Development of method for hazard prediction of deep-seated landslide based on stream water chemistry affected by bedrock weathering

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K14747
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Forest science
• Research Institution: The University of Tokyo (2017); University of Tsukuba (2015-2016)
• Principal Investigator: Hotta Norifumi 東京大学, 大学院農学生命科学研究科(農学部), 准教授 (00323478)
• Co-Investigator(Kenkyū-buntansha): 地頭薗 隆 鹿児島大学, 農水産獣医学域農学系, 教授 (50145455) ; 小田 智基 東京大学, 大学院農学生命科学研究科(農学部), 助教 (70724855)
• Co-Investigator(Renkei-kenkyūsha): Yamakawa Yosuke 筑波大学, 生命環境系, 助教 (20611601)
• Research Collaborator: Lee ShingPing 台湾成功大学 ; Tsai Yuan-Jung 台湾成功大学
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 深層崩壊 / 基岩風化 / 水文過程 / 渓流水質

Outline of Final Research Achievements

Based on the hypothesis that formation of a potential slip surface in the base rock layer can be detected through changes of stream water chemistry, we collected water samples and analyzed to develop a method for hazard prediction of deep-seated landslide in Taiwan where potential landslide areas have been identified. Regardless of geological setting, most of the water was Ca-HCO3 type, which is common for shallow groundwater. EC and SiO2 concentration showed convergence with increasing watershed size. There was a significant negative relationship between EC and Si for the water samples from the Chaochou Formation, where the potential landslides were concentrated, while the correlation was positive for water from other geologies. The negative correlation can occur if there is an uneven distribution of layers with preferential ground water flow inferring that the combination of EC and Si could be effective for determining the risk of the potential landslides.

Free Research Field

砂防工学