災害と文明-わが国の風水害の変遷史-

Abstract

As my retirement speech on 4 February, 1994, historical changes in natural water disasters in Japan were presented in relation to changes in civilization. By using data of Japanese literature chronological table an index for Japanese civilizations is introduced to qualify their change. Its historical change shows clearly changes in Japanese civilizations since the Taiho-Ritsuryo was introduced in 600. In terms of a time scale of 10000 years changes in civilization that are rise and fall of civilizations are first considered in relation to the occurrence of natural disasters. The Jomon civilization that mainly is of a hunting and gathering society felt off due to a long term climate change.In the historical periods after the Jomon era, especially in the Yayoi era the first development for irrigation and reclamation was made, but it caused flood disasters as well as drought, famines and plagues resulting in a decay of the Tenpyo-civilization and a decrease in total population. In the period from the 10th to 16th centuries, Japanese civilizations were created, but due to changing of the societies many civilizations were born and felt off due to natural disasters, and changed to another civilizations.In the Edo era that is called as a rice society, in terms of a time scale of 300 years, the second development of irrigation and reclamation was widely and very extensively made in the whole areas of Japanese islands, but in the middle of 18th century serious natural disasters took place such as flood disasters, drought, famines and plagues, as well as riots and disorders by which the total population was decreased. Since the Meiji restoration was made in 1868 the Japanese society was changed from the rice socity to an industorial one by introducing western cultures effectively. The Meiji civilization of democratic society has developed greatly to the present Japanese civilization that is called as a grobal civilization by Nakayama. Changes in total dead and missing persons due to water disasters show a periodicity of about 55 years clearly in close relation to the social activities evaluated by rice and iron production rates relative to the total population. The periodicity in disasters may be due to the solar activity through Yoshimura's cycle.