I have a similar bank and most of my initial weed growth occurred in the water, which I think reduced the erosion a great deal. My banks are a little steeper than yours and are stepped in two, 1 meter increments and the weeds seem to be doing well in that first 1 meter depth.
For the most part the weeds act as a poor mans rip rap.
If the erosion is caused by wave action and/or run off the problem may solve its self, if from ground water rock rip rap maybe the answer.
One question has the water level been low enough for you to see the extend of dam,age?
