Author(s): Wenjun Liu; Bo Wang; Yakun Guo

Linked Author(s): Wenjun Liu, Bo Wang, Yakun Guo

Keywords: Dam-break; Compound channel; Flood evolution; Water level; Discharge distribution

Abstract: Understanding the propagation of flood in the channel is important for risk management and emergency actions in practical work. However, there are still few studies on the characteristics of flood propagation in the compound channel. This study uses the computational fluid dynamics software package FLOW-3D to analyze the propagation of dam-break flood under different flow conditions. The ratio Dr of the initial floodplain water depth hf to the main channel water depth hm ranges from 0 to 0.5 in this study. It is found that: (1) when there is no water in the downstream, the average wavefront speed of the flow in the main channel is significantly higher than that in the floodplain, roughly showing a relationship of about twice. The average wavefront speed of the main channel and the floodplain first decreases and then tends to be stable with different water depth ratios; (2) the position where the wave height reaches the maximum in the main channel and the floodplain is near the dam site, and the maximum wave height value decreases with the increase of the evolution distance. The maximum dimensionless wave height value in the main channel is about 0.38 and occurs in the dry bed condition; while it is about 0.29 in the floodplain and occurs when hm = 0.05m, hf = 0m, and the it is roughly 0.29 after dimensionless; (3) in the case of dry bed, the discharge proportion of the floodplain shows the characteristics of rising first and then gradually decreasing, and the maximum discharge proportion of the floodplain is between 21% and 31% at different section locations. When the water depth ratio Dr = 0.09 – 0.50, the maximum discharge proportion of the floodplain is basically maintained at around 82%. The current research results have improved our understanding of the evolution of dam-break flood in the compound channel and provide a reference for similar events that may occur in the real life.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022797

Year: 2022