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2021 Vol.8, Issue 4

Original Article

Numerical Experiment of Driftwood Generation and Deposition Patterns by Tsunami

쓰나미에 의한 유목의 생성과 퇴적패턴의 수치모의실험

Tae Un Kang1
,
Chang-Lae Jang2*
,
Nam Joo Lee3
,
Won Ho Lee2
강 태운1
,
장 창래2*
,
이 남주3
,
이 원호2
1Department of Civil Engineering, Korea National University of Transportation, 50 Daehak-ro, Chungju-si, Chungbuk, 27460, Korea, Postdoctoral researcher
2Department of Civil Engineering, Korea National University of Transportation, 50 Daehak-ro, Chungju-si, Chungbuk, 27460, Korea, Professor
3Department of Civil Engineering, Kyungsung University, Busan 48434, Korea, Professor
1한국교통대학교 건설환경도시교통공학부 박사후 연구원
2한국교통대학교 건설환경도시교통공학부 교수
3경성대학교 건설환경도시공학부 교수
*Corresponding Author
31 December 2021. pp. 165-178
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Abstract

We studied driftwood behaviors including generation and deposition in a tsunami using a numerical simulation. We used an integrated two-dimensional numerical model, which included a driftwood dynamics model. The study area was Sendai, Japan. Observation data collected by Inagaki et al. (2012) were used to verify the simulation results by comparing them with driftwood deposition patterns. A simplified model was developed to consider the threshold of driftwood generation by the drag force of water flows. To consider the volume of driftwood generated, we estimated the total wood number in the study area using Google Earth. Therefore, we simulated more than 13,000 pieces of driftwood that were generated and transported inland from approximately 300,000 trees that were growing in the forest. The final distribution of the driftwood was similar to the observation data. The reproducibility of the generation and deposition patterns of driftwood showed good agreement in terms of longitudinal deposition pattern. In the future, a sensitivity analysis on driftwood parameters, such as the size of the wood, boundary conditions, and grid size, will be implemented to predict the travel patterns of driftwood. Such modeling will be a useful methodology for disaster prediction based on water flow and driftwood.

Keywords
Driftwood generation model
Driftwood dynamics model
Tsunami simulation
Tohoku earthquake

본 연구는 유목의 생성 및 퇴적과 쓰나미 흐름을 수치모형을 활용하여 실험하였다. 이를 위해 2차원 수심적분흐름모형과 유목동역학모형을 사용하였다. 연구지역은 일본 센다이(Sendai)해안가로서 관측자료(Inagaki et al. 2012)를 이용하여 시뮬레이션 결과와 유목의 퇴적패턴을 비교검증하였다. 본 연구를 위해 흐름의 항력으로 인해 유목이 발생하는 단순화된 모형이 개발되었다. 또한 유목 발생량을 고려하기 위해 Google Earth를 활용하여 연구지역의 퇴적된 유목 수를 추정하였으며 그 결과, 해안숲의 30만 그루의 나무으로부터 13000개 이상의 유목이 발생하여 내륙으로 이송되는 수치모의를 수행하였다. 이 수치실험 결과는 Inagaki et al. (2012)의 관측데이터와 유사하였다. 또한, 유목의 발생과 퇴적 패턴의 재현성은 종방향 퇴적패턴에서 높은 상관성을 나타냈다. 추후에는 목재의 크기, 경계 조건, 격자 크기와 같은 유목 매개변수에 대한 민감도 분석을 구축하여 유목의 이동패턴을 분석할 필요가 있을 것으로 판단된다. 이러한 모델링은 물의 흐름과 유목에 따른 재해예측에 유용한 방법론이 될 것으로 기대된다.

키워드
유목생성모형
유목동역학모형
쓰나미 흐름모의
토호쿠 지진
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Information
  • Publisher :Korean Society of Ecology and Infrastructure Engineering
  • Publisher(Ko) :응용생태공학회
  • Journal Title :Ecology and Resilient Infrastructure
  • Journal Title(Ko) :응용생태공학회 논문집
  • Volume : 8
  • No :4
  • Pages :165-178
  • Received Date : 2021-10-12
  • Revised Date : 2021-11-08
  • Accepted Date : 2021-11-18
  • DOI :https://doi.org/10.17820/eri.2021.8.4.165
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