基于三维Copula函数的组合洪水研究

Combined Flood Research Based on Three-Dimensional Copula Function

摘要: 当某一条河流有多条支流汇入时，干流洪水与支流洪水的遭遇是威胁下游防洪控制点安全的主要因素，干支流洪水遭遇风险估计对于下游防洪安全具有重要意义。基于Copula函数易于将多个边缘分布构造成联合分布的优点，将其与频率组合法相结合，推导出了n维组合洪水分布函数表达式，并建立了相应的洪水遭遇风险估计模型。以雅砻江、鲜水河和庆大河洪水遭遇为例，采用双参数三维Copula函数对下游的洪水遭遇风险进行了估计，得到了下游组合洪水分布函数及防洪风险率。结果表明，该模型可以在一定程度上量化分析干支流洪水遭遇的随机性，为下游的防洪安全提供了一定的参考。

Abstract: When a river has multiple tributaries, the occurrence of mainstream floods and tributary floods is the main factor threatening the safety of downstream flood control points. The risk assessment of floods encountering is important for downstream flood control safety. Based on the Copula function which is easy to construct multiple edge distributions into multi-dimensional joint distribution, combining with the frequency composition method, the expression of n-dimensional combined flood distribution function is derived and the corresponding flood encounter risk estimation model is established. Taking the floods encountering of the Yalong River, the Xianshui River, and the Qingda River as an example, and using the two-parameter three-dimensional Copula function to estimate the downstream flood risk, the downstream combined flood distribution function and flood control risk rate were calculated. The results show that the model can quantitatively analyze the randomness of floods encountering and provide a certain reference for downstream flood control.