Traditional methods for assessing levee projects focus solely on single‐year economic data, evaluating only the reduction in flood‐related economic losses while neglecting the benefits of saving lives and the dynamic changes in the economy and population over the project's design life. This study introduces a dynamic evaluation method for flood control and waterlogging drainage benefits of levee projects, incorporating economic and demographic changes. The total benefits are categorized into economic and life‐saving components. Separate hydrodynamic models for flood routing in river channels and rainfall‐waterlogging models in the basin are established. Through comparative analysis (with and without projects), the number of lives saved and the economic benefits generated by flood control and waterlogging drainage can be estimated. The Value of Statistical Life (VSL) is used to monetize life benefits, and calculation methods for flood control and waterlogging drainage benefits that considers both economic and life benefits are proposed. Then, a dynamic model incorporating regional GDP growth rates and population change coefficients is constructed, which can quantify the above‐mentioned benefits over the project's lifespan. A case study demonstrates that annual benefits increase from CNY 10.6 million in the base year to CNY 34.4 million by the end of the design life, with flood control benefits accounting for 59.1% and drainage benefits for 40.9%. It provides a comprehensive tool to assess long‐term project value, supporting investment decisions and improving benefit assessment systems for disaster risk reduction in levee projects.

Traditional methods for calculating embankment flood control benefits (FCBs) fail to fully consider multiple benefit categories and require repeated flood simulations and loss estimations. This study defines embankment FCB as encompassing economic, life, health, and environmental benefits, which arise from the embankment's mitigation of flood-induced economic losses, loss of life, health impacts, and environmental damage. By introducing the value of a statistical life (VSL), a monetary quantification method of loss of life is proposed. By analyzing the ratio of injuries to deaths and the ratio of value of statistical injury to VSL, a monetary quantification method for health impacts is proposed. Combined with the environmental loss rate and the monetary value of the environment, the monetary value of environmental impacts is calculated. Based on the monetized value of comprehensive flood losses, this study proposes a simplified frequency method that only requires flood simulations and loss calculations under no-project conditions. A case study is conducted to verify the method, and the results indicate that economic benefits hold an absolute advantage in the total FCB, but the life, health, and environmental benefits should never be overlooked. The method has broad application prospects in comprehensive benefit evaluation and benefit–cost analysis of embankments.

Probabilistic analysis of overtopping is an important aspect of dam construction, and the uncertainty in the construction progress complicates the calculation of overtopping probabilities. Construction progress is significantly influenced by human factors, making it difficult to assign an accurate probability distribution. Although the interval non-probabilistic reliability (INPR) method can estimate the likelihood of events with unknown probability distributions, its calculation results for the overtopping probability have significant errors. To improve the rationality of the results, we developed a method that adopted flood frequency of the upstream flood level to correct the traditional INPR calculations, developing an improved model. Taking the Qianping Reservoir as an example, the overtopping probabilities for three construction schedules were calculated, and the results were compared with a flood routing calculation. The results indicated that the improved approach significantly improves the rationality of the calculations, and the results effectively reflected the impact of construction progress uncertainty on overtopping probabilities.

Ecological water supply has been integrated into the water supply scope of numerous water diversion projects, yet ecosystem complexity makes ecological benefit assessment difficult. Traditional quantitative methods for water supply benefits mainly focus on economic benefits from productive and domestic water use, ignoring the ecological benefits and real-time benefit changes over the project service period. This study categorizes ecological water supply separately in benefit calculation and considers enhanced ecosystem service value brought by ecological water replenishment. Based on emergy analysis, the water resource values of domestic, productive, and ecological water supply are calculated individually, and a water supply benefits evaluation model is established in combination with corresponding water supply volumes. A dynamic evaluation method for the project service period is further proposed using a Grey Model (1,1). Verified via the Yangtze-to-Huaihe Water Diversion Project (Henan section), results indicate that from 2021 to 2070, comprehensive water supply benefits increase yearly from 5.19 billion yuan to 16.18 billion yuan. Productive water supply provides the largest benefits (67–74%), followed by urban domestic (19–25%), rural domestic (5–7%), and ecological water supply (1–2%). This study constructs a comprehensive, systematic, and dynamic evaluation system, supporting the holistic assessment of the long-term economic and environmental impacts of water diversion projects.