Analysis of Landslide Triggering Rainfall Threshold for Prediction of Landslide Occurrence

Abstract

Landslide occurs mostly during rainy seasons in Korea, and rainfall is the largest factor causing landslides. This study is intended to establish the rainfall standard to predict the risk of landslides, taking into account of regional / geological characteristics. To that end, historical data of landslides and rainfall data were investigated and analyzed. To predict the landslide risk using rainfall data, rainfall data which were related to causing landslide previously, was selected and analyzed to establish the rainfall standards and real-time rainfall approach was applied to establish the rainfall standards and determine the potential risk. Reliability in predicting the landslide risk using rainfall data, is heavily dependent on the spatial density of rainfall observatory stations and in this study the risk analysis using rainfall data focuses on predicting the time of landslide occurrences. In this study, rainfall standards by region are proposed using 250 landslide historic data and past rainfall data. Reliability of established rainfall standards was verified and rainfall standards would lead to reliable prediction of landslide occurrence time.

The optimal rainfall thresholds and probabilistic rainfall conditions for a landslide early warning system for Chuncheon, Republic of Korea

“…A rainfall event is divided by a nonrainfall period in an objective way to separate the case whether the rainfall event affects the landslide. In general, studies distinguish rainfall events based on a 24-h non-rainfall period (Guzzetti et al 2008;Saito et al 2010;Chen et al 2015;Kim et al 2013;Oh and Park 2014;Hong et al 2016;Kang and Kim 2016;Lee and Kim 2017;Park et al 2018). Brunetti et al (2010) separated rainfall events based on a non-rainfall period to account for different meteorological regimes, 48-h periods without rainfall during the dry and warm season (May-September), and 96-h periods without rainfall during the wet and cold season (October-April).…”

Critical Continuous Rainfall Map for Forecasting Shallow Landslide Initiations in Busan, Korea

“…In terms of the geological conditions of Korea, weathered residual soils in hillslope areas can be represented by poorly or well graded sand according to the Unified Soil Classification System [6,34]. Based on this geological background, numerous previous studies that analyzed the relationship between rainfall characteristics and landslides in Korea set the minimum non-rainfall period as 24 h [35][36][37][38]. In addition, the well-qualified in situ monitoring results of Lee et al [39], which measured matric suction in a natural slope, corroborates the relevance of the period of 24 h as the minimum duration required for the matric suction of a soil to return to its initial state following a sharp decrease due to rainfall infiltration during wet seasons.…”