Application of conditional probability model in frequency calculation of inconsistent hydrologic series

LI Lingjie;KANG Yan;SONG Songbai;DENG Ruiqiang;JIN Yirong;College of Water Resources and Architectural Engineering,Northwest A&F University;Nanjing Hydraulic Research Institute;

conditional probability model;;inconsistent;;hydrologic series;;frequency analysis;;jump variation

【Objective】This study investigated the application of conditional probability model in frequency analysis of inconsistent hydrologic series to provide basis for hydrologic frequency analysis in a changing environment.【Method】The method based on conditional probability model was applied to analyze annual average discharge series with jump variation at three gauge stations of Linjiacun,Zhangjiashan and Zhuangtou in Wei River basin.Four hydrological frequency distribution curves including two-parameter lognormal distribution,three-parameter lognormal distribution,Gumbel distribution and P-Ⅲ distribution were selected and their parameters were estimated by simulated annealing-particle swarm algorithm.Indicators such as the efficiency coefficient R2 were adopted to evaluate the fitness of models and studentized residuals were analyzed for optimal model rationality.【Result】The efficiency coefficients of series at three gauge stations between theoretical and empirical frequencies all exceeded 0.96,and the studentized residuals of optimal model obeyed the normal distribution.The results based on conditional probability model were reasonable and reliable.【Conclusion】With definitely physical significance,rigorous theory and better imitative effect,conditional probability model provides an effective way for frequency analysis of inconsistent hydrologic series.