Editing 23a:Irrigation

{{quality|Exceptional|23:10, 4 April 2012 (UTC)}}{{av}}
'''Irrigation''' is the process of making rocky ground suitable for [[farming]]. This is done by [[flood]]ing it with [[water]]; once the water is removed, the tiles are labeled as "muddy".  This is also called '''muddying''' the floor, as the dry floor tile is then a "muddy <type of stone> floor".  Once an area is muddy, you can then build [[farm plot]]s. During the winter, all of the mud in your fortress will dry up, so each spring you will need to irrigate your farming areas once again.

Irrigation is the single most important aspect in setting up farm rooms. The main purpose of this article is to introduce you to how to irrigate your farms, and how to prevent embarrassing mistakes: many a fortress has failed because design mistake in the irrigation scheme drowned every single dwarf inside.

However, there's more to be considered: the crops from your fields will be taken to the food stockpile; from there, they may be taken to other workshops for further processing into (e.g.) flour, drinks et cetera, taken back to the food pile, and finally be taken to the dining hall to be consumed. In the workshops or when eating the plants, seeds may be recovered that eventually need to find their way back to the fields. In order to run an efficient fortress, you should strive to keep the ways short. You may not yet have any of these buildings, and it may be a long time until you want even some of them. But keep in mind that food production will eventually evolve into a major compound, and given the fact that every dwarf pops in for a snack time and again, it will likely become the heart of your fortress. 

==Pre-Irrigation==

It is not guaranteed that the [[cave river]] will flood when you find it, but this often happens. It's also not too uncommon that the river floods before you have your irrigation system working. In both cases you can begin farming the muddy areas then and there. Do not be shy of setting up the farm plots right in the middle of the corridor, no harm will come to the plants even if there's constant traffic across the fields.

This may not be a solution for all times, however, it may allow you to get started with farming several weeks earlier than if you wait for "proper" farm rooms to be finished. 

==Nile-style farming==

Since the [[cave river]] will flood every spring, summer, and autumn, the lazy dwarf can just carve out space next to the river and let it flood. Once the flood has receded, the floor is muddy and ready to be farmed.

Pros
* Doesn't require [[mechanism]]s, [[floodgate]]s, or much planning
* No risk of causing permanent floods
* Very easy to set up 

Cons
* If a farmer is right next to the river when it floods, he could be swept into it when it floods
* Monsters from the river can kill your farmers (keep a few soldiers nearby)
* The farm must be next to the river

An advanced variation of this is to dig an enclosed farm area connected to the river by [[fortification]]s. These will allow water through while keeping river monsters outside, and also ensuring that your farmers will never be washed away into the river.

==Controlled flooding==

For all controlled irrigation schemes, you will need [[floodgate]]s, [[door]]s, and [[mechanism]]s. You may also need to dig some [[channel]]s.

===A few words about how stuff works===

Mechanisms are used to build traps or [[lever]]s. Using more mechanisms, you may connect all sorts of other things to a lever, like drawbridges or floodgates, thus allowing you to control them remotely. 

Floodgates block water when they are closed. When opened, they will allow any adjacent water to pass through them.

Floodgates work like this: If adjacent to a river, they'll let water into channels when open. If adjacent to a filled channel, they'll flood the area around when open. 
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In the above example, the floodgate will allow water into the channel. If it's closed, the channel will run dry. If it's open, the channel will fill up. The water will not run over. In order to get the water out of the channel and into a room, you will need yet another floodgate:
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 ≈≈≈X_____X..
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In reality, a floodgate actually is "a floodgate with a bit of channel attached to it". So you may skip the channel between the floodgates and build something like this:
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 ≈≈≈XX.......
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You cannot see it, but to the game that's two floodgates with a channel between them. So all is well.

===Your first farm room, step by step===

You will need two [[floodgate]]s, five [[mechanism]]s, and at least one [[door]].

You can construct floodgates at a [[mason's workshop]], a [[carpenter's workshop]] or a [[metalsmith's forge]]. It is recommended to use the mason's workshop since rocks are overly plentiful. Setups with one floodgate are possible, but sometimes dangerous, so we'll use two floodgates in our example.

Mechanisms are made at a [[mechanic's workshop]]. They're made of stone, so you should have no problems in getting the materials. You'll need two mechanisms for each item you connect a lever to, and one mechanism to build the lever itself. Both floodgates can be connected to the same lever, so this requires a total of five mechanisms.

The door can also be made at the Mason's.

Before you can start planning out your farm you must locate the river. To do this, just dig into the mountain until the game notifies that the river has been found. The river will sometimes flood your cavern as you hit it, sometimes not.

TIP: You do not need a room for the workshops, but can build them outside in front of the cliff wall and have the floodgates and mechanisms made while your miners are still digging for the river. This usually works even in very dangerous areas; however, some small risk always remains.

Found the river? Now, things should be looking something like this:
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 █████████≈≈≈≈≈≈███
 .........≈≈≈≈≈████
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At this point you should have the floodgates ready to be deployed. We are going to make two rooms; The farming area where you will be planting your plants and a control niche where you will situate your lever. Dig out your farm next to the river and deploy the first floodgate with {{K|b}}{{K|x}} - a [[miner]] will come along and place it:
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 ███.......X≈≈≈≈≈██
 ███.....████≈≈≈≈≈█
 ███.....███≈≈≈≈≈██
 ███.██████≈≈≈≈≈≈██
 ███.█████≈≈≈≈≈≈███
 .........≈≈≈≈≈████
 ████████≈≈≈≈≈≈████

Next, it's time to dig out the control niche and build the lever and the door that will block the water flow.
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 ███.......X≈≈≈≈≈██
 ███.....████≈≈≈≈≈█
 ███.....███≈≈≈≈≈██
 ███┼██████≈≈≈≈≈≈██
 █ò█.█████≈≈≈≈≈≈███
 .........≈≈≈≈≈████
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Now, hook up the first floodgate to the lever. Select the lever with {{K|q}} and assign a new task, "Link up floodgate". Select the floodgate you just put down and a dwarf should bring the first mechanism to the floodgate and then the second mechanism to the lever. There, you have just linked the floodgate to the lever.

Connect the outer floodgate to the lever before you deploy the inner floodgate. Floodgates are impassable -- your mechanic cannot reach the outer gate once the inner is in place.

You may, however, safely dig the channel while the outer floodgate is being connected. Next, deploy the other floodgate and link it to the same lever.
The result should look like this.
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 ███.....X_X≈≈≈≈≈██
 ███.....████≈≈≈≈≈█
 ███.....███≈≈≈≈≈██
 ███┼██████≈≈≈≈≈≈██
 █ò█.█████≈≈≈≈≈≈███
 .........≈≈≈≈≈████
 ████████≈≈≈≈≈≈████

This is a simple, but fully operational farm room. Now lock the door (with {{K|q}}). This is important since a wandering dwarf (or pet!) could open it accidentally while you're irrigating, thus drowning the entire fortress.

Once the door is locked tight, pull the lever to open both floodgates. Water should now be gushing into your farming room and filling it. Pull the lever again to cut the water flow and drain the room, and voilà, you've got mud ready for farming!

===Variations, safety precautions, wholly different approaches===

As stated above, you don't actually need the channel between the floodgates. This here would also work:
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 ███......XX≈≈≈≈≈██
 ███.....████≈≈≈≈≈█
 ███.....███≈≈≈≈≈██
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 █ò█.█████≈≈≈≈≈≈███
 .........≈≈≈≈≈████
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Two floodgates, no channel.

As mentioned above, you should make sure the door is tightly closed. This sounds easier than it actually is – especially later in the game when you've gotten used to things, you may forget to check every single door. Or, worse, one door might be stuck because of some bit of debris. One ought to see this, but in reality countless fortresses have been lost to embarrassing irrigation accidents.

As a simple safety precaution, you may place a channel in front of your door. Why? Because channels will "catch" artificial floods. The flood will fill the channel and stop, unless there's a way around the channel. Make sure that the lever can still be reached if the channel is filled.
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 ███......XX≈≈≈≈≈██
 ███.....████≈≈≈≈≈█
 ███.....███≈≈≈≈≈██
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 █ò█_█████≈≈≈≈≈≈███
 .........≈≈≈≈≈████
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From a mere irrigation point of view, you do not need the door at all. The channel will prevent the water from spilling into your fortress and that's that. However, a door may still be a good idea to keep dwarves and pets out of the area: it has already happened that a hapless dwarf walked straight into the flooded area and drowned.

===One-floodgate farming===

You don't actually need two floodgates. Just dig a channel that connects to the river – lo and behold, it will fill with water all on itself, no floodgate needed. You still need a floodgate on the inside end of the channel to get the water out of the channel again, though.

However, there is a slight catch to that approach: as soon as the channel is finished, water will rush in, while the dwarf who dug the channel is still standing in it. Usually all will end well, but occasionally a dwarf will swim into the wrong direction, or can't make up his mind and drown.
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 ███.....X__≈≈≈≈≈██
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 █ò█_█████≈≈≈≈≈≈███
 .........≈≈≈≈≈████
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===Alternate channeless irrigation===

Since floodgates block water, we can take advantage of a bend in the river to create a freely-accessible floodgate system that requires no channel. Both floodgates can be placed before mechanisms are connected. In a narrow corridor, it might look like this:
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 ███......XX≈≈≈≈≈██
 ███........█≈≈≈≈≈█
 ███.....███≈≈≈≈≈██
 ███┼██████≈≈≈≈≈≈██
 █ò█_█████≈≈≈≈≈≈███
 .........≈≈≈≈≈████
 ████████≈≈≈≈≈≈████

Note that the "corner" of the river is vital to prevent flooding; you must not let flood water touch the river. The main catch to creating this style of floodgate is that you generally don't know the exact shape of the river at that point until you break through the wall or until you build a bridge across the river.

===Fixing irrigation mistakes===
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Normal irrigation requires only one exposed tile of water, and if you're trying to avoid nile-style farming, this makes a mess of the room. To fix this, put a floodgate in front of each exposed tile of water:
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 ...██≈≈≈≈≈≈██
 ...█≈≈≈≈≈≈███
 ..X≈≈≈≈≈≈████
 ..X≈≈≈≈≈≈████
 ...█≈≈≈≈≈≈███
 ...█≈≈≈≈≈≈███

This will not flood your farm, so add one more floodgate to the left of either existing gate:
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 ...██≈≈≈≈≈≈██
 ...█≈≈≈≈≈≈███
 ..X≈≈≈≈≈≈████
 .XX≈≈≈≈≈≈████
 ...█≈≈≈≈≈≈███
 ...█≈≈≈≈≈≈███

Only the two bottom floodgates need to be connected to a lever for the floodgates to function as planned. As an added bonus, your mechanic will be able to attach both floodgates simultaneously.

===Bridged Channel Farming (better access)===

Farms can be set 'back' from the river without causing blocking paths by building [[bridge]]s over the channels. This design principle allows a farm to sit away from the river in the centre of several rooms which can provide quick access for storage or processing.

Additionally, this design uses floodgates to block wall access, meaning that the system is always sealed from dwarves or other creatures trying to take shortcuts through this area when needed for operation. When closed, the floodgates are flush with the walls, sealing the room, and when open, water quickly floods the area again preventing access.

===Using the outdoor river===
Using the river from outside is almost exactly like using the underground river. One benefit, however, is that it is far safer to dig a channel directly next to the river without a "safety" floodgate, because dwarves can swim out to the side, unlike in a cave where there are walls in the way. This makes it easier to set up a One-Floodgate system (see above).

Depending on your mental image of the map, you may consider channeling water from the outside river to be sending water "uphill", which may either be explained away via "dwarven mechanics", or with the mountain simply on the same level (with the channel providing no slope at all, and the river just filling it in). Some prefer to keep their mental image of the cliff face being uphill intact, and prefer not to use the outside river for this reason. Also, using the outside river may result in problems when besieged.

{{Category|Agriculture}}