Geomorphological Interpretation Method on the Potential Location of Barrier Lake Induced by Massive Landslide

In recent years, frequent heavy rainfall and strong earthquakes have caused numerous landslides, debris flows, and barrier lake disasters in Taiwan. This study applies terrain analysis on real landslide barrier lakes to develop an interpretation method for the potential location of barrier lake induced by a massive landslide. This study applies GIS and a 1 m-resolution DEM to analyze landslide cases. First, a microtopographic feature database for a massive landslide is established, from which types of large landslide masses are identified. Next, the length and width boundaries of the landslide body are determined. The SLBL sliding-surface estimation method proposed by Jaboyedoff et al. (2019) is then applied, assuming the landslide scarp and the outcrop point as the start and end boundaries of the sliding surface, and using a quadratic parabolic equation to infer the intermediate failure surface. Finally, the cross-sectional areas of the segmented transverse profiles along the longitudinal sliding surface are calculated to estimate the landslide volume. After obtaining the landslide volume, the equivalent friction method is used to estimate the horizontal transportation distance of the landslide mass, in order to assess whether the landslide debris can reach the opposite river bank and form a landslide dam that blocks the river. Subsequently, the model proposed by Chen et al. (2014) is applied to infer the dam length. Together with the dam length, water depth, and channel width are used to calculate the minimum blocking volume. Last, by comparing the actual landslide volume with the minimum blocking volume, it is then determined whether a landslide lake can be formed. 25 landslide barrier lake events in the Gaoping River Basin, Taiwan, were used to test the interpretation method for potential locations. This interpretation method can serve as a predictive tool for identifying potential landslide barrier lake sites, thereby reducing the impact of disasters.