[H-DS09] 人間環境と災害リスク

[HDS09-P10] The effect of abrupt society transformation on flood risk management among farmers in China, 1930s~1950s

*劉 暢¹、川崎 昭如²、城山 智子³ (1.東京大学、2.東京大学未来ビジョン研究センター、3.東京大学経済学研究科)

キーワード：ABM、洪水リスク管理、社会変動、長江流域

As the longest river in Asia, the Yangtze River has shown its impact on human societies with floods recorded since 12th century. In 1931, the Yangtze River has manifested its force again with one of the deadliest floods ever recorded in Chinese history, causing 422,499 deaths, damages to more than 25.2 million people and 58.7 billion m² farmland. Similar flood occurred again in 1954, resulting in 31,762 deaths, damages to 18.9 million people and 31.7 billion m² farmland. Researches have shown that 1954 flood being larger and higher compared to 1931 flood. However, it is still unclear for what reason that a more severe flood leading to less damage. Here we assumed such discrepancy could be ascribed to drastic society transformation in 1930s and 1950s (e.g., increase of absentee landlords in 1930s, and the land reform movement in 1950s). To further understand its effect on flood risk management among farmers, an agent-based model named Farmer Landlord Inundation Production (FLIP) was developed. The model was constructed by simulating each farmer’s movement decision during floods based on different hydrological and economic circumstances. Then it was applied to the simulation of multiple villages in Hubei Province (along the mid-reach of Yangtze River) on the basis of reconstructed daily inundation from July to September, 1931 and 1954. Our results have shown that the farmers’ mitigation decision was highly sensitive to the relief amount and distribution timing, indicating a possible decrease of refugees from 70% to 15% between 1931 and 1954. Overall, we demonstrate how society transformation are likely to affect the disaster risk management in a different way from traditional countermeasures. We anticipate our research to be a starting point towards deeper understanding of human and hazard, and the knowledge of which is likely to be applicable to many other regions and times.