Implement rising rivers during rainfall, shelving here because it doesn't work very well
* Server prebakes the lowest and highest river levels and lerps between them
Problem is after a few proc gen tests in most cases this looks bad and results in a visible water edge
We'd need actual water physics? Not worth it
https://files.facepunch.com/jarryd-campi/2026/November/Unity_yXJIos8h4u.mp4