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A heavy flood and a drought caused by the recent environmental changes emphasized the importance of water in the future. In addition, the urban development and many changes in waterfront have made to improve the quality of human life. The representative cases of changes in the urban waterfront are the installation of reservoirs or bridges, the development in ecological space in the river channel, complex leisure wellbeing facilities, and the cut-and-cover system of river channel. However, these facilities are installed as the structures in existing rivers, and they are unfortunately working as an obstacle to the flow of the waterway. In particular, if hydraulic structures such as cut-and-cover road and brides affecting river channels are installed, geomorphologic changes in the cross-section of river channel and problems of the urban drainage system may cause n overflow of the river and a burst in the bank due to level rise and decrease in total cross section of running water. The peak flow rate around the bridge was 4.52 m/s in 40m of span length and 2.018 m/s 20m of span length. According to increase of the bridge, the peak flow rate regarding bridges types was 4.532m/s in a round shape, 4.392m/s in a square, and 4.392m/s in a rectangle, and a square most highly affected the peak flow rate of bridges.