• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.245-245
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• 2015

In the recent years, due to long-lasting heavy rainfall events, a large number of landslides have been observed in the mountainous area of the world. Such landslides can also form a dam as it blocks the course of a river, which may burst and cause a catastrophic flood. Numerical analysis of landslide dam formation is rarely available, while laboratory experimental studies often use assumed shape to analyze the landslide dam failure and flood hydraulics in downstream. In this study, both experimental and numerical studies have been carried out to investigate the formation of landslide dam. Two case laboratory experiments were conducted in two flumes simultaneously. The first flume (2.0 m 0.6 m 0.5 m) was set at $22^{\circ}$ and $27^{\circ}$ slope to generate the landslide using rainfall intensity of 70.0 mm/hr. On the other hand, the second flume (1.5 m 0.25 m 0.3 m) was set perpendicularly at the downstream end of the first flume to receive the landslide mass forming landslide dam. The formation of landslide dam was observed at $15^{\circ}$ slope of the second flume. The whole processes including the landslide initiation and movement of the landslide mass into the second channel was captured by three digital cameras. In numerical analysis, a two-dimensional (2D) seepage flow model, a 2D slope stability model (Spencer method) and a 2D landslide dam-geometry evaluation model were coupled as a single unit. This developed model can determine the landslide occurrence time, the failure mass and the geometry of landslide dam deposited in the second channel. The data obtained from numerical simulation results has good agreement with the experimental measurements.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.196-196
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• 2016

Landslide dam failure presents as a severe natural disaster due to its adverse impact to people and property. If the landslide dams failed, the discharge of a huge volume of both water and sediment could result in a catastrophic flood in the downstream area. In most of previous studies, breaching process used to be considered as a constructed dam, rather than as a landslide dam. Their erosion rate was assumed to relate to discharge by a sediment transport equation. However, during surface erosion of landslide dam, the sediment transportation regime is greatly dependent on the slope surface and the sediment concentration in the flow. This study aims to accurately simulate the outflow hydrograph caused by landslide dam by overtopping through a 2D surface flow erosion/deposition model. The lateral erosion velocity in this model was presented as a function of the shear stress on the side wall. The simulated results were then compared and it was coherent with the results obtained from the experiments.

• Journal of the Society of Disaster Information
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• v.18 no.4
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• pp.687-698
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• 2022

Purpose: This study was conducted to understand the public awareness of landslide and check dams in 2015-2020 using the big data platform 'Hyean' and to confirm the utilization of this platform in disaster prevention areas. Method: The total amount, number of detection by period by media, and affirmative and negative trends of a search for 'landslide' and 'check dam' in 2015-2020 were analyzed using a keyword search of 'Hyean.' Result: There is significant lack of public awareness of check dam compared to landslide, and the trend is more noticeable in the conspicuous gap of data amount between the news and SNS media. The number and the timing of the search for 'landslide' coincided with the actual occurrence of landslide, while the detection of 'check dam' was less related to it. Relatively affirmative preception for the check dam is inferred, but it was difficult to confirm accurate statistical affirmative and negative trends in the disaster prevention field using 'Hyean.' Conclusion: Unlike the experts who expect positive public awareness of check dam, the statistic results show that the public awareness of the check dam as an effective countermeasure against landslide was extremely low. Active promotion of erosion control projects should be carried out first, and a balanced sample survey should accompany online and periodic field surveys. Since there is a limit to grasping the effective perception in the field of disaster prevention area using 'Hyean', it should be very cautious to establish local/governmental policies using it.

• Journal of Industrial Technology
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• v.28 no.A
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• pp.3-10
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• 2008

This paper is to investigate the characteristics of debris flow landslides in Gangwon Province through literature review, data collection and analyses and site investigation. As results of data analyses about landslides occurred currently in this province, the landslide in the form of debris flow is found to be 55 %. Therefore major loss and costs are caused by discharge of soil and rock fragments from landslide. From results of analyzing the geometrical characteristics of landslide, length of most of landslide is less than 200 m, their width is in the range of 10 - 40 m, most of them are know to be occurred in lower elevation than 400 m. Slope angle is in the range of 25 - 35 degrees. Comparing the period of rainfall intensity with the time of landslide being occurred, occurrence of landslide is quite related to duration of a heavy rainfall. For measures of controlling water flow discharge and debris flow, considering geological and topographical ground conditions, appropriate selection and building check dam, erosion control dam and ring net is very beneficial for reducing the loss and costs caused by the landslide of debris flow.

• Economic and Environmental Geology
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• v.24 no.3
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• pp.309-318
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• 1991

Analysis for landslides was studied in framework of Chungju dam right abutment, 6.5km northeast of Chungju city. $5.5{\times}10^6m^3$ landslide materials were excavated during dam construction for safety of the Chungju dam. Geology of study area is composed mainly of meta sediments such as dolomitic limestone, quartzite and schist which are dipping toward the Nam Han river. Scanline survey of discontinuities was performed for slope stability, resistivity exploration was performed for the evaluation of potential failure plane, and direct shear strength test of rocks and soils was performed for the effect on landslide. Monitoring systems of tiltmeter, tensiometer, ground water observation hole and level monument were installed during dam construction and interpreted for the evaluation of slope instability. Kinematic solution of the geological structure and evaluation using safety factor for slope may prove the failure of the slope.

• Journal of The Geomorphological Association of Korea
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• v.26 no.1
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• pp.1-14
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• 2019

Large landslide is a type of mass movement that causes drastic landform changesin a short period, and it causes huge human and property damage over a large area. The purpose of this study is to categorize the types and characteristics of large landslides around the Kokomeren River basin, Kyrgyzstan and to discuss the geomorphic development after the large landslides. The topographic analysis about a total of 20 landslides documented collapsed volumes of 0.01 to 1.10 km³, height drops of 180 to 1,770 m, and runout distances of 1,200 to 5,400 m. Rock avalanche and rockslide are identified as major types of large-scale landslides in the study area. Rock avalanches can be divided into P-type, J-type, and S-type based on the features of slope failure and kinematic characteristics of rock debris. Landslide synchronistic landforms such as trimlines, transverse ridges, longitudinal ridges, levees, and hummocks are well developed in the rock avalanche. The pieces of evidence of landslide dam, landslide-dammed lake, and remnant outburst flood deposits are observed in the upstream and downstream where the rockslides occurred. The Ak-Kiol landslide dam is the best example of a geomorphic development due to lake spillover and the large landslides were likely to be triggered by huge paleo-seismic events.

• Korean Journal of Agricultural Science
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• v.37 no.2
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• pp.223-229
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• 2010

This study is to analyze location conditions for erosion control dams to be constructed in Chungcheongnam-do, Daejeon Metropolitan City, Chungcheongbuk-do and Gyeongsangbuk-do in order to establish proper conditions for erosion control dams in the future. 199 sites where erosion control dams are expected to be built in 2010 were chosen and investigated in terms of 12 factors including basin area, basin slope, and landslide risk. The results showed that erosion control dams for Chungcheongnam-do and Daejeon Metropolitan City are mostly impermeable gravity dams mainly composed of concrete. In contrast, Chungcheongbuk-do and Gyeongsangbuk-do are increasing the number of permeable or compound erosion control dams. Basin analysis at planned erosion control dam sites showed that at least 44.5% of the total area has high landslide risk. Gyeongsangbuk-do had the largest basin area for erosion control dam sites at 157.3ha, followed by Chungcheongbuk-do at 64.4ha and Chungcheongnam-do at 54.8ha. Analysis of sand deposits in the Chungcheongnam-do erosion control dam built in 2010 confirmed an average deposit of 971.8m3. The sand deposit capacity and amount of sediment control for erosion control dams have a very low correlation with basin area or flow path slope, and this needs to be addressed in future sand deposit capacity designs.

• Spatial Information Research
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• v.20 no.3
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• pp.57-66
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• 2012

Gangwon-do has been suffering extensive landslide dam age, because its geography consists mainly of mountains. Analyzing the related factors is crucial for landslide prediction. We digitized the landslide and non-landslide spots on an aerial photo obtained right after a disaster in Inje, Gangwon-do. Three landslide factors-topographic, forest type, and soil factors-w ere statistically analyzed through GIS overlap analysis between topographic map, forest type map, and soil map. The analysis showed that landslides occurred mainly between the inclination of $20^{\circ}$ and $35^{\circ}$, and needleleaf tree area is more vulnerable to a landslide. About soil properties, an area with shallow effective soil depth and parent material of acidic rock has a greater chance of landslide.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.133-145
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• 2010

This study analyzed the characteristics of sediment produce by landslide triggered by rainfall. One-dimensional unsaturated groundwater model and infinite slope stability analysis were used to estimate the behavior of soil moisture and slope stability according to rainfall, respectively. Slope stability analysis was performed considering on soil depth and characteristics of trees. As the results considering on recovery of the failed slopes, much amount of sediment was produced in 1963, 1970, and 2002. As the results of verification of simulation results using Landsat 5 TM images, we can find differences of landslide location between the results from model and satellite images. These differences can be caused by uncertainties of the rough parameters in the model. However, in the case that Obong-dam basin was divided into two subbasin, Wangsan-chun and Doma-chun basin, the results of each subbasin show errors around 20%. And only 4% of error occurred in the case of comparing landslide area on the entire Obong-dam basin. These errors seem insignificant considering on the errors which can be caused from the analyses in this study such as estimation of sediment produce, soil cover classification, and estimation of landslide area.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.4
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• pp.229-239
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• 2019

A model of landslides is developed using the shallow water equations to simulate time-dependent performance of landslides. The shallow water equations are derived using the (b, s) coordinate system which can be applied in both river and ocean. The finite volume scheme employing the HLL approximate Riemann solver and the total variation diminishing (TVD) limiter is applied to deal with the numerical discontinuities occurring in landslides. For dam-break water flow and debris flow, numerical results are compared with analytical solutions and experimental data and good agreements are observed. The developed landslide model is successfully applied to predict subaerial and submarine landslides. It is found that the subaerial landslide propagates faster than the submarine landslide and the speed of propagation becomes faster with steeper bottom slope and less bottom roughness.