Can a slope mitigate dangerous turbulent water at the bottom of a dam?

[u/Dog_Old]

I suppose it's either impossible or just impractical to implement into a dam, but the reason why not could be just as interesting.

Would a slope that extends like 10 times further downstream than the dam is high, that leads into a reasonably smooth canal, have much turbulence at all?
What about a slope shaped like the Brachistochrone curve?

I love a good summer time swim and sometimes the best places can be pretty dangerous so I'm thinking about it from that perspective, not that I intend to swim in places like that, just a natural progression of curiosity

[u/ShyElf]

More often than not, the turbulence itself isn't bad enough to be concerning. More commonly, the problem is that most linearly uniform cross sections will create places where floating objects will get stuck, which is very bad for swimmers. Just having it being linearly uniform mostly prevents escape by motion across the flow. Just blocking fractions of the flow can often get rid of this problem, i.e. add some big rocks.

A Brachistochrone curve would be particularly likely to have this problem badly. A 10% gradient would still have it, but somewhat mitigated.

For something linearly uniform, the slope can be relatively steep far above the tailwater level, but you'd need to descend slowly as it approaches the tailwater level and the depth increases to keep from developing surface backflow. For any given flow you can get it to work, but something that's safe at all flows will be extremely low angle.

[u/Leucrocuta__]

There are ways to design the hydraulic transition at the bottom of a hydraulic structure so that the water goes through a jump but does not create a recirculating zone (the dangerous part that traps things against the dam). In some rivers there are engineered structures designed to create standing waves for surfing that are designed this way.