THE SENSITIVITY OF SPATIAL VARIATION SOIL THICKNESS AND RAINFALL ON SHALLOW LANDSLIDE TRIGGERING PATTERNS

Abstract

 The basic controls leading to slope failure driven by rainfall are still not well quantified. Therefore, the uncertainty input parameters are considered, such as soil properties and spatial variation of soil thickness, and different spatial resolutions of a grid cell. Those parameters are well-known essential factors controlling shallow landslides. In this paper, the physically-based model is used to evaluate the effect of spatial variation of soil thickness, the spatial distribution of rainfall, and spatial resolution at the Uchi and Gofukuya rivers basin, Marumori town on Typhoon Hagibis event. The model prediction accuracy is evaluated by ROC curve for different scenarios selected by soil thickness model, distribution rainfall, and spatial resolution. As a result of the model, the soil thickness is an important parameter and related to the slip failure plane. In addition, the distribution of rainfall, rainfall intensity and slope gradient affect landslides by increased driving force that causes different landslide characteristics in Uchi and Gofukuya river basins.