Some results:
When there's a waterfall in any part of a brook, the tiles on the bottom of it act as a water source... this didn't seem to be the case with an underground river in one of my older forts. Weird.
Brook tiles consist of two 'structures' - a natural 'wall' passable for liquids and a 'grate' over it. Both named 'brook'. It's possible to dig out the bottom wall layer and leave the 'grating'. Essentially, in a stone layer, you can mine brooks for stone.
Also, five pumps on one side are enough to drain a four tile brook.
It's a bit messy now... there's mud everywhere and the brook is interrupted by channels. I had pumps installed to get the water out of the construction site. I removed them after building floodgates for one branch and a bridge for the other, hooked up to a single lever.
It seems the cascade doesn't overflow.. it just doesn't go anywhere yet.
I'll need to get some 3d visualizer going before I start planning for the next stage.
Two migrants arrived, a peasant and some woodcrafter. One will be an animal trainer for the spiders and will be given a crossbow. The other will be a fine mason. I'll need lots of blocks for building.
There are more spiders than dwarves now. Terrifying.
Map as of now (late winter) :
http://mkv25.net/dfma/map-5720-beerbane.
Still can't get the .net thing to work, so there are no PoIs set. Is there a way to add them manually?Edit: I had javascript turned off.