Numerical study of impact pressure and force of cascading dam-break floods on the downstream dam

Cascading dam-break floods are among the most catastrophic natural disasters, causing significant casualties worldwide. Currently, research on cascading dam-break scenarios primarily focuses on the gradual dam-breaching and flood evolution processes. However, the research on the impact of cascading dam-break flood on downstream dam surface is rarely reported. Therefore, this study addresses this gap by establishing a shallow water hydrodynamic model based on the finite volume method. We conduct a numerical investigation into the effects of various parameters, including dam spacing, channel bed slope, initial water depths in upstream, middle and downstream reservoirs, and different cascading dam-break processes (two-stage and three-stage), on the impact on the downstream dam surface. The following conclusion can be drawn: factors such as dam spacing, bed slope and water depth have a significant impact on the impact pressure and force of downstream dam surface. All other conditions remain unchanged, the larger the dam spacing, the higher the peak and average values of downstream impact pressure, and the later the arrival time of dam-break floods on the downstream dam. The greater the bed slope, the higher the impact pressure, and the earlier the arrival time of the dam-break floods. The deeper the upstream or middle water depth, the greater the peak value and occurrence time of the impact pressure. The smaller the downstream water depth, the lower the impact pressure. The impact time of the three-stage dam-break floods is slightly later than that of the two-stage dam-break floods, but its peak and average impact pressure are higher. This study offers valuable scientific guidance and technical support for disaster prevention and mitigation strategies concerning cascading dam-break floods.