Hydrologic Modeling for Simulation of Rainfall-Runoff at Major Control Points of Geum River Watershed

With the recent increase in frequency of extreme hydrological events and climate change, the number of natural disasters increased dramatically in Korea. In this study daily rainfall and discharge data was extracted from Daecheong dam, Yongdam dam, Gongju, Gyuam and Ganggyeong, the major control points of Geum river watershed. The rainfall data from 83 rainfall stations was spatially distributed and utilized as input data in Streamflow Synthesis and Reservoir Regulation (SSARR) rainfall-runoff model. The major input parameters are Soil Moisture Index (SMI), Baseflow Infiltration Index (BII), Surface ¬Subsurface Separation (S-SS) and Lag time (Ts). For the calibration of parameters of SSARR model, the rainfall and discharge data 2006∼2007 year was prepared using the stage-discharge rating curve at the major control point of Geum river watershed. The hydrologic parameters of the SSARR model were verified utilizing 2004 year data. Model calibration results showed that the average relative error during 2006∼2007 year decreased significantly after the calibration. Verification of the model also showed reduction in relative error. Overall model results showed that the quantity of designed flood during 2007 year at all major control points of the Geum river watershed is relatively more as compared to 2006 year. The results of this study can be useful for hydraulic structures designing; landscape planning and can serve as basic data to cope with the flood risk at Geum river watershed in future.