• Journal of the Korean Geotechnical Society
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• v.31 no.5
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• pp.47-58
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• 2015

Triggering rainfall and geologic conditions with the state of slope hazard were investigated based on the field investigation and collected data on the slope hazard during the period between 2011 and 2014 in Korea. Analysis results showed that most of slope hazards occurred in metamorphic rock and debris flow was the most frequent type of slope hazard. Slope hazard increased when the higher monthly mean rainfall was recorded. However, most of slope hazard occurred when certain time elapsed after the moment of maximum hourly rainfall. Finally, more than one month of long-term rainfall was shown to be related to the frequency of slope hazard in the period.

• Journal of the Korean Geotechnical Society
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• v.26 no.10
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• pp.27-38
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• 2010

In every summer season, most of the slope failures and debris flows occurr due to seasonal rain, typhoon, and localized extreme rainfall in Gangwon Province where 83% of the area is of mountain region. To investigate the slope-hazard triggering rainfall characteristics in Gangwon Province, slope hazard data, precipitation records, and forest fire data were collected and the DATABASE was constructed. Analysis results based on the DATABASE showed that many slope hazards occurred when there was little rainfall and the preceding rainfall had more effect on the slope hazard than the rainfall intensity at the day of hazard. It also showed that the burned area by forest fire was highly susceptible to slope hazard with low rainfall intensity, and the slope hazard in burned area showed highest frequency, especially, under the rainfall below 2-year return period.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5C
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• pp.263-271
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• 2008

Investigation and analysis of the debris flow characteristics such as basin topography, geologic conditions of initiation location and triggering rainfall are required to systematically mitigate debris flow hazard. In this paper, 48 debris flows which had caused some damages to the highway in the past 5 years are investigated and their characteristics of basic topography and triggering rainfall are analyzed. Debris flows are found to occur in small basins having the area of $0.01{\sim}0.65km^2$ range and mostly initiated by the surficial failure of natural slope having the inclination of 29~55 degree during the intense rainfall. As for the triggering rainfall, rainfall of 2 to 5 year recurrence frequency are found to be able to trigger the debris flow and magnitude of debris flow in a basin could depend on the rainfall intensity and cumulative amount.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.375-380
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• 2005

In Korea, most landslides are occurred during the rainy season from June to September and have a shallow failure plane parallel to the slope. For these types of rainfall-induced failures, the most important factors triggering slope unstability is not the increase of pore water pressure but the decrease of the matric suction of unsaturated soils by rainfall infiltration. So it is essential to landslide hazard assessment that defines the characteristics of infiltration in natural slopes. In this study, field measurements have been carried out in order to monitor in-situ volumetric water contents and ground water table, at several depths and locations on a natural slope. The results show that rainfall infiltration is correlated with antecedent water contents, rainfall intensity and total rainfall. The ground water table was varied sensitively by every rainfall event.

• Journal of Korea Water Resources Association
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• v.56 no.5
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• pp.311-323
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• 2023

In order to reduce disaster damage by localized heavy rains, floods, and urban inundation, it is important to know in advance whether natural disasters occur. Currently, heavy rain watch and heavy rain warning by the criteria of the Korea Meteorological Administration are being issued in Korea. However, since this one criterion is applied to the whole country, we can not clearly recognize heavy rain damage for a specific region in advance. Therefore, in this paper, we tried to reset the current criteria for a special weather report which considers the regional characteristics and to predict the damage caused by rainfall after 1 hour. The study area was selected as Gyeonggi-province, where has more frequent heavy rain damage than other regions. Then, the rainfall inducing disaster or hazard-triggering rainfall was set by utilizing hourly rainfall and heavy rain damage data, considering the local characteristics. The heavy rain damage prediction model was developed by a decision tree model and a random forest model, which are machine learning technique and by rainfall inducing disaster and rainfall data. In addition, long short-term memory and deep neural network models were used for predicting rainfall after 1 hour. The predicted rainfall by a developed prediction model was applied to the trained classification model and we predicted whether the rain damage after 1 hour will be occurred or not and we called this as 1ST-Model. The 1ST-Model can be used for preventing and preparing heavy rain disaster and it is judged to be of great contribution in reducing damage caused by heavy rain.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.171-179
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• 2013

In recent years in Korea, Typhoon Rusa (2002), Typhoon Maemi (2003), and the localized extreme rainfall followed by Typhoon Ewiniar in 2006 devastated residential areas, roads, and agricultural lands in Gangwon province where 90% of the area is in mountainous regions. Most of the economic losses and casualties were concentrated in the area near the mountain valleys and creeks due to the floods and debris flows. In this study, DATABASE, which includes a total 180 debris flow events in the Gangwon area, was created by collecting the hazard records and field investigations of existing debris flow sites. Analysis results showed that the most of the debris flows in Gangwon province initiated from the small slope failure with relatively steep slope of $18.1^{\circ}$. And they flowed short distances about 420 m in gentle slope with the average angle of $18.1^{\circ}$. In addition, rainfall condition was important for the triggering of debris flow not only at the day of debris flow but also extended period of rainfall before debris flow.