NRC video D

Crest Erosion

 

The separation between the calm water level and the berm crest is limited in this test model setup.

The consequence is that, in the beginning, the passing waves exert sufficient energy on the erosive forces necessary to make more room for themselves. By increasing the free water depth, the wave's rotational flow cycle for subsequent wave passage is better accommodated.

There is perhaps evidence of some amount of upstream slope failure preceding the considerable amount of surface erosion leading to crest lowering.