Critical Duration of Rainfall Induced Landslides

Being a mountainous country, a lot of landslides and debris flow happen very often in South Korea. Many researchers tried to find accurate criteria to predict it by analyzing all influence factors. Rainfall, particularly, is one of the most important factor,s because its properties can be changed dramatically in a short period of time. However, until now, it isunclearwhich antecedent rainfall duration is the most critical one and best for landslide prediction. In this study, an analysis on multiple cases of antecedent rainfall duration was conducted basing on the concept, "Within the same rainfall duration, the one with the most rainfall precipitation is the critical one." A true or false experiment was carried out based on the concept (true when the cumulated rainfall precipitation within antecedent rainfall duration is maximum and false when it is not). The concept was proved to be true in many cases. The highest percentage of individual case was found in 40 days with 88.9% and two cases combination was found in 1 h and 40 days, 3 h and 40 days, and 1 day and 40 days with 91.7% of overall data.