Nonlinear transformation of waves above submerged structures: Application to coastal protection

On the base of data of laboratory experiment the transformation of waves above reefs was investigated. The possibility of essential decreasing not only wave height, but the mean period of waves was testified. It was revealed that a system of two reefs better reduces the mean wave period. The decreasing of the mean wave period depends on the distance between the reefs. It was shown that submerged structures can influence on transport of sediments due to change of asymmetry of waves passing above them.