Abstract: In recent years, significant channel evolution has occurred in a braided reach of the lower Yellow River (LYR), and a key factor of its channel lateral deformation is bank erosion that has negative influence on the stability of this reach. To investigate the bank erosion, this study develops a cross-section-scale conceptual model for simulating the time development of bank erosion at the cross-sections of Fanzhuang and Jiahetan observed in the flood season of 2004, and identifies the key factors of bank erosion. The results indicate that the calculated cumulative erosion widths were 413 m and 733 m for these two typical sections, agreeing well with the observations in-situ; the calculated time variations in bank erosion width were consistent with those in lateral bank-toe erosion width, demonstrating the unfavorable effect of large lateral erosion widths on bank stability. By the calculations, erosion width is decreased with an increase in soil erosion strength. The decreases in bank erosion width were 34% and 33% at Fanzhuang and Jiahetan respectively when soil erosion strength increasing from 0.1 to 0.3 N/m2. And at these two sections, the bank erosion widths were decreased by 10% and 7% respectively when the bank-toe deposition ratio of collapsed soil increasing from 50% to 100%, showing a favorable effect of high bank-toe deposition ratios on river bank stability.

Key words: bank erosion, bank soil properties, conceptual model, braided reach, lower Yellow River