Thanks...:-) I knew someone here would know. I didn't understand a lot of your explanation but I surmise that your answer is "yes"?
Not just yes, but also that if it could be seen in a dry area, there is remedial action you can take. If you don't know it is occuring because it is hidden by water on the protected side, it will eventually undermine that whole section of the levee and cause a major failure above it.