基于Copula函数的黄河上中下游水沙丰枯遭遇对比分析OA

To reveal the complex synergistic variation patterns of runoff and sediment in the Yellow River,a joint distribution model for runoff and sediment was constructed using two-and three-dimensional Copula functions based on runoff and sediment load data from three hydrologi-cal stations located in the upper-middle-lower reaches of the Yellow River Basin from 2002 to 2022.The encounter probabilities of abundant and deficient conditions for runoff and sediment transport load in the basin were calculated.The results indicate that:The runoff and sediment load at each hydrological station show a significant correlation at the significance level of P<0.01,with the strongest correlation observed at the Lijin hydrological station in the lower reach(Pearson and Kendall rank correlation coefficients were 0.958 and 0.823,respectively).The Gumbel and Gaussian Copula functions are found to be the most suitable for describing the two-dimensional joint distribution of runoff and sediment transport load within each hydrological station and the three-dimensional joint distribution of runoff or sediment transport load across different hydrological stations,respectively.At the hydrological station scale,the synchronous probabilities of runoff and sediment transport load are relatively high,with the maximum synchronous probability(77.35％)recorded at the Lijin hydrological station in the lower reach,following the order of simultaneous abundance>simultaneous normal>simultaneous deficiency.Among asynchronous encounters,the combi-nation of"one normal and one deficient"exhibits the highest probability.At the basin spatial scale,the asynchronous probabilities of abun-dant or deficient conditions for runoff or sediment transport load across different hydrological stations are significantly higher than the synchro-nous probabilities(asynchronous probabilities:70.80％for runoff,66.54％for sediment transport load).Among synchronous encounters,simultaneous abundance has the highest probability.In the Yellow River Basin,the encounter of abundant and deficient conditions for runoff and sediment transport load is primarily synchronous within individual hydrological stations but predominantly asynchronous across spatial scales.The strongest synchrony occurs in the lower reach,while the most significant asynchrony is observed in the middle reach.