The Probability Density Evolution Method for Flood Frequency Analysis: A Case Study of the Nen River in China

摘要

A new approach for flood frequency analysis based on the probability density evolution method (PDEM) is proposed. It can avoid the problem of linear limitation for flood frequency analysis in a parametric method and avoid the complex process for choosing the kernel function and window width in the nonparametric method. Based on the annual maximum peak discharge (AMPD) in 54 years from the Dalai hydrologic station which is located on the downstream of Nen River in Heilongjiang Province of China, a joint probability density function (PDF) model about AMPD is built by the PDEM. Then, the numerical simulation results of the joint PDF model are given by adopting the one-sided difference scheme which has the property of direction self-adaptive. After that, according to the relationship between the marginal function and joint PDF, the PDF of AMPD can be obtained. Finally, the PDF is integrated and the frequency curve could be achieved. The results indicate that the flood frequency curve obtained by the PDEM has a better agreement with the empirical frequency than that of the parametric method widely used at present. The method based on PDEM is an effective way for hydrologic frequency analysis.