Thank you for the question.
I know there has been a lot of research in rivers since the nineties and more recently in coastal engineering to try to incorporate natural solutions. The historic method is to basically put in a lot of rock and, in very high-wave environments, to put in interlocking armour stone that will not move. The intent is that it will move as little as possible. There is a recognition that if it moves, it's going to fail.
Second, in some cases, like a vertical wall, it may not have as good a habitat, so there is a movement to try to incorporate more mobile revetments. We have a research project right now on what's called a dynamic revetment of rock that moves to a stable position, but still protects the bank. We'll also possibly incorporate vegetation to stabilize the top of the bank.