• Title/Summary/Keyword: sediment-related disaster

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A study on the Sediment Disaster Response System in Japan (일본의 토사재해 대응체계에 대한 연구)

  • Lee, Woo-Jin
    • Journal of Digital Convergence
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    • v.16 no.7
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    • pp.47-54
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    • 2018
  • Sediment disaster happen frequently in our country every year, and a lot of lives and the properties have been lost because of them. Non-structural measures for prevention of sediment disaster have been introduced by prefectures based on the Sediment-related Disaster Prevention Law established after the devastating rainstorm damage in Hiroshima in 1999. They include formulation of sediment disaster warning and evacuation standard rainfall and designation of sediment disaster warning zones and sediment disaster special warning zones. As a practical example, this research focused on the case of "TEC-FORCE" of "MLIT of Japan" as a method of utilizing professional workforce and the sediment disaster warning information delivery system in Kagoshima. In the future, it will be called for prevention and reduction of damages by utilizing professional workforce and sediment disaster response system such as Japan.

Management Strategy of Sediment-Related Disasters for Adaptation to Climate Change

  • Chun, Kun-Woo;Kim, Suk-Woo;Lee, Youn-Tae
    • Journal of Forest and Environmental Science
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    • v.34 no.2
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    • pp.192-195
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    • 2018
  • To establish a management strategy of sediment-related disasters for adaptation to climate change, it is necessary to 1) understand the specific details and problems about the present status, 2) systematize related technologies by using exact numerical values obtained from physically-based analysis, and 3) ensure the basic guidelines are applied to field elastically. To achieve these successfully, detailed guidelines are required by scientifically considering the utilization and impact of related technology on the field. Here, detailed guidelines should include 1) the development of a basic plan, 2) enhancement of relevant technical instructions, 3) establishment of survey and inspection methods, 4) procedure of erosion control works in urban living sphere, and 5) proactive countermeasures against sediment-related disaster caused by earthquakes.

Analyzing the Occurrence Trend of Sediment-Related Disasters and Post-Disaster Recovery Cases in Mountain Regions in N orth Korea Based on a Literature Review and Satellite Image Observations (문헌 및 위성영상에 기초한 북한의 산지토사재해 발생경향 및 복구사례 분석)

  • Kim, Kidae;Kang, Minjeng;Kim, Suk Woo
    • Journal of Korean Society of Forest Science
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    • v.110 no.3
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    • pp.419-430
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    • 2021
  • This study investigated spatiotemporal trends of sediment-related disasters in North Korea from 1960 to 2019 and post-disaster recovery cases based on a literature review and satellite images. Results showed that occurrence status of sediment-related disasters was initially externally reported in 1995 (during the Kim Jongil era); their main triggering factor was heavy summer rainfall. Furthermore, forest degradation rate was positively correlated with population density (R2 = 0.4347, p = 0.02) and occurrence number of sediment-related disasters was relatively high on the west coast region, where both variables showed high values. This indicates that human activity was a major cause of forest degradation and thus, significantly affected sediment-related disasters in mountain regions. Finally, sediment- related disasters due to shallow landslides, debris flow, and slow-moving landslides were observed in undisturbed forest regions and human-impacted forest regions, including terraced fields, opencast mines, forest roads, and post-wildfire areas, via satellite image analysis. These disaster-hit areas remained mostly abandoned without any recovery works, whereas hillside erosion control work (e.g., treeplanting with terracing) or torrent erosion control work (e.g., check dam, debris flow guide bank) were implemented in certain areas. These findings can provide reference information to expand inter-Korean exchange and cooperation in forest rehabilitation and erosion control works of North Korea.

International Research Trend on Mountainous Sediment-related Disasters Induced by Earthquakes (지진 유발 산지토사재해 관련 국외 연구동향 분석)

  • Lee, Sang-In;Seo, Jung-Il;Kim, Jin-Hak;Ryu, Dong-Seop;Seo, Jun-Pyo;Kim, Dong-Yeob;Lee, Chang-Woo
    • Journal of Korean Society of Forest Science
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    • v.106 no.4
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    • pp.431-440
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    • 2017
  • The 2016 Gyeongju Earthquake ($M_L$ 5.8) (occurred on September 12, 2016) and the 2017 Pohang Earthquake ($M_L$ 5.4) (occurred on November 15, 2017) caused unprecedented damages in South Korea. It is necessary to establish basic data related to earthquake-induced mountainous sediment-related disasters over worldwide. In this study, we analyzed previous international studies on the earthquake-induced mountainous sediment-related disasters, then classified research areas according to research themes using text-mining and co-word analysis in VOSviewer program, and finally examined spatio-temporal research trends by research area. The result showed that the related-researches have been rapidly increased since 2005, which seems to be affected by recent large-scale earthquakes occurred in China, Taiwan and Japan. In addition, the research area related to mountainous sediment-related disasters induced by earthquakes was classified into four subjects: (i) mechanisms of disaster occurrence; (ii) rainfall parameters controlling disaster occurrence; (iii) prediction of potential disaster area using aerial and satellite photographs; and (iv) disaster risk mapping through the modeling of disaster occurrence. These research areas are considered to have a strong correlation with each other. On the threshold year (i.e., 2012-2013), when cumulative number of research papers was reached 50% of total research papers published since 1987, proportions per unit year of all research areas should increase. Especially, the proportion of the research areas related to prediction of potential disaster area using aerial and satellite photographs is highly increased compared to other three research areas. These trends are responsible for the rapidly increasing research papers with study sites in China, and the research papers examined in Taiwan, Japan, and the United States have also contributed to increases in all research areas. The results are could be used as basic data to present future research direction related to mountainous sediment-related disasters induced by earthquakes in South Korea.

Development on Prediction Algorithm of Sediment Discharge by Debris Flow for Decision of Location and Scale of the Check Dam (사방댐 위치 및 규모 결정을 위한 토석류 토사유출량 예측 알고리즘 개발)

  • Kim, Kidae;Woo, Choongshik;Lee, Changwoo;Seo, Junpyo;Kang, Minjeng
    • Journal of the Society of Disaster Information
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    • v.16 no.3
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    • pp.586-593
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    • 2020
  • Purpose: This study aims to develop an algorithm for predicting sediment discharge by debris flow, and develop GIS-based decision support system for optimal arrangement of check dam. Method: The average stream width and flow length were used to predict the cumulative sediment discharge by debris flow. At this time, the amount of slope failure on source area and average flow length were utilized as input factors. Result: The predicted sediment discharge calculated through the algorithm was 1.1 times different on average compared to the actual sediment discharge by debris flow. In addition, the program is an objective indicator that selects the location and size of the check dam, and it can help practitioners make rational decisions. Conclusion: The soil erosion control works are being implemented every year. Therefore, it is expected that the GIS-based decision support system for location and size of the check dam will contribute to the prevention of sediment-related disasters.

Estimating Temporal and Spatial Variation of Sediment Transport Processes using a Distributed Catchment Model (분포형 유역모델을 이용한 유사 운반과정의 시·공간적 변동 해석)

  • Koo, Bhon K.;Cho, Jae-Heon
    • Journal of Korean Society on Water Environment
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    • v.23 no.6
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    • pp.872-880
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    • 2007
  • For effective management of sediment-related diffuse pollution, it is of utmost importance to estimate spatial variation of sediment transport processes within a catchment. A mathematical model can play a critical role in estimating sediment transport processes at the catchment scale provided that the model structure is appropriate for representing major sediment transport processes of the catchment of interest. This paper introduces a distributed catchment model River Basin Water Quality Simulator (RBWQS) and presents some results of its application to a small rural catchment in Korea. The model has been calibrated and validated for a wet period using hourly hydrographs and sediment concentrations observed at the catchment outlet. Based on the model simulation results, the spatial variation of sediment transport processes across the catchment and the effects of paddy fields and small reservoirs on hydrology and sediment transport have been analyzed at the catchment scale.

Research Trends on Soil Erosion Control Engineering in North Korea (북한의 사방공학 분야 연구동향 분석)

  • Kim, Kidae;Kang, Minjeng;Kim, Dongyeob;Lee, Changwoo;Woo, Choongshik;Seo, Junpyo
    • Journal of Korean Society of Forest Science
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    • v.108 no.4
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    • pp.469-483
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    • 2019
  • North Korea has experienced floods and sediment-related disasters annually since the 1970s due to deforestation. It is of paramount importance that technologies and trends related to forest restoration and soil erosion control engineering be properly understood in a bid to reduce damage from sediment-related disasters in North Korea, and to effect national territorial management following unification. This paper presents a literature review and bibliometric analysis including 146 related articles published in North Korea. First, we analyzed the textual characteristics of the articles. We then employed the VOSviewer software package to classify the research topic and analyzed this topic based on the time change. The results showed that articles on the topic have consistently increased since the 1990s. In addition, research related to soil erosion control engineering has been classified into four subjects in North Korea: (i) assessment of hazard area on soil erosion and soil loss, sediment related-disasters; (ii) hydraulic and hydrologic understanding of forests; (iii) reasonable construction of soil erosion control structures; and (iv) effects and management plan of soil erosion control works. The proportion of research related to the (ii) hydraulic and hydrologic understanding of forests had been significant during the reign of Kim Ilsung. However, the proportion of research related to the (i) assessment of hazard area on soil erosion and soil loss, sediment-related disasters, increased during the reign of Kim Jongil and Kim Jongun. Using these results, our analysis indicated that an interest in and need for soil erosion control engineering in North Korea has continually increased. The results of this study are expected to serve as a basis for preparing forestry cooperation between North and South Korea, and to serve as essential data for better understanding soil erosion control engineering in North Korea.

NUMERICAL MODELLING OF SHEET-FLOW TRANSPORT UNDER WAVE AND CURRENT

  • Bakhtiary, Abbas-Yeganeh;Hotoshi Gotoh;Tetsuo Sakai
    • Water Engineering Research
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    • v.3 no.2
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    • pp.75-84
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    • 2002
  • An Euler-Lagrange two-phase flow model is presented fur simulation sheet-flow transport under wave and current. The flow is computed by solving the Reynolds Averaged Navier-Stokes equation in conjunction with the k-$\varepsilon$ turbulence model for turbulence closure. The sediment transport is introduced as a motion of granular media under the action of unsteady flow from the Lagragian point of view. In other word, motion of every single particle is numerically traced with Movable Bed Simulator (MBS) code based on the Distinct Element Method (DEM), in which the frequent interparticle collision of the moving particles during the sheet-flow transport is sophisticatedly taken into account. The particle diameter effect on time-dependent developing process of sheet-flow transport is investigated, by using three different diameter sizes of sediment. The influence of an imposed current on oscillatory sheet-flow transport is also investigated. It is concluded that the sediment transport rate increases due to the relaxation process related to the time-lag between flow velocity and sediment motion.

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Case Study on Preventing method of Sediment-Related Disaster for damage reduce (토사재해 저감 대책방안을 위한 사례)

  • Baek, Yong;Kim, Bu-Saeng;Park, Kyung-Boo;Kim, Hak-Jun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.10a
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    • pp.611-614
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    • 2006
  • 매년 발생하는 산사태에 대한 피해를 최소화하기 위하여 일본의 사면 붕괴와 대책방안에 대한 조사를 실시하였다. 지난 2006년 7월 강원도 영서지방에 발생한 산사태 피해 현황을 살펴보고 사방기술의 선진국인 일본을 방문, 이에 대한 자료를 수집 분석하였다. 산악지형으로 구성된 지형이 국내와 매우 유사하고 자연재해가 더욱 많은 일본의 선진 사방대책에 대한 기술을 습득하여 국내형의 기술개발과 정책결정에 도움을 얻고자 본 조사를 실시하였다. 본고는 수집된 자료를 바탕으로 국내의 정황과 비교하며 정리한 것이다.

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Evaluation of the Applicability of Sediment Discharge Measurement in Mountain Stream using the Load-cell Sensor (Load-cell Sensor를 이용한 산지 토사유출량 계측의 현장 적용성 검토)

  • Seo, Jun-Pyo;Lee, Ki-Hwan;Kim, Dong-Yeob;Woo, Choong-Shik;Lee, Chang-Woo;Lee, Heon-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.1
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    • pp.644-653
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    • 2018
  • Landslides occur frequently due to the effects of heavy rainfall and typhoons caused by climate change. Erosion control measures are needed to effectively prevent landslide damage. In order to improve their efficiency, it is necessary to quantitatively measure the sediment discharge from the mountain stream. In this study, a load cell sensor was installed in a mountain stream and the measured values were compared according to the applicability and load test type in the mountain stream. The result of the load test showed that the effect of the loading type (load test 1, 2) was low at average (loadings) of 0.4kgf and 0.6kgf at sites 1 and 2, respectively. The load factor was also derived by regression analysis to increase the accuracy of the measured values. According to the results of the load factor (normalized) to the load-cell measurement value, the output value increased by 14.8% and 24.6% in sites 1 and 2, respectively, and was calculated to be similar to the reference value. The load cell sensor enabled us to quantitatively estimate the amount of sediment discharge in the mountain stream through time series analysis with the water level and rainfall information. If the monitoring is carried out for a long time, it can be used to find the sediment discharge mechanism for the mountain stream. In addition, applying sensors such as load-cells to a mountain stream is expected to contribute to the development of related industries, such as the manufacturing of measurement sensors.