SEDIMENT INTRUSION INTO GAMO LAGOON BY WAVE OVERTOPPING

The Gamo Lagoon is located in Miyagi Prefecture, Japan. Aerial photographs have been being taken for the coastal area including the lagoon every month or every two months since 1990 up to the present. These aerial photographs are used to detect the occurrence of wave overtopping and resultant sediment intrusion into the lagoon during storm waves. Furthermore, overtopping rate is estimated considering the height of the sand barrier. In collaboration with surveying data, the volumetric concentration of sediment in the overwash flow is estimated. It is found that the estimated concentration obtained in the present study is comparable to laboratory experiment by Kobayashi et al. (1996) in a small-scale wave flume.