一种新的洪水过程随机模拟方法研究

洪水随机模拟是防洪安全设计的新途径。利用Gumbel-Hougaard Copula构造边缘分布为PⅢ型分布的两变量联合分布,用以描述洪峰和洪量。根据该联合分布进行随机抽样同时模拟洪峰和洪量系列并转化成洪水过程线,从而建立一种新的洪水过程随机模拟方法。该方法用峰量联合分布代替单独的洪峰和洪量的分布,能够考虑洪峰和洪量之间的相关性,克服了分离处理峰、量的缺点。与现有的洪水随机模拟模型相比,如季节性一阶自回归模型和典型解集模型,文中提出的模型所模拟的洪峰和洪量统计特征的相对平均偏差和相对均方误差等指标均较优,能够更好地保持实测系列洪峰和洪量的统计特征。

A New Random Simulation Method for Constructing Synthetic Flood Hydrographs

The random simulation of flood hydrographs is a new way for hydrological safety design. The Gumbel Hougaard Copula was employed to construct a bivariate joint probability distribution for describing flood peak and flood volume, whose marginal distributions are both the Pearson type III. From the derived joint probability distribution of flood peak and flood volume, the flood peak series sample and the flood volume series sample were randomly drawn simultaneously and used to construct the synthetic flood hydrographs. The joint probability distribution of flood peak and flood volume could reflect the correlation between flood peak and flood volume much better than the two separate one-variable probability distributions, one only for flood peak and the other only for flood volume. Compared with other models used for flood random simulation, such as the seasonal first-order autoregressive model and the disaggregation model, the method proposed here performed much better, in terms of the bias and the root mean square error.