2004 Volume 20 Pages 539-544
Formative mechanism of iron sand layer on the foreshore of the eroded beach was investigated through field observation and numerical simulation considering density difference of the bed materials. Field observation was carried out at the Ohga coast in Tateyama Bay. On this coast, a river mouth jetty was built, resulting in the formation of wave shadow zone. Sand was transported by longshore sand transport from outside to inside the wave shadow zone. Eroded beach was covered by the black sand containing much iron sand. Accumulation mechanism was predicted by the one-line model of beach changes, considering density difference of the bed materials. Observed phenomenon was well explained by this model.
