Sediment from the upstream channel has been deposited near the Nakdong River Estuary Barrage (NREB) due to the mild slope and decreased velocity. The annual mechanical dredging to ensure the flood capacity has been performed to remove the deposited sediment. However, the dredging method is not considered as an effective countermeasure due to high cost and long time to operate. Therefore, many methods for sedimentation reduction have been proposed for NREB. Especially, the channel contraction method to mitigate sedimentation problem by changing the channel geometry from 2 km to 3 km upstream of NREB has been recently suggested as an effective countermeasure. However, there is the possibility that the channel contraction method induces flood level increase compared to original condition. Therefore, it is necessary to investigate quantitatively the flood level changes in the upstream and downstream section due to the channel contraction method for NREB. In this study, water level changes by 10% channel contraction of whole width has been evaluated using the HEC-RAS model and simulated with and without channel contraction for various flood discharge. As a result, water level in the section where the channel was contracted was decreased by 0.02 m and flood level at the upstream of channel contracted was increased up to 0.015 m for the 500-year flood.

본 연구에서는 2차원 하상변동 수치모형인 CCHE2D 모형을 이용하여 낙동강하구둑에서의 퇴사저감 방안을 분석하였 다. 현재 매년 시행되고 있는 준설방법에 대한 효과를 정량적으로 분석하였으며 준설방법을 대체할 수 있는 퇴사저감 방법으로 하폭축소를 통한 퇴사저감 방안에 대해 모의를 수행하였다. 분석에 사용된 모형은 각각 유사량 공식과 유사이송 형태에 대해 모형 검보정을 수행하였으며 낙동강하국둑의 경우 Ackers and White (1973) 공식과 소류사