Development of time-variant landslide-prediction software considering three-dimensional subsurface unsaturated flow

An accurate landslide-susceptibility assessment is fundamental for preventing landslides and minimizing damage. In this study, a new time-variant slope-stability (TiVaSS) model for landslide prediction is developed. A three-dimensional (3D) subsurface flow model is coupled with the infinite slope-stability model to consider the effect of horizontal water movement in the subsurface. A 3D Richards' equation is solved numerically for the subsurface flow. To overcome the massive computational requirements of the 3D subsurface flow module, partially implicit temporal discretization and the simplification of first-order spatial discretization are proposed and applied in TiVaSS. A graphical user interface and two-dimensional data visualization are supported in TiVaSS. The model is applied to a 2011 Mt. Umyeon landslide in the Republic of Korea, and its overall performance is satisfactory.