• 제목, 요약, 키워드: Debris flow

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Field Investigation of Debris Flow Hazard Area on the Roadside and Evaluating Efficiency of Debris barrier

  • Lee, Jong Hyun;Lee, Jung Yub;Yoon, Sang Won;Oak, Young Suk;Kim, Jae Jeong;Kim, Seung Hyun
    • The Journal of Engineering Geology
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    • v.25 no.4
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    • pp.439-447
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    • 2015
  • In this study, specific sections vulnerable to debris flow damage were selected, and a complete enumeration survey was performed for the sections with debris flow hazards. Based on this, the characteristics of the sections with debris flow hazards and the current status of actions against debris flow were examined, and an efficient installation plan for a debris flow damage prevention method that is required in the future was suggested. The results indicated that in the Route 56 section where the residential density is relatively higher between the two model survey sections, facilities for debris flow damage reduction were insufficient compared to those in the Route 6 section which is a mountain area. It is thought that several sites require urgent preparation of a facility for debris flow damage reduction. In addition, a numerical analysis showed that for debris barriers installed as a debris flow damage prevention method, distributed installation of a number of small-scale barriers facilities within a valley part was more effective than single installation of a large-scale debris barrier at the lower part of a valley.

Simulation of Debris Flow Deposit in Mt. Umyeon

  • Won, Sangyeon;Kim, Gihong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.33 no.6
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    • pp.507-516
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    • 2015
  • Debris flow is a representative natural disaster in Korea and occurs frequently every year. Recently, it has caused considerable damage to property and considerable loss of life in both mountainous and urban regions. Therefore, It is necessary to estimate the scope of damage for a large area in order to predict the debris flow. A response model such as the random walk model(RWM) can be used as a useful tool instead of a physics-based numerical model. RWM is a probability model that simplifies both debris flows and sedimentation characteristics as a factor of slopes for a subjective site and represents a relatively simple calculation method compared to other debris flow behavior calculation models. Although RWM can be used to analyzing and predicting the scope of damage caused by a debris flow, input variables for terrain conditions are yet to be determined. In this study, optimal input variables were estimated using DEM generated from the Aerial Photograph and LiDAR data of Mt. Umyeon, Seoul, where a large-scale debris flow occurred in 2011. Further, the deposition volume resulting from the debris flow was predicted using the input variables for a specific area in which the deposition volume could not be calculated because of work restoration and the passage of time even though a debris flow occurred there. The accuracy of the model was verified by comparing the result of predicting the deposition volume in the debris flow with the result obtained from a debris flow behavior analysis model, Debris 2D.

Debris Flow Risk Evaluation and Ranking Method for Drainage Basin adjacent to Road (도로인근 유역의 토석류 위험평가 및 등급화 방안)

  • Kim, Kyung-Suk;Jang, Hyun-Ick
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.279-290
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    • 2010
  • Technical countermeasures against debris flow should be established upon the risk level of the target location. Risk of debris flow should consider the hazard imposed by debris flow and vulnerability of the facilities to debris flow. In this research, we have defined the target location for risk evaluation and suggested scoring method of hazard of debris flow and vulnerability of road to debris flow. By defining risk rank into 6 categories in terms of possibility of damage during rainfall and using the risk scores of 46 debris flow cases, we have suggested risk ranking matrix. The method can be used in ranking the drainage basin adjacent to road by simply determining the hazard with vulnerability score and can be used for planning the debris flow countermeasures.

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Analysis of Characteristic of Debris Flow with Angle of Slope (흐름 경사면의 경사도에 따른 토석류 흐름의 특성 분석)

  • Lee, Jun Seon;Song, Chang Geun;Lee, Seung Oh
    • Journal of the Korean Society of Safety
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    • v.31 no.2
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    • pp.49-56
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    • 2016
  • In Korea, there exist many mountains, and sudden storms occur during the summer season. When severe rainstorm events occur in steep slope topography, risk of debris flow is increased. Once debris flow occurs in urban area, it may cause casualties and physical damages due to rapid debris flow velocity along a steep slope. Accordingly, preventing method of sediment-related disaster for demage mitigation are essential. Recently, various studies on debris flow have been conducted. However, the prediction of the physical propagation of debris flow along the steep slope was not thoroughly investigated. Debris flow is characterized by various factors such as topography, properties of debris flow, amount of debris flow. In the study the numerical simulation was focused on the topographic factor. Fundamental analysis of the risk area was implemented with emphasis on the propagation length, thickness, and the development of maximum velocity. The proposed results and the methodology of estimating the structural vulnerability would be helpful in predicting the behavior and the risk assessment of debris flow in urban area. These results will be able to estimate the vulnerability of urban areas affected the most damage by debris flow.

Effect of Land Slope on Propagation due to Debris Flow Behavior (전파면의 경사에 따른 토석류 흐름양상에 대한 연구)

  • Lee, Jun Seon;Song, Chang Geun;Kim, Hong Teak;Lee, Seung Oh
    • Journal of the Korean Society of Safety
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    • v.30 no.3
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    • pp.52-58
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    • 2015
  • As sudden rainfall has happened, the debris flow has occurred in the mountain area. Recently sudden rainfall occurred so frequently caused by abnormal climate. Thus debris flow hazard had consecutively increased damage because of debris flow. Recently, Enormous damage due to debris flow have occurred in Korea. Various studies have been conducted to prevent search debris flow hazard. This study was carried out for debris flow behavior according to the land slope on propagation. It is the important one among factors that are related to the propagation over the city with respect to debris flow discharge and depth. For the numerical simulations in this study, the land slope was varied of 5, 0, $-5^{\circ}$ to investigate the debris flow behavior with the FLO-2D, often recommended by FEMA to simulate debris flow. To verify the performance of FLO-2D, comparison with the USGS experiments (Iverson et al, 2010) was conducted. From numerical results the propagation length of the debris flow was found the most sensitive one. Maximum of debris flow thickness and velocity and structural vulnerabilities were investigated to the effect of land slope. They was became smaller according to land slope of 5, -5, $0^{\circ}$ in the order. As a result, debris flow behavior analysis about the effect of the land slope could contribute to understand the vulnerability of city for debris flow hazards.

Development of GIS-based Debris Flow Simulation Program (GIS 기반의 토석류 시뮬레이션 프로그램 개발)

  • Wie, Gwang-Jae;Lee, Young-Kyun;Lee, Dong-Ha;Suh, Yong-Cheol
    • Journal of the Korean Society of Hazard Mitigation
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    • v.10 no.1
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    • pp.49-55
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    • 2010
  • This study describes a development of GIS-based program called Debris Flow Analyzer for simulating the hazard extent of debris flow on the assumption that is uniform continuous, incompressible, unsteady. The Debris Flow Analyzer was designed to process debris flow numerical simulation with Finite Difference Formulation; smoothed DEM, slope, debris flow directions, extract valley, debris volume, water volume, debris flow moving speed, effective viscosity, dynamic friction coefficient. Also, it is expected that we can be improved the inform of debris flow hazard map by Google Earth.

Analysis of Debris Flow Deposition based on Topographic Characteristics of Debris Flow Path (유하부 지형 특성에 따른 토석류 퇴적 분석)

  • Kim, Gihong;Youn, Junhee
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.31 no.6_1
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    • pp.471-481
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    • 2013
  • Recently, the frequency of debris flow disaster has increased, which is one of the natural disasters during extremely heavy rainfall condition. This paper described the analysis method about deposition characteristics of debris flow using topographic characteristics of debris flow path. First, we observed topographic changes by differencing high- resolution LiDAR DEMs acquired before and after the occurrence of debris flow event. We assumed that deposition on outside of debris flow path was generated by movements due to the inertia of debris flows. Then, we analyzed three topographic characteristics of debris flow path: slope in flow direction, transition angle of flow path, and the net efficiency(L/H) of debris flows defined by the ratio of transport length(L) and elevation difference(H). We applied this method to Umyeon Mountain debris flow event in July 2011. The results showed that deposition on outside of debris flow path due to the inertia of debris flows was significantly related to the transition angle of debris flow path. Also, we figured out that there were more frequent such depositions in locations where the ratio of 'transition angle / (L/H)' is over 8.

Model experiment for calculation of debris flow's shock force (Use dry materials) (토석류 충격력 산정을 위한 모형실험(건조시료 활용))

  • Kim, Jin-Hwan;Lee, Yong-Soo;Cho, Gyu-Tae;Choi, Won-Hun
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1271-1274
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    • 2009
  • One of the landslide, Debris flow means flow mixed of rocks, gravels, sand and soil with water. Debris flow occurred in summer by passed the rainy season and typhoon. Especially, Localized heavy rain derived from abnormal weather caused debris flow independent of season. It is increase to collapse of house, bridge, roads by debris flow but countermeasure studies about occurrence cause, movement pattern, damage scale about debris flow are insufficient. This study performed debris flow model experiment using dry material and calculated shock force predicted debris flow occurrence.

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A Study on Scale at a Debris Flow Landslide Damaged Area (토석류 산사태 피해지의 규모에 관한 연구)

  • Sin, Sung-Sick;Choi, Young-Nam;Yoo, Nam-Jae
    • Journal of Industrial Technology
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    • v.36
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    • pp.57-63
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    • 2016
  • In this study characteristics of debris flow landslide were investigated on the focus of debris flow disaster occurred by heavy rainfall in 2013 at Goeun-ri around Kaeryoung Mt. in Chuncheon-si. Appropriate method for estimating scale of debris flow was investigated by comparing those values from soil loss by Universal Soil Loss Equation, debris flow yield rate obtained by field survey of investigating debris flow path from initiation and erosion to deposition and other methods. As results of this study, it might be an opportunity of contributing to construct the data base for determining the size of erosion control facilities in future.

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Movement and Deposition Characteristics of Debris Flow According to Rheological Factors (유동학적 인자에 따른 토석류의 이동 및 퇴적 특성)

  • Lee, Mi-Ji;Kim, Yun-Tae
    • Journal of the Korean Geotechnical Society
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    • v.29 no.5
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    • pp.19-27
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    • 2013
  • Most of the landslides induced by rainfall in summer rainy season appear in the type of debris flow. Debris flow gives a lot of economic losses and human casualties due to high moving velocity and volume of debris flow. In order to analyze movement and deposition characteristics of debris flow, numerical analysis using FLO-2D program was conducted with various viscosities and yield stresses. As a result of numerical analysis, velocity and runout distance of debris flow decreased as its viscosity increased due to resisting force between particles of debris flow. Consequently, flow depth of debris flow increased and impact force decreased. Yield stress of debris flow affected its initiation and deposition characteristics. As yield stress increased, runout distance of debris flow decreased and its impact force increased. Based on the results of numerical analysis, it was found that velocity of debris flow mainly depended on viscosity, while deposition characteristics (runout distance, deposition width, deposition area) of debris flow depended on both viscosity and yield stress.