Multi-dimensional evaluation and implications of flood control dispatching effectiveness for typhoon “Co-may”

To reveal the performance characteristics of flood control operations and the mechanism of risk redistribution in the Taihu Lake Basin under compound typhoon hazards, this study employed multi-source observations and a hydrologic–hydrodynamic model. By comparing three typical typhoons—“Co-may” (2025), “In-Fa” (2021), and “Haikui” (2012)—a multi-dimensional evaluation framework encompassing flood safety, operational response, system recovery, and comprehensive resilience was constructed. This framework quantitatively assessed the effectiveness of the full-process refined scheduling strategy: “pre-discharge, detention, peak-shifting, and intensive drainage.” Key findings include: (1) Typhoon “Co-may” impacted the basin for six consecutive days, producing the highest basin-averaged 1-hour rainfall intensity (10.0 mm) since 1990. The rainstorm center was biased northward, with the maximum 3-day rainfall in the Wucheng-Xiyu area ranking fifth since 1951. (2) Refined scheduling significantly enhanced basin-wide resilience. By initiating pre-discharge 1-3 days in advance and optimizing outflow allocation—67% via northern outlets (2,553 m³/s), 25% via southern outlets (967 m³/s), and 8% via eastern outlets (282 m³/s)—the peak water level of Taihu Lake exceeded the warning threshold by only 0.10 m. Recession durations were shortened to 3 days for the lake and 4–5 days for the northern river network, outperforming historical responses. (3) However, vulnerabilities in multi-scale coordination were exposed. A single-day water level surge of 1.17 m at the Linqiao station on the Wangyu River revealed a “flood routing” effect caused by the superposition of basin-scale flood conveyance, localized forced drainage, and downstream storm surge, leading to risk redistribution toward critical local nodes. The study demonstrates that, supported by extended forecast lead times and improved accuracy, refined operations can substantially enhance flood resilience. Nevertheless, challenges persist regarding forecast reliability and the amplification of local node vulnerability. These findings provide a scientific basis for advancing an adaptive, closed-loop “forecast-operation-feedback” system in the Taihu Basin to balance holistic flood security with localized risk control.