Presenting regional shallow landslide movement on three-dimensional digital terrain

• We developed a distributed cell model for presenting regional landslide movement.
• The debris is routed from one cell to another on three-dimensional digital terrain.
• Empirical travel distance equations are adopted as movement cessation criteria.
• The landslide size effect and uncertainties in travel distance are considered.
• The model predicts well the movement traces and deposition locations.

A storm can trigger numerous shallow landslides on hilly terrains. This paper presents a distributed cell model for presenting regional shallow landslide movement on a three-dimensional digital terrain. The model consists of five components; namely, a digital terrain module, a spatial rainfall distribution module, an infiltration analysis module, a slope stability evaluation module, and a movement prediction module. The locations and volumes of landslides are analyzed first through rainfall infiltration and slope stability analyses. The detached material is assumed to move along the steepest path from one cell to a lower cell. Empirical equations that are developed based on local landslide inventories are adopted as a landslide movement cessation criterion. The effect of landslide size on travel distance is considered by grouping unstable cells that are bounded at least at one side or corner. The uncertainties in soil shear strength parameters and the landslide movement process are considered in determining the possible bounds of travel distance. The movement analysis method is applied to a 164.5 km2 hilly terrain in the Wenchuan earthquake zone to test its performance in presenting regional shallow landslide movement. The method predicts the volume of landslides reasonably well. The observed and computed movement traces and deposition locations of the detached material also agree reasonably well. The volume of individual landslide and travel distance may be substantially underestimated if the size effect is not considered.