산지재해 위험성 분석을 위한 지상 LiDAR 지형자료 구축에 관한 연구

Mountain disasters, such as landslides and debris flows, are becoming more prevalent due to abnormal weather patterns. Debris flows, triggered by heavy rainfall, are causing escalating damage to residential areas and roads as they surge down mountain streams. In order to both mitigate this damage and comprehend the underlying causes of such mountain disasters, comprehensive field investigations were carried out in regions where debris flows had transpired. To establish spatial information for analyzing vulnerable areas, GIS data were employed. Additionally, precise measurements of the actual extent of debris flow in targeted zones were obtained through the utilization of terrestrial LiDAR scanning. Subsequently, the process of debris flow was replicated using FLO-2D, a numerical model designed for such scenarios. This simulation incorporated actual rainfall data that had precipitated debris flow incidents, as well as probability-based rainfall data corresponding to return periods of 30, 50, and 100 years. Key parameters, including flow depth, velocity, and diffusion area, were compared across different scenarios. The sedimentation area of the section where debris flow originated, as determined from terrestrial LiDAR scan data, was estimated to be approximately 21,300 square meters. The outcomes of the FLO-2D simulation revealed that the diffusion area for Case I was approximately 20,900 m2, while the simulated diffusion area for a 100-year return period was calculated to be 40,725 m2. Furthermore, flow depth, velocity and diffusion area exhibited a gradual incremental trend in simulation results.

<p>The impact of mountain disasters on human society continues to increase under the background of climate change and social economy development, especially for the developing countries or regions with relatively backward social and economic development level and fragile natural ecological environment. China is one of the countries suffered most serious mountain disasters in the world. In particular, after Wenchuan earthquake in 2008, the frequency and scale of secondary mountain disasters caused by heavy rainfall and the earthquake increased significantly, which seriously threatens the life and property safety and post-disaster reconstruction in earthquake-hit areas. Therefore, some events with mass deaths and injuries occurred. For example, on July 10, 2013, the massive landslide in Sanxi Village, Zhongxing Town, Dujiangyan City, Sichuan Province caused 166 deaths or missing. On June 24, 2017, the high mountain collapse in Xinmu Village, Dixi Town, Maoxian County, Sichuan Province buried 62 farm houses, caused 10 deaths, 73 missing and 3 injures. What’s more, mountain disasters also caused mass deaths and injuries in some areas less affected by Wenchuan earthquake. On June 28, 2012, the large debris flow occurred in Aizi Gully, Ningnan County, Sichuan Province, China was the annually most serious debris flow in construction site in China, resulting in 40 deaths or missing. On June 28, 2020, debris flow caused 17 deaths or missing in Caogu Township, Mianning County, Liangshan Prefecture, China. Lots of disaster cases show that disaster awareness and emergency capacity are the base of scientific emergency avoidance，which  is one of the important ways to reduce the casualties of mountain disasters in high-risk areas. Through the analysis of disaster cases, the experience and lessons of mountain disasters in western China were summarized and the measures to avoid mass deaths and injuries in the process of mountain disaster emergency avoidance were explored. So this research aims to  provide a scientific basis for the reduction of casualties in mountain disasters in similar areas.</p>

The tourism development in Longmenshan of Chengdu City is being confronted with a lot of mountain disasters such as debris flows, slopes instable, and landslides at present. Therefore mountain disasters are becoming a question of common interest in local tourism development. The purpose of the paper was to integrate the relationship of dynamics between mountain disasters impact and tourism industry adaptation in the mountain area of Longmenshan in Chengdu City, and understanding vulnerability and exploring ways to enhance mountain people's adaptive capacities for tourism development. With its rich tourism resources, the mountain area of Longmenshan is promising and potential to develop tourism industry. However, mountain disasters are affecting the already fragile mountain ecosystems and the unsustainable tourism development styles are also existed. Therefore, our paper aims to promote tourism development in conjunction with mountain disasters prevention and mitigation in Longmenshan on the base of government support in the long term.

Torrential rains occurring during the unpredictable climate change cause many mountain disasters in vulnerable areas. This study is to analyze the debris flow mechanism by applying the multiplier of the vulnerable area debris flow prediction model presented by USACE to the erosion or sedimentation model. The higher the typhoon category, the higher the debris flow peak value, and the frequency of peaks of flow discharge with long durations increased. Analysis of changes in vegetation density showed that the initial peak value of the debris flow reaching the bottom was highest due to dense vegetation, and high-amplitude fluctuations appeared due to energy dissipation. In the case of heavy rainfall, the peak value of debris flow increased by more than 22%, and fluctuations of flow discharge occurred earlier at the elapsed time. In addition, debris flow fluctuations with high wave heights appeared, and the high-amplitude band width also appeared to be quite long. The analysis of present study will provide information for developing and prevention disaster reduction measures in vulnerable areas.

The scale of mountain disasters and the frequency of their occurrence are increasing due to climate change and land development. The country of 64% is composed of mountainous areas and most of the rainfall is concentrated in summer, making Korea vulnerable to mountain disasters. In particular, as the frequency of landslides and debris flow increases, countermeasures to reduce the mountain disasters are required. In this study, we simulated the debris flow based on the investigation on site where debris flows occurred and evaluated the vulnerability of the facilities that actually damaged. The simulation result coincided with an accuracy of about 62% for the area damaged by the actual debris flow. The impact forces about 2.0 to 24.8 kPa were generated in the section where the actual damage occurred. In addition, the vulnerability was found to be higher than 0.6.

<p>The frequent occurrences of mountain disasters have posed a huge threat to the safety of life and property of settlement residents, which bring serious challenges to the post-disaster reconstruction and sustainable development of the affected area, especially in countryside resort areas. The countryside resort areas are populated with tourists whose risk perception and risk behaviours against mountain hazards are unpredictable, which has made the evacuation difficult or even worsened the situation when mountain hazards occur. How to evacuate evacuees to safety in mountain disasters is an important issue for disaster emergency management. By far, little attention has been given to emergency evacuation during mountain disasters in China. Based on mountain disaster events from 2008 to 2019, and 1385 households samples that obtained by stratified random sampling and questionnaire survey, this study has proved ‘Public Participation Monitoring and Warning System’ (PPMWS) is an essential tool to reduce related deaths. Furthermore, the roles and interfaces of different stakeholders in emergency evacuation process are discussed for the purpose to find out the unforeseen circumstances and vulnerable spots. The results show that the farmhouse owners and monitoring personnels play the key roles in emergency evacuation process. The evacuation model led by monitoring personnels is summarized and feasible measures to reduce risks and casualties of mountain disasters are proposed and applied in Longmenshan Town, Pengzhou, Sichuan. The results of this study will improve the efficiency of evacuation and provide scientific support for mountain disaster risk management in mountainous area.</p>

Sensitivity analysis about small watershed is an important way to objectively understand the development characteristics of debris flow ditches. With the support of Remote Sensing and Geographic Information System technologies, Dongchuan County with frequent debris flow development in Kunming, Yunnan Province, southwest China was selected as the research object, the Landsat image and Digital Elevation Model were used to interpret the small watersheds on both sides of the Xiaojiang River. By selecting four indicators of fault zone, slope, gully density and land use as the impact factors, the sensitivity coefficients were quantitatively calculated. The following research results were obtained: The distribution feature of debris flow small watersheds was that, the Dongchuan fault zone was the axis which small watersheds were symmetrically distributed on; the sensitivity of the Dongchuan fault zone was the highest in the buffer distance of 5-10 km, which was prone to debris flow disasters; the debris flow was most sensitive in the slope range of 40°-50°; the debris flow was most sensitive to the gully density of 0.6-0.9 km/km2 with broken surface; three types of land use such as bare land, water and construction land had high sensitivity coefficient and were easy to cause mountain disasters. According to the sensitivity coefficients of the above impact factors, the stacking method superposition analysis was carried out to obtain the sensitivity distribution of debris flow disasters in Dongchuan County. The medium sensitive area accounted for 53.84% of the total area, and the high sensitive area accounted for 27.02% of the total area. The medium sensitive area and the high sensitive area were the main areas where debris flow occurred. This study has certain reference significance for disaster prevention, soil and water conservation by quantitative calculation and comparison of debris flow disaster sensitivity.

This paper discusses the causes of debris flow, landslide, collapse, water and soil erosion and other mountain disasters in the high mountain-plateau transitional region in northwest Sichuan. Through analysis of geological structure, lithology, earthquakes, landforms, hydrologic regime, meteorological conditions and man-made factors, the authors conclude that the natural conditions of this region favor the formation of debris flow, landslides and other mountain disasters. Moreover, the irrational economic activities of humans such as destroying forest ecosystems stimulate the occurrence of mountain disasters.

A two-dimensional debris and mud flow model that considers both laminar and turbulence flow was developed. Subsequently, the model was applied to a debris flow that occurred in Asaminami, Hiroshima, Japan in August 2014. The applicability of the model and the debris flow characteristics are discussed. The calculated horizontal distribution of sediment deposited in the Asaminami residential area was in good agreement with the horizontal distribution of the deposited large rocks and driftwood. This result indicates that the fine material in the downstream area was transported by water flow resulting from heavy rain that occurred after the debris flow. The scale of the initial debris flow was small; however, it increased with time, because eroded bed material and water were entrained to it. Therefore, it is important to reproduce the development process of debris flows to predict the amount of sediment produced, the deepest flow depth, the maximum flow velocity, and the inundation area. The averaged velocity of the simulated debris flow was about 9 m/s, and the velocity at the entrance to the residential area was about 8 m/s. This kind of information can be used to design sediment deposition dams. The travel time of the simulated debris flow from the upstream end of the main channel to the entrance of the residential area was 96 s. This kind of information can be used for making evacuation plans. Valley bed steps can suppress the deepest flow depth which is very important for the design of check dams; therefore, the high-resolution elevation data and fine numerical grids that reproduce step shapes are required to accurately calculate the deepest flow depth and maximum flow velocity.

Climate change increases the frequency of localized heavy rains and typhoons. As a result, mountain disasters, such as landslides and earthworks, continue to occur, causing damage to roads and residential areas downstream. Moreover, large-scale civil engineering works, including dam construction, cause rapid changes in the terrain, which harm the stability of residential areas. Disasters, such as landslides and earthenware, occur extensively, and there are limitations in the field of investigation; thus, there are many studies being conducted to model terrain geometrically and to observe changes in terrain according to external factors. However, conventional topography methods are expressed in a way that can only be interpreted by people with specialized knowledge. Therefore, there is a lack of consideration for three-dimensional visualization that helps non-experts understand. We need a way to express changes in terrain in real time and to make it intuitive for non-experts to understand. In conventional height-based terrain modeling and simulation, there is a problem in which some of the sampled data are irregularly distorted and do not show the exact terrain shape. The proposed method utilizes a hierarchical vertex cohesion map to correct inaccurately modeled terrain caused by uniform height sampling, and to compensate for geometric errors using Hausdorff distances, while not considering only the elevation difference of the terrain. The mesh reconstruction, which triangulates the three-vertex placed at each location and makes it the smallest unit of 3D model data, can be done at high speed on graphics processing units (GPUs). Our experiments confirm that it is possible to express changes in terrain accurately and quickly compared with existing methods. These functions can improve the sustainability of residential spaces by predicting the damage caused by mountainous disasters or civil engineering works around the city and make it easy for non-experts to understand.

Co-operation between Chinese and German geo-scientists in Tibet and adjacentareas started in 1981 with the Sino-German Joint Expedition to the Northeastern part of the Qinghai-Xizang (Tibet) Plateau, led by Prof. Dr. Jtirgen H6vermann (G6ttingen) and Prof. Wang Wenying (Lanzhou/Xian). Later several further Sino-German Joint Expeditions were conducted in China. The editors had the opportunity of participating in one of these expeditions to Tibet in 1989 led by Prof. J. H6vermann and Prof. Li Jian (Chengdu). Based on this expedition further detailed investigations, especially in geomorphology, palaeoclimate and applied geomorphology along the eastern margin of the Tibetan Plateau, were made in summer 1991. In this volume results from this 1991 expedition (inside rectangle of Fig 1) as well as from the 1989 and 1992 expeditions (outside rectangle of Fig 1) are presented. The 1991 expedition was led by Prof. Tang Bangxing, Dr. Liu Shijian and Dr. F. Lehmkuhl, altogether six Chinese and two German scientists participated (including: Prof. Li Jian, Prof. Wang Chenghua, M. S. Li Lihua, M. S. Wang Yangchung and Dipl.-Geogr. B. Damm). Since 1989 there has also been close co-operation between the Institute of Geography of G6ttingen University, the Institute of Botany of Hohenheim University (Prof. Dr. Dr. B. Frenzel) and the Institute of Mountain Disasters & Environment (Chinese Academy of Sciences) in Chengdu. This group, too, has conducted an expedition in 1992, led by Prof. B. Frenzel and Prof. Tang Bangxing, in which the editors could also participate. The main investigation area of 1991 was the Nianbaoyeze Mountains and the adjacent areas at the margin of northwestern Sichuan Province and Qinghai. The highest peak of Nianbaoyeze (5369m) is about 800m above the surrounding peneplain. Pleistocene glacial landforms are well preserved, a few glaciers still exist. An introduction to physical geography with special reference to the Pleistocene glaciations in the eastern fringe of the Tibetan Plateau, of the Nianbaoyeze Mountains in particular, is presented by F. Lehmkuhl and Liu Shijian. Palaeo-surfaces and the history of the upper Huang He valley are analysed by F. Lehmkuhl and J. Sp6nemann. Mountain disasters were another goal of investigation. Tang Bangxing, Liu Suqing and Liu Shijian have studied debris flows and their distribution at the Minjiang throughout the catchment and in other regions in western Sichuan. Liu Shijian examines the impact of debris flows on quartz-grain surfaces, and discusses this method as a possibility to separate debris flow from morainic deposits. J. B6hner describes southeastern Tibet and the adjacent areas with respect to the varying climatic circulation. N. Niehoff contributes on the chemistry of the precipitation in this area (results of the 1992 expedition). A. Br/iuning presents observations from tree ring analysis (samples from the 1989, 1991 and 1992 expeditions) with regard to the climate of the historical period. The palaeoclimate of eastern Tibet is shown in a larger context with some results from Western and Central China. H. J. Pachur, B. W/.innemann, Linyuan Zhang, Hucai Zhang and Yuzheng Ma focus on floodplain sediments in the transition zone to the Loess Plateau near the divide between the Huang He and Yangtze river systems (see No. 1 in Fig 1). Finally, K.T. Rost focusses on palaeoclimate conditions of the Qinling Mountains and their foreland facing the Loess Plateau (No. 2 in Fig 1). The editors wish to express their sincere thanks to Prof. Dr. J. H6vermann for his effort to initiate these expeditions in Central Asia, for his support and for frequent stimulating discussions. We would like to thank not only the authors for their contributions but also the Chinese Academy of Sciences, the Deutsche Forschungsgemeinschaft, the Max-Planck-Gesellschaft and the Gesellschaft ftir Technische Zusammenarbeit for their financial support. We have to thank all members of the expeditions, including the technical and administration staff, the drivers, Tibetan horse guides etc., for the good co-operation and their help during the various expeditions.

Tailing dam failure can result in flash floods, not only infrastructure damage and potential loss of life but also environmental and economic impacts. The flow resulting from a tailing dam failure is typically classified as debris flow (mud) with high solid content. This study examines a hypothetical tailing dam failure at a confidential site in Java by comparing non-Newtonian debris (mud) and Newtonian non-debris (water) flow conditions under sunny and rainy days. Flood inundation from this tailing dam failure is simulated using the HEC-RAS 2D. The embankment breach of the tailing dam is modeled at both the left and right sides to compare the worst-case impacts. The results show that non-Newtonian debris flow creates a larger inundation area than non-debris flow, while the maximum flow velocity is lower in debris flow than in non-debris flow. The largest flood inundation occurs when the right embankment fails under rainy conditions. The flood extends to the river estuary, with the downstream area modeled using the Highest High-Water Level (HHWL) as the worst-case scenario. Maximum flow depths range 4–5 meters in residential areas, decreasing to 1–2 meters towards the downstream. Flow velocities at the breach point reach more than 5 m/s, decreasing to 0–1 m/s as it moves toward the estuary and beach. These findings contribute to a more comprehensive flood hazard assessment for overtopping dam break cases at tailings dams, helping identify high-risk zones and critical mitigation priorities.

SUMMARY Mountain disaster occurrence has a close relationship with human activities. It is the human activity that aggravates the mountain disasters and environment deterioration. Therefore, during the process of social and economic development, regulating human behaviour, reasonably utilizing and protecting natural resources and environment by means of controlling the human approach, i.e. industrial economy, regional economy allocation, river basin economy, scientific technology and population resettlement, are important approaches to the prevention and management of mountain disasters. The analysis of several cases in China shows that effective combination of civil engineering measures, bioengineering measures and human behaviour could play an important role in ensuring mountain disaster prevention and environmental sustainable develop ment. However, in the long run, prevention of mountain disasters and environmental deterioration is just regulating management of the human effect and human behaviour, but not civil engineering and bio-engineering measures. In 1994, the State Council, China, approved ‘China 21st Agenda’, that regarded disaster prevention and mitigation as important national policies with the goals of ensuring country, society, economy development, and confirmed decreasing nature human disaster losses as the total aim and action plan of country disaster prevention and mitigation management.

A large amount of loose landslide deposits caused by a strong earthquake can cause several mountain disasters (slope failures, debris flows, and others) under heavy rainfall conditions. Loose landslide deposits are sensitive to water due to their special structural properties, such as loose structure and wide grading. There are complex conformational and mechanical responses of loose deposits, but the initial conditions and formation mechanisms of mountain disasters can be described by several different parameters. Among these parameters, the property of failure is one of the most important, and it is used to describe extremely dangerous situations for each kind of disaster. In this study, a two-dimensional particle flow code platform (PFC2D) was used to simulate the failure properties, and a laboratory test verified the validity of the numerical experiments. Different sample scales (S1, 150 × 300 mm; S2, 300 × 600 mm; S3, 600 × 1200 mm) and fine particle contents smaller than 5 mm (f-1, 20%; f-2, 30%; f-3, 40%) were considered. The simulation results show that failure stress increases with increasing sample scale or fine particle content under low confining pressure and decreases under high confining pressure. The tendency of failure stresses to vary mutates with different fine particle contents when the confining pressure changes. The mutation value of the confining pressure is 280 kPa. In addition, the phenomenon of strain softening becomes less obvious when the confining pressure increases.

The engineering effect of endogenic processes in Himalayan orogen is a frontier problem of basic scientific research in the field of geosciences and engineering. In the longitude direction, based on the tectonic and lithological differences, the Himalayan orogenic belt is divided into 3 parts: Tethys Himalaya, Higher Himalaya and Lesser Himalaya. These studies reveal the universal law that the engineering geological characteristics and disaster effects of the different parts are restricted by endogenic processes. This paper presents the following arguments. Firstly, the rapid uplift of Higher and Lesser Himalaya under the mechanism of compressional collision and orogeny, the earthquakes are mainly thrust fault type and have high earthquake intensity and high frequency. The dominant direction of geostress is close to NE-WS. The terrain develops to a large height difference. The river cuts strongly. The Mountain disaster is serious. Secondly, the Tethys Himalaya belongs to the detachment system and is in a relatively subsidence state. The earthquakes are mainly normal fault type. The seismicity is relatively weak. The geostress direction is close to the E-S. The terrain evolution is trending towards weakening the terrain. And the avalanche disaster is serious. Lastly, the marine glacial landforms, glacial lakes and glacial debris flows are unique to the Higher Himalaya. These may be important issues in controlling the trans-Himalayan railway line scheme. According to the understanding that there are significant differences in the engineering effects of the above parts, this paper puts forward the suggestion of taking the structural division as the railway engineering geological zoning. Taking the traffic corridor of the proposed China-Nepal railway as an example, the engineering geological zoning map is drawn. The research is helpful to advance the theory of Himalayan orogen to the level of engineering application. At the stage of railway large-scale scheme comparison and selection, it provides a new way to obtain information in wide area, high efficiency and low cost.