Greetings, quick question rwilliams, it looks like you managed to nicely irrigate that room, and I was wondering just how. I'm pretty confused by irrigation. How did you manage to just "take water" from the river? With a screw pump? What is that grey 'X' bordering the river. Also, do those levers have anything to do with it? And finally, where did the water go after it flooded over the floor?
Thanks!
Sure. I dug a channel from close to the river to the room, then I built a flood gate (that's the X) in the channel, then I connected the river to the flood gate. Also make sure you have a flood gate in any other entrance to the room that will be flooded so you don't flood your fortress, and I built kind of a U shaped hall between just in case if I messed up I'd hopefully have time to close the flood gate before my actual fort got wet.
Here's what it would look like from the side.
The two levers control the two flood gates, a mechanic can make them and set them up.
In my original pictures you can see a long hallway off to the left. It leads to a chasm which is where the water goes. This is not pictured in my MS Paint drawing, but if you think of the perspective of the drawing, the viewer would be standing in the drainage channel.
For more specifics, I found that the wiki articles on flood gates, water pressure, and mechanisms made things understandable to me.
Hope this helps.