Thank you so much for your really thoughtful feedback, means a lot coming from someone who also feels/live this issue on a daily basis !
We'll consider the idea you sketched: a single, persistent surface world (degraded and flooded) that visibly repairs itself as the player frees the buried rivers, unlocking new areas as it heals, instead of separate day-levels. It actually reinforces our core idea, eventhough the level design might be harder.
Considering the loss condition (since our fail state is still open), the flood pressure you described (and the Swindle reference) give us a clean way to fill it. We'll probably go for a lighter flooding gauge rather than a full day-budget, since our structure is more linear.
Thanks again for taking the time to read our project : valeu e abraços !