| Title |
Flow Characteristics and Riverbed Change Simulation on Bridge-intensive Section |
| Keywords |
HEC-RAS;RMA2;SED2D;Bed change;하상변동 |
| Abstract |
When the hydraulic structures, such as bridge and weir, are consecutively installed to a short section of a river with com-plicated cross section, analyzing the flow characteristics and the riverbed change modality of the river is very important. In the 250 m section of the Taehwa river near the Samho-bridge, which passes through Ulsan city, three bridges has been installed, and the tributary water is flowing into both up and downstream of the section, Due to these factors, when the flood occurs, the cross section of the river changes vastly by the water level change and scour, Even so, due to the fact that the Samho-bridge divides the section into two parts, the national river and the regional river, each part is being analyzed separately by the one-dimensional model. In this study, the flow characteristics due to the bridge concentration and the tributary water inflow were jointly analyzed for both up and downstream by using the one-dimensional HEC-RAS model and the two-dimensional SMS model, such as RMA2, The riverbed change modality of the section was also investigated by using the SED2D model. The results showed that the water level difference between the HEC-RAS and RMA2 was 0.87 m when applied to the three con-secutive bridges. The riverbed change simulation using SED2D showed that the maximum scour was 0,231 m and it occurred at the Samho-bridge, which located in the middle and has short pier distance, 1n conclusion, when planning the river maintenance for the regions with concentrated bridges or the sections with severe changes in cross-section and flow, estimating the flood elevation by two-dimensional model and establishing countermeasures for the scouring of the bridge are required. In addition, an integrated analysis on both the national river and the regional river is necessary. |