Editing 40d:Irrigation

{{Quality|Exceptional|20:28, 30 April 2013 (UTC)}}

'''Irrigation''' is the process of making rocky ground suitable for [[farming]]. This is done by [[flood]]ing it with [[water]]; when the water evaporates, 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".  Inside [[cave]]s, [[rock]] cavern floor tiles that are covered with water instantly become muddy tiles, which you can then build [[farm plot]]s on.   

Once muddied, ground never needs to be re-irrigated, unless the muddying is removed by dwarven construction (see [[Irrigation#De-Irrigation|below]]).  "Muddied" tiles are not technically wet once any actual water is gone, and damp stone or soil (from nearby water sources) will not cause muddying.

There are several methods for getting the water onto (and then off of) the floor tiles.  Dwarf Fortress uses reasonably-realistic water dynamics, including measures of [[water depth]]. A depth of 7 is full, depths of 1 will evaporate, leaving the stone wet and thus suitable for farming. Your goal in irrigation is to get a section of ground to be 1/7s, so it will evaporate to muddy. Usually it can't be avoided that part of the section will be flooded with higher levels, but water will disperse and eventually evaporate. If the water level gets too high and no 1/7 tiles exist (or not for long, replaced by shifting 2/7 tiles), the water will not evaporate.  

[[Smooth]]ed floors that are muddied will remain smooth, however if/when [[shrub]]s or [[tower-cap]]s grow, that tile will then revert to a rough stone floor tile. If the floor was engraved, this will also destroy the engraving, resulting in an unhappy thought if it was a masterwork (and a message about "the impertinent vegetation" having defaced a work of art).

 

On the other hand, constructed floors that have been muddied will '''not''' allow the growth of shrubs and tower-caps.

Some locations have layers of [[soil]]* more than one z-levels thick. It is not necessary to irrigate soil in order to grow crops on soil; it is possible to build a farm plot for the dwarven crops such as [[plump helmet]]s directly on any underground soil tiles. This method obviates the need for irrigation entirely, so is recommended for beginners.

(* Note: ''Any'' type of [[soil]] is the same for this purpose in Dwarf Fortress, so you can build farm plots on sand, mud, clay, whatever.)

Once an underground river is discovered, [[Tower-cap]]s and bushes will ''also'' grow on any unimproved (i.e., non-irrigated, non-farm plot) underground soil. Irrigating is recommended for improving tower-cap farms.  

[[Stone]] floors can be irrigated conveniently from a water source on the level below, by use of a [[screw pump]].  Simply dig a channel to access the water on z-1, install a pump and set to Start Pump Manually ({{k|q}} + {{k|Enter}}). Any dwarf with the 'Pump Operating' duty active will quickly pump enough water to irrigate a large area (so rapidly that irrigating other rooms becomes a concern!). This can be improved by installing a second pump to draw water out of the room, allowing you to rapidly drain the room in the event of over-filling, or by other creative designs.  

Dig a channel tile down from a tunnel, preferably near a well or other water source, and dig a farm room below (and preferably around) the channel tile on the lower level. Create a [[zone]] on the channel tile above, and make it a pond. Your dwarves will automatically attempt to fill it with water carried in buckets. As they dump water in, it will muddy the floor on the lower level, spreading out to surrounding tiles once the second bucket load drops. After it has been sufficiently muddied, disable or remove the pond zone. Since dwarves can build farm plots in 1 unit deep water, you can place your plot right away once all desired tiles are covered.

Due to the low demand in infrastructure, items and water management, this is one of the fastest and the safest way to irrigate a floor. Dwarves carry 1/7 unit of water per trip. It's slower if the water source is far away, but still very manageable compared to digging an aqueduct and building floodgates or even pumps.

As above, a farm plot built on any soil tile marked [[Tile_attributes|Above Ground]] can be used to grow outdoor crops such as [[whip vine]] without irrigation.

Outdoor irrigation of rocky locations is possible using similar techniques; you may have to construct walls to make water channels, pumps to get it out of rivers, and/or stairs up to pour water down on top of a pond zone. This will serve to make muddy tiles suitable for a farm plot; however, be warned -- in mountain [[biome|biomes]] (where you are most likely to feel the need to irrigate outdoors), no outdoor seeds will grow in rocky locations anyway. (The specific message is, "No seeds available for this location"). However, these techniques do work just fine for muddying individual rocky tiles breaking up your farm in a non-mountain [[biome]].

Muddy stone can be cleaned by building furniture (such as a [[bed]] or [[statue]]) or a paved [[road]] on top of it. Muddy soil can also be cleaned up by building a dirt road on top of it.

# {{K|d}}ig from the [[farm plot]] to any source of water, but keep a single tile of [[wall]] between the newbuilt passage and the water.

# Build a [[floodgate]], and three [[mechanism]]s. (If you're worried about delay, use [[door]]s instead of floodgates.

# Build a [[lever]] and link it to the floodgate.

#: Alternatively, have the miner dig a [[channel]] ({{K|d}},{{K|h}}) on that last wall from the Z-level above. This is much safer, since the miner will dig out the wall without actually having to stand in the way of the water.

Here's a relatively safe and simple irrigation plan.  As shown it's set up for an underground [[tower-cap]] farm, but can easily be adapted to any level, surface or deep underground.   

This is a passive system - it's never connected to the river, so it won't do anything unless manned by a dwarf, and it doesn't need any levers or floodgates to work - or to ''stop'' working.  Unless you forget about it, no [[flood]]ing should occur - and even if you do and it does, it's foolproof to stop.

Now, the trick is to use a pump on the surface level to provide the water, the pressure, and the control.  Build your pump next to the river - (if it's a [[brook]] you'll have to channel 1 tile of the brook for the inflow - don't breach the tunnel!).  For the outflow, build a retaining wall around the start of your irrigation tunnel.  

:''(* This can work from a [[murky pool]], but that is not an infinite source of water.  Plan accordingly.)''

The water settles out and [[evaporation]] begins immediately.  You can then seal up the tunnel or ignore it as you choose (even if you later, accidentally, breach the river/brook, the u-bend won't cause flooding if the irrigation is on the same level, as shown above.)

One drawback is that the lower tunnel will stay full of water, which can be a small problem if you ever, later wish to expand the tunnel for other purposes. One or more drawbridges, acting to block the passage, will allow you to seal it later for easier expansion projects, and, if your first effort, is a good safe opportunity to practice in a non-critical situation. (See also: [[fun]].)

The reservoir method involves building a small reservoir between two [[floodgate|floodgates]] and a farming chamber about 7 times as large as the reservoir. A reservoir of 12 tiles, for instance, can water a 70 tile chamber effectively. Water is let into the reservoir by lowering, then raising one floodgate. The other floodgate then releases the water into the farming chamber. It spreads around, then evaporates after becoming 1 deep.

The reservoir may be built above the plot to be irrigated with a [[hatch]] or [[bridge]] in the floor, to one side using floodgates, or below and [[pump]]ed upwards. Note that [[Bridge|bridges]], in their default state, will block water from falling between levels. The large surface area you can get this way can make the water spread over your farm area much faster than by using floodgates.

It is possible to achieve the same result using a natural pond as the water reservoir. Doing so is easier in the short term but it is not advised if you want to keep replenishing your reservoir for other uses, such as [[well]](s), for natural ponds have a very finite amount of water available. On particular maps, natural ponds can replenish themselves at the beginning of each spring.

577/6 = 96 1/6; rounding up, this gives 97. This is the number of floor tiles in the smaller room: a 9X10 room with 7 extra tiles. Be aware, however, that if you make your "large" room ''too'' large, some of the water from the "small" room will [[evaporate]] before reaching the other end, and you will not have enough [[water]] to coat the floor. This behavior was observed in a room of 42X35 tiles.

Now, get digging. The water supply connects to the smaller filling room by a 1-tile hole where a door or [[floodgate]] will go. The filling room connects to the growing room the same way, and the growing room needs a door too. Remember to have the [[door|doors]] in place before breaching the water source and flooding the water supply line!

When you do breach the water source, immediately forbid the first door your miner runs through (see, this is why we use doors), which should be the door closest to the water source. Don't bother forbidding the other two. Link all three doors to three separate [[lever|levers]] and test the system. Close the door between the filling chamber and main farm area and open the door that leads to the water source. When the filling chamber is full, close the door to the water source, close the door leading to the farm, and open the door between the [[farm]] and filling chamber. The water should spread out and coat the entire farm in a thin layer of water. At this time, plant your farms and begin the wait until they yield products.

Underground rivers are often what makes living in freezing climates possible, because they don't freeze over. Its very easy to tap one if you know what you're doing.  Once you've located it, pick out a good spot for your farm room and dig it out.  Make sure you're on the same level as the water; that is, where the actual water is located, not where the 'Open Space' is.  Channel out one tile in the farm room and replace it with a floor hatch.  Dig a narrow tunnel to the underground river and put a wall grate and a floodgate in it.  Link the floodgate and hatch to separate levers.  Dig one level down and dig a drainage shaft from the tile below the hatch to the point where the river 'drops'; you'll see a 5x5 area of 'Open Space'. When you are ready, dig a small tunnel and channel out the floor so you breach the river below and send it into your grate and floodgate.  Open the floodgate to water your crops, close it when you're done and open the hatch to drain.

NOTE: The grate is necessary to filter out nasty creatures that might otherwise come in with the water.  Keep in mind that a wall grate can be destroyed by a swimming building destroyer, so you may want to keep the floodgate in front of it closed when water is not needed.

{{Category|Agriculture}}