Long-term area change of two tidal flats in Japan and its future projection due to sea level rise

This study investigates century-scale area changes of two tidal flats in Japan facing the Ariake Sea and the Yatsushiro Sea, and Tokyo Bay, and their future projections in order to estimate the effect of sea level rise due to climate change on the tidal flats. The long term area change shows notable erosion of tidal flats due to the large scale of landfill reclamation in cities for coastal development and sea reclamation in localities for farmland development, during the period of Japan's rapid growth after 1950s. The future projections using the recent sea bed topography and estimation result of sea level rise show that there is much difference between the future projections with and without consideration of vertical accretion rate. It is estimated that tidal flat erosion up to tens of square kilometers may occur in a long term even only in the study areas. Possibility of serious damage of tidal flats was indicated, though more precise estimation considering other effects such as flood characteristic change due to the climate change is needed in the future.