I just came across this excellent case study of
Vetiver grass used for erosion control and reforestation on Vanuatu.
I think earthworks is the best spot to put this, because it is being used for the same purposes as most earthwork structures: rainwater sinking, sediment trapping, erosion control, terracing etc...
This is one of the best writeups I have seen of a vetiver installation, with long term evaluation of benefits. The final images of the improved ocean water quality and reef habitat are really impressive.