The objective of this study is to achieve the dynamic optimization of the flood limited water level (FLWL) in parallel reservoirs, using Luhun Reservoir and Guxian Reservoir as case studies. The innovation lies in establishing a dynamic control optimization model for the FLWL of parallel reservoirs, considering the uncertainty in the forecasting period of the flood forecast due to the varying locations of the rainstorm center from upstream to downstream. To commence, the Fisher optimal segmentation method is employed for flood season staging to determine the staged FLWL of each reservoir. Subsequently, considering the uncertainty in the foresight period, the upper range of the dynamic FLWL is determined through the improved pre-discharge capacity constraint method and Monte Carlo simulation. Finally, a multi-objective optimization model is established to determine the optimal dynamic FLWL control operation scheme for parallel reservoirs, utilizing the Non-Dominated Sorting Genetic Algorithm II (NSGA-II). This model takes into account both downstream flood control requirements and the water supply benefits of the parallel reservoirs. Through the optimization of the scheme, the water supply of the parallel reservoirs can be augmented by 15,347.6 m³ during the flood season. This optimization effectively achieves a harmonious balance between flood control and water supply, holding significant implications for mitigating drought risks amid changing conditions.

In recent years, the increasing frequency of extreme rainfall has exacerbated urban waterlogging, which has seriously constrained the sustainable development of cities. Given the problem that the impact of social information on waterlogging risk is easy to ignore in the urban risk waterlogging assessment process, it is of great significance to carry out a comprehensive waterlogging risk assessment and identify the waterlogging risk for urban waterlogging prevention and control. Based on the hazard–vulnerability assessment framework, this study comprehensively considers the flood disaster hazard and socio-economic vulnerability to carry out a multi-scenario urban waterlogging risk assessment in the central urban area of Zhoukou. The results show that, in comprehensive risk assessment, the area proportions are expressed as medium risk > low risk > higher risk > high risk. For a single waterlogging hazard assessment, the area proportions are shown as low risk > medium risk > higher risk > high risk. The difference ranges in area proportions of low, medium, higher, and high risk are (−61.00%, −54.00%), (49.00%, 56.00%), (1.30%, 2.70%), and (1.80%, 4.00%), respectively. It can be seen that compared with the single waterlogging hazard assessment, in the comprehensive waterlogging risk assessment with the introduction of the vulnerability factor, the waterlogging risk in the area with highly waterlogging vulnerability increases correspondingly, while the waterlogging risk in the area with low waterlogging vulnerability decreases relatively, and the waterlogging risk assessment results are more in line with the actual situation.