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In July 2023, four devastating landslides occurred in Yecheon County, South Korea, due to heavy rainfall. These landslides resulted in 10 deaths, one injury, and the evacuation of around 500 people. The landslides occurred in different locations, including forest roads and natural slopes, and were caused by the liquefaction of collapsed soil into debris flows. The study emphasizes the vulnerability of South Korea to nocturnal heavy rains during the summer and recommends the establishment of early warning systems and check dams to mitigate the risks of sediment-related disasters in mountainous regions. The authors of the study, Seungjun Lee, Hyunuk An, Minseok Kim, and Song Eu, declare no conflicts of interest, ensuring the credibility of their findings. [Extracted from the article]

Following the MPPS installation (2018-2021), rainfall events exceeding the threshold also occurred yearly; however, their intensities were much lower than those of the 2022 landslide-triggering rainfall event (Fig. 3Hyetograph and cumulative curve of the heavy rainfall event that triggered the landslide at the study site The rainfall intensity-duration (I-D) conditions that triggered the landslide on August 9, 2022, exceeded the threshold for South Korea (Fig. This landslide happened during a lull of the continuing rain with a relatively low intensity of 4.5 mm/h. Before the beginning of the rainfall event that triggered the landslide, the 3-day (i.e., 72 h), 5-day, and 7-day antecedent rainfall amounted to 0 mm, 46 mm, and 72 mm, respectively. [Extracted from the article]

Debris flow generated by landslides due to intense rainfall can cause extensive damage to residential areas. To predict and prevent the severity of such damage, several numerical models have been developed. However, there are limited studies regarding the entrainment and erosion effect of debris flow. This research aims to analyze several erosion–entrainment models for the selection of erosion–entrainment models in debris-flow analysis. The study focuses on landslides that occurred in the Raemian and Sindonga apartment basins in Mt. Umyeon, Republic of Korea, on July 27, 2011. The impact area, entrainment volume, maximum velocity, inundated depth, and erosion shape resulting from the debris-flow modeling were compared with field data. The simulation results of each erosion–entrainment model were assessed through the receiver operating characteristic method. [ABSTRACT FROM AUTHOR]

The intensity-duration (I-D) threshold is considered an effective indicator for landslides triggered by short-term high-intensity rainfall and long-term low-intensity rainfall. However, previous studies have not considered the influence of antecedent rainfall. Herein, we analyzed hourly rainfall data for 613 shallow landslides that occurred from 1963 to 2018 in South Korea to obtain rainfall thresholds and investigated the effect of antecedent rainfall conditions on threshold variations. The I-D and IMAP-D, which is normalized by dividing I by mean annual precipitation (MAP), thresholds were determined to be I = 10.40D–0.31 and IMAP = 0.006D–0.26 (4 ≤ D (h) ≤ 84), respectively, at the 2nd percentile level through quantile regression analysis. These thresholds were lower than other local thresholds (i.e., excluding global and regional thresholds), suggesting that the southern region of the Korean Peninsula was more susceptible to rainfall-induced landslides. Although the effective length of antecedent rainfall was not presented herein, the I-D threshold of landslide-triggering rainfall was confirmed to be low for the absolute and/or calibrated antecedent rainfalls greater than event cumulative rainfall at 5, 7, 10, and 20 days prior to the event. Such differences in I can be greater at shorter durations; however, these differences gradually decrease as D increases, suggesting that they lose their effect as soil water content increases. The results of the current study can improve the understanding of the effect of antecedent rainfall conditions on landslide occurrence and should be further tested with respect to the hydrologic response of hillslopes by considering regional climate and local site conditions. [ABSTRACT FROM AUTHOR]