I don't seem to understand any of your post... but I will say that rivers don't act like conventional water sources. first of all, you can drain a river into itself, by screw-pumping and diverting the water further upstream. It'll overflow the banks, but not nearly as much as it should, and with proper abuse of walls you can likely get it to completely be absorbed into the river without more water coming at you, effectively quantum-dumping water. The same is also partly true of murky pools, as they'll absorb a certain amount of water more than they should.
Also, rivers drain off the edge, but will flow backwards under the right circumstances. I finally floodgated by river, but during the process I noted that my screw pumps had water at 0/7, and then down the river it slowly rose up to about 4/7, and then towards the edge of the map it was down to 1/7 where it left the map. This implied that water was draining from the middle of the river, and leaving via the map edge and via my screw pumps. Eventually though, I managed to build floodgates mid-river, and waited... and waited... and waited about two seasons, before it all drained away or evaporated. It didn't help that rainwater will refill a river.
In the end, it looks like rivers do NOT like to be tampered with, and will continue on their predestined course unless drastically altered. You may want to drain a river into an aquifer or ocean, or set up a magma system to steam it away once it's pulled away from the river proper. Simply allowing it outshoots doesn't seem to be enough, as a river 4 wide being drained by its full width, will not easily dry up.
Author
Topic: rivers defy logic (Read 708 times)