中文摘要：

将洪水过程遭遇概化为洪水量级和发生时间间隔的数学约束条件，基于多维联合分布建模的思想，采用混合vonMises分布描述长江和清江洪水发生的间隔时间，基于Copula函数构建了两江年最大15天洪量与其间隔时间的联合分布，建立了两江洪水过程遭遇的风险计算模型，得出两江洪水发生时间遭遇的风险率为21．9％，分析了两江不同频率洪水遭遇组合的风险特征，为清江和长江水库联合补偿调度提供科学依据。

英文摘要：

Coincidence of flood hydrograph can be generalized as mathematical constraints of date interval and magnitude for flood occurrence. A multivariate hydrological analysis model was developed to estimate the flood coincidence risk between the Yangtze and the Qing River. In this model, the mixed von Mises distribution was introduced to describe the interval, and a Copula function was adopted to establish a trivariate distribution of the 15-days flood volume and its interval for each river. By this model, a coincidence risk of 21.9% was evaluated, the risk characteristics for different combinations of flood frequencies of the two rivers were analyzed. The results would provide a technical support to the united compensational operation of reservoirs on the Yangtze and the Qing River.