Histroical typhoon track reconstruction during the last 1000 years by using lagoonal lamina sediment

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K03995
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: Shimane University
• Principal Investigator: Katsuki Kota 島根大学, 学術研究院環境システム科学系, 講師 (20423270)
• Co-Investigator(Kenkyū-buntansha): 瀬戸 浩二 島根大学, 学術研究院環境システム科学系, 准教授 (60252897)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 海跡湖 / 堆積物 / 古台風 / 完新世 / 年縞

Outline of Final Research Achievements

Based on the varve lagoonal sediment in Japan, the timing of paleo-typhoon attacks and its induced floods was reconstructed. Sub-annual-scale environmental and ecosystem changes since the mid-18th century were reconstructed in Lake Hiruga. Analyses of siliceous phytoplankton and chemical composition of laminated sediments were conducted to determine the impacts of irregular hazards and anthropogenic work on the lagoon ecosystem. The peaks of freshwater phytoplankton showed a freshening events caused by local extreme event written in the historical document. We also reconstructed the paleo-flood event by using the laminated sediment which obtained from the eastern part of Izumo Plain. Based on the comparison with the paleo-typhoon record of the eastern coast of Korea, it is clear that more typhoons hit the San'in region and eastern Korea at Late Mid-Holocene than at present. The timing of northward shift of the westerly wind has a strong influence on this northward typhoon path.

Free Research Field

古環境

Academic Significance and Societal Importance of the Research Achievements

年代精度での分析が可能な年縞堆積物を用い，堆積物中のイベント層と気象記録や歴史文献に記された災害記録との直接対比を行った．これは台風・洪水災害時にどのような堆積が行われるのかを示す重要な結果であり，古台風の復元研究における基礎研究としての学術的意味を持つ．また，本研究でしめされた日韓の洪水記録の対比による中期完新世の気候変動と台風の経路変化の関係は，温暖期の台風経路を予測する側面があり，将来の台風変動を予測への貢献が期待できる．