采用超定量取样方法,从洪水发生时间和量级两个方面考虑,建立了基于Copula函数的洪水发生时间和量级的两变量联合分布,提出了一种新的分期设计洪水计算方法,并与现有的方法进行比较.应用实例结果表明:所推求的分期设计洪水既能符合防洪标准要求,又能够满足分期设计洪水与年设计洪水的关系;主汛期的设计值相对年最大设计值有小幅度增加,而非主汛期设计值则小于年最大设计值;比现有的分期设计洪水计算方法更加合理可行,为分期设计洪水分析计算提供了一条新的途径. Taking the time and magnitude of flood occurrence as an example, this paper established a new joint flood and storm flood forecasting method based on Copula function, The results show that the proposed design flood can meet the requirements of flood control standards and the relationship between staged design flooding and annual design flood. The design value of the main flood season is smaller than the annual maximum design value But the non-main flood season design value is less than the annual maximum design value. It is more reasonable and feasible than the existing staged design flood calculation method, which provides a new way for staged design flood analysis and calculation.