Abstract：
In order to evaluate the impact of the Longyangxia Reservoir construction on the relationship between runoff and sediment load (RRSL) in the upper reaches of the Yellow River, the runoff and sediment load monitoring data are used to identify variation point by sliding correlation coefficient method. Then with Copula function, the various countering situations of runoff and sediment load before and after variation are proposed to innovatively reveal their changing relations. The results demonstrate that (1) the reservoir construction exerts a great impact on the RRSL in the upper reaches of the Yellow River with the occurring variation point in 1987. The correlation of runoff and sediment load is presented better before variation but tends to worse decrease after variation. (2) Either before or after variation, runoff follows the generalized extreme value distribution, while sediment load before variation obeys the normal distribution, but the lognormal distribution after variation. Meanwhile, Frank Copula function accurately simulates the RRSL before variation, whereas Clayton Copula function is selected after variation. (3) The probability of synchronous rich and poor runoff and sediment load is higher before variation. After variation, the RRSL decreases significantly; their synchronous probability decreases by 45.67%. Meanwhile, the asynchronous probability of their extreme events evidently increases. The joint recurrence and co-recurrence intervals before variation are smaller than those after variation, along with the decreasing of their volume peak. This study provides new knowledge of runoff and sediment load influenced by reservoir construction, and also offers guidance for flood control and sediment load-discharge schemes of reservoir.
摘要：
为了评估龙羊峡水库建设对黄河上游径流与泥沙负荷关系（RRSL）的影响，利用径流和泥沙负荷监测数据，通过滑动相关系数法识别变化点。然后用Copula函数，提出了径流和泥沙负荷变化前后的各种对抗情况，以创新性地揭示它们的变化关系。结果表明：（1）水库建设对黄河上游RRSL的影响很大，发生点在1987年。径流和泥沙负荷的相关性在变化前表现得更好，但在变化后趋于下降。（2）在变化之前或之后，径流遵循广义极值分布，而变化前的泥沙负荷服从正态分布，而是变化后的对数正态分布。同时,FrankCopula函数准确地模拟了变化前的RRSL，而ClaytonCopula函数是在变异后选择的。(3)径流和输沙负荷在变化前同步富贫的概率较高。变异后,RRSL显著降低；它们的同步概率降低了45.67%。同时,他们极端事件的异步概率明显增加。变异前的关节复发和共同复发间隔小于变异后的关节复发和共同复发间隔，随着它们的体积峰值的减小。这项研究为水库建设影响的径流和泥沙负荷提供了新的知识，并为水库的防洪和排沙方案提供指导。
