In this study, the watershed and water body models were linked for the simulation of the Nakding river flow. This is a pre-step study for the estimation of the effect of the flow and water quality on the climate change. For models of watershed and river flow, the SWAT and EFDC were used, respectively. The runoff discharge at each boundary points for the simulation of the river flow was provided from the drainage basin model. The calculated runoff discharge by the SWAT model was compared with the measured data of the Ministry of Environment at 13 locations along the Nakdong river and 30 locations along the tributary streams. The computed water discharge was shown to be similar with the measured data. For the model calibration and verification, % difference, NSE, and $R^2$ were computed. The computed % difference was within 15% except of a few points. The NSE and $R^2$ were also within a fair level. The Nakdong river flow of 2007 was simulated by using the EFDC model. The comparison with the measured data showed that the model reflected the actual values of low and high flow well. Also, it was confirmed that the acceleration and deceleration in the curved areas were appropriately simulated. The movement of dye injected at the upstream boundary was simulated. The result showed that the arrival time up to the estuary dam was computed to be about 65 days.