Long-term beach morphological change under anthropogenic impacts would include many important processes for the study of coastal engineering. Beach morphological change on the Hasaki coast of Japan was influenced by anthropogenic events. From 1965 to 1977, approximately 50 million cubic meters of sediment were dumped into the nearshore zone on the north side of the coast for disposal of the sediment generated during the construction of the Kashima Port, which is an artificially-excavated port. A beach reclamation was conducted at the north edge of the coast in 1975, and a breakwater was started to extend at the south edge from 1989. Artificial headlands were also constructed on the southern part of the coast. Here, we investigated the morphological changes from 1961 to 2013 on the Hasaki coast by comparing the shoreline positions extracted from fifteen aerial photographs, which were taken every 3 to 5 years.
We found significant trend of shoreline advancement with the spatial variation due to longshore sediment transport in the past shoreline evolution on the Hasaki coast. The first shoreline advance around the northern part of the coast from 1969 to 1984 was considered to be caused by an increase in the total sediment volume on the coast due to the dump of the excavated sediments. The second shoreline advance after 1993, which was caused over the whole of the coast from 1993 to 1996 and around the southern part of the coast after 1996, was considered to be caused by landward cross-shore sediment transport. Since the time when the artificial headlands were constructed was almost the same period of remarkable advance around the southern part of the coast from 2002, they possibly contributed to trapping of the cross-shore and longshore sediment transport, but the reason why the sediments were transported landward is still unknown.