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[Grimmash]

So I picked a nice embark with a river running across the middle, a major river about 11 tiles wide.  I want to build my fort as two towers with a connecting bridge across the middle.  And I wanted to get this done early, as once you reach a certain population/wealth sieges become non-trivial obstacles to above ground projects.  So this means once the initial basics are set up, time to get cracking on the river project!  I'm documenting the progress here to show another potentially useful river containment method.

Goal:  Dam the river with the ability to control the flow after the dam is complete.

Initial Design:  Build two walled in water control stations to channel water off map, draining the river.  Then, build a bridge across the river bed to provide easy control.

Initial Report:

After getting farms and a dormitory dug into a hillside, construction began.  I dug tunnels under the river from the temporary fort, and they surface on both sides of the river.  Walls have been erected to completely enclose the tunnels from all but flying hostiles.  Once this was complete, each water house had a 1x7 raising bridge built at water level, and a 1x7 drop chute built behind the bridge.  The drop chute falls to the first solid stone layer, to prevent future cavern breaching from causing trees to grow in the drainage tunnels.  From the drop chute, 1 tile wide tunnels were dug to the map edge and fortifications were put in place to drain water.

After these constructions were complete, the tiles on the river edge were channeled to provide a river outlet.  So far drainage is going as planned.  The river has fallen from 7/7 water to 4/7 water downstream, and 1/7 water at the edge of the map.  This has taken 2 months.

A further progress report will follow once riverbed begins to show up.

[ImagoDeo]

I would've gone with a multiple water wheel and pump setup, personally. It's (in my view) simpler.

Backpumping a river is pretty darn easy with the Dwarven Black Ho--I mean, screw pump. Even an 11-wide river is small potatoes so long as you know how to build a good containing wall and power train. It drains things a helluva lot faster too, and all of its components are quickly and easily secured with materials obtainable within the first few days of an outpost's existence.

Once you've successfully drained down to the riverbed, though, build a raising bridge. You'll have to remove some ramps from the riverbed before you'll be able to construct the bridge. Once it's in place, hook it to a lever and boom! instant raising or lowering dam. You can even deconstruct the entire pump setup when you're done.

One last note: wherever there is mud, there will be tree growth. I would construct roads through the drainage tunnels if I were you. It's the only thing that stops plant life.

[Lielac]

One last note: wherever there is mud, there will be tree growth. I would construct roads through the drainage tunnels if I were you. It's the only thing that stops plant life.

Nnnnot quite. Stockpiles suppress plant growth while active, although once removed after a significant period of time you will get abrupt tree growth. It's still a good replacement if you're low on materials.

[Sutremaine]

You can also dig it out of up stairs instead of flat floor.

[Grimmash]

Simpler in what way?  I am just digging hole and building bridges.  I'm not trying to be difficult, but machinery adds to the complexity, by my thinking.  As for trees... Damn it.  I only need to lay a central pylon once I get this working, so that should be pretty quick.  Worst case I'll fastdwarf to kill any pesky trees on the south end of the river.

A second point - I wanted something that left as much terrain unsullied as possible on the surface.  I guess that is why i went with natural drainage.  Now that i have the embark I might do a comparison between the gravity chute and pump methods at some point.  I suppose i should learn water wheels and axles and all that at some point.  The only power system i have ever used is windmills powering millstones in MWDF for bonemeal.

The raising bridge on the river bed is planned as the permanent damming solution.  Although once the pylon is built, i'm not sure why i would need to reblock the river.  I might just build a well feeder intothe river bed along with the pylon to get it all done in one go.

[deoxy]

At least in 40d, a farm plot would also prevent plant growth (and, shortly after placement, remove all plants from the plot, except grown trees).  You don't even have to actually complete the farm, just place it.  Again, that's 40d, so I don't know if that works anymore.

[VerdantSF]

The Twins of House Frey?

[wierd]

Another way is just to dump magma into the river, and let it plug up the flow, then dig into the resulting cason of obsidian to make a bulwark, build whatever you need there, including floodgates, then dig out the no longer needed/useful obsidian with channeling.


A word of caution with temperate biomes, water, mechanisms, and freezing.

The floodgates can magically deconstruct themselves after the spring thaw.

[Grimmash]

The basic draining is finished.  I ended up using a hybrid method.  In addition to the drop chutes, I build a bridge across the river and mounted screw pumps, pumping out of the flow source direction into tunnels made of walls that then dumped back into the chutes.  I did this because the central flow of the river seemed to defeat the edge-chute draining.

In the end it took well into Autumn of the second year of the fort to drain down to the river bed.  This was in part due to a failed attempt to rescue a corpse from the bottom of the chute.  I failed, unfortunately.  This led to a month or so of one chute being empty.  There was also a Dark Strangler siege that lasted about a month.

The most interesting finding was that you cannot build constructions on the river bed.  You need to somehow remove the river bed tiles via stairs or channeling or whatever, build a solid construction platform, such as walls on the z-level below, and then build your walls, bridges and what have you on top of that.

Tomorrow I will post pictures of the setup for anyone who might be interested.