40d:Water flow

Water Flow (Why isn't my waterwheel turning?)

What is water flow? The obvious answer would be moving water, but things seem more and less complicated than this in practice. A waterwheel needs flow to function, and it needs 4/7 or higher water. These are two different things. a stagnant loop of 4/7 water from a murky pond will not power a waterwheel as it is not flowing. However a dead end channel from a river or brook will. In fact twice I have tested and show that a dead end channel from a river or brook will continue to power the waterwheel after you block it off with a floodgate. Strange. Nor does distance seem to matter other than for the time it takes to fill the channel to 4/7. I went from corner to corner of the map, a nice long path on a 3x3 map, channeled directly from a river, dead end, and there at the extreme end of the dead end is a happily turning waterwheel. I blocked it off with a floodgate again and laughed. Either floodgates or sourced water seems to have a bug. Floodgates prevent water from passing, but the flow necessary to power a waterwheel seems to go straight though with a smile.

Water that is not directly from a brook or river is much more difficult to satisfy a waterwheel with. Water that is not directly connected to a river or brook has no natural flow. This can be because you used a diagonal baffle to eliminate the pressure so you can safely take the water down to your fortress, or it can be because you pumped the water in, or it can be because you took the water from a murky pool. In any event, your water doesn't have any natural flow. Generating flow with a screw pump to satisfy a water wheel is a lot more picky. Here if all three tiles under the waterwheel are the same level i.e. 4/7 then chances are your waterwheel just stopped. On the other hand it does not seem to matter if one of those three tiles is 0/7 as long as at least one of the tiles under it are 4/7 or higher.

Also, I find that hooking up waterwheels in series (i.e. a 1x6, 1x9 . . . ) will not generate extra power, but might prove useful to more reliably catch that elusive flow in a branch of water being pushed around only by a screw pump. If they are all hooked up together with gears and axles they will all turn together as long as any one of the wheels finds flow. While this wastes 10 power for every extra wheel you use in this manner, it can be a real useful problem solving trick for keeping your underground machinery working reliably. I personally find it ironic, since an active water pump pushed water around much faster than any river, but since the water is not sourced flow is assumed to be zero unless there is an obvious difference in the water levels.

• Sourced water (river, brook, spring) behaves differently than unsourced water for powering a waterwheel.
  • Dead ends don't seem to be a problem with water flow from sourced water.
    • Floodgates do not seem to stop flow from sourced water. Bug?
      • Unsourced water is more difficult to show flow in. More testing needed.