Evaluating the Impact of DEM Resolution on Landslide Hazard Assessment: A Comparative Study Using LiDAR and 1:5000 Topographic Map-Derived DEMs

The increasing frequency and intensity of extreme rainfall events due to climate change have significantly heightened the risk of natural disasters such as floods and landslides in South Korea. The 2011 Mt. Majeok landslide in Chuncheon resulted in 13 fatalities and 26 injuries, revealing critical limitations of conventional 1:5000-scale topographic map-derived DEMs in capturing fine-scale terrain features essential for accurate debris flow and slope failure analysis. This study quantifies systematic differences in terrain derivative outputs and hazard classification patterns between a high-resolution LiDAR-derived DEM (<0.5 m, resampled to 5 m) and a conventional 1:5000-scale contour-derived TIN DEM (5 m) for landslide hazard assessment in a documented historical disaster catchment. FLO-2D and SINMAP models were applied to debris flow and slope stability simulations within the Mt. Majeok watershed. Since slope stability indices are computed quantities dependent on input terrain data, the LiDAR result was adopted as the high-resolution reference. SINMAP analysis revealed a sequential pattern of resolution-induced discrepancies from flow direction through terrain derivatives to stability index classification (CSI = 0.565, Kappa = 0.589). FLO-2D simulation showed that the TIN-based DEM overestimated inundation extent by 10.5 percentage points, with the LiDAR-based simulation reducing false alarm inundation area by 10.5 percentage points relative to the TIN-based result—a margin with direct operational implications for evacuation zone delineation in high-risk mountain communities. These findings demonstrate that LiDAR-derived DEMs produce markedly different spatial patterns of hazard classification and flow simulation compared to contour-derived DEMs; the reported discrepancy magnitudes are specific to the geomorphological context of the Mt. Majeok watershed and should be interpreted as inter-product differences rather than absolute accuracy measures, with direct implications for sustainable disaster risk management in mountainous environments.