Pawat Wattanachareekul, Takuya Inoue, Tatsuhiko Uchida, Riho Kido
Received 26 December, 2024
Accepted 5 July, 2025
Published online 26 September, 2025

Pawat Wattanachareekul¹⁾, Takuya Inoue¹⁾, Tatsuhiko Uchida¹⁾, Riho Kido¹⁾

1) Graduate School of Advanced Science and Engineering, Hiroshima University, Japan

The alternate bar, a single row of mobile bars, plays a crucial role in river morphodynamics at the reach scale. Global warming is expected to alter river flow discharge patterns worldwide, which may impact alternate bars and river morphology. However, the effects of changes in flow discharge characteristics, such as flood duration and discharge, on alternate bar formation remain poorly understood. This study used numerical simulations to investigate how variations in flow discharge influence alternate bar development. The hydrograph models applied are composed of four stages: a rising limb with a constant discharge increase, a peak flow stage with steady discharge, a falling limb with a constant discharge decrease, and a low flow stage with steady discharge. We experimented with different peak discharge values, durations, and transition periods to clarify the dynamics involved with alternate bars. Results indicate that peak discharge duration is crucial for alternate bar development, especially when the transition period is short. Prolonged peak discharge durations result in different trends of alternate bar development at lower and higher discharges. However, the importance of peak discharge duration diminishes with longer transitional discharge periods.

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