Analysis using a numerical model is important to understand the sediment transport mechanism associated with
erosion and sedimentation near weirs and other hydraulic structures within riverine systems. The local riverbed
change near a hydraulic structure (Gangjeong-Goryong multi-function weir in the Nakdong river) was analyzed in
order to examine the effect of hydraulic structures on local bed change. A 2D numerical model (CCHE-2D) was
employed to simulate the sedimentation and erosion over a reach (25 km) including the weir. For the calibration and
verification of the model, rainfall data from a real event (Typoon ‘Ewiniar’ in 2006) were used for flow and stage
simulation. And the simulated results show a good agreement with the observed data for the whole domain. From the
result, it was found that the installation and operation of the weir could aggravate bed changes by typhoon between
movable weirs, and which resulted in redistribution of sediment.