关键词: 洪水复盘，分布式水文模型，暴雨时空统计分析，“23·7”特大洪水，北三河流域，海河流域

Abstract: The flood control of Beisan River basin，a sub-basin in Haihe River Basin，which covers three administrative areas of Beijing，Tianjin and Hebei，strongly affects social and economic development of North China.In order to effectively address the new challenges of flood prevention against extreme rainstorms under the climate change impacts，a new retrospective approach of flood is proposed in this paper.Taking the "23·7" large flood of the Beisan River basin as an example，we simulate and analyze the flood process with the distributed spatiotemporally-mixed runoff model and combined with spatiotemporal statistical analysis.The results shows that the Nash coefficients of the simulated result is over 0.7，and the relative errors of the flood peaks are lower than 5%，which demonstrates that the proposed approach possesses higher applicability in flood simulation and has good performance in describing runoff generation mechanism.The Beiyun River basin is dominated by saturation excess runoff mechanism.And the Chaobai River basin shows both saturation excess runoff mechanism and mixed runoff mechanism，especially at the place of the mountainous-plain transition area near the rainfall concentration area，it shows obvious mixed runoff mechanism.It is suggested that the flood prevention system of the basin should be improved in the future，focusing on improvement of rainwater monitoring capacity.The retrospective analysis approach presented in this paper can provide a technical reference for other regional flood simulation in China.

Key words: retrospective analysis on flood； distributed hydrological model； floods temporal and spatial statistical analysis； “23·7” catastrophic flood； Beisan River Basin； Haihe River Basin