's cave-in section lands on layer 3's dug out area, sometimes layer 1's caved in section may change into layer 3's soil type. Making it an aquifer too. Thus making the cave-in method impossible for that area.
The freezing method
If you are playing in a freezing or very cold landscape, where it snows in winter and instantly freezes water on the map, you can dig out a 3x3 hole in the ground using Template:Ls, and make it deeper and deeper until you reach the aquifer level. Once you reach the damp rock, tunnel into it with an up/down staircase - the incoming water will freeze after a few moments. The central square of the 3x3 hole should be tunnelable ice, so you can get to the rock beneath. If there are two aquifer levels, for example, you can just make a larger initial hole, and make a smaller one for the level after.
If your fortress is in a zone that gets warm, build walls around the inside of the hole to stop the water coming in once the ice melts.
Note: There is a bug that may prevent this from working, sometimes ice walls don't produce an ice floor tile above them, instead leaving it as "open space" which prevents the player from digging downwards. Simplest method is to construct a wooden (or stone, if you have any) floor and then remove it. After the floor is removed, a natural ice floor will remain. An alternative means that will work is to set the tile 1 z-level ABOVE your missing ice floor tile as a Template:L, and FILL IT. The first Template:L of water that goes on it will create that missing ice floor tile the instant the water is dumped on it, and you will receive a cancellation message that the pond has gone away. Dezone the pond Template:L, and get back to work breaching that ice. Keep in mind that you will need an unfrozen water source to use to fill your bucket, so have a working Template:L or underground pond ready beforehand for this to work.
The pump method
The pumping method uses multiple Template:L to keep an area dry long enough to smooth or Template:L off the edges, stopping the flow of water. It requires no special environment or resources, other than wood and dwarves (and patience). Most commonly, a moderately sized section of the aquifer layer is channeled out and several screw pumps are built facing it. Directly behind each of the screw pumps a few tiles are channeled out to receive and dispose of the pumped water. When the pumps are activated, they should pump water faster than the aquifer can produce it, allowing masons to smooth or build walls around your future staircase. You will get job cancellations during this process, as stray 2/7's of water interrupt the building process. Just unsuspend the construction when this happens, as long a dwarf manages to touch the wall before canceling, it will move incrementally toward completion and eventually finish. Depending on the availability of screw pumps and dwarves, you may need to wall off one corner or side at a time, then move the pumps and repeat. When drilling through more than one aquifer layer, be sure to leave yourself enough room to build additional layers of pumps and water disposal channels on lower levels.
Things to consider:
- Flowing water will cause parents to drop their infants, leading to job cancellations and occasionally fun.
- Mechanical Template:L may come in handy, but dwarf power works just fine and is much more portable.
- Channels can sometimes be used in place of walls, causing water produced by by the aquifer on one level to immediately fall and be consumed by the aquifer on the level below.
- This method may take a while.
- Aquifers do not create water in diagonal tiles, but do create water in hollow tiles directly below them. Therefore, you will want to dig two z-levels below the lowest aquifer layer before continuing with your fortress.
The modding method
By editing the the raws and removing the [AQUIFER] tag from all of the appropriate entries in inorganic_stone_layer.txt and inorganic_stone_soil.txt it is possible to remove all aquifers from the world. Make sure you do this before creating a new world to play on. (Then again, why not just embark on a place that isn't all aquifer... what are you looking for, adamantine?) Some might regard this method as cheating, so use it at your own discretion.
Breaking through to an existing space
With a typical double-layer aquifer (with an unsafe layer beneath it that fills from above) it is not easy to push through a stairwell where you'd like, even if you have access to the space beneath. Start by ensuring 24 building materials (wood or stone) are available close by on the layer above the top aquifer, and that a large space (at least 25x25 or so, preferably larger) is available on the top safe layer under the aquifer, four layers beneath the first. Dig or build an up-down stair at the same position on the upper and lower safe levels, and surround the top up-down stair with 8 down-stairs for better access. Have at least three legendary diggers and half a dozen moderately skilled masons close by and idle. It also helps to have a stairway or open space leading down from the lower level to relieve water buildup at the point you'll make the hole.
Start by digging an up/down stairway upward from the bottom safe stairway into the bottom (third) layer. Water will start pouring out into the bottom level. Designate the next two squares up (on the aquifer levels) as up-down stairs to link the two, and wait until the diggers get started on them. Then designate a 3x3x3 block around these as up-down stairs on the two aquifer levels and the unsafe level beneath. Once they're built very large amounts of water will be pouring down into the lower space. Warning: unlike in the previous version, diggers now make a habit of canceling designations that they feel they can't get to, such as if the lower level is too flooded for them to approach. Make sure all 27 up-down stairs are dug out ASAP. Then wall six squares on the top level (leaving two to be walled once the corners are filled in), and proceed downward from completed walls until you've walled squares on all three levels. After you finish, I'm not sure if it's technically necessary to construct up-down stairs in the space you dug out by designation in order to stop all water leakage.
Going around
If your embark site is covered by multiple biomes, there is a chance the aquifer is not present in every biome. In some maps this may be indicated by an outcropping of stone in a landscape otherwise composed of soil; in other maps the change in biome might be visible as a change in soil type or vegetation type or density. You might be able to dig down through a biome that doesn't have an aquifer, to a Z-level below the aquifer, and then (if you wish) tunnel beneath the aquifer to the previously inaccessible region.
Even if all the biomes of your site contain aquifers, they might not all be at the same Z-level. So you still might be able to dig down in one biome, reaching a Z-level beneath the aquifer in another biome.
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