The 2003 annual meeting of the Sedimentological Society of Japan was held as its first meeting after the renewal of this society at Yayoi Theater, University of Tokyo in April, 2003. The symposium titled “New Horizons and Prospects in Sedimentology” on the first day of the meeting consisted of nine speakers, including two foreign ones, from various specialized fields in sedimentology. We invited Dr. Seung-Soo Chun from Korea and Dr. Li Sitian from China for constructing collaboration of study of sedimentology in East Asia. We were sorry that Dr. Li Sitian was absent for social disturbance in Beijing, China caused by SARS. Dr. Chun gave a talk, “Sedimentation and Holocene Evolution of Macrotidal-flat Depositional System in the Southwestern Coasts of Korean Peninsula”. My talk as the president of the Sedimentological Society of Japan focused on the future of sedimentology in Japan as well as of the Sedimentological Society of Japan. I have done researches on modern fluvial and tidal deposits and depositional environments for more than ten years. Sedimentology on modern sediments and depositional environments are connected with social sedimentology. For example, the role of dams in rivers for environmental sciences is questionable, that is, the role must be discussed in social sedimentology. Because dams in the river break the transportation system of sediments to the sea, beach sands are hardly supplied through the river, and most of the beaches in the Japanese coasts are in erosional condition. As one of the fields in which sedimentologists are able to do social contribution vigorously, I propose the system of “doctors for natural disaster”. Doctors of natural disaster observe geology, geography and ecology in the area. Based on the results of observations and the occasional characteristics, they point out hazardous areas and estimate type, size and frequency of natural disasters; for example, landslide caused by huge earthquake and debris flow after massive rain fall. And the most important role of doctors of natural disaster is to educate citizen how to act appropriately before and during disasters. This position of doctors of natural disaster in each municipality will be contribute reduction of damage by natural disasters.
Sedimentation in the open-coast tidal flats of southwestern Korea is controlled by the combination of wave and tide with seasonal variation. Environmental oscillation takes place between tide-dominated muddy deposition in summer and wave-dominated sandy deposition in winter. Winter storm is a major factor in sedimentation and preservation in the intertidal zone, producing extensive wave-generated parallel lamination and short-wavelength HCS/SCS. Winter storm waves dominate sedimentation over the long term in this setting, resulting in predominant preservation of amalgamated storm beds which are very similar to those associated with shoreface. It causes much confusion in differentiation between deposits in true shoreface and open-coast tidal flat, suggesting that some ancient shoreface deposits should be reinterpreted in terms of the concept of open-coast tidal-flat sedimentation. The retrograding, coarsening-upward, late Holocene succession in this open coast has resulted from low sedimentation rates under low to moderate rates of sea-level rise. It shows a reverse pattern as compared with the models developed in embayed tidal flats with high sedimentation rate such as Jade- and Fundy-bay tidal flats which show a prograding, fining-upward succession. This result suggests that most southwestern open coasts in Korean Peninsula would have much higher potential to experience coastal erosion and inundation with the future sea-level rise than the coasts developed under high sediment supply.