Based on six flood indexes

presenting time domain and dynamic characteristic

a concept of the flood energy level is proposed in this paper. The fuzzy kmeans cluster model with simulation annealing algorithm is used to calculate the flood energy level. The value of flood energy level is obtaind from the most superior objective function. The Beijiang catchment is taken as a case study. The results show that the hydraulic engineering can improve the basin defense performance

which has transferred from an open to a defense basin

with reducing possibility of the flood energy level diameter jumps. The reasonable human activities can weaken the branch flood energy level and alleviate the flood prevention pressure. The concept of flood energy level and its computation model have provided new methods for flood classification

frequency computation and flood disaster appraisal and can be applied in other domains.