Relationship between DEM Resolutions and Site Classification in Korea

Abstract

Slope data derived from DEM can be an important indicator for site classification. It can be various due to the use of different resolutions of DEMs. We studied that resolutions may effect to the results of the site classification. We used 1, 3, 6, 9, ~ 27, 30 arc-sec DEM resolutions to illustrate deviations in the site classifications. 1 arc-sec DEM is from ASTER GDEM made by METI and NASA. Other maps are resampled from 1 arc-sec DEM for this study. DTED Level 0 is made by NIMA and USGS. We limited the study area into the south-eastern Korea to save the analyzing time occurring due to the size of the data. As the results, the largest difference within the site classification categories considering each resolution is site C (very dense soil and soft rock). If we reclassify the sites with Vs30 range by the slope criteria, less than 180 m/sec area has the largest difference. In the high resolution map, the areas with the stiffest and the modest gradient have been bigger than those shown on the low resolution map. But, other areas in the low resolution map are bigger than in the high resolution map. In the low resolution, it is resulted overestimated or underestimated because differences of slopes are averaged in the same grid. On the other hand, those areas in the high resolution are illustrated well. Also, site classification by slope has been agreed with borehole site classification re