Flood overtopping failure of the no-overtopped rockfill cofferdam,which has bad influence on the safety of the water resources and hydropower project and downstream,is characterized by randomness and fuzziness based on fuzzy probabilistic theory.A mathematical model for random fuzzy risk analysis of construction diversion system was established.Observed flood sequence was applied to determine annual maximum water level sequence before cofferdam.The maximum entropy principle and variational method were introduced to deduce the probability distribution of maximum upstream water level.Finally,the method was applied in a navigation and hydropower Junction project.The result showed that the model is effective,the maximum entropy distribution fits well with water level sample data,not only the analytic expression of water retaining risk can be given, but also the rational evaluation of flood overtopping failure risk can be acquired,providing more valuable information for the decision-making of construction diversion standard and safety evaluation of diversion system.
