Assessment of vegetation and landslide hazard using innovative approaches

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K20736
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 4:Geography, cultural anthropology, folklore, and related fields
• Research Institution: Nagoya University (2022); Kanto Gakuin University (2020-2021)
• Principal Investigator: Saito Hitoshi 名古屋大学, 環境学研究科, 准教授 (00709628)
• Co-Investigator(Kenkyū-buntansha): 手代木 功基 摂南大学, 国際学部, 講師 (10635080) ; 内山 庄一郎 国立研究開発法人防災科学技術研究所, マルチハザードリスク評価研究部門, 特別研究員 (30507562)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: 斜面崩壊 / 土砂災害 / 草原 / 植生回復 / ドローン / 高精細地形情報 / 阿蘇山

Outline of Final Research Achievements

Vegetation cover is an important factor in hillslope stability. The objective of this study is to explore topographic characteristics and vegetation recovery in rainfall-induced and coseismic landslide scars at the Aso volcano in Japan. We focus on the temporal changes and effect of topography on vegetation recovery using multitemporal satellite images from 2010 to 2020, and finer spatial resolution data from unmanned aerial vehicles. This study validates grass vegetation recovery using the normalized difference vegetation index (NDVI). The NDVI rapidly increases in landslide scars after the events. The results indicate that NDVI at both landslide scars will reach the same level as the pre-landslide grass vegetation within 12 years. The slope aspect direction determines the topographic effects of grass vegetation recovery. The north- to west-facing landslide scars seemed to experience rapid grass vegetation recovery.

Free Research Field

自然地理学

Academic Significance and Societal Importance of the Research Achievements

斜面崩壊は、土砂災害を引き起こすとともに、主要な植生の攪乱要因である。また崩壊跡地での植生回復は、斜面の安定性や生態系を検討する上で重要である。本研究では、阿蘇山の草原での斜面崩壊地の特徴や、崩壊跡地が約10～12年程度でもとの草原景観に戻る結果、及び斜面の地形による回復状況の違いを示した。これらの結果は、阿蘇山で頻発する斜面崩壊の脆弱性評価や、斜面崩壊と草地景観との関係を検討する上で重要である。