This study aims to investigate inundation characteristics such as inundated area, inundation depth according to variation in
return period of design rainfall and to draw a comparison between the inundation characteristics by adapting design storm
using dual-drainage model. Lidar data is used to construct terrain data with 1m × 1m resolution in Cheongju. The designed
storm by return periods(10year, 30year, 50year and 200year) are acquired from Intensity Duration Frequency curve, which
are distributed in 5 minutes interval using Huff’s method. As a results, the inundation volume is linearly increased, but
inundated area is gradually increased in accordance with swell of return period for design storm. On the other hands, as a
result of calculating discharge capacity for each points, deficit of discharge capacity is not observed using designed storm of
10 year return period at every points. If the return period is increased up more than 10 years, both the deficit of discharge
capacity for each PT and entire study area are enlarged drastically.