shear stress from water in an open channel is a function of the depth and the velocity. should be plenty of both. good news is the aux spillway is off to one side, so there is bedrock down only 30 feet.
Sycamore
Why do you say "bedrock down 30 feet?"
Undermining of the auxiliary spillway was why they have increased the main spillway flow to over 100,000 CFS attempting to lower water levels below the auxiliary.
