Increase in disaster potential caused by excess use of land in coastal zone

Relationship between long-term change in land use and increase in disaster potential of a coast was investigated through the comparison of past photographs, taking the Tojo and Maebara coasts as the example. In 1950s, there was a wide sandy beach at the Tojo coast but the coastal forest was artificially expanded very close to the shoreline as well as the construction of the Kamogawa Sea World, resulting in narrowing the natural sand dune area. On the Maebara coast, located southwest of the Tojo coast, a seawall was constructed very close to the shoreline, resulting in the expansion of the residential area. Then, detached breakwaters were built to protect this area and the fishing port breakwaters were also built, resulting in significant shoreline recession on the Tojo coast. These case studies clearly show that these coasts became vulnerable against coastal disaster due to the man-made activities. This is of concern in coping with expecting sea level rise.