Rainfall data is measured by rain gauge and the effects of wind speed on the data have not been considered when the data is distributed. The calculated runoff using there rainfall data could be underestimated or overestimated. In this study, therefore, the rainfall data was calibrated using the wind speed, and the runoff was analayzed in the Geum Cheon catchment which has impervious area more than 90% of the catchment. SWMM model was used to calculate the runoff. Runoff characteristics were analyzed in dry, wet, and entire period. In wet period, the peak discharge has increased about 1.3 times than the runoff in dry period. The amount of total discharge in wet period has increased upto 1.3 times as well. The amount of rainfall and runoff has increased as the wind speed increase. Therefore, when stormwater pipes are designed, the wind speed should be considered to avoid underestimated runoff calculation which could cause urban flood.