Numerical Analysis on Channel Width Variation for River Bed Stabilization Upstream of the Weir

摘要

Numerical simulations for bed change and bank erosion were performed using a two-dimensional numerical model to analyze the effect of channel width variation on bed change for the 4.2 km section upstream of Changnyeong-Haman Weir in the Nakdong River of South Korea. Simulation result of bed degradation without bank erosion for 120 days with 1,000 m(3)/s of flow discharge was about 2 m greater than the case of simulation with bank erosion. The narrow channel section was continuously degraded over time in the simulation with the fixed boundary for bank lines. However, bed degradation decreased as the channel width increased when bank erosion or artificial width extension were considered in the modeling. The equilibrium condition for topographical changes in the study reach was demonstrated by the modeling results with different channel width and simulation time.