Simulating the Extent of Landslide Damage using LAHARZ: A Case Study for Yecheon-gun, Gyeongsangbuk-do

Background and objective: As climate change intensifies extreme rainfall events, the global risk of landslides continues to rise. In Korea, existing landslide hazard maps and warning systems often prove inadequate for accurately predicting large-scale or complex slope failures. Consequently, empirical models like LAHARZ, which enable the rapid assessment of debris-flow volume-extent relationships, are drawing increased attention. This study examines whether LAHARZ can be effectively applied in Yecheon-gun a non-volcanic region to efficiently estimate landslide damage extents and strengthen local disaster preparedness. Methods: We collected debris-flow occurrence data from a July 2023 heavy rainfall event and derived a 5 m-resolution DEM from 1:5,000 topographic maps. Using satellite imagery, we delineated observed debris-flow areas in threesub-regions (Baekseok-ri, Geumgok-ri, Beolbang-ri) and input these datasets into LAHARZ to generate estimated damage extents, which were then compared with actual damage footprints. Results: In the simpler terrain of Baekseok-ri, the model's estimated damage extents closely matched observed debrisflow footprints, demonstrating robust performance. However, at multi-source sites (Beolbang-ri and Geumgok-ri), the estimated inundation ranges were either over- or underestimated. These discrepancies underscore the challenge of accurately capturing flow confluence when relying solely on volume-driven empirical formulas. Conclusion: LAHARZ proves effective for rapid damage-extent estimation in single-source debris-flow events, yet it may fail to capture key physical interactions in more complex terrains where multiple initiation points merge. Incorporating high-resolution DEM data, physical modeling techniques, and field measurements is recommended to enhance the model's accuracy and applicability in non-volcanic regions such as Yecheon County.