Flood hydrograph coincidence analysis of the upper Yangtze River and Dongting Lake, China

In hydrological research, flood events can be analyzed by hydrograph coincidence. The duration of the is a key variable to calculate coincidence risk probability and determining whether occurs, while actual neglected in most existing related research. This paper creatively proposes novel method analyze establishing five-dimensional joint distribution volumes, durations interval time for two hydrologic stations. More specifically, taking annual maximum upper Yangtze River input from Dongting Lake as an example, Pearson Type III mixed von Mises distributions were used establish marginal time. Subsequently, based on vine copula was established probability. results verified comparison with historical sequence, which show that during 1951–2002, probabilities corresponding its event volumes 2.00 × 1011 m3, 4.00 6.00 m3 are 0.213, 0.123, 0.049, respectively. It has provided theoretical support control safety management middle lower River. study also demonstrates significant beneficial role regulation Three Gorges Water Conservancy Project mitigating volume decreased 0.141.