as possible. For reference, that much water would cover approximately 20,000 football fields in a foot deep of water.
A dam break, even of a smaller reservoir, is a wall of water coming downhill at freight train speeds. You don’t want to be downstream.
The water will move fast through the downstream canyon, and won’t dissipate until it hits a valley. It will then flood the river banks well above the natural flood stage.
Best case scenario is the river first passes through a wide unpopulated valley up high before it hits lower and more populated areas. Worst case scenario is it overtops and breaches downstream dams thereby compounding the problem.