The full flood sequence was blocked in in about a week, with another week of polishing the animation. There really wasn't a ton of time for this sequence.
I made my own 'lite' water shaders for VFX on the project where we needed meshes for waterfalls, waves, and overflowing water.
I used cinemachine to fill out camera movement as the wave banks and jumps down a dolly track through town. Cars and water splashes where hand animated on top.