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복합재해 영향을 고려한 산불 후 산사태 잠재적 피해 위험도 분석

Analysis of the potential landslide hazard after wildfire considering compound disaster effect

  • 이종욱 (서울대학교 환경대학원 협동과정 조경학) ;
  • 이동근 (서울대학교 조경.지역시스템공학부) ;
  • 송영일 (환경정책평가연구원 국가기후변화적응센터)
  • Lee, Jong-Ook (Interdisciplinary Program in Landscape Architecture, Seoul National University) ;
  • Lee, Dong-Kun (Department of Landscape Architecture and Rural system Engineering, Seoul National University) ;
  • Song, Young-Il (Korea Environment Institute, Korea Adaptation Center for Climate Change)
  • 투고 : 2018.09.28
  • 심사 : 2018.12.17
  • 발행 : 2019.02.28

초록

Compound disaster is the type that increases the impact affected by two or more hazard events, and attention to compound disaster and multi-hazards risk is growing due to potential damages which are difficult to predict. The objective of this study is to analyze the possible impacts of post-fire landslide scenario quantitatively by using TRIGRS (Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Analysis), a physics-based landslide model. In the case of wildfire, soil organic material and density are altered, and saturated hydraulic conductivity decrease because of soil exposed to high temperature. We have included the change of soil saturated hydraulic conductivity into the TRIGRS model through literature review. For a case study, we selected the area of $8km^2$ in Pyeongchang County. The landslide modeling process was calibrated before simulate the post-wildfire impact based on landslide inventory data to reduce uncertainty. As a result, the mean of the total factor of safety values in the case of landslide was 2.641 when rainfall duration is 1 hour with rainfall intensity of 100mm per day, while the mean value for the case of post-wildfire landslide was lower to 2.579, showing potential landslide occurrence areas appear more quickly in the compound disaster scenario. This study can be used to prevent potential losses caused by the compound disaster such as post-wildfire debris flow or landslides.

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Figure 1. Relation of multi-hazard risk causing compound disaster

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Figure 2. Location and topography of the study area, (a) Key map and satellite image (from Google map), (b) Digital elevation map (meter) (c) Slope map (degree,°)

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Figure 3. ROC graph (IZLT =1.0×10-7))

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Figure 4. TRIGRS modeling result maps of post-wildfire landslide compound disaster case compared to landslide single disaster case (rainfall intensity of 100mm/day), (a) Landslide single disaster case (rainfall duration-1h), (b)Landslide single disaster case (rainfall duration-4h), (c) Post-wildfire landslide compound disaster case (rainfall duration-1h), (d) Post-wildfire landslide compound disaster case(rainfall duration-4h)

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Figure 5. TRIGRS modeling result graphs of post-wildfire landslide compound disaster case compared to landslide single disaster case (rainfall intensity of 100mm/day), (a) Changes of factor of safety (FS) at different rainfall duration, (b) Changes of total area of FS less than 1 at different rainfall duration

Table 1. Type of compound disaster and description

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Table 2. Summary of soil property values used for modelling

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Table 3. Result of ROC analysis

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과제정보

연구 과제 주관 기관 : 환경부

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