Effect of Digital Elevation Model Resolution on Shallow Landslide Modeling Using TRIGRS.

In Korea, landslide damage areas have increased significantly from the 1990s to the 2000s owing to increases in rainfall intensity and the number of rainy days in addition to indiscriminate land development. This study was conducted to predict shallow landslide-prone areas by using the transient rainfall infiltration and grid-based regional slope-stability model (TRIGRS). A landslide event that occurred on July 27, 2011, in Mt. Umyeon, Seoul, was modeled, and the stability results were compared with 140 observed landslide points in both time and location to evaluate the performance of TRIGRS. Simulated outcomes from five different raster cells of 5, 10, 15, 20, and 25 m with the same background information were compared to identify the ultimate grid scale. The results revealed that in location estimation, smaller grid size resulted in more accurate results. However, the 10 and 15 m grid sizes gave better results in the timing assessment When the best grid size was considered TRIGRS overestimated the unstable area, but it gave impressive results in location prediction with approximately 78% of the observed points accurately predicted by an approximately 76% chance of including slope failure. However, the timing estimation was less reliable with approximately 40% of the observed landslide locations well predicted. Despite some limitations of data acquisition, TRIGRS is a strong tool for shallow landslide estimation, particularly in large areas where input data for simulation is not fully available. [ABSTRACT FROM AUTHOR]