Predicting the Initiation Area of a Debris Flow Using Geomorphological Characteristics and a Physically-Based Model

Abstract

A debris flow is a phenomenon in which sediment matter and water become mixed and flow down to a deposition area, thereby causing significant damage to people and property. In Korea, majority of the past debris flows initiated in the form of shallow landslides during rainfall. To address the hazards associated with debris flows, it is necessary to establish a method for predicting the location of the debris flow initiation. In this study, we propose a method for predicting the source of a debris flow by incorporating geomorphological characteristics and designing a physically-based model. The geomorphological characteristics associated with the initiation area of the debris flow were determined by analyzing previous literature. The physically-based model was developed by incorporating landslide inventory data, rainfall data, and geotechnical characteristics, and the map of safety factor less than 1.2 was thereby established. Furthermore, the region prone to the occurrence of debris flows was identified by the superposition of each unstable pixel obtained from the geomorphological characteristics and the physically-based model. The proposed method was validated through quantitative index analysis. The obtained results indicate that compared to other methods, the proposed method has a high success index and a low error index for predicting the source of a debris flow.