"Working with (presumably) an irregular channel, and a non-constant flow is going to be a right pain," etc...

Yeah, the way it will surge around and spill over and splash up in a 'natural channel bed', it may even apparently flow uphill (for short distances) in places where it gets up a good 'head of steam' once she starts flowing... that's what 'safety margins' are for...

Also will depend whether you get a 'big burst' failure, or a slow 'catastrophic leak to destruction' too - and my crystal ball is currently out for repair... :-)

No need to panic, but sensible precautions are always useful for those not completely precisely informed...