The Dadu river basin in China. Cascade reservoir systems serve as the strategic backbone of basin security. However, the inherent complexity of these systems introduces complex risk transmission mechanisms. A failure in an upstream reservoir readily precipitates compounding failures downstream, resulting in catastrophic damage. Nevertheless, the mechanisms of risk transmission between cascade reservoirs and the quantification of these effects remain poorly understood. In this study, a hydrodynamic model for cascading failure flood routing was developed, explicitly considering the transmission of dam-break floods and interval discharge among multiple reservoirs. The development of dam-breach characteristic parameters and the variation of breach discharge were incorporated to obtain spatiotemporal hydraulic parameters. Furthermore, the risk transmission mechanism was revealed from a risk energy perspective, interpreting dam breaks as forms of energy release, absorption, and accumulation. The risk transmission effects were then quantified by calculating the dynamic variations of the risk transmission coefficient γ. Cascade risk transmission is revealed to follow a dynamic evolution trajectory involving blocking, attenuation, and superposition mechanisms, rather than a mere static transfer. The controlling reservoir acts as a pivotal hub between risk mitigation and aggravation: while an intact intermediate reservoir attenuated peak discharge by 12.9% (from 47,293.6 to 41,168.9 m³/s), its subsequent failure amplified the peak to 79,250.2 m³ /s, demonstrating a massive increase in disaster intensity. This phase transition is explicitly quantified by the dynamic trajectory of γ, which decreased from 0 to −0.12 (attenuation phase) before surging to 0.36 (superposition phase) during successive failures. These findings confirm that cascading failures are driven by energy accumulation and transformation, providing a critical quantitative basis for downstream risk assessment and the optimization of basin-wide security strategies. • A hydrodynamic model incorporates dynamic breaching and spatiotemporal continuity. • Dynamic risk transmission effects are quantified based on an energy perspective. • Cascade break risk transmission evolves via blocking, attenuation, superposition. • Intact controlling dams greatly attenuate flood risk, but cascade breaks magnify it.
Sun et al. (Wed,) studied this question.