I love the idea with the excavator!
This fixes the issue with the "I'ma pull a lake out of my pocket" water tile mod, but you can still place an infinite source of water relatively easily.
Would it be technically possible to convert lake tiles into "water tanks"?
This would mean a smallish lake not connected to a larger one could be "used up", after which it converts to the "empty canal" tiles again.
This way you can't just create a tiny square puddle that feeds your nuclear reactor forever. You also can't create a huge channel from a single tiny natural water tile.
You would have to dig a canal to tap a natural lake, and keep the canal there until the natural lake is used up, in which case you would go tap the next natural lake.
You could also add a small recovery rate to the lake tile "water tanks", to simulate rain. You could tie this to the "desert vs. grass" modifier during map creation. "greener" maps would replenish lakes faster.
We're getting into overhaul territory here, but I think your channel idea is awesome.
Throw in some biters that can swim or fly (does this mod already exist?) and you have a perfectly balanced system .
This would also go well with a mod to manufacture and build bridges across your channels.
Together with the cargo ship mod I'm imagining a Venice-like factory with ships instead of trains. How pretty you could make it!
Some more crazy ideas:
The excavator would finally be a good way to get rid of the (eyes)ore patches in the middle of your base. Make it so that they return a small amount of the resources + stones.
Make a "shredder and compressor" machine similar to the excavator that instead of excavating will fill a hole, and feed it with any materials. Finally a way of getting rid of trash (looking at you wood and U-238).
Digging through biter creep will have a small chance of spawning a biter (lol).
Digging through an oil field should produce a lake of oil. Should an oil lake mix with water it will immediately turn into the green polluted water, which you can fill with landfill. Finally a way of getting rid of oil patches.
You could also fill a channel with oil and set it on fire. I need that burning moat around my factory fortress!
