Flow over embankment

[Sith Ratino 0]

Hi all, 

I have simulated embankment in gssha. I have offset the embankment up to 0.5m over the land surface. However, in the result, the overland flow did not move over the embankment with the flood depth of more than 0.5m. I would like to know how to set the overland flow to flow over the embankment, while the flood depth is more than the embankment height. 

Thanks so much. 

Ratino